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Author SHA1 Message Date
Ahmet Eray Karadag
7eff54dfd2 ocfs2: convert remaining read-only checks to ocfs2_emergency_state 
Now that the centralized `ocfs2_emergency_state()` helper is available,
refactor remaining filesystem-wide checks for `ocfs2_is_soft_readonly` and
`ocfs2_is_hard_readonly` to use this new function.

To ensure strict consistency with the previous behavior and guarantee no
functional changes, the call sites continue to explicitly return -EROFS
when the emergency state is detected.  This standardizes the check logic
while preserving the existing error handling flow.

Link: https://lkml.kernel.org/r/3421641b54ad6b6e4ffca052351b518eacc1bd08.1764728893.git.eraykrdg1@gmail.com
Co-developed-by: Albin Babu Varghese <albinbabuvarghese20@gmail.com>
Signed-off-by: Albin Babu Varghese <albinbabuvarghese20@gmail.com>
Signed-off-by: Ahmet Eray Karadag <eraykrdg1@gmail.com>
Reviewed-by: Heming Zhao <heming.zhao@suse.com>
Reviewed-by: Joseph Qi <joseph.qi@linux.alibaba.com>
Cc: Changwei Ge <gechangwei@live.cn>
Cc: David Hunter <david.hunter.linux@gmail.com>
Cc: Joel Becker <jlbec@evilplan.org>
Cc: Jun Piao <piaojun@huawei.com>
Cc: Junxiao Bi <junxiao.bi@oracle.com>
Cc: Mark Fasheh <mark@fasheh.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
 2025-12-10 16:07:43 -08:00
Ahmet Eray Karadag
752ba0976b ocfs2: add ocfs2_emergency_state helper and apply to setattr 
Patch series "ocfs2: Refactor read-only checks to use
ocfs2_emergency_state", v4.

Following the fix for the `make_bad_inode` validation failure (syzbot ID:
b93b65ee321c97861072), this separate series introduces a new helper
function, `ocfs2_emergency_state()`, to improve and centralize read-only
and error state checking.

This is modeled after the `ext4_emergency_state()` pattern, providing a
single, unified location for checking all filesystem-level emergency
conditions.  This makes the code cleaner and ensures that any future
checks (e.g., for fatal error states) can be added in one place.

This series is structured as follows:

1.  The first patch introduces the `ocfs2_emergency_state()` helper
    (currently checking for -EROFS) and applies it to `ocfs2_setattr`
    to provide a "fail-fast" mechanism, as suggested by Albin
    Babu Varghese.
2.  The second patch completes the refactoring by converting all
    remaining read-only checks throughout OCFS2 to use this new helper.


This patch (of 2):

To centralize error checking, follow the pattern of other filesystems like
ext4 (which uses `ext4_emergency_state()`), and prepare for future
enhancements, this patch introduces a new helper function:
`ocfs2_emergency_state()`.

The purpose of this helper is to provide a single, unified location for
checking all filesystem-level emergency conditions.  In this initial
implementation, the function only checks for the existing hard and soft
read-only modes, returning -EROFS if either is set.

This provides a foundation where future checks (e.g., for fatal error
states returning -EIO, or shutdown states) can be easily added in one
place.

This patch also adds this new check to the beginning of `ocfs2_setattr()`.
This ensures that operations like `ftruncate` (which triggered the
original BUG) fail-fast with -EROFS when the filesystem is already in a
read-only state.

Link: https://lkml.kernel.org/r/cover.1764728893.git.eraykrdg1@gmail.com
Link: https://lkml.kernel.org/r/e9e975bcaaff8dbc155b70fbc1b2798a2e36e96f.1764728893.git.eraykrdg1@gmail.com
Co-developed-by: Albin Babu Varghese <albinbabuvarghese20@gmail.com>
Signed-off-by: Albin Babu Varghese <albinbabuvarghese20@gmail.com>
Signed-off-by: Ahmet Eray Karadag <eraykrdg1@gmail.com>
Suggested-by: Heming Zhao <heming.zhao@suse.com>
Reviewed-by: Heming Zhao <heming.zhao@suse.com>
Reviewed-by: Joseph Qi <joseph.qi@linux.alibaba.com>
Cc: Mark Fasheh <mark@fasheh.com>
Cc: Joel Becker <jlbec@evilplan.org>
Cc: Junxiao Bi <junxiao.bi@oracle.com>
Cc: Changwei Ge <gechangwei@live.cn>
Cc: Jun Piao <piaojun@huawei.com>
Cc: David Hunter <david.hunter.linux@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
 2025-12-10 16:07:43 -08:00
Ally Heev
01da5216c5 checkpatch: add uninitialized pointer with __free attribute check 
Uinitialized pointers with __free attribute can cause undefined behavior
as the memory randomly assigned to the pointer is freed automatically when
the pointer goes out of scope.  add check in checkpatch to detect such
issues.

Link: https://lkml.kernel.org/r/20251203-aheev-checkpatch-uninitialized-free-v7-1-841e3b31d8f3@gmail.com
Signed-off-by: Ally Heev <allyheev@gmail.com>
Suggested-by: Dan Carpenter <dan.carpenter@linaro.org>
Link: https://lore.kernel.org/all/8a4c0b43-cf63-400d-b33d-d9c447b7e0b9@suswa.mountain/
Link: https://lore.kernel.org/all/58fd478f408a34b578ee8d949c5c4b4da4d4f41d.camel@HansenPartnership.com/
Acked-by: Dan Williams <dan.j.williams@intel.com>
Reviewed-by: Krzysztof Kozlowski <krzk@kernel.org>
Acked-by: Joe Perches <joe@perches.com>
Cc: Andy Whitcroft <apw@canonical.com>
Cc: David Hunter <david.hunter.linux@gmail.com>
Cc: Dwaipayan Ray <dwaipayanray1@gmail.com>
Cc: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: James Bottomley <james.bottomley@HansenPartnership.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Lukas Bulwahn <lukas.bulwahn@gmail.com>
Cc: Menon, Nishanth <nm@ti.com>
Cc: Stephen Boyd <sboyd@kernel.org>
Cc: Viresh Kumar <vireshk@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
 2025-12-10 16:07:42 -08:00
Andy Shevchenko
e6b4d264c8 args: fix documentation to reflect the correct numbers 
The macro uses up to 15 arguments.  Reflect this in the top level comment.

Link: https://lkml.kernel.org/r/20251201201018.765475-1-andriy.shevchenko@linux.intel.com
Fixes: d51e783c17 ("lsm: count the LSMs enabled at compile time")
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Reviewed-by: Randy Dunlap <rdunlap@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
 2025-12-10 16:07:42 -08:00
Prithvi Tambewagh
039bef30e3 ocfs2: fix kernel BUG in ocfs2_find_victim_chain 
syzbot reported a kernel BUG in ocfs2_find_victim_chain() because the
`cl_next_free_rec` field of the allocation chain list (next free slot in
the chain list) is 0, triggring the BUG_ON(!cl->cl_next_free_rec)
condition in ocfs2_find_victim_chain() and panicking the kernel.

To fix this, an if condition is introduced in ocfs2_claim_suballoc_bits(),
just before calling ocfs2_find_victim_chain(), the code block in it being
executed when either of the following conditions is true:

1. `cl_next_free_rec` is equal to 0, indicating that there are no free
chains in the allocation chain list
2. `cl_next_free_rec` is greater than `cl_count` (the total number of
chains in the allocation chain list)

Either of them being true is indicative of the fact that there are no
chains left for usage.

This is addressed using ocfs2_error(), which prints
the error log for debugging purposes, rather than panicking the kernel.

Link: https://lkml.kernel.org/r/20251201130711.143900-1-activprithvi@gmail.com
Signed-off-by: Prithvi Tambewagh <activprithvi@gmail.com>
Reported-by: syzbot+96d38c6e1655c1420a72@syzkaller.appspotmail.com
Closes: https://syzkaller.appspot.com/bug?extid=96d38c6e1655c1420a72
Tested-by: syzbot+96d38c6e1655c1420a72@syzkaller.appspotmail.com
Reviewed-by: Joseph Qi <joseph.qi@linux.alibaba.com>
Cc: Mark Fasheh <mark@fasheh.com>
Cc: Joel Becker <jlbec@evilplan.org>
Cc: Junxiao Bi <junxiao.bi@oracle.com>
Cc: Changwei Ge <gechangwei@live.cn>
Cc: Jun Piao <piaojun@huawei.com>
Cc: Heming Zhao <heming.zhao@suse.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
 2025-12-10 16:07:42 -08:00
Pasha Tatashin
bf2c7bf5c4 liveupdate: luo_core: fix redundant bound check in luo_ioctl() 
The kernel test robot reported a Smatch warning:
kernel/liveupdate/luo_core.c:402 luo_ioctl() warn: unsigned 'nr' is
never less than zero.

This occurs because 'nr' is unsigned and LIVEUPDATE_CMD_BASE is currently
defined as 0, making the check (nr < LIVEUPDATE_CMD_BASE) always false.

Remove the explicit lower bound check.  The logic remains correct because
'nr' is unsigned; if nr is less than LIVEUPDATE_CMD_BASE, the expression
(nr - LIVEUPDATE_CMD_BASE) will wrap around to a large positive value. 
This will inevitably be larger than ARRAY_SIZE(luo_ioctl_ops) and be
caught by the upper bound check.

Link: https://lkml.kernel.org/r/20251130010919.1488230-1-pasha.tatashin@soleen.com
Signed-off-by: Pasha Tatashin <pasha.tatashin@soleen.com>
Reported-by: kernel test robot <lkp@intel.com>
Closes: https://lore.kernel.org/oe-kbuild-all/202511280300.6pvBmXUS-lkp@intel.com/
Reviewed-by: Mike Rapoport (Microsoft) <rppt@kernel.org>
Cc: David Matlack <dmatlack@google.com>
Cc: Pratyush Yadav <pratyush@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
 2025-12-10 16:07:42 -08:00
Deepanshu Kartikey
2a4f33430e ocfs2: validate inline xattr size and entry count in ocfs2_xattr_ibody_list 
Add comprehensive validation of inline xattr metadata in
ocfs2_xattr_ibody_list() to prevent out-of-bounds access and
use-after-free bugs when processing corrupted inline xattrs.

The patch adds two critical validations:

1. Validates i_xattr_inline_size before use:
   - Ensures it does not exceed block size
   - Ensures it is at least large enough for xattr header
   - Prevents pointer arithmetic with corrupted size values that could
     point outside the inode block

2. Validates xattr entry count (xh_count):
   - Calculates maximum entries that can fit in the inline space
   - Rejects counts that exceed this limit
   - Prevents out-of-bounds array access in subsequent code

Without these checks, a corrupted filesystem with invalid inline xattr
metadata can cause the code to access memory beyond the allocated space.
For example:
- A corrupted i_xattr_inline_size of 0 would cause header pointer
  calculation to point past the end of the block
- A corrupted xh_count of 22 with inline_size of 256 would cause
  array access 7 entries beyond the 15 that actually fit (the syzbot
  reproducer used xh_count of 20041), leading to use-after-free when
  accessing freed memory pages

The validation uses the correct inline_size (from di->i_xattr_inline_size)
rather than block size, ensuring accurate bounds checking for inline
xattrs specifically.

Link: https://lkml.kernel.org/r/20251120041145.33176-1-kartikey406@gmail.com
Link: https://lore.kernel.org/all/20251111073831.2027072-1-kartikey406@gmail.com/ [v1]
Link: https://lore.kernel.org/all/20251117063217.5690-1-kartikey406@gmail.com/ [v2]
Link: https://lore.kernel.org/all/20251117114224.12948-1-kartikey406@gmail.com/ [v3]
Signed-off-by: Deepanshu Kartikey <kartikey406@gmail.com>
Reported-by: syzbot+ab0ad25088673470d2d9@syzkaller.appspotmail.com
Closes: https://syzkaller.appspot.com/bug?extid=ab0ad25088673470d2d9
Tested-by: syzbot+ab0ad25088673470d2d9@syzkaller.appspotmail.com
Suggested-by: Heming Zhao <heming.zhao@suse.com>
Reviewed-by: Heming Zhao <heming.zhao@suse.com>
Acked-by: Joseph Qi <joseph.qi@linux.alibaba.com>
Cc: Mark Fasheh <mark@fasheh.com>
Cc: Joel Becker <jlbec@evilplan.org>
Cc: Junxiao Bi <junxiao.bi@oracle.com>
Cc: Changwei Ge <gechangwei@live.cn>
Cc: Jun Piao <piaojun@huawei.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
 2025-12-10 16:07:42 -08:00
Lalit Shankar Chowdhury
acce46aaf8 fs/fat: remove unnecessary wrapper fat_max_cache() 
fat_max_cache() always returned FAT_MAX_CACHE and did not use the inode
parameter. So, use the FAT_MAX_CACHE constant directly.

Link: https://lkml.kernel.org/r/20251127175431.126516-1-lalitshankarch@gmail.com
Signed-off-by: Lalit Shankar Chowdhury <lalitshankarch@gmail.com>
Acked-by: OGAWA Hirofumi <hirofumi@mail.parknet.co.jp>
Cc: Christian Brauner <brauner@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
 2025-12-10 16:07:42 -08:00
Thorsten Blum
d86fea4294 ocfs2: replace deprecated strcpy with strscpy 
strcpy() has been deprecated [1] because it performs no bounds checking on
the destination buffer, which can lead to buffer overflows.  Replace it
with the safer strscpy().  No functional changes.

Link: https://www.kernel.org/doc/html/latest/process/deprecated.html#strcpy [1]
Link: https://lkml.kernel.org/r/20251126114419.92539-1-thorsten.blum@linux.dev
Signed-off-by: Thorsten Blum <thorsten.blum@linux.dev>
Reviewed-by: Joseph Qi <joseph.qi@linux.alibaba.com>
Cc: Mark Fasheh <mark@fasheh.com>
Cc: Joel Becker <jlbec@evilplan.org>
Cc: Junxiao Bi <junxiao.bi@oracle.com>
Cc: Changwei Ge <gechangwei@live.cn>
Cc: Jun Piao <piaojun@huawei.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
 2025-12-10 16:07:42 -08:00
Edward Adam Davis
4ac577ae74 ocfs2: check tl_used after reading it from trancate log inode 
The fuzz image has a truncate log inode whose tl_used is bigger than
tl_count so it triggers the BUG in ocfs2_truncate_log_needs_flush() [1].

As what the check in ocfs2_truncate_log_needs_flush() does, just do same
check into ocfs2_get_truncate_log_info() when truncate log inode is
reading in so we can bail out earlier.

