20 hotfixes. 10 are cc:stable and the remainder address post-6.16 issues

or aren't considered necessary for -stable kernels.  17 of these fixes are
 for MM.
 
 As usual, singletons all over the place, apart from a three-patch series
 of KHO followup work from Pasha which is actually also a bunch of
 singletons.
 -----BEGIN PGP SIGNATURE-----
 
 iHUEABYKAB0WIQTTMBEPP41GrTpTJgfdBJ7gKXxAjgUCaKfFVwAKCRDdBJ7gKXxA
 jvZGAQCCRTRgwnYsH0op9Rlxs72zokENbErSzXweWLez31pNpAD/S7bVSjjk1mXr
 BQ24ZadKUUomWkghwCusb9VomMeneg0=
 =+uBT
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Merge tag 'mm-hotfixes-stable-2025-08-21-18-17' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm

Pull misc fixes from Andrew Morton:
 "20 hotfixes. 10 are cc:stable and the remainder address post-6.16
  issues or aren't considered necessary for -stable kernels. 17 of these
  fixes are for MM.

  As usual, singletons all over the place, apart from a three-patch
  series of KHO followup work from Pasha which is actually also a bunch
  of singletons"

* tag 'mm-hotfixes-stable-2025-08-21-18-17' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm:
  mm/mremap: fix WARN with uffd that has remap events disabled
  mm/damon/sysfs-schemes: put damos dests dir after removing its files
  mm/migrate: fix NULL movable_ops if CONFIG_ZSMALLOC=m
  mm/damon/core: fix damos_commit_filter not changing allow
  mm/memory-failure: fix infinite UCE for VM_PFNMAP pfn
  MAINTAINERS: mark MGLRU as maintained
  mm: rust: add page.rs to MEMORY MANAGEMENT - RUST
  iov_iter: iterate_folioq: fix handling of offset >= folio size
  selftests/damon: fix selftests by installing drgn related script
  .mailmap: add entry for Easwar Hariharan
  selftests/mm: add test for invalid multi VMA operations
  mm/mremap: catch invalid multi VMA moves earlier
  mm/mremap: allow multi-VMA move when filesystem uses thp_get_unmapped_area
  mm/damon/core: fix commit_ops_filters by using correct nth function
  tools/testing: add linux/args.h header and fix radix, VMA tests
  mm/debug_vm_pgtable: clear page table entries at destroy_args()
  squashfs: fix memory leak in squashfs_fill_super
  kho: warn if KHO is disabled due to an error
  kho: mm: don't allow deferred struct page with KHO
  kho: init new_physxa->phys_bits to fix lockdep

.mailmap

@@ -226,6 +226,8 @@ Domen Puncer <domen@coderock.org>
 Douglas Gilbert <dougg@torque.net>
 Drew Fustini <fustini@kernel.org> <drew@pdp7.com>
 <duje@dujemihanovic.xyz> <duje.mihanovic@skole.hr>
+Easwar Hariharan <easwar.hariharan@linux.microsoft.com> <easwar.hariharan@intel.com>
+Easwar Hariharan <easwar.hariharan@linux.microsoft.com> <eahariha@linux.microsoft.com>
 Ed L. Cashin <ecashin@coraid.com>
 Elliot Berman <quic_eberman@quicinc.com> <eberman@codeaurora.org>
 Enric Balletbo i Serra <eballetbo@kernel.org> <enric.balletbo@collabora.com>

MAINTAINERS

@@ -16058,6 +16058,23 @@ F:	mm/mempolicy.c
 F:	mm/migrate.c
 F:	mm/migrate_device.c
 
