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mm, vmstat: remove the NR_WRITEBACK_TEMP node_stat_item counter

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The only user of the counter (FUSE) was removed in commit 0c58a97f91
("fuse: remove tmp folio for writebacks and internal rb tree") so follow
the established pattern of removing the counter and hardcoding 0 in
meminfo output, as done recently with NR_BOUNCE.  Update documentation for
procfs, including for the value for Bounce that was missed when removing
its counter.

Also remove the mention of NR_WRITEBACK_TEMP implications from a comment
in wb_position_ratio(). The rest of the comment there about fuse setting
bdi->max_ratio to 1% is still correct.

[vbabka@suse.cz: v2]
  Link: https://lkml.kernel.org/r/5a848e15-6a57-4ecb-a015-d4f358b8a5d3@suse.cz
Link: https://lkml.kernel.org/r/20250625-nr_writeback_removal-v1-1-7f2a0df70faa@suse.cz
Signed-off-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Brendan Jackman <jackmanb@google.com>
Cc: Danilo Krummrich <dakr@kernel.org>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Jan Kara <jack@suse.cz>
Cc: Jeff Layton <jlayton@kernel.org>
Cc: Jeffle Xu <jefflexu@linux.alibaba.com>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Joanne Koong <joannelkoong@gmail.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Kirill A. Shuemov <kirill.shutemov@linux.intel.com>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Maxim Patlasov <mpatlasov@parallels.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Miklos Szeredi <mszeredi@redhat.com>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Tejun Heo <tj@kernel.org>
Cc: Zach O'Keefe <zokeefe@google.com>
Cc: Zi Yan <ziy@nvidia.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
This commit is contained in:
Vlastimil Babka 2025-06-25 17:51:52 +02:00 committed by Andrew Morton
parent ed6a9068a0
commit 8356a5a3b0
7 changed files with 8 additions and 13 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

8
Documentation/filesystems/proc.rst
View File

@ -1196,12 +1196,14 @@ SecPageTables
Memory consumed by secondary page tables, this currently includes
KVM mmu and IOMMU allocations on x86 and arm64.
NFS_Unstable
Always zero. Previous counted pages which had been written to
Always zero. Previously counted pages which had been written to
the server, but has not been committed to stable storage.
Bounce
Memory used for block device "bounce buffers"
Always zero. Previously memory used for block device
"bounce buffers".
WritebackTmp
Memory used by FUSE for temporary writeback buffers
Always zero. Previously memory used by FUSE for temporary
writeback buffers.
CommitLimit
Based on the overcommit ratio ('vm.overcommit_ratio'),
this is the total amount of memory currently available to

2
drivers/base/node.c
View File

@ -500,7 +500,7 @@ static ssize_t node_read_meminfo(struct device *dev,
nid, K(node_page_state(pgdat, NR_SECONDARY_PAGETABLE)),
nid, 0UL,
nid, 0UL,
nid, K(node_page_state(pgdat, NR_WRITEBACK_TEMP)),
nid, 0UL,
nid, K(sreclaimable +
node_page_state(pgdat, NR_KERNEL_MISC_RECLAIMABLE)),
nid, K(sreclaimable + sunreclaimable),

3
fs/proc/meminfo.c
View File

@ -121,8 +121,7 @@ static int meminfo_proc_show(struct seq_file *m, void *v)
show_val_kb(m, "NFS_Unstable: ", 0);
show_val_kb(m, "Bounce: ", 0);
show_val_kb(m, "WritebackTmp: ",
global_node_page_state(NR_WRITEBACK_TEMP));
show_val_kb(m, "WritebackTmp: ", 0);
show_val_kb(m, "CommitLimit: ", vm_commit_limit());
show_val_kb(m, "Committed_AS: ", committed);
seq_printf(m, "VmallocTotal: %8lu kB\n",

1
include/linux/mmzone.h
View File

@ -206,7 +206,6 @@ enum node_stat_item {
NR_FILE_PAGES,
NR_FILE_DIRTY,
NR_WRITEBACK,
NR_WRITEBACK_TEMP, /* Writeback using temporary buffers */
NR_SHMEM, /* shmem pages (included tmpfs/GEM pages) */
NR_SHMEM_THPS,
NR_SHMEM_PMDMAPPED,

4
mm/page-writeback.c
View File

@ -1101,9 +1101,7 @@ static void wb_position_ratio(struct dirty_throttle_control *dtc)
* such filesystems balance_dirty_pages always checks wb counters
* against wb limits. Even if global "nr_dirty" is under "freerun".
* This is especially important for fuse which sets bdi->max_ratio to
* 1% by default. Without strictlimit feature, fuse writeback may
* consume arbitrary amount of RAM because it is accounted in
* NR_WRITEBACK_TEMP which is not involved in calculating "nr_dirty".
* 1% by default.
*
* Here, in wb_position_ratio(), we calculate pos_ratio based on
* two values: wb_dirty and wb_thresh. Let's consider an example:

2
mm/show_mem.c
View File

@ -246,7 +246,6 @@ static void show_free_areas(unsigned int filter, nodemask_t *nodemask, int max_z
" shmem_pmdmapped:%lukB"
" anon_thp:%lukB"
#endif
" writeback_tmp:%lukB"
" kernel_stack:%lukB"
#ifdef CONFIG_SHADOW_CALL_STACK
" shadow_call_stack:%lukB"
@ -273,7 +272,6 @@ static void show_free_areas(unsigned int filter, nodemask_t *nodemask, int max_z
K(node_page_state(pgdat, NR_SHMEM_PMDMAPPED)),
K(node_page_state(pgdat, NR_ANON_THPS)),
#endif
K(node_page_state(pgdat, NR_WRITEBACK_TEMP)),
node_page_state(pgdat, NR_KERNEL_STACK_KB),
#ifdef CONFIG_SHADOW_CALL_STACK
node_page_state(pgdat, NR_KERNEL_SCS_KB),

1
mm/vmstat.c
View File

@ -1251,7 +1251,6 @@ const char * const vmstat_text[] = {
[I(NR_FILE_PAGES)] = "nr_file_pages",
[I(NR_FILE_DIRTY)] = "nr_dirty",
[I(NR_WRITEBACK)] = "nr_writeback",
[I(NR_WRITEBACK_TEMP)] = "nr_writeback_temp",
[I(NR_SHMEM)] = "nr_shmem",
[I(NR_SHMEM_THPS)] = "nr_shmem_hugepages",
[I(NR_SHMEM_PMDMAPPED)] = "nr_shmem_pmdmapped",