[1]
(syz.0.17,5491,0):ocfs2_truncate_log_needs_flush:5830 ERROR: bug expression: le16_to_cpu(tl->tl_used) > le16_to_cpu(tl->tl_count)
kernel BUG at fs/ocfs2/alloc.c:5830!
RIP: 0010:ocfs2_truncate_log_needs_flush fs/ocfs2/alloc.c:5827 [inline]
Call Trace:
 ocfs2_commit_truncate+0xb64/0x21d0 fs/ocfs2/alloc.c:7372
 ocfs2_truncate_file+0xca2/0x1420 fs/ocfs2/file.c:509
 ocfs2_setattr+0x1520/0x1b40 fs/ocfs2/file.c:1212
 notify_change+0xc1a/0xf40 fs/attr.c:546
 do_truncate+0x1a4/0x220 fs/open.c:68

Link: https://lkml.kernel.org/r/tencent_B24B1C1BE225DCBA44BB6933AB9E1B1B0708@qq.com
Reported-by: syzbot+f82afc4d4e74d0ef7a89@syzkaller.appspotmail.com
Closes: https://syzkaller.appspot.com/bug?extid=f82afc4d4e74d0ef7a89
Tested-by: syzbot+f82afc4d4e74d0ef7a89@syzkaller.appspotmail.com
Signed-off-by: Edward Adam Davis <eadavis@qq.com>
Reviewed-by: Joseph Qi <joseph.qi@linux.alibaba.com>
Cc: Mark Fasheh <mark@fasheh.com>
Cc: Joel Becker <jlbec@evilplan.org>
Cc: Junxiao Bi <junxiao.bi@oracle.com>
Cc: Changwei Ge <gechangwei@live.cn>
Cc: Jun Piao <piaojun@huawei.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
 2025-12-10 16:07:41 -08:00
Dan Carpenter
b2135d1cb0 liveupdate: luo_file: don't use invalid list iterator 
If we exit a list_for_each_entry() without hitting a break then the list
iterator points to an offset from the list_head.  It's a non-NULL but
invalid pointer and dereferencing it isn't allowed.

Introduce a new "found" variable to test instead.

Link: https://lkml.kernel.org/r/aSlMc4SS09Re4_xn@stanley.mountain
Fixes: 3ee1d673194e ("liveupdate: luo_file: implement file systems callbacks")
Signed-off-by: Dan Carpenter <dan.carpenter@linaro.org>
Reported-by: kernel test robot <lkp@intel.com>
Closes: https://lore.kernel.org/r/202511280420.y9O4fyhX-lkp@intel.com/
Reviewed-by: Mike Rapoport (Microsoft) <rppt@kernel.org>
Reviewed-by: Pasha Tatashin <pasha.tatashin@soleen.com>
Cc: Pratyush Yadav <pratyush@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
 2025-12-10 16:07:41 -08:00
Andy Shevchenko
aa514a297a calibrate: update header inclusion 
While cleaning up some headers, I got a build error on this file:

init/calibrate.c:20:9: error: call to undeclared function 'kstrtoul'; ISO C99 and later do not support implicit function declarations [-Wimplicit-function-declaration]

Update header inclusions to follow IWYU (Include What You Use) principle.

Link: https://lkml.kernel.org/r/20251124230607.1445421-1-andriy.shevchenko@linux.intel.com
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
 2025-11-27 14:24:45 -08:00
Ilias Stamatis
6fb3acdebf Reinstate "resource: avoid unnecessary lookups in find_next_iomem_res()" 
Commit 97523a4edb ("kernel/resource: remove first_lvl / siblings_only
logic") removed an optimization introduced by commit 756398750e
("resource: avoid unnecessary lookups in find_next_iomem_res()").  That
was not called out in the message of the first commit explicitly so it's
not entirely clear whether removing the optimization happened
inadvertently or not.

As the original commit message of the optimization explains there is no
point considering the children of a subtree in find_next_iomem_res() if
the top level range does not match.

Reinstating the optimization results in performance improvements in
systems where /proc/iomem is ~5k lines long.  Calling mmap() on /dev/mem
in such platforms takes 700-1500μs without the optimisation and 10-50μs
with the optimisation.

Note that even though commit 97523a4edb removed the 'sibling_only'
parameter from next_resource(), newer kernels have basically reinstated it
under the name 'skip_children'.

Link: https://lore.kernel.org/all/20251124165349.3377826-1-ilstam@amazon.com/T/#u
Fixes: 97523a4edb ("kernel/resource: remove first_lvl / siblings_only logic")
Signed-off-by: Ilias Stamatis <ilstam@amazon.com>
Acked-by: David Hildenbrand (Red Hat) <david@kernel.org>
Cc: Andriy Shevchenko <andriy.shevchenko@linux.intel.com>
Cc: Baoquan He <bhe@redhat.com>
Cc: "Huang, Ying" <huang.ying.caritas@gmail.com>
Cc: Nadav Amit <nadav.amit@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
 2025-11-27 14:24:45 -08:00
Breno Leitao
3fa805c37d vmcoreinfo: track and log recoverable hardware errors 
Introduce a generic infrastructure for tracking recoverable hardware
errors (HW errors that are visible to the OS but does not cause a panic)
and record them for vmcore consumption.  This aids post-mortem crash
analysis tools by preserving a count and timestamp for the last occurrence
of such errors.  On the other side, correctable errors, which the OS
typically remains unaware of because the underlying hardware handles them
transparently, are less relevant for crash dump and therefore are NOT
tracked in this infrastructure.

Add centralized logging for sources of recoverable hardware errors based
on the subsystem it has been notified.

hwerror_data is write-only at kernel runtime, and it is meant to be read
from vmcore using tools like crash/drgn.  For example, this is how it
looks like when opening the crashdump from drgn.

	>>> prog['hwerror_data']
	(struct hwerror_info[1]){
		{
			.count = (int)844,
			.timestamp = (time64_t)1752852018,
		},
		...

This helps fleet operators quickly triage whether a crash may be
influenced by hardware recoverable errors (which executes a uncommon code
path in the kernel), especially when recoverable errors occurred shortly
before a panic, such as the bug fixed by commit ee62ce7a1d ("page_pool:
Track DMA-mapped pages and unmap them when destroying the pool")

This is not intended to replace full hardware diagnostics but provides a
fast way to correlate hardware events with kernel panics quickly.

Rare machine check exceptions—like those indicated by mce_flags.p5 or
mce_flags.winchip—are not accounted for in this method, as they fall
outside the intended usage scope for this feature's user base.

[leitao@debian.org: add hw-recoverable-errors to toctree]
  Link: https://lkml.kernel.org/r/20251127-vmcoreinfo_fix-v1-1-26f5b1c43da9@debian.org
Link: https://lkml.kernel.org/r/20251010-vmcore_hw_error-v5-1-636ede3efe44@debian.org
Signed-off-by: Breno Leitao <leitao@debian.org>
Suggested-by: Tony Luck <tony.luck@intel.com>
Suggested-by: Shuai Xue <xueshuai@linux.alibaba.com>
Reviewed-by: Shuai Xue <xueshuai@linux.alibaba.com>
Reviewed-by: Hanjun Guo <guohanjun@huawei.com>	[APEI]
Cc: Bjorn Helgaas <bhelgaas@google.com>
Cc: Bob Moore <robert.moore@intel.com>
Cc: Borislav Betkov <bp@alien8.de>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: James Morse <james.morse@arm.com>
Cc: Konrad Rzessutek Wilk <konrad.wilk@oracle.com>
Cc: Len Brown <lenb@kernel.org>
Cc: Mahesh Salgaonkar <mahesh@linux.ibm.com>
Cc: Mauro Carvalho Chehab <mchehab@kernel.org>
Cc: "Oliver O'Halloran" <oohall@gmail.com>
Cc: Omar Sandoval <osandov@osandov.com>
Cc: Thomas Gleinxer <tglx@linutronix.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
 2025-11-27 14:24:44 -08:00
Mike Rapoport (Microsoft)
7b71205ae1 kho: fix restoring of contiguous ranges of order-0 pages 
When contiguous ranges of order-0 pages are restored, kho_restore_page()
calls prep_compound_page() with the first page in the range and order as
parameters and then kho_restore_pages() calls split_page() to make sure
all pages in the range are order-0.

However, since split_page() is not intended to split compound pages and
with VM_DEBUG enabled it will trigger a VM_BUG_ON_PAGE().

Update kho_restore_page() so that it will use prep_compound_page() when it
restores a folio and make sure it properly sets page count for both large
folios and ranges of order-0 pages.

Link: https://lkml.kernel.org/r/20251125110917.843744-3-rppt@kernel.org
Fixes: a667300bd5 ("kho: add support for preserving vmalloc allocations")
Signed-off-by: Mike Rapoport (Microsoft) <rppt@kernel.org>
Reported-by: Pratyush Yadav <pratyush@kernel.org>
Cc: Alexander Graf <graf@amazon.com>
Cc: Pasha Tatashin <pasha.tatashin@soleen.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
 2025-11-27 14:24:44 -08:00
Mike Rapoport (Microsoft)
4bc84cd539 kho: kho_restore_vmalloc: fix initialization of pages array 
Patch series "kho: fixes for vmalloc restoration".

Pratyush reported off-list that when kho_restore_vmalloc() is used to
restore a vmalloc_huge() allocation it hits VM_BUG_ON() when we
reconstruct the struct pages in kho_restore_pages().

These patches fix the issue.


This patch (of 2):

In case a preserved vmalloc allocation was using huge pages, all pages in
the array of pages added to vm_struct during kho_restore_vmalloc() are
wrongly set to the same page.

Fix the indexing when assigning pages to that array.

Link: https://lkml.kernel.org/r/20251125110917.843744-1-rppt@kernel.org
Link: https://lkml.kernel.org/r/20251125110917.843744-2-rppt@kernel.org
Fixes: a667300bd5 ("kho: add support for preserving vmalloc allocations")
Signed-off-by: Mike Rapoport (Microsoft) <rppt@kernel.org>
Reviewed-by: Pratyush Yadav <pratyush@kernel.org>
Cc: Alexander Graf <graf@amazon.com>
Cc: Pasha Tatashin <pasha.tatashin@soleen.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
 2025-11-27 14:24:44 -08:00
Jarkko Sakkinen
c39eab75a5 MAINTAINERS: TPM DEVICE DRIVER: update the W-tag 
I migrated test suite to git.kernel.org so that all my kernel stuff is
consolidated to one single place:

https://git.kernel.org/pub/scm/linux/kernel/git/jarkko/linux-tpmdd-test.git/about/

Link: https://lkml.kernel.org/r/20251125160353.2300402-1-jarkko@kernel.org
Signed-off-by: Jarkko Sakkinen <jarkko@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
 2025-11-27 14:24:44 -08:00
Thorsten Blum
af06a40474 init: replace simple_strtoul with kstrtoul to improve lpj_setup 
Replace simple_strtoul() with the recommended kstrtoul() for parsing the
'lpj=' boot parameter.

Check the return value of kstrtoul() and reject invalid values.  This adds
error handling while preserving existing behavior for valid values, and
removes use of the deprecated simple_strtoul() helper.

Link: https://lkml.kernel.org/r/20251122114539.446937-2-thorsten.blum@linux.dev
Signed-off-by: Thorsten Blum <thorsten.blum@linux.dev>
Cc: Christian Brauner <brauner@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
 2025-11-27 14:24:43 -08:00
Ran Xiaokai
40cd0e8dd2 KHO: fix boot failure due to kmemleak access to non-PRESENT pages 
When booting with debug_pagealloc=on while having:
CONFIG_KEXEC_HANDOVER_ENABLE_DEFAULT=y
CONFIG_DEBUG_KMEMLEAK_DEFAULT_OFF=n
the system fails to boot due to page faults during kmemleak scanning.

This occurs because:
With debug_pagealloc is enabled, __free_pages() invokes
debug_pagealloc_unmap_pages(), clearing the _PAGE_PRESENT bit for freed
pages in the kernel page table.  KHO scratch areas are allocated from
memblock and noted by kmemleak.  But these areas don't remain reserved but
released later to the page allocator using init_cma_reserved_pageblock(). 
This causes subsequent kmemleak scans access non-PRESENT pages, leading to
fatal page faults.

Mark scratch areas with kmemleak_ignore_phys() after they are allocated
from memblock to exclude them from kmemleak scanning before they are
released to buddy allocator to fix this.

[ran.xiaokai@zte.com.cn: add comment]
  Link: https://lkml.kernel.org/r/20251127122700.103927-1-ranxiaokai627@163.com
Link: https://lkml.kernel.org/r/20251122182929.92634-1-ranxiaokai627@163.com
Signed-off-by: Ran Xiaokai <ran.xiaokai@zte.com.cn>
Reviewed-by: Mike Rapoport (Microsoft) <rppt@kernel.org>
Reviewed-by: Pratyush Yadav <pratyush@kernel.org>
Cc: Alexander Graf <graf@amazon.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Changyuan Lyu <changyuanl@google.com>
Cc: Pasha Tatashin <pasha.tatashin@soleen.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
 2025-11-27 14:24:43 -08:00
Sourabh Jain
fb5c364427 Documentation/ABI: new kexec and kdump sysfs interface 
Add an ABI document for following kexec and kdump sysfs interface:

- /sys/kernel/kexec/loaded
- /sys/kernel/kexec/crash_loaded
- /sys/kernel/kexec/crash_size
- /sys/kernel/kexec/crash_elfcorehdr_size
- /sys/kernel/kexec/crash_cma_ranges

Link: https://lkml.kernel.org/r/20251118114507.1769455-4-sourabhjain@linux.ibm.com
Signed-off-by: Sourabh Jain <sourabhjain@linux.ibm.com>
Acked-by: Baoquan He <bhe@redhat.com>
Cc: Aditya Gupta <adityag@linux.ibm.com>
Cc: Dave Young <dyoung@redhat.com>
Cc: Hari Bathini <hbathini@linux.ibm.com>
Cc: Jiri Bohac <jbohac@suse.cz>
Cc: Madhavan Srinivasan <maddy@linux.ibm.com>
Cc: Mahesh J Salgaonkar <mahesh@linux.ibm.com>
Cc: Pingfan Liu <piliu@redhat.com>
Cc: Ritesh Harjani (IBM) <ritesh.list@gmail.com>
Cc: Shivang Upadhyay <shivangu@linux.ibm.com>
Cc: Vivek Goyal <vgoyal@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
 2025-11-27 14:24:43 -08:00
Sourabh Jain
5c991b6d9b Documentation/ABI: mark old kexec sysfs deprecated 
The previous commit ("kexec: move sysfs entries to /sys/kernel/kexec")
moved all existing kexec sysfs entries to a new location. The ABI
document is updated to include a note about the deprecation of the old
kexec sysfs entries.

The following kexec sysfs entries are deprecated:
- /sys/kernel/kexec_loaded
- /sys/kernel/kexec_crash_loaded
- /sys/kernel/kexec_crash_size
- /sys/kernel/crash_elfcorehdr_size
- /sys/kernel/kexec_crash_cma_ranges

Link: https://lkml.kernel.org/r/20251118114507.1769455-3-sourabhjain@linux.ibm.com
Signed-off-by: Sourabh Jain <sourabhjain@linux.ibm.com>
Acked-by: Baoquan He <bhe@redhat.com>
Cc: Aditya Gupta <adityag@linux.ibm.com>
Cc: Dave Young <dyoung@redhat.com>
Cc: Hari Bathini <hbathini@linux.ibm.com>
Cc: Jiri Bohac <jbohac@suse.cz>
Cc: Madhavan Srinivasan <maddy@linux.ibm.com>
Cc: Mahesh J Salgaonkar <mahesh@linux.ibm.com>
Cc: Pingfan Liu <piliu@redhat.com>
Cc: Ritesh Harjani (IBM) <ritesh.list@gmail.com>
Cc: Shivang Upadhyay <shivangu@linux.ibm.com>
Cc: Vivek Goyal <vgoyal@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
 2025-11-27 14:24:43 -08:00
Sourabh Jain
cf4340bdd9 kexec: move sysfs entries to /sys/kernel/kexec 
Patch series "kexec: reorganize kexec and kdump sysfs", v6.