+MEMORY MANAGEMENT - MGLRU (MULTI-GEN LRU)
+M:	Andrew Morton <akpm@linux-foundation.org>
+M:	Axel Rasmussen <axelrasmussen@google.com>
+M:	Yuanchu Xie <yuanchu@google.com>
+R:	Wei Xu <weixugc@google.com>
+L:	linux-mm@kvack.org
+S:	Maintained
+W:	http://www.linux-mm.org
+T:	git git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
+F:	Documentation/admin-guide/mm/multigen_lru.rst
+F:	Documentation/mm/multigen_lru.rst
+F:	include/linux/mm_inline.h
+F:	include/linux/mmzone.h
+F:	mm/swap.c
+F:	mm/vmscan.c
+F:	mm/workingset.c
+
 MEMORY MANAGEMENT - MISC
 M:	Andrew Morton <akpm@linux-foundation.org>
 M:	David Hildenbrand <david@redhat.com>
@@ -16248,8 +16265,10 @@ S:	Maintained
 W:	http://www.linux-mm.org
 T:	git git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
 F:	rust/helpers/mm.c
+F:	rust/helpers/page.c
 F:	rust/kernel/mm.rs
 F:	rust/kernel/mm/
+F:	rust/kernel/page.rs
 
 MEMORY MAPPING
 M:	Andrew Morton <akpm@linux-foundation.org>

fs/squashfs/super.c

@@ -187,10 +187,15 @@ static int squashfs_fill_super(struct super_block *sb, struct fs_context *fc)
 	unsigned short flags;
 	unsigned int fragments;
 	u64 lookup_table_start, xattr_id_table_start, next_table;
-	int err;
+	int err, devblksize = sb_min_blocksize(sb, SQUASHFS_DEVBLK_SIZE);
 
 	TRACE("Entered squashfs_fill_superblock\n");
 
+	if (!devblksize) {
+		errorf(fc, "squashfs: unable to set blocksize\n");
+		return -EINVAL;
+	}
+
 	sb->s_fs_info = kzalloc(sizeof(*msblk), GFP_KERNEL);
 	if (sb->s_fs_info == NULL) {
 		ERROR("Failed to allocate squashfs_sb_info\n");
@@ -201,12 +206,7 @@ static int squashfs_fill_super(struct super_block *sb, struct fs_context *fc)
 
 	msblk->panic_on_errors = (opts->errors == Opt_errors_panic);
 
-	msblk->devblksize = sb_min_blocksize(sb, SQUASHFS_DEVBLK_SIZE);
+	msblk->devblksize = devblksize;
-	if (!msblk->devblksize) {
-		errorf(fc, "squashfs: unable to set blocksize\n");
-		return -EINVAL;
-	}
-
 	msblk->devblksize_log2 = ffz(~msblk->devblksize);
 
 	mutex_init(&msblk->meta_index_mutex);

include/linux/iov_iter.h

@@ -160,7 +160,7 @@ size_t iterate_folioq(struct iov_iter *iter, size_t len, void *priv, void *priv2
 
 	do {
 		struct folio *folio = folioq_folio(folioq, slot);
-		size_t part, remain, consumed;
+		size_t part, remain = 0, consumed;
 		size_t fsize;
 		void *base;
 
@@ -168,14 +168,16 @@ size_t iterate_folioq(struct iov_iter *iter, size_t len, void *priv, void *priv2
 			break;
 
 		fsize = folioq_folio_size(folioq, slot);
-		base = kmap_local_folio(folio, skip);
+		if (skip < fsize) {
-		part = umin(len, PAGE_SIZE - skip % PAGE_SIZE);
+			base = kmap_local_folio(folio, skip);
-		remain = step(base, progress, part, priv, priv2);
+			part = umin(len, PAGE_SIZE - skip % PAGE_SIZE);
-		kunmap_local(base);
+			remain = step(base, progress, part, priv, priv2);
-		consumed = part - remain;
+			kunmap_local(base);
-		len -= consumed;
+			consumed = part - remain;
-		progress += consumed;
+			len -= consumed;
-		skip += consumed;
+			progress += consumed;
+			skip += consumed;
+		}
 		if (skip >= fsize) {
 			skip = 0;
 			slot++;

include/linux/migrate.h

@@ -79,6 +79,7 @@ void migration_entry_wait_on_locked(swp_entry_t entry, spinlock_t *ptl)
 void folio_migrate_flags(struct folio *newfolio, struct folio *folio);
 int folio_migrate_mapping(struct address_space *mapping,
 		struct folio *newfolio, struct folio *folio, int extra_count);
+int set_movable_ops(const struct movable_operations *ops, enum pagetype type);
 