All existing kexec and kdump sysfs entries are moved to a new location,
/sys/kernel/kexec, to keep /sys/kernel/ clean and better organized.
Symlinks are created at the old locations for backward compatibility and
can be removed in the future [01/03].

While doing this cleanup, the old kexec and kdump sysfs entries are
marked as deprecated in the existing ABI documentation [02/03]. This
makes it clear that these older interfaces should no longer be used.
New ABI documentation is added to describe the reorganized interfaces
[03/03], so users and tools can rely on the updated sysfs interfaces
going forward.


This patch (of 3):

Several kexec and kdump sysfs entries are currently placed directly under
/sys/kernel/, which clutters the directory and makes it harder to identify
unrelated entries.  To improve organization and readability, these entries
are now moved under a dedicated directory, /sys/kernel/kexec.

The following sysfs moved under new kexec sysfs node
+------------------------------------+------------------+
|    Old sysfs name         |     New sysfs name        |
|  (under /sys/kernel)      | (under /sys/kernel/kexec) |
+---------------------------+---------------------------+
| kexec_loaded              | loaded                    |
+---------------------------+---------------------------+
| kexec_crash_loaded        | crash_loaded              |
+---------------------------+---------------------------+
| kexec_crash_size          | crash_size                |
+---------------------------+---------------------------+
| crash_elfcorehdr_size     | crash_elfcorehdr_size     |
+---------------------------+---------------------------+
| kexec_crash_cma_ranges    | crash_cma_ranges          |
+---------------------------+---------------------------+

For backward compatibility, symlinks are created at the old locations so
that existing tools and scripts continue to work.  These symlinks can be
removed in the future once users have switched to the new path.

While creating symlinks, entries are added in /sys/kernel/ that point to
their new locations under /sys/kernel/kexec/.  If an error occurs while
adding a symlink, it is logged but does not stop initialization of the
remaining kexec sysfs symlinks.

The /sys/kernel/<crash_elfcorehdr_size | kexec/crash_elfcorehdr_size>
entry is now controlled by CONFIG_CRASH_DUMP instead of
CONFIG_VMCORE_INFO, as CONFIG_CRASH_DUMP also enables CONFIG_VMCORE_INFO.

Link: https://lkml.kernel.org/r/20251118114507.1769455-1-sourabhjain@linux.ibm.com
Link: https://lkml.kernel.org/r/20251118114507.1769455-2-sourabhjain@linux.ibm.com
Signed-off-by: Sourabh Jain <sourabhjain@linux.ibm.com>
Acked-by: Baoquan He <bhe@redhat.com>
Cc: Aditya Gupta <adityag@linux.ibm.com>
Cc: Dave Young <dyoung@redhat.com>
Cc: Hari Bathini <hbathini@linux.ibm.com>
Cc: Jiri Bohac <jbohac@suse.cz>
Cc: Madhavan Srinivasan <maddy@linux.ibm.com>
Cc: Mahesh J Salgaonkar <mahesh@linux.ibm.com>
Cc: Pingfan Liu <piliu@redhat.com>
Cc: Ritesh Harjani (IBM) <ritesh.list@gmail.com>
Cc: Shivang Upadhyay <shivangu@linux.ibm.com>
Cc: Vivek Goyal <vgoyal@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
 2025-11-27 14:24:42 -08:00
Pratyush Yadav
11047466ef test_kho: always print restore status 
Currently the KHO test only prints a message on success, and remains
silent on failure.  This makes it difficult to notice a failing test.  A
failing test is usually more interesting than a successful one.

Always print the test status after attempting restore.

Link: https://lkml.kernel.org/r/20251118181046.23321-1-pratyush@kernel.org
Signed-off-by: Pratyush Yadav <pratyush@kernel.org>
Reviewed-by: Pasha Tatashin <pasha.tatashin@soleen.com>
Reviewed-by: Mike Rapoport (Microsoft) <rppt@kernel.org>
Acked-by: SeongJae Park <sj@kerneel.org>
Cc: Alexander Graf <graf@amazon.com>
Cc: Pratyush Yadav <pratyush@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
 2025-11-27 14:24:42 -08:00
Pratyush Yadav
b15515155a kho: free chunks using free_page() instead of kfree() 
Before commit fa759cd75b ("kho: allocate metadata directly from the
buddy allocator"), the chunks were allocated from the slab allocator using
kzalloc().  Those were rightly freed using kfree().

When the commit switched to using the buddy allocator directly, it missed
updating kho_mem_ser_free() to use free_page() instead of kfree().

Link: https://lkml.kernel.org/r/20251118182218.63044-1-pratyush@kernel.org
Fixes: fa759cd75b ("kho: allocate metadata directly from the buddy allocator")
Signed-off-by: Pratyush Yadav <pratyush@kernel.org>
Reviewed-by: Pasha Tatashin <pasha.tatashin@soleen.com>
Reviewed-by: Mike Rapoport (Microsoft) <rppt@kernel.org>
Cc: Alexander Graf <graf@amazon.com>
Cc: David Matlack <dmatlack@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
 2025-11-27 14:24:42 -08:00
Pasha Tatashin
724bf8c559 selftests/liveupdate: add kexec test for multiple and empty sessions 
Introduce a new kexec-based selftest, luo_kexec_multi_session, to validate
the end-to-end lifecycle of a more complex LUO scenario.

While the existing luo_kexec_simple test covers the basic end-to-end
lifecycle, it is limited to a single session with one preserved file. 
This new test significantly expands coverage by verifying LUO's ability to
handle a mixed workload involving multiple sessions, some of which are
intentionally empty.  This ensures that the LUO core correctly preserves
and restores the state of all session types across a reboot.

The test validates the following sequence:

Stage 1 (Pre-kexec):

  - Creates two empty test sessions (multi-test-empty-1,
    multi-test-empty-2).
  - Creates a session with one preserved memfd (multi-test-files-1).
  - Creates another session with two preserved memfds
    (multi-test-files-2), each containing unique data.
  - Creates a state-tracking session to manage the transition to
    Stage 2.
  - Executes a kexec reboot via the helper script.

Stage 2 (Post-kexec):

  - Retrieves the state-tracking session to confirm it is in the
    post-reboot stage.
  - Retrieves all four test sessions (both the empty and non-empty
    ones).
  - For the non-empty sessions, restores the preserved memfds and
    verifies their contents match the original data patterns.
  - Finalizes all test sessions and the state session to ensure a clean
    teardown and that all associated kernel resources are correctly
    released.

This test provides greater confidence in the robustness of the LUO
framework by validating its behavior in a more realistic, multi-faceted
scenario.

Link: https://lkml.kernel.org/r/20251125165850.3389713-19-pasha.tatashin@soleen.com
Signed-off-by: Pasha Tatashin <pasha.tatashin@soleen.com>
Reviewed-by: Mike Rapoport (Microsoft) <rppt@kernel.org>
Tested-by: David Matlack <dmatlack@google.com>
Cc: Aleksander Lobakin <aleksander.lobakin@intel.com>
Cc: Alexander Graf <graf@amazon.com>
Cc: Alice Ryhl <aliceryhl@google.com>
Cc: Andriy Shevchenko <andriy.shevchenko@linux.intel.com>
Cc: anish kumar <yesanishhere@gmail.com>
Cc: Anna Schumaker <anna.schumaker@oracle.com>
Cc: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
Cc: Bjorn Helgaas <bhelgaas@google.com>
Cc: Borislav Betkov <bp@alien8.de>
Cc: Chanwoo Choi <cw00.choi@samsung.com>
Cc: Chen Ridong <chenridong@huawei.com>
Cc: Chris Li <chrisl@kernel.org>
Cc: Christian Brauner <brauner@kernel.org>
Cc: Daniel Wagner <wagi@kernel.org>
Cc: Danilo Krummrich <dakr@kernel.org>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: David Jeffery <djeffery@redhat.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Guixin Liu <kanie@linux.alibaba.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Ira Weiny <ira.weiny@intel.com>
Cc: Jann Horn <jannh@google.com>
Cc: Jason Gunthorpe <jgg@nvidia.com>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Joanthan Cameron <Jonathan.Cameron@huawei.com>
Cc: Joel Granados <joel.granados@kernel.org>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Lennart Poettering <lennart@poettering.net>
Cc: Leon Romanovsky <leon@kernel.org>
Cc: Leon Romanovsky <leonro@nvidia.com>
Cc: Lukas Wunner <lukas@wunner.de>
Cc: Marc Rutland <mark.rutland@arm.com>
Cc: Masahiro Yamada <masahiroy@kernel.org>
Cc: Matthew Maurer <mmaurer@google.com>
Cc: Miguel Ojeda <ojeda@kernel.org>
Cc: Myugnjoo Ham <myungjoo.ham@samsung.com>
Cc: Parav Pandit <parav@nvidia.com>
Cc: Pratyush Yadav <pratyush@kernel.org>
Cc: Pratyush Yadav <ptyadav@amazon.de>
Cc: Randy Dunlap <rdunlap@infradead.org>
Cc: Roman Gushchin <roman.gushchin@linux.dev>
Cc: Saeed Mahameed <saeedm@nvidia.com>
Cc: Samiullah Khawaja <skhawaja@google.com>
Cc: Song Liu <song@kernel.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Stuart Hayes <stuart.w.hayes@gmail.com>
Cc: Tejun Heo <tj@kernel.org>
Cc: Thomas Gleinxer <tglx@linutronix.de>
Cc: Thomas Weißschuh <linux@weissschuh.net>
Cc: Vincent Guittot <vincent.guittot@linaro.org>
Cc: William Tu <witu@nvidia.com>
Cc: Yoann Congal <yoann.congal@smile.fr>
Cc: Zhu Yanjun <yanjun.zhu@linux.dev>
Cc: Zijun Hu <quic_zijuhu@quicinc.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
 2025-11-27 14:24:42 -08:00
Pasha Tatashin
a003bdb9ec selftests/liveupdate: add simple kexec-based selftest for LUO 
Introduce a kexec-based selftest, luo_kexec_simple, to validate the
end-to-end lifecycle of a Live Update Orchestrator session across a
reboot.

While existing tests verify the uAPI in a pre-reboot context, this test
ensures that the core functionality—preserving state via Kexec Handover
and restoring it in a new kernel—works as expected.

The test operates in two stages, managing its state across the reboot by
preserving a dedicated "state session" containing a memfd.  This mechanism
dogfoods the LUO feature itself for state tracking, making the test
self-contained.

The test validates the following sequence:

Stage 1 (Pre-kexec):
 - Creates a test session (test-session).
 - Creates and preserves a memfd with a known data pattern into the test
   session.
 - Creates the state-tracking session to signal progression to Stage 2.
 - Executes a kexec reboot via a helper script.

Stage 2 (Post-kexec):
 - Retrieves the state-tracking session to confirm it is in the
   post-reboot stage.
 - Retrieves the preserved test session.
 - Restores the memfd from the test session and verifies its contents
   match the original data pattern written in Stage 1.
 - Finalizes both the test and state sessions to ensure a clean
   teardown.

The test relies on a helper script (do_kexec.sh) to perform the reboot and
a shared utility library (luo_test_utils.c) for common LUO operations,
keeping the main test logic clean and focused.

Link: https://lkml.kernel.org/r/20251125165850.3389713-18-pasha.tatashin@soleen.com
Signed-off-by: Pasha Tatashin <pasha.tatashin@soleen.com>
Reviewed-by: Zhu Yanjun <yanjun.zhu@linux.dev>
Reviewed-by: Mike Rapoport (Microsoft) <rppt@kernel.org>
Tested-by: David Matlack <dmatlack@google.com>
Cc: Aleksander Lobakin <aleksander.lobakin@intel.com>
Cc: Alexander Graf <graf@amazon.com>
Cc: Alice Ryhl <aliceryhl@google.com>
Cc: Andriy Shevchenko <andriy.shevchenko@linux.intel.com>
Cc: anish kumar <yesanishhere@gmail.com>
Cc: Anna Schumaker <anna.schumaker@oracle.com>
Cc: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
Cc: Bjorn Helgaas <bhelgaas@google.com>
Cc: Borislav Betkov <bp@alien8.de>
Cc: Chanwoo Choi <cw00.choi@samsung.com>
Cc: Chen Ridong <chenridong@huawei.com>
Cc: Chris Li <chrisl@kernel.org>
Cc: Christian Brauner <brauner@kernel.org>
Cc: Daniel Wagner <wagi@kernel.org>
Cc: Danilo Krummrich <dakr@kernel.org>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: David Jeffery <djeffery@redhat.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Guixin Liu <kanie@linux.alibaba.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Ira Weiny <ira.weiny@intel.com>
Cc: Jann Horn <jannh@google.com>
Cc: Jason Gunthorpe <jgg@nvidia.com>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Joanthan Cameron <Jonathan.Cameron@huawei.com>
Cc: Joel Granados <joel.granados@kernel.org>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Lennart Poettering <lennart@poettering.net>
Cc: Leon Romanovsky <leon@kernel.org>
Cc: Leon Romanovsky <leonro@nvidia.com>
Cc: Lukas Wunner <lukas@wunner.de>
Cc: Marc Rutland <mark.rutland@arm.com>
Cc: Masahiro Yamada <masahiroy@kernel.org>
Cc: Matthew Maurer <mmaurer@google.com>
Cc: Miguel Ojeda <ojeda@kernel.org>
Cc: Myugnjoo Ham <myungjoo.ham@samsung.com>
Cc: Parav Pandit <parav@nvidia.com>
Cc: Pratyush Yadav <pratyush@kernel.org>
Cc: Pratyush Yadav <ptyadav@amazon.de>
Cc: Randy Dunlap <rdunlap@infradead.org>
Cc: Roman Gushchin <roman.gushchin@linux.dev>
Cc: Saeed Mahameed <saeedm@nvidia.com>
Cc: Samiullah Khawaja <skhawaja@google.com>
Cc: Song Liu <song@kernel.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Stuart Hayes <stuart.w.hayes@gmail.com>
Cc: Tejun Heo <tj@kernel.org>
Cc: Thomas Gleinxer <tglx@linutronix.de>
Cc: Thomas Weißschuh <linux@weissschuh.net>
Cc: Vincent Guittot <vincent.guittot@linaro.org>
Cc: William Tu <witu@nvidia.com>
Cc: Yoann Congal <yoann.congal@smile.fr>
Cc: Zijun Hu <quic_zijuhu@quicinc.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
 2025-11-27 14:24:41 -08:00
Pasha Tatashin
80bab43f6f selftests/liveupdate: add userspace API selftests 
Introduce a selftest suite for LUO.  These tests validate the core
userspace-facing API provided by the /dev/liveupdate device and its
associated ioctls.

The suite covers fundamental device behavior, session management, and the
file preservation mechanism using memfd as a test case.  This provides
regression testing for the LUO uAPI.

The following functionality is verified:

Device Access:
    Basic open and close operations on /dev/liveupdate.
    Enforcement of exclusive device access (verifying EBUSY on a
    second open).

Session Management:
    Successful creation of sessions with unique names.
    Failure to create sessions with duplicate names.

File Preservation:
    Preserving a single memfd and verifying its content remains
    intact post-preservation.
    Preserving multiple memfds within a single session, each with
    unique data.
    A complex scenario involving multiple sessions, each containing
    a mix of empty and data-filled memfds.