 #else
 
@@ -100,6 +101,10 @@ static inline int migrate_huge_page_move_mapping(struct address_space *mapping,
 {
 	return -ENOSYS;
 }
+static inline int set_movable_ops(const struct movable_operations *ops, enum pagetype type)
+{
+	return -ENOSYS;
+}
 
 #endif /* CONFIG_MIGRATION */
 

kernel/Kconfig.kexec

@@ -97,6 +97,7 @@ config KEXEC_JUMP
 config KEXEC_HANDOVER
 	bool "kexec handover"
 	depends on ARCH_SUPPORTS_KEXEC_HANDOVER && ARCH_SUPPORTS_KEXEC_FILE
+	depends on !DEFERRED_STRUCT_PAGE_INIT
 	select MEMBLOCK_KHO_SCRATCH
 	select KEXEC_FILE
 	select DEBUG_FS

kernel/kexec_handover.c

@@ -144,14 +144,34 @@ static int __kho_preserve_order(struct kho_mem_track *track, unsigned long pfn,
 				unsigned int order)
 {
 	struct kho_mem_phys_bits *bits;
-	struct kho_mem_phys *physxa;
+	struct kho_mem_phys *physxa, *new_physxa;
 	const unsigned long pfn_high = pfn >> order;
 
 	might_sleep();
 
-	physxa = xa_load_or_alloc(&track->orders, order, sizeof(*physxa));
+	physxa = xa_load(&track->orders, order);
-	if (IS_ERR(physxa))
+	if (!physxa) {
-		return PTR_ERR(physxa);
+		int err;
+
+		new_physxa = kzalloc(sizeof(*physxa), GFP_KERNEL);
+		if (!new_physxa)
+			return -ENOMEM;
+
+		xa_init(&new_physxa->phys_bits);
+		physxa = xa_cmpxchg(&track->orders, order, NULL, new_physxa,
+				    GFP_KERNEL);
+
+		err = xa_err(physxa);
+		if (err || physxa) {
+			xa_destroy(&new_physxa->phys_bits);
+			kfree(new_physxa);
+
+			if (err)
+				return err;
+		} else {
+			physxa = new_physxa;
+		}
+	}
 
 	bits = xa_load_or_alloc(&physxa->phys_bits, pfn_high / PRESERVE_BITS,
 				sizeof(*bits));
@@ -544,6 +564,7 @@ err_free_scratch_areas:
 err_free_scratch_desc:
 	memblock_free(kho_scratch, kho_scratch_cnt * sizeof(*kho_scratch));
 err_disable_kho:
+	pr_warn("Failed to reserve scratch area, disabling kexec handover\n");
 	kho_enable = false;
 }
 

mm/balloon_compaction.c

@@ -254,4 +254,10 @@ const struct movable_operations balloon_mops = {
 	.putback_page = balloon_page_putback,
 };
 
+static int __init balloon_init(void)
+{
+	return set_movable_ops(&balloon_mops, PGTY_offline);
+}
+core_initcall(balloon_init);
+
 #endif /* CONFIG_BALLOON_COMPACTION */

mm/damon/core.c

@@ -845,6 +845,18 @@ static struct damos_filter *damos_nth_filter(int n, struct damos *s)
 	return NULL;
 }
 
+static struct damos_filter *damos_nth_ops_filter(int n, struct damos *s)
+{
+	struct damos_filter *filter;
+	int i = 0;
+
+	damos_for_each_ops_filter(filter, s) {
+		if (i++ == n)
+			return filter;
+	}
+	return NULL;
+}
+
 static void damos_commit_filter_arg(
 		struct damos_filter *dst, struct damos_filter *src)
 {
@@ -871,6 +883,7 @@ static void damos_commit_filter(
 {
 	dst->type = src->type;
 	dst->matching = src->matching;
+	dst->allow = src->allow;
 	damos_commit_filter_arg(dst, src);
 }
 
@@ -908,7 +921,7 @@ static int damos_commit_ops_filters(struct damos *dst, struct damos *src)
 	int i = 0, j = 0;
 
 	damos_for_each_ops_filter_safe(dst_filter, next, dst) {
-		src_filter = damos_nth_filter(i++, src);
+		src_filter = damos_nth_ops_filter(i++, src);
 		if (src_filter)
 			damos_commit_filter(dst_filter, src_filter);
 		else

mm/damon/sysfs-schemes.c

@@ -2158,8 +2158,8 @@ static void damon_sysfs_scheme_rm_dirs(struct damon_sysfs_scheme *scheme)
 {
 	damon_sysfs_access_pattern_rm_dirs(scheme->access_pattern);
 	kobject_put(&scheme->access_pattern->kobj);
-	kobject_put(&scheme->dests->kobj);
 	damos_sysfs_dests_rm_dirs(scheme->dests);
+	kobject_put(&scheme->dests->kobj);
 	damon_sysfs_quotas_rm_dirs(scheme->quotas);
 	kobject_put(&scheme->quotas->kobj);
 	kobject_put(&scheme->watermarks->kobj);

mm/debug_vm_pgtable.c

@@ -990,29 +990,34 @@ static void __init destroy_args(struct pgtable_debug_args *args)
 
 	/* Free page table entries */
 	if (args->start_ptep) {
+		pmd_clear(args->pmdp);
 		pte_free(args->mm, args->start_ptep);
 		mm_dec_nr_ptes(args->mm);
 	}
 
 	if (args->start_pmdp) {
+		pud_clear(args->pudp);
 		pmd_free(args->mm, args->start_pmdp);
 		mm_dec_nr_pmds(args->mm);
 	}
 
 	if (args->start_pudp) {
+		p4d_clear(args->p4dp);
 		pud_free(args->mm, args->start_pudp);
 		mm_dec_nr_puds(args->mm);
 	}
 
-	if (args->start_p4dp)
+	if (args->start_p4dp) {
+		pgd_clear(args->pgdp);
 		p4d_free(args->mm, args->start_p4dp);
+	}
 
 	/* Free vma and mm struct */
 	if (args->vma)
 		vm_area_free(args->vma);
 
 	if (args->mm)
-		mmdrop(args->mm);
+		mmput(args->mm);
 }
 
 static struct page * __init

mm/memory-failure.c

@@ -853,9 +853,17 @@ static int hwpoison_hugetlb_range(pte_t *ptep, unsigned long hmask,
 #define hwpoison_hugetlb_range	NULL
 #endif
 
+static int hwpoison_test_walk(unsigned long start, unsigned long end,
+			     struct mm_walk *walk)
+{
+	/* We also want to consider pages mapped into VM_PFNMAP. */
+	return 0;
+}
+
 static const struct mm_walk_ops hwpoison_walk_ops = {
 	.pmd_entry = hwpoison_pte_range,
 	.hugetlb_entry = hwpoison_hugetlb_range,
+	.test_walk = hwpoison_test_walk,
 	.walk_lock = PGWALK_RDLOCK,
 };
 

mm/migrate.c

@@ -43,8 +43,6 @@
 #include <linux/sched/sysctl.h>
 #include <linux/memory-tiers.h>
 #include <linux/pagewalk.h>
-#include <linux/balloon_compaction.h>
-#include <linux/zsmalloc.h>
 
 #include <asm/tlbflush.h>
 
@@ -53,6 +51,33 @@
 #include "internal.h"
 #include "swap.h"
 
+static const struct movable_operations *offline_movable_ops;
+static const struct movable_operations *zsmalloc_movable_ops;
+
+int set_movable_ops(const struct movable_operations *ops, enum pagetype type)
+{
+	/*
+	 * We only allow for selected types and don't handle concurrent
+	 * registration attempts yet.
+	 */
+	switch (type) {
+	case PGTY_offline:
+		if (offline_movable_ops && ops)
+			return -EBUSY;
+		offline_movable_ops = ops;
+		break;
+	case PGTY_zsmalloc:
+		if (zsmalloc_movable_ops && ops)
+			return -EBUSY;
+		zsmalloc_movable_ops = ops;
+		break;
+	default:
+		return -EINVAL;
+	}
+	return 0;
+}
+EXPORT_SYMBOL_GPL(set_movable_ops);
+
 static const struct movable_operations *page_movable_ops(struct page *page)
 {
 	VM_WARN_ON_ONCE_PAGE(!page_has_movable_ops(page), page);
@@ -62,15 +87,12 @@ static const struct movable_operations *page_movable_ops(struct page *page)
 	 * it as movable, the page type must be sticky until the page gets freed
 	 * back to the buddy.
 	 */
-#ifdef CONFIG_BALLOON_COMPACTION
 	if (PageOffline(page))
 		/* Only balloon compaction sets PageOffline pages movable. */
-		return &balloon_mops;
+		return offline_movable_ops;
-#endif /* CONFIG_BALLOON_COMPACTION */
-#if defined(CONFIG_ZSMALLOC) && defined(CONFIG_COMPACTION)
 	if (PageZsmalloc(page))
-		return &zsmalloc_mops;
+		return zsmalloc_movable_ops;
-#endif /* defined(CONFIG_ZSMALLOC) && defined(CONFIG_COMPACTION) */
+
 	return NULL;
 }
 