Note: This test suite is limited to verifying the pre-kexec functionality
of LUO (e.g., session creation, file preservation).  The post-kexec
restoration of resources is not covered, as the kselftest framework does
not currently support orchestrating a reboot and continuing execution in
the new kernel.

Link: https://lkml.kernel.org/r/20251125165850.3389713-17-pasha.tatashin@soleen.com
Signed-off-by: Pasha Tatashin <pasha.tatashin@soleen.com>
Reviewed-by: Pratyush Yadav <pratyush@kernel.org>
Reviewed-by: Mike Rapoport (Microsoft) <rppt@kernel.org>
Tested-by: David Matlack <dmatlack@google.com>
Cc: Aleksander Lobakin <aleksander.lobakin@intel.com>
Cc: Alexander Graf <graf@amazon.com>
Cc: Alice Ryhl <aliceryhl@google.com>
Cc: Andriy Shevchenko <andriy.shevchenko@linux.intel.com>
Cc: anish kumar <yesanishhere@gmail.com>
Cc: Anna Schumaker <anna.schumaker@oracle.com>
Cc: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
Cc: Bjorn Helgaas <bhelgaas@google.com>
Cc: Borislav Betkov <bp@alien8.de>
Cc: Chanwoo Choi <cw00.choi@samsung.com>
Cc: Chen Ridong <chenridong@huawei.com>
Cc: Chris Li <chrisl@kernel.org>
Cc: Christian Brauner <brauner@kernel.org>
Cc: Daniel Wagner <wagi@kernel.org>
Cc: Danilo Krummrich <dakr@kernel.org>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: David Jeffery <djeffery@redhat.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Guixin Liu <kanie@linux.alibaba.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Ira Weiny <ira.weiny@intel.com>
Cc: Jann Horn <jannh@google.com>
Cc: Jason Gunthorpe <jgg@nvidia.com>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Joanthan Cameron <Jonathan.Cameron@huawei.com>
Cc: Joel Granados <joel.granados@kernel.org>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Lennart Poettering <lennart@poettering.net>
Cc: Leon Romanovsky <leon@kernel.org>
Cc: Leon Romanovsky <leonro@nvidia.com>
Cc: Lukas Wunner <lukas@wunner.de>
Cc: Marc Rutland <mark.rutland@arm.com>
Cc: Masahiro Yamada <masahiroy@kernel.org>
Cc: Matthew Maurer <mmaurer@google.com>
Cc: Miguel Ojeda <ojeda@kernel.org>
Cc: Myugnjoo Ham <myungjoo.ham@samsung.com>
Cc: Parav Pandit <parav@nvidia.com>
Cc: Pratyush Yadav <ptyadav@amazon.de>
Cc: Randy Dunlap <rdunlap@infradead.org>
Cc: Roman Gushchin <roman.gushchin@linux.dev>
Cc: Saeed Mahameed <saeedm@nvidia.com>
Cc: Samiullah Khawaja <skhawaja@google.com>
Cc: Song Liu <song@kernel.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Stuart Hayes <stuart.w.hayes@gmail.com>
Cc: Tejun Heo <tj@kernel.org>
Cc: Thomas Gleinxer <tglx@linutronix.de>
Cc: Thomas Weißschuh <linux@weissschuh.net>
Cc: Vincent Guittot <vincent.guittot@linaro.org>
Cc: William Tu <witu@nvidia.com>
Cc: Yoann Congal <yoann.congal@smile.fr>
Cc: Zhu Yanjun <yanjun.zhu@linux.dev>
Cc: Zijun Hu <quic_zijuhu@quicinc.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
 2025-11-27 14:24:41 -08:00
Pratyush Yadav
15fc11bb2c docs: add documentation for memfd preservation via LUO 
Add the documentation under the "Preserving file descriptors" section of
LUO's documentation.

Link: https://lkml.kernel.org/r/20251125165850.3389713-16-pasha.tatashin@soleen.com
Signed-off-by: Pratyush Yadav <ptyadav@amazon.de>
Co-developed-by: Pasha Tatashin <pasha.tatashin@soleen.com>
Signed-off-by: Pasha Tatashin <pasha.tatashin@soleen.com>
Reviewed-by: Mike Rapoport (Microsoft) <rppt@kernel.org>
Tested-by: David Matlack <dmatlack@google.com>
Cc: Aleksander Lobakin <aleksander.lobakin@intel.com>
Cc: Alexander Graf <graf@amazon.com>
Cc: Alice Ryhl <aliceryhl@google.com>
Cc: Andriy Shevchenko <andriy.shevchenko@linux.intel.com>
Cc: anish kumar <yesanishhere@gmail.com>
Cc: Anna Schumaker <anna.schumaker@oracle.com>
Cc: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
Cc: Bjorn Helgaas <bhelgaas@google.com>
Cc: Borislav Betkov <bp@alien8.de>
Cc: Chanwoo Choi <cw00.choi@samsung.com>
Cc: Chen Ridong <chenridong@huawei.com>
Cc: Chris Li <chrisl@kernel.org>
Cc: Christian Brauner <brauner@kernel.org>
Cc: Daniel Wagner <wagi@kernel.org>
Cc: Danilo Krummrich <dakr@kernel.org>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: David Jeffery <djeffery@redhat.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Guixin Liu <kanie@linux.alibaba.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Ira Weiny <ira.weiny@intel.com>
Cc: Jann Horn <jannh@google.com>
Cc: Jason Gunthorpe <jgg@nvidia.com>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Joanthan Cameron <Jonathan.Cameron@huawei.com>
Cc: Joel Granados <joel.granados@kernel.org>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Lennart Poettering <lennart@poettering.net>
Cc: Leon Romanovsky <leon@kernel.org>
Cc: Leon Romanovsky <leonro@nvidia.com>
Cc: Lukas Wunner <lukas@wunner.de>
Cc: Marc Rutland <mark.rutland@arm.com>
Cc: Masahiro Yamada <masahiroy@kernel.org>
Cc: Matthew Maurer <mmaurer@google.com>
Cc: Miguel Ojeda <ojeda@kernel.org>
Cc: Myugnjoo Ham <myungjoo.ham@samsung.com>
Cc: Parav Pandit <parav@nvidia.com>
Cc: Pratyush Yadav <pratyush@kernel.org>
Cc: Randy Dunlap <rdunlap@infradead.org>
Cc: Roman Gushchin <roman.gushchin@linux.dev>
Cc: Saeed Mahameed <saeedm@nvidia.com>
Cc: Samiullah Khawaja <skhawaja@google.com>
Cc: Song Liu <song@kernel.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Stuart Hayes <stuart.w.hayes@gmail.com>
Cc: Tejun Heo <tj@kernel.org>
Cc: Thomas Gleinxer <tglx@linutronix.de>
Cc: Thomas Weißschuh <linux@weissschuh.net>
Cc: Vincent Guittot <vincent.guittot@linaro.org>
Cc: William Tu <witu@nvidia.com>
Cc: Yoann Congal <yoann.congal@smile.fr>
Cc: Zhu Yanjun <yanjun.zhu@linux.dev>
Cc: Zijun Hu <quic_zijuhu@quicinc.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
 2025-11-27 14:24:41 -08:00
Pratyush Yadav
b3749f174d mm: memfd_luo: allow preserving memfd 
The ability to preserve a memfd allows userspace to use KHO and LUO to
transfer its memory contents to the next kernel.  This is useful in many
ways.  For one, it can be used with IOMMUFD as the backing store for IOMMU
page tables.  Preserving IOMMUFD is essential for performing a hypervisor
live update with passthrough devices.  memfd support provides the first
building block for making that possible.

For another, applications with a large amount of memory that takes time to
reconstruct, reboots to consume kernel upgrades can be very expensive. 
memfd with LUO gives those applications reboot-persistent memory that they
can use to quickly save and reconstruct that state.

While memfd is backed by either hugetlbfs or shmem, currently only support
on shmem is added.  To be more precise, support for anonymous shmem files
is added.

The handover to the next kernel is not transparent.  All the properties of
the file are not preserved; only its memory contents, position, and size. 
The recreated file gets the UID and GID of the task doing the restore, and
the task's cgroup gets charged with the memory.

Once preserved, the file cannot grow or shrink, and all its pages are
pinned to avoid migrations and swapping.  The file can still be read from
or written to.

Use vmalloc to get the buffer to hold the folios, and preserve it using
kho_preserve_vmalloc().  This doesn't have the size limit.

Link: https://lkml.kernel.org/r/20251125165850.3389713-15-pasha.tatashin@soleen.com
Signed-off-by: Pratyush Yadav <ptyadav@amazon.de>
Co-developed-by: Pasha Tatashin <pasha.tatashin@soleen.com>
Signed-off-by: Pasha Tatashin <pasha.tatashin@soleen.com>
Reviewed-by: Mike Rapoport (Microsoft) <rppt@kernel.org>
Tested-by: David Matlack <dmatlack@google.com>
Cc: Aleksander Lobakin <aleksander.lobakin@intel.com>
Cc: Alexander Graf <graf@amazon.com>
Cc: Alice Ryhl <aliceryhl@google.com>
Cc: Andriy Shevchenko <andriy.shevchenko@linux.intel.com>
Cc: anish kumar <yesanishhere@gmail.com>
Cc: Anna Schumaker <anna.schumaker@oracle.com>
Cc: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
Cc: Bjorn Helgaas <bhelgaas@google.com>
Cc: Borislav Betkov <bp@alien8.de>
Cc: Chanwoo Choi <cw00.choi@samsung.com>
Cc: Chen Ridong <chenridong@huawei.com>
Cc: Chris Li <chrisl@kernel.org>
Cc: Christian Brauner <brauner@kernel.org>
Cc: Daniel Wagner <wagi@kernel.org>
Cc: Danilo Krummrich <dakr@kernel.org>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: David Jeffery <djeffery@redhat.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Guixin Liu <kanie@linux.alibaba.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Ira Weiny <ira.weiny@intel.com>
Cc: Jann Horn <jannh@google.com>
Cc: Jason Gunthorpe <jgg@nvidia.com>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Joanthan Cameron <Jonathan.Cameron@huawei.com>
Cc: Joel Granados <joel.granados@kernel.org>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Lennart Poettering <lennart@poettering.net>
Cc: Leon Romanovsky <leon@kernel.org>
Cc: Leon Romanovsky <leonro@nvidia.com>
Cc: Lukas Wunner <lukas@wunner.de>
Cc: Marc Rutland <mark.rutland@arm.com>
Cc: Masahiro Yamada <masahiroy@kernel.org>
Cc: Matthew Maurer <mmaurer@google.com>
Cc: Miguel Ojeda <ojeda@kernel.org>
Cc: Myugnjoo Ham <myungjoo.ham@samsung.com>
Cc: Parav Pandit <parav@nvidia.com>
Cc: Pratyush Yadav <pratyush@kernel.org>
Cc: Randy Dunlap <rdunlap@infradead.org>
Cc: Roman Gushchin <roman.gushchin@linux.dev>
Cc: Saeed Mahameed <saeedm@nvidia.com>
Cc: Samiullah Khawaja <skhawaja@google.com>
Cc: Song Liu <song@kernel.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Stuart Hayes <stuart.w.hayes@gmail.com>
Cc: Tejun Heo <tj@kernel.org>
Cc: Thomas Gleinxer <tglx@linutronix.de>
Cc: Thomas Weißschuh <linux@weissschuh.net>
Cc: Vincent Guittot <vincent.guittot@linaro.org>
Cc: William Tu <witu@nvidia.com>
Cc: Yoann Congal <yoann.congal@smile.fr>
Cc: Zhu Yanjun <yanjun.zhu@linux.dev>
Cc: Zijun Hu <quic_zijuhu@quicinc.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
 2025-11-27 14:24:41 -08:00
Pratyush Yadav
8def18633e liveupdate: luo_file: add private argument to store runtime state 
Currently file handlers only get the serialized_data field to store their
state.  This field has a pointer to the serialized state of the file, and
it becomes a part of LUO file's serialized state.

File handlers can also need some runtime state to track information that
shouldn't make it in the serialized data.

One such example is a vmalloc pointer.  While kho_preserve_vmalloc()
preserves the memory backing a vmalloc allocation, it does not store the
original vmap pointer, since that has no use being passed to the next
kernel.  The pointer is needed to free the memory in case the file is
unpreserved.

Provide a private field in struct luo_file and pass it to all the
callbacks.  The field's can be set by preserve, and must be freed by
unpreserve.

Link: https://lkml.kernel.org/r/20251125165850.3389713-14-pasha.tatashin@soleen.com
Signed-off-by: Pratyush Yadav <ptyadav@amazon.de>
Co-developed-by: Pasha Tatashin <pasha.tatashin@soleen.com>
Signed-off-by: Pasha Tatashin <pasha.tatashin@soleen.com>
Reviewed-by: Mike Rapoport (Microsoft) <rppt@kernel.org>
Tested-by: David Matlack <dmatlack@google.com>
Cc: Aleksander Lobakin <aleksander.lobakin@intel.com>
Cc: Alexander Graf <graf@amazon.com>
Cc: Alice Ryhl <aliceryhl@google.com>
Cc: Andriy Shevchenko <andriy.shevchenko@linux.intel.com>
Cc: anish kumar <yesanishhere@gmail.com>
Cc: Anna Schumaker <anna.schumaker@oracle.com>
Cc: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
Cc: Bjorn Helgaas <bhelgaas@google.com>
Cc: Borislav Betkov <bp@alien8.de>
Cc: Chanwoo Choi <cw00.choi@samsung.com>
Cc: Chen Ridong <chenridong@huawei.com>
Cc: Chris Li <chrisl@kernel.org>
Cc: Christian Brauner <brauner@kernel.org>
Cc: Daniel Wagner <wagi@kernel.org>
Cc: Danilo Krummrich <dakr@kernel.org>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: David Jeffery <djeffery@redhat.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Guixin Liu <kanie@linux.alibaba.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Ira Weiny <ira.weiny@intel.com>
Cc: Jann Horn <jannh@google.com>
Cc: Jason Gunthorpe <jgg@nvidia.com>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Joanthan Cameron <Jonathan.Cameron@huawei.com>
Cc: Joel Granados <joel.granados@kernel.org>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Lennart Poettering <lennart@poettering.net>
Cc: Leon Romanovsky <leon@kernel.org>
Cc: Leon Romanovsky <leonro@nvidia.com>
Cc: Lukas Wunner <lukas@wunner.de>
Cc: Marc Rutland <mark.rutland@arm.com>
Cc: Masahiro Yamada <masahiroy@kernel.org>
Cc: Matthew Maurer <mmaurer@google.com>
Cc: Miguel Ojeda <ojeda@kernel.org>
Cc: Myugnjoo Ham <myungjoo.ham@samsung.com>
Cc: Parav Pandit <parav@nvidia.com>
Cc: Pratyush Yadav <pratyush@kernel.org>
Cc: Randy Dunlap <rdunlap@infradead.org>
Cc: Roman Gushchin <roman.gushchin@linux.dev>
Cc: Saeed Mahameed <saeedm@nvidia.com>
Cc: Samiullah Khawaja <skhawaja@google.com>
Cc: Song Liu <song@kernel.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Stuart Hayes <stuart.w.hayes@gmail.com>
Cc: Tejun Heo <tj@kernel.org>
Cc: Thomas Gleinxer <tglx@linutronix.de>
Cc: Thomas Weißschuh <linux@weissschuh.net>
Cc: Vincent Guittot <vincent.guittot@linaro.org>
Cc: William Tu <witu@nvidia.com>
Cc: Yoann Congal <yoann.congal@smile.fr>
Cc: Zhu Yanjun <yanjun.zhu@linux.dev>
Cc: Zijun Hu <quic_zijuhu@quicinc.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
 2025-11-27 14:24:40 -08:00
Pratyush Yadav
ed6f45f81b mm: shmem: export some functions to internal.h 
shmem_inode_acct_blocks(), shmem_recalc_inode(), and
shmem_add_to_page_cache() are used by shmem_alloc_and_add_folio().  This
functionality will be used by memfd LUO integration.

Link: https://lkml.kernel.org/r/20251125165850.3389713-13-pasha.tatashin@soleen.com
Signed-off-by: Pratyush Yadav <ptyadav@amazon.de>
Signed-off-by: Pasha Tatashin <pasha.tatashin@soleen.com>
Reviewed-by: Mike Rapoport (Microsoft) <rppt@kernel.org>
Tested-by: David Matlack <dmatlack@google.com>
Cc: Aleksander Lobakin <aleksander.lobakin@intel.com>
Cc: Alexander Graf <graf@amazon.com>
Cc: Alice Ryhl <aliceryhl@google.com>
Cc: Andriy Shevchenko <andriy.shevchenko@linux.intel.com>
Cc: anish kumar <yesanishhere@gmail.com>
Cc: Anna Schumaker <anna.schumaker@oracle.com>
Cc: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
Cc: Bjorn Helgaas <bhelgaas@google.com>
Cc: Borislav Betkov <bp@alien8.de>
Cc: Chanwoo Choi <cw00.choi@samsung.com>
Cc: Chen Ridong <chenridong@huawei.com>
Cc: Chris Li <chrisl@kernel.org>
Cc: Christian Brauner <brauner@kernel.org>
Cc: Daniel Wagner <wagi@kernel.org>
Cc: Danilo Krummrich <dakr@kernel.org>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: David Jeffery <djeffery@redhat.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Guixin Liu <kanie@linux.alibaba.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Ira Weiny <ira.weiny@intel.com>
Cc: Jann Horn <jannh@google.com>
Cc: Jason Gunthorpe <jgg@nvidia.com>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Joanthan Cameron <Jonathan.Cameron@huawei.com>
Cc: Joel Granados <joel.granados@kernel.org>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Lennart Poettering <lennart@poettering.net>
Cc: Leon Romanovsky <leon@kernel.org>
Cc: Leon Romanovsky <leonro@nvidia.com>
Cc: Lukas Wunner <lukas@wunner.de>
Cc: Marc Rutland <mark.rutland@arm.com>
Cc: Masahiro Yamada <masahiroy@kernel.org>
Cc: Matthew Maurer <mmaurer@google.com>
Cc: Miguel Ojeda <ojeda@kernel.org>
Cc: Myugnjoo Ham <myungjoo.ham@samsung.com>
Cc: Parav Pandit <parav@nvidia.com>
Cc: Pratyush Yadav <pratyush@kernel.org>
Cc: Randy Dunlap <rdunlap@infradead.org>
Cc: Roman Gushchin <roman.gushchin@linux.dev>
Cc: Saeed Mahameed <saeedm@nvidia.com>
Cc: Samiullah Khawaja <skhawaja@google.com>
Cc: Song Liu <song@kernel.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Stuart Hayes <stuart.w.hayes@gmail.com>
Cc: Tejun Heo <tj@kernel.org>
Cc: Thomas Gleinxer <tglx@linutronix.de>
Cc: Thomas Weißschuh <linux@weissschuh.net>
Cc: Vincent Guittot <vincent.guittot@linaro.org>
Cc: William Tu <witu@nvidia.com>
Cc: Yoann Congal <yoann.congal@smile.fr>
Cc: Zhu Yanjun <yanjun.zhu@linux.dev>
Cc: Zijun Hu <quic_zijuhu@quicinc.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
 2025-11-27 14:24:40 -08:00
Pratyush Yadav
e165e2a257 mm: shmem: allow freezing inode mapping 
To prepare a shmem inode for live update, its index -> folio mappings must
be serialized.  Once the mappings are serialized, they cannot change since
it would cause the serialized data to become inconsistent.  This can be
done by pinning the folios to avoid migration, and by making sure no
folios can be added to or removed from the inode.

While mechanisms to pin folios already exist, the only way to stop folios
being added or removed are the grow and shrink file seals.  But file seals
come with their own semantics, one of which is that they can't be removed.
This doesn't work with liveupdate since it can be cancelled or error out,
which would need the seals to be removed and the file's normal
functionality to be restored.

Introduce SHMEM_F_MAPPING_FROZEN to indicate this instead.  It is internal
to shmem and is not directly exposed to userspace.  It functions similar
to F_SEAL_GROW | F_SEAL_SHRINK, but additionally disallows hole punching,
and can be removed.

Link: https://lkml.kernel.org/r/20251125165850.3389713-12-pasha.tatashin@soleen.com
Signed-off-by: Pratyush Yadav <ptyadav@amazon.de>
Signed-off-by: Pasha Tatashin <pasha.tatashin@soleen.com>
Reviewed-by: Mike Rapoport (Microsoft) <rppt@kernel.org>
Tested-by: David Matlack <dmatlack@google.com>
Cc: Aleksander Lobakin <aleksander.lobakin@intel.com>
Cc: Alexander Graf <graf@amazon.com>
Cc: Alice Ryhl <aliceryhl@google.com>
Cc: Andriy Shevchenko <andriy.shevchenko@linux.intel.com>
Cc: anish kumar <yesanishhere@gmail.com>
Cc: Anna Schumaker <anna.schumaker@oracle.com>
Cc: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
Cc: Bjorn Helgaas <bhelgaas@google.com>
Cc: Borislav Betkov <bp@alien8.de>
Cc: Chanwoo Choi <cw00.choi@samsung.com>
Cc: Chen Ridong <chenridong@huawei.com>
Cc: Chris Li <chrisl@kernel.org>
Cc: Christian Brauner <brauner@kernel.org>
Cc: Daniel Wagner <wagi@kernel.org>
Cc: Danilo Krummrich <dakr@kernel.org>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: David Jeffery <djeffery@redhat.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Guixin Liu <kanie@linux.alibaba.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Ira Weiny <ira.weiny@intel.com>
Cc: Jann Horn <jannh@google.com>
Cc: Jason Gunthorpe <jgg@nvidia.com>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Joanthan Cameron <Jonathan.Cameron@huawei.com>
Cc: Joel Granados <joel.granados@kernel.org>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Lennart Poettering <lennart@poettering.net>
Cc: Leon Romanovsky <leon@kernel.org>
Cc: Leon Romanovsky <leonro@nvidia.com>
Cc: Lukas Wunner <lukas@wunner.de>
Cc: Marc Rutland <mark.rutland@arm.com>
Cc: Masahiro Yamada <masahiroy@kernel.org>
Cc: Matthew Maurer <mmaurer@google.com>
Cc: Miguel Ojeda <ojeda@kernel.org>
Cc: Myugnjoo Ham <myungjoo.ham@samsung.com>
Cc: Parav Pandit <parav@nvidia.com>
Cc: Pratyush Yadav <pratyush@kernel.org>
Cc: Randy Dunlap <rdunlap@infradead.org>
Cc: Roman Gushchin <roman.gushchin@linux.dev>
Cc: Saeed Mahameed <saeedm@nvidia.com>
Cc: Samiullah Khawaja <skhawaja@google.com>
Cc: Song Liu <song@kernel.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Stuart Hayes <stuart.w.hayes@gmail.com>
Cc: Tejun Heo <tj@kernel.org>
Cc: Thomas Gleinxer <tglx@linutronix.de>
Cc: Thomas Weißschuh <linux@weissschuh.net>
Cc: Vincent Guittot <vincent.guittot@linaro.org>
Cc: William Tu <witu@nvidia.com>
Cc: Yoann Congal <yoann.congal@smile.fr>
Cc: Zhu Yanjun <yanjun.zhu@linux.dev>
Cc: Zijun Hu <quic_zijuhu@quicinc.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
 2025-11-27 14:24:40 -08:00
Pratyush Yadav
6ff1610ced mm: shmem: use SHMEM_F_* flags instead of VM_* flags 
shmem_inode_info::flags can have the VM flags VM_NORESERVE and VM_LOCKED. 
These are used to suppress pre-accounting or to lock the pages in the
inode respectively.  Using the VM flags directly makes it difficult to add
shmem-specific flags that are unrelated to VM behavior since one would
need to find a VM flag not used by shmem and re-purpose it.

Introduce SHMEM_F_NORESERVE and SHMEM_F_LOCKED which represent the same
information, but their bits are independent of the VM flags.  Callers can
still pass VM_NORESERVE to shmem_get_inode(), but it gets transformed to
the shmem-specific flag internally.

No functional changes intended.

Link: https://lkml.kernel.org/r/20251125165850.3389713-11-pasha.tatashin@soleen.com
Signed-off-by: Pratyush Yadav <ptyadav@amazon.de>
Signed-off-by: Pasha Tatashin <pasha.tatashin@soleen.com>
Reviewed-by: Mike Rapoport (Microsoft) <rppt@kernel.org>
Tested-by: David Matlack <dmatlack@google.com>
Cc: Aleksander Lobakin <aleksander.lobakin@intel.com>
Cc: Alexander Graf <graf@amazon.com>
Cc: Alice Ryhl <aliceryhl@google.com>
Cc: Andriy Shevchenko <andriy.shevchenko@linux.intel.com>
Cc: anish kumar <yesanishhere@gmail.com>
Cc: Anna Schumaker <anna.schumaker@oracle.com>
Cc: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
Cc: Bjorn Helgaas <bhelgaas@google.com>
Cc: Borislav Betkov <bp@alien8.de>
Cc: Chanwoo Choi <cw00.choi@samsung.com>
Cc: Chen Ridong <chenridong@huawei.com>
Cc: Chris Li <chrisl@kernel.org>
Cc: Christian Brauner <brauner@kernel.org>
Cc: Daniel Wagner <wagi@kernel.org>
Cc: Danilo Krummrich <dakr@kernel.org>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: David Jeffery <djeffery@redhat.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Guixin Liu <kanie@linux.alibaba.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Ira Weiny <ira.weiny@intel.com>
Cc: Jann Horn <jannh@google.com>
Cc: Jason Gunthorpe <jgg@nvidia.com>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Joanthan Cameron <Jonathan.Cameron@huawei.com>
Cc: Joel Granados <joel.granados@kernel.org>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Lennart Poettering <lennart@poettering.net>
Cc: Leon Romanovsky <leon@kernel.org>
Cc: Leon Romanovsky <leonro@nvidia.com>
Cc: Lukas Wunner <lukas@wunner.de>
Cc: Marc Rutland <mark.rutland@arm.com>
Cc: Masahiro Yamada <masahiroy@kernel.org>
Cc: Matthew Maurer <mmaurer@google.com>
Cc: Miguel Ojeda <ojeda@kernel.org>
Cc: Myugnjoo Ham <myungjoo.ham@samsung.com>
Cc: Parav Pandit <parav@nvidia.com>
Cc: Pratyush Yadav <pratyush@kernel.org>
Cc: Randy Dunlap <rdunlap@infradead.org>
Cc: Roman Gushchin <roman.gushchin@linux.dev>
Cc: Saeed Mahameed <saeedm@nvidia.com>
Cc: Samiullah Khawaja <skhawaja@google.com>
Cc: Song Liu <song@kernel.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Stuart Hayes <stuart.w.hayes@gmail.com>
Cc: Tejun Heo <tj@kernel.org>
Cc: Thomas Gleinxer <tglx@linutronix.de>
Cc: Thomas Weißschuh <linux@weissschuh.net>
Cc: Vincent Guittot <vincent.guittot@linaro.org>
Cc: William Tu <witu@nvidia.com>
Cc: Yoann Congal <yoann.congal@smile.fr>
Cc: Zhu Yanjun <yanjun.zhu@linux.dev>
Cc: Zijun Hu <quic_zijuhu@quicinc.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
 2025-11-27 14:24:39 -08:00
Pasha Tatashin
7a5afa7ea8 MAINTAINERS: add liveupdate entry 
Add a MAINTAINERS file entry for the new Live Update Orchestrator
introduced in previous patches.

Link: https://lkml.kernel.org/r/20251125165850.3389713-10-pasha.tatashin@soleen.com
Signed-off-by: Pasha Tatashin <pasha.tatashin@soleen.com>
Reviewed-by: Mike Rapoport (Microsoft) <rppt@kernel.org>
Reviewed-by: Pratyush Yadav <pratyush@kernel.org>
Tested-by: David Matlack <dmatlack@google.com>
Cc: Aleksander Lobakin <aleksander.lobakin@intel.com>
Cc: Alexander Graf <graf@amazon.com>
Cc: Alice Ryhl <aliceryhl@google.com>
Cc: Andriy Shevchenko <andriy.shevchenko@linux.intel.com>
Cc: anish kumar <yesanishhere@gmail.com>
Cc: Anna Schumaker <anna.schumaker@oracle.com>
Cc: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
Cc: Bjorn Helgaas <bhelgaas@google.com>
Cc: Borislav Betkov <bp@alien8.de>
Cc: Chanwoo Choi <cw00.choi@samsung.com>
Cc: Chen Ridong <chenridong@huawei.com>
Cc: Chris Li <chrisl@kernel.org>
Cc: Christian Brauner <brauner@kernel.org>
Cc: Daniel Wagner <wagi@kernel.org>
Cc: Danilo Krummrich <dakr@kernel.org>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: David Jeffery <djeffery@redhat.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Guixin Liu <kanie@linux.alibaba.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Ira Weiny <ira.weiny@intel.com>
Cc: Jann Horn <jannh@google.com>
Cc: Jason Gunthorpe <jgg@nvidia.com>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Joanthan Cameron <Jonathan.Cameron@huawei.com>
Cc: Joel Granados <joel.granados@kernel.org>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Lennart Poettering <lennart@poettering.net>
Cc: Leon Romanovsky <leon@kernel.org>
Cc: Leon Romanovsky <leonro@nvidia.com>
Cc: Lukas Wunner <lukas@wunner.de>
Cc: Marc Rutland <mark.rutland@arm.com>
Cc: Masahiro Yamada <masahiroy@kernel.org>
Cc: Matthew Maurer <mmaurer@google.com>
Cc: Miguel Ojeda <ojeda@kernel.org>
Cc: Myugnjoo Ham <myungjoo.ham@samsung.com>
Cc: Parav Pandit <parav@nvidia.com>
Cc: Pratyush Yadav <ptyadav@amazon.de>
Cc: Randy Dunlap <rdunlap@infradead.org>
Cc: Roman Gushchin <roman.gushchin@linux.dev>
Cc: Saeed Mahameed <saeedm@nvidia.com>
Cc: Samiullah Khawaja <skhawaja@google.com>
Cc: Song Liu <song@kernel.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Stuart Hayes <stuart.w.hayes@gmail.com>
Cc: Tejun Heo <tj@kernel.org>
Cc: Thomas Gleinxer <tglx@linutronix.de>
Cc: Thomas Weißschuh <linux@weissschuh.net>
Cc: Vincent Guittot <vincent.guittot@linaro.org>
Cc: William Tu <witu@nvidia.com>
Cc: Yoann Congal <yoann.congal@smile.fr>
Cc: Zhu Yanjun <yanjun.zhu@linux.dev>
Cc: Zijun Hu <quic_zijuhu@quicinc.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
 2025-11-27 14:24:39 -08:00
Pasha Tatashin
906a330624 docs: add luo documentation 
Add the documentation files for the Live Update Orchestrator