mm/mremap.c

@@ -323,6 +323,25 @@ static inline bool arch_supports_page_table_move(void)
 }
 #endif
 
+static inline bool uffd_supports_page_table_move(struct pagetable_move_control *pmc)
+{
+	/*
+	 * If we are moving a VMA that has uffd-wp registered but with
+	 * remap events disabled (new VMA will not be registered with uffd), we
+	 * need to ensure that the uffd-wp state is cleared from all pgtables.
+	 * This means recursing into lower page tables in move_page_tables().
+	 *
+	 * We might get called with VMAs reversed when recovering from a
+	 * failed page table move. In that case, the
+	 * "old"-but-actually-"originally new" VMA during recovery will not have
+	 * a uffd context. Recursing into lower page tables during the original
+	 * move but not during the recovery move will cause trouble, because we
+	 * run into already-existing page tables. So check both VMAs.
+	 */
+	return !vma_has_uffd_without_event_remap(pmc->old) &&
+	       !vma_has_uffd_without_event_remap(pmc->new);
+}
+
 #ifdef CONFIG_HAVE_MOVE_PMD
 static bool move_normal_pmd(struct pagetable_move_control *pmc,
 			pmd_t *old_pmd, pmd_t *new_pmd)
@@ -335,6 +354,8 @@ static bool move_normal_pmd(struct pagetable_move_control *pmc,
 
 	if (!arch_supports_page_table_move())
 		return false;
+	if (!uffd_supports_page_table_move(pmc))
+		return false;
 	/*
 	 * The destination pmd shouldn't be established, free_pgtables()
 	 * should have released it.
@@ -361,15 +382,6 @@ static bool move_normal_pmd(struct pagetable_move_control *pmc,
 	if (WARN_ON_ONCE(!pmd_none(*new_pmd)))
 		return false;
 
-	/* If this pmd belongs to a uffd vma with remap events disabled, we need
-	 * to ensure that the uffd-wp state is cleared from all pgtables. This
-	 * means recursing into lower page tables in move_page_tables(), and we
-	 * can reuse the existing code if we simply treat the entry as "not
-	 * moved".
-	 */
-	if (vma_has_uffd_without_event_remap(vma))
-		return false;
-
 	/*
 	 * We don't have to worry about the ordering of src and dst
 	 * ptlocks because exclusive mmap_lock prevents deadlock.
@@ -418,6 +430,8 @@ static bool move_normal_pud(struct pagetable_move_control *pmc,
 
 	if (!arch_supports_page_table_move())
 		return false;
+	if (!uffd_supports_page_table_move(pmc))
+		return false;
 	/*
 	 * The destination pud shouldn't be established, free_pgtables()
 	 * should have released it.
@@ -425,15 +439,6 @@ static bool move_normal_pud(struct pagetable_move_control *pmc,
 	if (WARN_ON_ONCE(!pud_none(*new_pud)))
 		return false;
 
-	/* If this pud belongs to a uffd vma with remap events disabled, we need
-	 * to ensure that the uffd-wp state is cleared from all pgtables. This
-	 * means recursing into lower page tables in move_page_tables(), and we
-	 * can reuse the existing code if we simply treat the entry as "not
-	 * moved".
-	 */
-	if (vma_has_uffd_without_event_remap(vma))
-		return false;
-
 	/*
 	 * We don't have to worry about the ordering of src and dst
 	 * ptlocks because exclusive mmap_lock prevents deadlock.
@@ -1620,7 +1625,7 @@ static void notify_uffd(struct vma_remap_struct *vrm, bool failed)
 
 static bool vma_multi_allowed(struct vm_area_struct *vma)
 {
-	struct file *file;
+	struct file *file = vma->vm_file;
 