Link: https://lkml.kernel.org/r/20251125165850.3389713-9-pasha.tatashin@soleen.com
Signed-off-by: Pasha Tatashin <pasha.tatashin@soleen.com>
Reviewed-by: Mike Rapoport (Microsoft) <rppt@kernel.org>
Reviewed-by: Pratyush Yadav <pratyush@kernel.org>
Tested-by: David Matlack <dmatlack@google.com>
Cc: Aleksander Lobakin <aleksander.lobakin@intel.com>
Cc: Alexander Graf <graf@amazon.com>
Cc: Alice Ryhl <aliceryhl@google.com>
Cc: Andriy Shevchenko <andriy.shevchenko@linux.intel.com>
Cc: anish kumar <yesanishhere@gmail.com>
Cc: Anna Schumaker <anna.schumaker@oracle.com>
Cc: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
Cc: Bjorn Helgaas <bhelgaas@google.com>
Cc: Borislav Betkov <bp@alien8.de>
Cc: Chanwoo Choi <cw00.choi@samsung.com>
Cc: Chen Ridong <chenridong@huawei.com>
Cc: Chris Li <chrisl@kernel.org>
Cc: Christian Brauner <brauner@kernel.org>
Cc: Daniel Wagner <wagi@kernel.org>
Cc: Danilo Krummrich <dakr@kernel.org>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: David Jeffery <djeffery@redhat.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Guixin Liu <kanie@linux.alibaba.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Ira Weiny <ira.weiny@intel.com>
Cc: Jann Horn <jannh@google.com>
Cc: Jason Gunthorpe <jgg@nvidia.com>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Joanthan Cameron <Jonathan.Cameron@huawei.com>
Cc: Joel Granados <joel.granados@kernel.org>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Lennart Poettering <lennart@poettering.net>
Cc: Leon Romanovsky <leon@kernel.org>
Cc: Leon Romanovsky <leonro@nvidia.com>
Cc: Lukas Wunner <lukas@wunner.de>
Cc: Marc Rutland <mark.rutland@arm.com>
Cc: Masahiro Yamada <masahiroy@kernel.org>
Cc: Matthew Maurer <mmaurer@google.com>
Cc: Miguel Ojeda <ojeda@kernel.org>
Cc: Myugnjoo Ham <myungjoo.ham@samsung.com>
Cc: Parav Pandit <parav@nvidia.com>
Cc: Pratyush Yadav <ptyadav@amazon.de>
Cc: Randy Dunlap <rdunlap@infradead.org>
Cc: Roman Gushchin <roman.gushchin@linux.dev>
Cc: Saeed Mahameed <saeedm@nvidia.com>
Cc: Samiullah Khawaja <skhawaja@google.com>
Cc: Song Liu <song@kernel.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Stuart Hayes <stuart.w.hayes@gmail.com>
Cc: Tejun Heo <tj@kernel.org>
Cc: Thomas Gleinxer <tglx@linutronix.de>
Cc: Thomas Weißschuh <linux@weissschuh.net>
Cc: Vincent Guittot <vincent.guittot@linaro.org>
Cc: William Tu <witu@nvidia.com>
Cc: Yoann Congal <yoann.congal@smile.fr>
Cc: Zhu Yanjun <yanjun.zhu@linux.dev>
Cc: Zijun Hu <quic_zijuhu@quicinc.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
 2025-11-27 14:24:39 -08:00
Pasha Tatashin
16cec0d265 liveupdate: luo_session: add ioctls for file preservation 
Introducing the userspace interface and internal logic required to manage
the lifecycle of file descriptors within a session.  Previously, a session
was merely a container; this change makes it a functional management unit.

The following capabilities are added:

A new set of ioctl commands are added, which operate on the file
descriptor returned by CREATE_SESSION. This allows userspace to:
- LIVEUPDATE_SESSION_PRESERVE_FD: Add a file descriptor to a session
  to be preserved across the live update.
- LIVEUPDATE_SESSION_RETRIEVE_FD: Retrieve a preserved file in the
  new kernel using its unique token.
- LIVEUPDATE_SESSION_FINISH: finish session

The session's .release handler is enhanced to be state-aware.  When a
session's file descriptor is closed, it correctly unpreserves the session
based on its current state before freeing all associated file resources.

Link: https://lkml.kernel.org/r/20251125165850.3389713-8-pasha.tatashin@soleen.com
Signed-off-by: Pasha Tatashin <pasha.tatashin@soleen.com>
Reviewed-by: Pratyush Yadav <pratyush@kernel.org>
Reviewed-by: Mike Rapoport (Microsoft) <rppt@kernel.org>
Tested-by: David Matlack <dmatlack@google.com>
Cc: Aleksander Lobakin <aleksander.lobakin@intel.com>
Cc: Alexander Graf <graf@amazon.com>
Cc: Alice Ryhl <aliceryhl@google.com>
Cc: Andriy Shevchenko <andriy.shevchenko@linux.intel.com>
Cc: anish kumar <yesanishhere@gmail.com>
Cc: Anna Schumaker <anna.schumaker@oracle.com>
Cc: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
Cc: Bjorn Helgaas <bhelgaas@google.com>
Cc: Borislav Betkov <bp@alien8.de>
Cc: Chanwoo Choi <cw00.choi@samsung.com>
Cc: Chen Ridong <chenridong@huawei.com>
Cc: Chris Li <chrisl@kernel.org>
Cc: Christian Brauner <brauner@kernel.org>
Cc: Daniel Wagner <wagi@kernel.org>
Cc: Danilo Krummrich <dakr@kernel.org>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: David Jeffery <djeffery@redhat.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Guixin Liu <kanie@linux.alibaba.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Ira Weiny <ira.weiny@intel.com>
Cc: Jann Horn <jannh@google.com>
Cc: Jason Gunthorpe <jgg@nvidia.com>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Joanthan Cameron <Jonathan.Cameron@huawei.com>
Cc: Joel Granados <joel.granados@kernel.org>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Lennart Poettering <lennart@poettering.net>
Cc: Leon Romanovsky <leon@kernel.org>
Cc: Leon Romanovsky <leonro@nvidia.com>
Cc: Lukas Wunner <lukas@wunner.de>
Cc: Marc Rutland <mark.rutland@arm.com>
Cc: Masahiro Yamada <masahiroy@kernel.org>
Cc: Matthew Maurer <mmaurer@google.com>
Cc: Miguel Ojeda <ojeda@kernel.org>
Cc: Myugnjoo Ham <myungjoo.ham@samsung.com>
Cc: Parav Pandit <parav@nvidia.com>
Cc: Pratyush Yadav <ptyadav@amazon.de>
Cc: Randy Dunlap <rdunlap@infradead.org>
Cc: Roman Gushchin <roman.gushchin@linux.dev>
Cc: Saeed Mahameed <saeedm@nvidia.com>
Cc: Samiullah Khawaja <skhawaja@google.com>
Cc: Song Liu <song@kernel.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Stuart Hayes <stuart.w.hayes@gmail.com>
Cc: Tejun Heo <tj@kernel.org>
Cc: Thomas Gleinxer <tglx@linutronix.de>
Cc: Thomas Weißschuh <linux@weissschuh.net>
Cc: Vincent Guittot <vincent.guittot@linaro.org>
Cc: William Tu <witu@nvidia.com>
Cc: Yoann Congal <yoann.congal@smile.fr>
Cc: Zhu Yanjun <yanjun.zhu@linux.dev>
Cc: Zijun Hu <quic_zijuhu@quicinc.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
 2025-11-27 14:24:39 -08:00
Pasha Tatashin
7c722a7f44 liveupdate: luo_file: implement file systems callbacks 
This patch implements the core mechanism for managing preserved files
throughout the live update lifecycle.  It provides the logic to invoke the
file handler callbacks (preserve, unpreserve, freeze, unfreeze, retrieve,
and finish) at the appropriate stages.

During the reboot phase, luo_file_freeze() serializes the final metadata
for each file (handler compatible string, token, and data handle) into a
memory region preserved by KHO.  In the new kernel, luo_file_deserialize()
reconstructs the in-memory file list from this data, preparing the session
for retrieval.

Link: https://lkml.kernel.org/r/20251125165850.3389713-7-pasha.tatashin@soleen.com
Signed-off-by: Pasha Tatashin <pasha.tatashin@soleen.com>
Reviewed-by: Mike Rapoport (Microsoft) <rppt@kernel.org>
Reviewed-by: Pratyush Yadav <pratyush@kernel.org>
Tested-by: David Matlack <dmatlack@google.com>
Cc: Aleksander Lobakin <aleksander.lobakin@intel.com>
Cc: Alexander Graf <graf@amazon.com>
Cc: Alice Ryhl <aliceryhl@google.com>
Cc: Andriy Shevchenko <andriy.shevchenko@linux.intel.com>
Cc: anish kumar <yesanishhere@gmail.com>
Cc: Anna Schumaker <anna.schumaker@oracle.com>
Cc: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
Cc: Bjorn Helgaas <bhelgaas@google.com>
Cc: Borislav Betkov <bp@alien8.de>
Cc: Chanwoo Choi <cw00.choi@samsung.com>
Cc: Chen Ridong <chenridong@huawei.com>
Cc: Chris Li <chrisl@kernel.org>
Cc: Christian Brauner <brauner@kernel.org>
Cc: Daniel Wagner <wagi@kernel.org>
Cc: Danilo Krummrich <dakr@kernel.org>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: David Jeffery <djeffery@redhat.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Guixin Liu <kanie@linux.alibaba.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Ira Weiny <ira.weiny@intel.com>
Cc: Jann Horn <jannh@google.com>
Cc: Jason Gunthorpe <jgg@nvidia.com>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Joanthan Cameron <Jonathan.Cameron@huawei.com>
Cc: Joel Granados <joel.granados@kernel.org>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Lennart Poettering <lennart@poettering.net>
Cc: Leon Romanovsky <leon@kernel.org>
Cc: Leon Romanovsky <leonro@nvidia.com>
Cc: Lukas Wunner <lukas@wunner.de>
Cc: Marc Rutland <mark.rutland@arm.com>
Cc: Masahiro Yamada <masahiroy@kernel.org>
Cc: Matthew Maurer <mmaurer@google.com>
Cc: Miguel Ojeda <ojeda@kernel.org>
Cc: Myugnjoo Ham <myungjoo.ham@samsung.com>
Cc: Parav Pandit <parav@nvidia.com>
Cc: Pratyush Yadav <ptyadav@amazon.de>
Cc: Randy Dunlap <rdunlap@infradead.org>
Cc: Roman Gushchin <roman.gushchin@linux.dev>
Cc: Saeed Mahameed <saeedm@nvidia.com>
Cc: Samiullah Khawaja <skhawaja@google.com>
Cc: Song Liu <song@kernel.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Stuart Hayes <stuart.w.hayes@gmail.com>
Cc: Tejun Heo <tj@kernel.org>
Cc: Thomas Gleinxer <tglx@linutronix.de>
Cc: Thomas Weißschuh <linux@weissschuh.net>
Cc: Vincent Guittot <vincent.guittot@linaro.org>
Cc: William Tu <witu@nvidia.com>
Cc: Yoann Congal <yoann.congal@smile.fr>
Cc: Zhu Yanjun <yanjun.zhu@linux.dev>
Cc: Zijun Hu <quic_zijuhu@quicinc.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
 2025-11-27 14:24:38 -08:00
Pasha Tatashin
81cd25d263 liveupdate: luo_core: add user interface 
Introduce the user-space interface for the Live Update Orchestrator via
ioctl commands, enabling external control over the live update process and
management of preserved resources.

The idea is that there is going to be a single userspace agent driving the
live update, therefore, only a single process can ever hold this device
opened at a time.

The following ioctl commands are introduced:

LIVEUPDATE_IOCTL_CREATE_SESSION
Provides a way for userspace to create a named session for grouping file
descriptors that need to be preserved. It returns a new file descriptor
representing the session.

LIVEUPDATE_IOCTL_RETRIEVE_SESSION
Allows the userspace agent in the new kernel to reclaim a preserved
session by its name, receiving a new file descriptor to manage the
restored resources.

Link: https://lkml.kernel.org/r/20251125165850.3389713-6-pasha.tatashin@soleen.com
Signed-off-by: Pasha Tatashin <pasha.tatashin@soleen.com>
Reviewed-by: Mike Rapoport (Microsoft) <rppt@kernel.org>
Reviewed-by: Pratyush Yadav <pratyush@kernel.org>
Tested-by: David Matlack <dmatlack@google.com>
Cc: Aleksander Lobakin <aleksander.lobakin@intel.com>
Cc: Alexander Graf <graf@amazon.com>
Cc: Alice Ryhl <aliceryhl@google.com>
Cc: Andriy Shevchenko <andriy.shevchenko@linux.intel.com>
Cc: anish kumar <yesanishhere@gmail.com>
Cc: Anna Schumaker <anna.schumaker@oracle.com>
Cc: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
Cc: Bjorn Helgaas <bhelgaas@google.com>
Cc: Borislav Betkov <bp@alien8.de>
Cc: Chanwoo Choi <cw00.choi@samsung.com>
Cc: Chen Ridong <chenridong@huawei.com>
Cc: Chris Li <chrisl@kernel.org>
Cc: Christian Brauner <brauner@kernel.org>
Cc: Daniel Wagner <wagi@kernel.org>
Cc: Danilo Krummrich <dakr@kernel.org>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: David Jeffery <djeffery@redhat.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Guixin Liu <kanie@linux.alibaba.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Ira Weiny <ira.weiny@intel.com>
Cc: Jann Horn <jannh@google.com>
Cc: Jason Gunthorpe <jgg@nvidia.com>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Joanthan Cameron <Jonathan.Cameron@huawei.com>
Cc: Joel Granados <joel.granados@kernel.org>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Lennart Poettering <lennart@poettering.net>
Cc: Leon Romanovsky <leon@kernel.org>
Cc: Leon Romanovsky <leonro@nvidia.com>
Cc: Lukas Wunner <lukas@wunner.de>
Cc: Marc Rutland <mark.rutland@arm.com>
Cc: Masahiro Yamada <masahiroy@kernel.org>
Cc: Matthew Maurer <mmaurer@google.com>
Cc: Miguel Ojeda <ojeda@kernel.org>
Cc: Myugnjoo Ham <myungjoo.ham@samsung.com>
Cc: Parav Pandit <parav@nvidia.com>
Cc: Pratyush Yadav <ptyadav@amazon.de>
Cc: Randy Dunlap <rdunlap@infradead.org>
Cc: Roman Gushchin <roman.gushchin@linux.dev>
Cc: Saeed Mahameed <saeedm@nvidia.com>
Cc: Samiullah Khawaja <skhawaja@google.com>
Cc: Song Liu <song@kernel.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Stuart Hayes <stuart.w.hayes@gmail.com>
Cc: Tejun Heo <tj@kernel.org>
Cc: Thomas Gleinxer <tglx@linutronix.de>
Cc: Thomas Weißschuh <linux@weissschuh.net>
Cc: Vincent Guittot <vincent.guittot@linaro.org>
Cc: William Tu <witu@nvidia.com>
Cc: Yoann Congal <yoann.congal@smile.fr>
Cc: Zhu Yanjun <yanjun.zhu@linux.dev>
Cc: Zijun Hu <quic_zijuhu@quicinc.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
 2025-11-27 14:24:38 -08:00
Pasha Tatashin
0153094d03 liveupdate: luo_session: add sessions support 
Introduce concept of "Live Update Sessions" within the LUO framework.  LUO
sessions provide a mechanism to group and manage `struct file *` instances
(representing file descriptors) that need to be preserved across a
kexec-based live update.

Each session is identified by a unique name and acts as a container for
file objects whose state is critical to a userspace workload, such as a
virtual machine or a high-performance database, aiming to maintain their
functionality across a kernel transition.

This groundwork establishes the framework for preserving file-backed state
across kernel updates, with the actual file data preservation mechanisms
to be implemented in subsequent patches.

[dan.carpenter@linaro.org: fix use after free in luo_session_deserialize()]
  Link: https://lkml.kernel.org/r/c5dd637d7eed3a3be48c5e9fedb881596a3b1f5a.1764163896.git.dan.carpenter@linaro.org
Link: https://lkml.kernel.org/r/20251125165850.3389713-5-pasha.tatashin@soleen.com
Signed-off-by: Pasha Tatashin <pasha.tatashin@soleen.com>
Signed-off-by: Dan Carpenter <dan.carpenter@linaro.org>
Reviewed-by: Mike Rapoport (Microsoft) <rppt@kernel.org>
Reviewed-by: Pratyush Yadav <pratyush@kernel.org>
Tested-by: David Matlack <dmatlack@google.com>
Cc: Aleksander Lobakin <aleksander.lobakin@intel.com>
Cc: Alexander Graf <graf@amazon.com>
Cc: Alice Ryhl <aliceryhl@google.com>
Cc: Andriy Shevchenko <andriy.shevchenko@linux.intel.com>
Cc: anish kumar <yesanishhere@gmail.com>
Cc: Anna Schumaker <anna.schumaker@oracle.com>
Cc: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
Cc: Bjorn Helgaas <bhelgaas@google.com>
Cc: Borislav Betkov <bp@alien8.de>
Cc: Chanwoo Choi <cw00.choi@samsung.com>
Cc: Chen Ridong <chenridong@huawei.com>
Cc: Chris Li <chrisl@kernel.org>
Cc: Christian Brauner <brauner@kernel.org>
Cc: Daniel Wagner <wagi@kernel.org>
Cc: Danilo Krummrich <dakr@kernel.org>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: David Jeffery <djeffery@redhat.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Guixin Liu <kanie@linux.alibaba.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Ira Weiny <ira.weiny@intel.com>
Cc: Jann Horn <jannh@google.com>
Cc: Jason Gunthorpe <jgg@nvidia.com>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Joanthan Cameron <Jonathan.Cameron@huawei.com>
Cc: Joel Granados <joel.granados@kernel.org>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Lennart Poettering <lennart@poettering.net>
Cc: Leon Romanovsky <leon@kernel.org>
Cc: Leon Romanovsky <leonro@nvidia.com>
Cc: Lukas Wunner <lukas@wunner.de>
Cc: Marc Rutland <mark.rutland@arm.com>
Cc: Masahiro Yamada <masahiroy@kernel.org>
Cc: Matthew Maurer <mmaurer@google.com>
Cc: Miguel Ojeda <ojeda@kernel.org>
Cc: Myugnjoo Ham <myungjoo.ham@samsung.com>
Cc: Parav Pandit <parav@nvidia.com>
Cc: Pratyush Yadav <ptyadav@amazon.de>
Cc: Randy Dunlap <rdunlap@infradead.org>
Cc: Roman Gushchin <roman.gushchin@linux.dev>
Cc: Saeed Mahameed <saeedm@nvidia.com>
Cc: Samiullah Khawaja <skhawaja@google.com>
Cc: Song Liu <song@kernel.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Stuart Hayes <stuart.w.hayes@gmail.com>
Cc: Tejun Heo <tj@kernel.org>
Cc: Thomas Gleinxer <tglx@linutronix.de>
Cc: Thomas Weißschuh <linux@weissschuh.net>
Cc: Vincent Guittot <vincent.guittot@linaro.org>
Cc: William Tu <witu@nvidia.com>
Cc: Yoann Congal <yoann.congal@smile.fr>
Cc: Zhu Yanjun <yanjun.zhu@linux.dev>
Cc: Zijun Hu <quic_zijuhu@quicinc.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
 2025-11-27 14:24:38 -08:00
Pasha Tatashin
db8bed8082 kexec: call liveupdate_reboot() before kexec 
Modify the kernel_kexec() to call liveupdate_reboot().

This ensures that the Live Update Orchestrator is notified just before the
kernel executes the kexec jump.  The liveupdate_reboot() function triggers
the final freeze event, allowing participating FDs perform last-minute
check or state saving within the blackout window.

If liveupdate_reboot() returns an error (indicating a failure during LUO
finalization), the kexec operation is aborted to prevent proceeding with
an inconsistent state.  An error is returned to user.

Link: https://lkml.kernel.org/r/20251125165850.3389713-4-pasha.tatashin@soleen.com
Signed-off-by: Pasha Tatashin <pasha.tatashin@soleen.com>
Reviewed-by: Mike Rapoport (Microsoft) <rppt@kernel.org>
Reviewed-by: Pratyush Yadav <pratyush@kernel.org>
Tested-by: David Matlack <dmatlack@google.com>
Cc: Aleksander Lobakin <aleksander.lobakin@intel.com>
Cc: Alexander Graf <graf@amazon.com>
Cc: Alice Ryhl <aliceryhl@google.com>
Cc: Andriy Shevchenko <andriy.shevchenko@linux.intel.com>
Cc: anish kumar <yesanishhere@gmail.com>
Cc: Anna Schumaker <anna.schumaker@oracle.com>
Cc: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
Cc: Bjorn Helgaas <bhelgaas@google.com>
Cc: Borislav Betkov <bp@alien8.de>
Cc: Chanwoo Choi <cw00.choi@samsung.com>
Cc: Chen Ridong <chenridong@huawei.com>
Cc: Chris Li <chrisl@kernel.org>
Cc: Christian Brauner <brauner@kernel.org>
Cc: Daniel Wagner <wagi@kernel.org>
Cc: Danilo Krummrich <dakr@kernel.org>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: David Jeffery <djeffery@redhat.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Guixin Liu <kanie@linux.alibaba.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Ira Weiny <ira.weiny@intel.com>
Cc: Jann Horn <jannh@google.com>
Cc: Jason Gunthorpe <jgg@nvidia.com>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Joanthan Cameron <Jonathan.Cameron@huawei.com>
Cc: Joel Granados <joel.granados@kernel.org>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Lennart Poettering <lennart@poettering.net>
Cc: Leon Romanovsky <leon@kernel.org>
Cc: Leon Romanovsky <leonro@nvidia.com>
Cc: Lukas Wunner <lukas@wunner.de>
Cc: Marc Rutland <mark.rutland@arm.com>
Cc: Masahiro Yamada <masahiroy@kernel.org>
Cc: Matthew Maurer <mmaurer@google.com>
Cc: Miguel Ojeda <ojeda@kernel.org>
Cc: Myugnjoo Ham <myungjoo.ham@samsung.com>
Cc: Parav Pandit <parav@nvidia.com>
Cc: Pratyush Yadav <ptyadav@amazon.de>
Cc: Randy Dunlap <rdunlap@infradead.org>
Cc: Roman Gushchin <roman.gushchin@linux.dev>
Cc: Saeed Mahameed <saeedm@nvidia.com>
Cc: Samiullah Khawaja <skhawaja@google.com>
Cc: Song Liu <song@kernel.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Stuart Hayes <stuart.w.hayes@gmail.com>
Cc: Tejun Heo <tj@kernel.org>
Cc: Thomas Gleinxer <tglx@linutronix.de>
Cc: Thomas Weißschuh <linux@weissschuh.net>
Cc: Vincent Guittot <vincent.guittot@linaro.org>
Cc: William Tu <witu@nvidia.com>
Cc: Yoann Congal <yoann.congal@smile.fr>
Cc: Zhu Yanjun <yanjun.zhu@linux.dev>
Cc: Zijun Hu <quic_zijuhu@quicinc.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
 2025-11-27 14:24:38 -08:00
Pasha Tatashin
1aece82100 liveupdate: luo_core: integrate with KHO 
Integrate the LUO with the KHO framework to enable passing LUO state
across a kexec reboot.

This patch implements the lifecycle integration with KHO:

1. Incoming State: During early boot (`early_initcall`), LUO checks if
   KHO is active. If so, it retrieves the "LUO" subtree, verifies the
   "luo-v1" compatibility string, and reads the `liveupdate-number` to
   track the update count.

2. Outgoing State: During late initialization (`late_initcall`), LUO
   allocates a new FDT for the next kernel, populates it with the basic
   header (compatible string and incremented update number), and
   registers it with KHO (`kho_add_subtree`).

3. Finalization: The `liveupdate_reboot()` notifier is updated to invoke
   `kho_finalize()`. This ensures that all memory segments marked for
   preservation are properly serialized before the kexec jump.

Link: https://lkml.kernel.org/r/20251125165850.3389713-3-pasha.tatashin@soleen.com
Signed-off-by: Pasha Tatashin <pasha.tatashin@soleen.com>
Reviewed-by: Pratyush Yadav <pratyush@kernel.org>
Tested-by: David Matlack <dmatlack@google.com>
Reviewed-by: Mike Rapoport (Microsoft) <rppt@kernel.org>
Cc: Aleksander Lobakin <aleksander.lobakin@intel.com>
Cc: Alexander Graf <graf@amazon.com>
Cc: Alice Ryhl <aliceryhl@google.com>
Cc: Andriy Shevchenko <andriy.shevchenko@linux.intel.com>
Cc: anish kumar <yesanishhere@gmail.com>
Cc: Anna Schumaker <anna.schumaker@oracle.com>
Cc: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
Cc: Bjorn Helgaas <bhelgaas@google.com>
Cc: Borislav Betkov <bp@alien8.de>
Cc: Chanwoo Choi <cw00.choi@samsung.com>
Cc: Chen Ridong <chenridong@huawei.com>
Cc: Chris Li <chrisl@kernel.org>
Cc: Christian Brauner <brauner@kernel.org>
Cc: Daniel Wagner <wagi@kernel.org>
Cc: Danilo Krummrich <dakr@kernel.org>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: David Jeffery <djeffery@redhat.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Guixin Liu <kanie@linux.alibaba.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Ira Weiny <ira.weiny@intel.com>
Cc: Jann Horn <jannh@google.com>
Cc: Jason Gunthorpe <jgg@nvidia.com>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Joanthan Cameron <Jonathan.Cameron@huawei.com>
Cc: Joel Granados <joel.granados@kernel.org>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Lennart Poettering <lennart@poettering.net>
Cc: Leon Romanovsky <leon@kernel.org>
Cc: Leon Romanovsky <leonro@nvidia.com>
Cc: Lukas Wunner <lukas@wunner.de>
Cc: Marc Rutland <mark.rutland@arm.com>
Cc: Masahiro Yamada <masahiroy@kernel.org>
Cc: Matthew Maurer <mmaurer@google.com>
Cc: Miguel Ojeda <ojeda@kernel.org>
Cc: Myugnjoo Ham <myungjoo.ham@samsung.com>
Cc: Parav Pandit <parav@nvidia.com>
Cc: Pratyush Yadav <ptyadav@amazon.de>
Cc: Randy Dunlap <rdunlap@infradead.org>
Cc: Roman Gushchin <roman.gushchin@linux.dev>
Cc: Saeed Mahameed <saeedm@nvidia.com>
Cc: Samiullah Khawaja <skhawaja@google.com>
Cc: Song Liu <song@kernel.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Stuart Hayes <stuart.w.hayes@gmail.com>
Cc: Tejun Heo <tj@kernel.org>
Cc: Thomas Gleinxer <tglx@linutronix.de>
Cc: Thomas Weißschuh <linux@weissschuh.net>
Cc: Vincent Guittot <vincent.guittot@linaro.org>
Cc: William Tu <witu@nvidia.com>
Cc: Yoann Congal <yoann.congal@smile.fr>
Cc: Zhu Yanjun <yanjun.zhu@linux.dev>
Cc: Zijun Hu <quic_zijuhu@quicinc.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
 2025-11-27 14:24:37 -08:00
Pasha Tatashin
9e2fd062fa liveupdate: luo_core: Live Update Orchestrator 
Patch series "Live Update Orchestrator", v8.

This series introduces the Live Update Orchestrator, a kernel subsystem
designed to facilitate live kernel updates using a kexec-based reboot. 
This capability is critical for cloud environments, allowing hypervisors
to be updated with minimal downtime for running virtual machines.  LUO
achieves this by preserving the state of selected resources, such as
memory, devices and their dependencies, across the kernel transition.

As a key feature, this series includes support for preserving memfd file
descriptors, which allows critical in-memory data, such as guest RAM or
any other large memory region, to be maintained in RAM across the kexec
reboot.

The other series that use LUO, are VFIO [1], IOMMU [2], and PCI [3]
preservations.

Github repo of this series [4].

The core of LUO is a framework for managing the lifecycle of preserved
resources through a userspace-driven interface. Key features include:

- Session Management
  Userspace agent (i.e. luod [5]) creates named sessions, each
  represented by a file descriptor (via centralized agent that controls
  /dev/liveupdate). The lifecycle of all preserved resources within a
  session is tied to this FD, ensuring automatic kernel cleanup if the
  controlling userspace agent crashes or exits unexpectedly.

- File Preservation
  A handler-based framework allows specific file types (demonstrated
  here with memfd) to be preserved. Handlers manage the serialization,
  restoration, and lifecycle of their specific file types.

- File-Lifecycle-Bound State
  A new mechanism for managing shared global state whose lifecycle is
  tied to the preservation of one or more files. This is crucial for
  subsystems like IOMMU or HugeTLB, where multiple file descriptors may
  depend on a single, shared underlying resource that must be preserved
  only once.

- KHO Integration
  LUO drives the Kexec Handover framework programmatically to pass its
  serialized metadata to the next kernel. The LUO state is finalized and
  added to the kexec image just before the reboot is triggered. In the
  future this step will also be removed once stateless KHO is
  merged [6].

- Userspace Interface
  Control is provided via ioctl commands on /dev/liveupdate for creating
  and retrieving sessions, as well as on session file descriptors for
  managing individual files.

- Testing
  The series includes a set of selftests, including userspace API
  validation, kexec-based lifecycle tests for various session and file
  scenarios, and a new in-kernel test module to validate the FLB logic.




Introduce LUO, a mechanism intended to facilitate kernel updates while
keeping designated devices operational across the transition (e.g., via
kexec).  The primary use case is updating hypervisors with minimal
disruption to running virtual machines.  For userspace side of hypervisor
update we have copyless migration.  LUO is for updating the kernel.