 	/*
 	 * We can't support moving multiple uffd VMAs as notify requires
@@ -1633,15 +1638,17 @@ static bool vma_multi_allowed(struct vm_area_struct *vma)
 	 * Custom get unmapped area might result in MREMAP_FIXED not
 	 * being obeyed.
 	 */
-	file = vma->vm_file;
+	if (!file || !file->f_op->get_unmapped_area)
-	if (file && !vma_is_shmem(vma) && !is_vm_hugetlb_page(vma)) {
+		return true;
-		const struct file_operations *fop = file->f_op;
+	/* Known good. */
+	if (vma_is_shmem(vma))
+		return true;
+	if (is_vm_hugetlb_page(vma))
+		return true;
+	if (file->f_op->get_unmapped_area == thp_get_unmapped_area)
+		return true;
 
-		if (fop->get_unmapped_area)
+	return false;
-			return false;
-	}
-
-	return true;
 }
 
 static int check_prep_vma(struct vma_remap_struct *vrm)
@@ -1818,10 +1825,11 @@ static unsigned long remap_move(struct vma_remap_struct *vrm)
 	unsigned long start = vrm->addr;
 	unsigned long end = vrm->addr + vrm->old_len;
 	unsigned long new_addr = vrm->new_addr;
-	bool allowed = true, seen_vma = false;
 	unsigned long target_addr = new_addr;
 	unsigned long res = -EFAULT;
 	unsigned long last_end;
+	bool seen_vma = false;
+
 	VMA_ITERATOR(vmi, current->mm, start);
 
 	/*
@@ -1834,9 +1842,7 @@ static unsigned long remap_move(struct vma_remap_struct *vrm)
 		unsigned long addr = max(vma->vm_start, start);
 		unsigned long len = min(end, vma->vm_end) - addr;
 		unsigned long offset, res_vma;
-
+		bool multi_allowed;
-		if (!allowed)
-			return -EFAULT;
 
 		/* No gap permitted at the start of the range. */
 		if (!seen_vma && start < vma->vm_start)
@@ -1865,9 +1871,15 @@ static unsigned long remap_move(struct vma_remap_struct *vrm)
 		vrm->new_addr = target_addr + offset;
 		vrm->old_len = vrm->new_len = len;
 
-		allowed = vma_multi_allowed(vma);
+		multi_allowed = vma_multi_allowed(vma);
-		if (seen_vma && !allowed)
+		if (!multi_allowed) {
-			return -EFAULT;
+			/* This is not the first VMA, abort immediately. */
+			if (seen_vma)
+				return -EFAULT;
+			/* This is the first, but there are more, abort. */
+			if (vma->vm_end < end)
+				return -EFAULT;
+		}
 
 		res_vma = check_prep_vma(vrm);
 		if (!res_vma)
@@ -1876,7 +1888,7 @@ static unsigned long remap_move(struct vma_remap_struct *vrm)
 			return res_vma;
 
 		if (!seen_vma) {
-			VM_WARN_ON_ONCE(allowed && res_vma != new_addr);
+			VM_WARN_ON_ONCE(multi_allowed && res_vma != new_addr);
 			res = res_vma;
 		}
 

mm/zsmalloc.c

@@ -2246,8 +2246,15 @@ EXPORT_SYMBOL_GPL(zs_destroy_pool);
 
 static int __init zs_init(void)
 {
+	int rc __maybe_unused;
+
 #ifdef CONFIG_ZPOOL
 	zpool_register_driver(&zs_zpool_driver);
+#endif
+#ifdef CONFIG_COMPACTION
+	rc = set_movable_ops(&zsmalloc_mops, PGTY_zsmalloc);
+	if (rc)
+		return rc;
 #endif
 	zs_stat_init();
 	return 0;
@@ -2257,6 +2264,9 @@ static void __exit zs_exit(void)
 {
 #ifdef CONFIG_ZPOOL
 	zpool_unregister_driver(&zs_zpool_driver);
+#endif
+#ifdef CONFIG_COMPACTION
+	set_movable_ops(NULL, PGTY_zsmalloc);
 #endif
 	zs_stat_exit();
 }