This initial patch lays the groundwork for the LUO subsystem.

Further functionality, including the implementation of state transition
logic, integration with KHO, and hooks for subsystems and file
descriptors, will be added in subsequent patches.

Create a character device at /dev/liveupdate.

A new uAPI header, <uapi/linux/liveupdate.h>, will define the necessary
structures.  The magic number for IOCTL is registered in
Documentation/userspace-api/ioctl/ioctl-number.rst.

Link: https://lkml.kernel.org/r/20251125165850.3389713-1-pasha.tatashin@soleen.com
Link: https://lkml.kernel.org/r/20251125165850.3389713-2-pasha.tatashin@soleen.com
Link: https://lore.kernel.org/all/20251018000713.677779-1-vipinsh@google.com/ [1]
Link: https://lore.kernel.org/linux-iommu/20250928190624.3735830-1-skhawaja@google.com [2]
Link: https://lore.kernel.org/linux-pci/20250916-luo-pci-v2-0-c494053c3c08@kernel.org [3]
Link: https://github.com/googleprodkernel/linux-liveupdate/tree/luo/v8 [4]
Link: https://tinyurl.com/luoddesign [5]
Link: https://lore.kernel.org/all/20251020100306.2709352-1-jasonmiu@google.com [6]
Link: https://lore.kernel.org/all/20251115233409.768044-1-pasha.tatashin@soleen.com [7]
Link: https://github.com/soleen/linux/blob/luo/v8b03/diff.v7.v8 [8]
Signed-off-by: Pasha Tatashin <pasha.tatashin@soleen.com>
Reviewed-by: Pratyush Yadav <pratyush@kernel.org>
Reviewed-by: Mike Rapoport (Microsoft) <rppt@kernel.org>
Tested-by: David Matlack <dmatlack@google.com>
Cc: Aleksander Lobakin <aleksander.lobakin@intel.com>
Cc: Alexander Graf <graf@amazon.com>
Cc: Alice Ryhl <aliceryhl@google.com>
Cc: Andriy Shevchenko <andriy.shevchenko@linux.intel.com>
Cc: anish kumar <yesanishhere@gmail.com>
Cc: Anna Schumaker <anna.schumaker@oracle.com>
Cc: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
Cc: Bjorn Helgaas <bhelgaas@google.com>
Cc: Borislav Betkov <bp@alien8.de>
Cc: Chanwoo Choi <cw00.choi@samsung.com>
Cc: Chen Ridong <chenridong@huawei.com>
Cc: Chris Li <chrisl@kernel.org>
Cc: Christian Brauner <brauner@kernel.org>
Cc: Daniel Wagner <wagi@kernel.org>
Cc: Danilo Krummrich <dakr@kernel.org>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: David Jeffery <djeffery@redhat.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Guixin Liu <kanie@linux.alibaba.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Ira Weiny <ira.weiny@intel.com>
Cc: Jann Horn <jannh@google.com>
Cc: Jason Gunthorpe <jgg@nvidia.com>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Joanthan Cameron <Jonathan.Cameron@huawei.com>
Cc: Joel Granados <joel.granados@kernel.org>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Lennart Poettering <lennart@poettering.net>
Cc: Leon Romanovsky <leon@kernel.org>
Cc: Leon Romanovsky <leonro@nvidia.com>
Cc: Lukas Wunner <lukas@wunner.de>
Cc: Marc Rutland <mark.rutland@arm.com>
Cc: Masahiro Yamada <masahiroy@kernel.org>
Cc: Matthew Maurer <mmaurer@google.com>
Cc: Miguel Ojeda <ojeda@kernel.org>
Cc: Myugnjoo Ham <myungjoo.ham@samsung.com>
Cc: Parav Pandit <parav@nvidia.com>
Cc: Randy Dunlap <rdunlap@infradead.org>
Cc: Roman Gushchin <roman.gushchin@linux.dev>
Cc: Saeed Mahameed <saeedm@nvidia.com>
Cc: Samiullah Khawaja <skhawaja@google.com>
Cc: Song Liu <song@kernel.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Stuart Hayes <stuart.w.hayes@gmail.com>
Cc: Tejun Heo <tj@kernel.org>
Cc: Thomas Gleinxer <tglx@linutronix.de>
Cc: Thomas Weißschuh <linux@weissschuh.net>
Cc: Vincent Guittot <vincent.guittot@linaro.org>
Cc: William Tu <witu@nvidia.com>
Cc: Yoann Congal <yoann.congal@smile.fr>
Cc: Zijun Hu <quic_zijuhu@quicinc.com>
Cc: Pratyush Yadav <ptyadav@amazon.de>
Cc: Zhu Yanjun <yanjun.zhu@linux.dev>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
 2025-11-27 14:24:37 -08:00
Pasha Tatashin
7bd3643f94 kho: add Kconfig option to enable KHO by default 
Currently, Kexec Handover must be explicitly enabled via the kernel
command line parameter `kho=on`.

For workloads that rely on KHO as a foundational requirement (such as the
upcoming Live Update Orchestrator), requiring an explicit boot parameter
adds redundant configuration steps.

Introduce CONFIG_KEXEC_HANDOVER_ENABLE_DEFAULT.  When selected, KHO
defaults to enabled.  This is equivalent to passing kho=on at boot.  The
behavior can still be disabled at runtime by passing kho=off.

Link: https://lkml.kernel.org/r/20251114190002.3311679-14-pasha.tatashin@soleen.com
Signed-off-by: Pasha Tatashin <pasha.tatashin@soleen.com>
Reviewed-by: Mike Rapoport (Microsoft) <rppt@kernel.org>
Reviewed-by: Pratyush Yadav <pratyush@kernel.org>
Cc: Alexander Graf <graf@amazon.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Baoquan He <bhe@redhat.com>
Cc: Coiby Xu <coxu@redhat.com>
Cc: Dave Vasilevsky <dave@vasilevsky.ca>
Cc: Eric Biggers <ebiggers@google.com>
Cc: Kees Cook <kees@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
 2025-11-27 14:24:37 -08:00
Pasha Tatashin
de51999e68 kho: allow memory preservation state updates after finalization 
Currently, kho_preserve_* and kho_unpreserve_* return -EBUSY if KHO is
finalized.  This enforces a rigid "freeze" on the KHO memory state.

With the introduction of re-entrant finalization, this restriction is no
longer necessary.  Users should be allowed to modify the preservation set
(e.g., adding new pages or freeing old ones) even after an initial
finalization.

The intended workflow for updates is now:
1. Modify state (preserve/unpreserve).
2. Call kho_finalize() again to refresh the serialized metadata.

Remove the kho_out.finalized checks to enable this dynamic behavior.

This also allows to convert kho_unpreserve_* functions to void, as they do
not return any error anymore.

Link: https://lkml.kernel.org/r/20251114190002.3311679-13-pasha.tatashin@soleen.com
Signed-off-by: Pasha Tatashin <pasha.tatashin@soleen.com>
Reviewed-by: Mike Rapoport (Microsoft) <rppt@kernel.org>
Reviewed-by: Pratyush Yadav <pratyush@kernel.org>
Cc: Alexander Graf <graf@amazon.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Baoquan He <bhe@redhat.com>
Cc: Coiby Xu <coxu@redhat.com>
Cc: Dave Vasilevsky <dave@vasilevsky.ca>
Cc: Eric Biggers <ebiggers@google.com>
Cc: Kees Cook <kees@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
 2025-11-27 14:24:36 -08:00
Pasha Tatashin
d7255959b6 kho: allow kexec load before KHO finalization 
Currently, kho_fill_kimage() checks kho_out.finalized and returns early if
KHO is not yet finalized.  This enforces a strict ordering where userspace
must finalize KHO *before* loading the kexec image.

This is restrictive, as standard workflows often involve loading the
target kernel early in the lifecycle and finalizing the state (FDT) only
immediately before the reboot.

Since the KHO FDT resides at a physical address allocated during boot
(kho_init), its location is stable.  We can attach this stable address to
the kimage regardless of whether the content has been finalized yet.

Relax the check to only require kho_enable, allowing kexec_file_load to
proceed at any time.

Link: https://lkml.kernel.org/r/20251114190002.3311679-12-pasha.tatashin@soleen.com
Signed-off-by: Pasha Tatashin <pasha.tatashin@soleen.com>
Reviewed-by: Mike Rapoport (Microsoft) <rppt@kernel.org>
Reviewed-by: Pratyush Yadav <pratyush@kernel.org>
Cc: Alexander Graf <graf@amazon.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Baoquan He <bhe@redhat.com>
Cc: Coiby Xu <coxu@redhat.com>
Cc: Dave Vasilevsky <dave@vasilevsky.ca>
Cc: Eric Biggers <ebiggers@google.com>
Cc: Kees Cook <kees@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
 2025-11-27 14:24:36 -08:00
Pasha Tatashin
8e068a286a kho: update FDT dynamically for subtree addition/removal 
Currently, sub-FDTs were tracked in a list (kho_out.sub_fdts) and the
final FDT is constructed entirely from scratch during kho_finalize().

We can maintain the FDT dynamically:
1. Initialize a valid, empty FDT in kho_init().
2. Use fdt_add_subnode and fdt_setprop in kho_add_subtree to
   update the FDT immediately when a subsystem registers.
3. Use fdt_del_node in kho_remove_subtree to remove entries.

This removes the need for the intermediate sub_fdts list and the
reconstruction logic in kho_finalize().  kho_finalize() now only needs to
trigger memory map serialization.

Link: https://lkml.kernel.org/r/20251114190002.3311679-11-pasha.tatashin@soleen.com
Signed-off-by: Pasha Tatashin <pasha.tatashin@soleen.com>
Reviewed-by: Mike Rapoport (Microsoft) <rppt@kernel.org>
Reviewed-by: Pratyush Yadav <pratyush@kernel.org>
Cc: Alexander Graf <graf@amazon.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Baoquan He <bhe@redhat.com>
Cc: Coiby Xu <coxu@redhat.com>
Cc: Dave Vasilevsky <dave@vasilevsky.ca>
Cc: Eric Biggers <ebiggers@google.com>
Cc: Kees Cook <kees@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
 2025-11-27 14:24:36 -08:00
Pasha Tatashin
9a4301f715 kho: remove abort functionality and support state refresh 
Previously, KHO required a dedicated kho_abort() function to clean up
state before kho_finalize() could be called again.  This was necessary to
handle complex unwind paths when using notifiers.

With the shift to direct memory preservation, the explicit abort step is
no longer strictly necessary.

Remove kho_abort() and refactor kho_finalize() to handle re-entry.  If
kho_finalize() is called while KHO is already finalized, it will now
automatically clean up the previous memory map and state before generating
a new one.  This allows the KHO state to be updated/refreshed simply by
triggering finalize again.

Update debugfs to return -EINVAL if userspace attempts to write 0 to the
finalize attribute, as explicit abort is no longer supported.

Link: https://lkml.kernel.org/r/20251114190002.3311679-10-pasha.tatashin@soleen.com
Suggested-by: Mike Rapoport (Microsoft) <rppt@kernel.org>
Signed-off-by: Pasha Tatashin <pasha.tatashin@soleen.com>
Reviewed-by: Mike Rapoport (Microsoft) <rppt@kernel.org>
Reviewed-by: Pratyush Yadav <pratyush@kernel.org>
Cc: Alexander Graf <graf@amazon.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Baoquan He <bhe@redhat.com>
Cc: Coiby Xu <coxu@redhat.com>
Cc: Dave Vasilevsky <dave@vasilevsky.ca>
Cc: Eric Biggers <ebiggers@google.com>
Cc: Kees Cook <kees@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
 2025-11-27 14:24:36 -08:00
Pasha Tatashin
efa3a9775a kho: remove global preserved_mem_map and store state in FDT 
Currently, the serialized memory map is tracked via
kho_out.preserved_mem_map and copied to the FDT during finalization.  This
double tracking is redundant.

Remove preserved_mem_map from kho_out.  Instead, maintain the physical
address of the head chunk directly in the preserved-memory-map FDT
property.

Introduce kho_update_memory_map() to manage this property. This function
handles:
1. Retrieving and freeing any existing serialized map (handling the
   abort/retry case).
2. Updating the FDT property with the new chunk address.

This establishes the FDT as the single source of truth for the handover
state.

Link: https://lkml.kernel.org/r/20251114190002.3311679-9-pasha.tatashin@soleen.com
Signed-off-by: Pasha Tatashin <pasha.tatashin@soleen.com>
Reviewed-by: Mike Rapoport (Microsoft) <rppt@kernel.org>
Reviewed-by: Pratyush Yadav <pratyush@kernel.org>
Cc: Alexander Graf <graf@amazon.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Baoquan He <bhe@redhat.com>
Cc: Coiby Xu <coxu@redhat.com>
Cc: Dave Vasilevsky <dave@vasilevsky.ca>
Cc: Eric Biggers <ebiggers@google.com>
Cc: Kees Cook <kees@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
 2025-11-27 14:24:35 -08:00
Pasha Tatashin
71960fe134 kho: simplify serialization and remove __kho_abort 
Currently, __kho_finalize() performs memory serialization in the middle of
FDT construction.  If FDT construction fails later, the function must
manually clean up the serialized memory via __kho_abort().

Refactor __kho_finalize() to perform kho_mem_serialize() only after the
FDT has been successfully constructed and finished.  This reordering has
two benefits:
1. It avoids expensive serialization work if FDT generation fails.
2. It removes the need for cleanup in the FDT error path.

As a result, the internal helper __kho_abort() is no longer needed for
internal error handling.  Inline its remaining logic (cleanup of the
preserved memory map) directly into kho_abort() and remove the helper.

Link: https://lkml.kernel.org/r/20251114190002.3311679-8-pasha.tatashin@soleen.com
Signed-off-by: Pasha Tatashin <pasha.tatashin@soleen.com>
Reviewed-by: Mike Rapoport (Microsoft) <rppt@kernel.org>
Reviewed-by: Pratyush Yadav <pratyush@kernel.org>
Cc: Alexander Graf <graf@amazon.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Baoquan He <bhe@redhat.com>
Cc: Coiby Xu <coxu@redhat.com>
Cc: Dave Vasilevsky <dave@vasilevsky.ca>
Cc: Eric Biggers <ebiggers@google.com>
Cc: Kees Cook <kees@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
 2025-11-27 14:24:35 -08:00
Pasha Tatashin
e268689a52 kho: always expose output FDT in debugfs 
Currently, the output FDT is added to debugfs only when KHO is finalized
and removed when aborted.

There is no need to hide the FDT based on the state.  Always expose it
starting from initialization.  This aids the transition toward removing
the explicit abort functionality and converting KHO to be fully stateless.

Link: https://lkml.kernel.org/r/20251114190002.3311679-7-pasha.tatashin@soleen.com
Signed-off-by: Pasha Tatashin <pasha.tatashin@soleen.com>
Reviewed-by: Mike Rapoport (Microsoft) <rppt@kernel.org>
Reviewed-by: Pratyush Yadav <pratyush@kernel.org>
Cc: Alexander Graf <graf@amazon.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Baoquan He <bhe@redhat.com>
Cc: Coiby Xu <coxu@redhat.com>
Cc: Dave Vasilevsky <dave@vasilevsky.ca>
Cc: Eric Biggers <ebiggers@google.com>
Cc: Kees Cook <kees@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
 2025-11-27 14:24:35 -08:00