tools/include/linux/args.h

@@ -0,0 +1,28 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+
+#ifndef _LINUX_ARGS_H
+#define _LINUX_ARGS_H
+
+/*
+ * How do these macros work?
+ *
+ * In __COUNT_ARGS() _0 to _12 are just placeholders from the start
+ * in order to make sure _n is positioned over the correct number
+ * from 12 to 0 (depending on X, which is a variadic argument list).
+ * They serve no purpose other than occupying a position. Since each
+ * macro parameter must have a distinct identifier, those identifiers
+ * are as good as any.
+ *
+ * In COUNT_ARGS() we use actual integers, so __COUNT_ARGS() returns
+ * that as _n.
+ */
+
+/* This counts to 15. Any more, it will return 16th argument. */
+#define __COUNT_ARGS(_0, _1, _2, _3, _4, _5, _6, _7, _8, _9, _10, _11, _12, _13, _14, _15, _n, X...) _n
+#define COUNT_ARGS(X...) __COUNT_ARGS(, ##X, 15, 14, 13, 12, 11, 10, 9, 8, 7, 6, 5, 4, 3, 2, 1, 0)
+
+/* Concatenate two parameters, but allow them to be expanded beforehand. */
+#define __CONCAT(a, b) a ## b
+#define CONCATENATE(a, b) __CONCAT(a, b)
+
+#endif	/* _LINUX_ARGS_H */

tools/testing/selftests/damon/Makefile

@@ -4,6 +4,7 @@
 TEST_GEN_FILES += access_memory access_memory_even
 
 TEST_FILES = _damon_sysfs.py
+TEST_FILES += drgn_dump_damon_status.py
 
 # functionality tests
 TEST_PROGS += sysfs.sh

tools/testing/selftests/mm/mremap_test.c

@@ -5,10 +5,14 @@
 #define _GNU_SOURCE
 
 #include <errno.h>
+#include <fcntl.h>
+#include <linux/userfaultfd.h>
 #include <stdlib.h>
 #include <stdio.h>
 #include <string.h>
+#include <sys/ioctl.h>
 #include <sys/mman.h>
+#include <syscall.h>
 #include <time.h>
 #include <stdbool.h>
 
@@ -168,6 +172,7 @@ static bool is_range_mapped(FILE *maps_fp, unsigned long start,
 
 		if (first_val <= start && second_val >= end) {
 			success = true;
+			fflush(maps_fp);
 			break;
 		}
 	}
@@ -175,6 +180,15 @@ static bool is_range_mapped(FILE *maps_fp, unsigned long start,
 	return success;
 }
 
+/* Check if [ptr, ptr + size) mapped in /proc/self/maps. */
+static bool is_ptr_mapped(FILE *maps_fp, void *ptr, unsigned long size)
+{
+	unsigned long start = (unsigned long)ptr;
+	unsigned long end = start + size;
+
+	return is_range_mapped(maps_fp, start, end);
+}
+
 /*
  * Returns the start address of the mapping on success, else returns
  * NULL on failure.
@@ -733,6 +747,249 @@ out:
 				      dont_unmap ? " [dontunnmap]" : "");
 }
 
+#ifdef __NR_userfaultfd
+static void mremap_move_multi_invalid_vmas(FILE *maps_fp,
+		unsigned long page_size)
+{
+	char *test_name = "mremap move multiple invalid vmas";
+	const size_t size = 10 * page_size;
+	bool success = true;
+	char *ptr, *tgt_ptr;
+	int uffd, err, i;
+	void *res;
+	struct uffdio_api api = {
+		.api = UFFD_API,
+		.features = UFFD_EVENT_PAGEFAULT,
+	};
+
+	uffd = syscall(__NR_userfaultfd, O_NONBLOCK);
+	if (uffd == -1) {
+		err = errno;
+		perror("userfaultfd");
+		if (err == EPERM) {
+			ksft_test_result_skip("%s - missing uffd", test_name);
+			return;
+		}
+		success = false;
+		goto out;
+	}
+	if (ioctl(uffd, UFFDIO_API, &api)) {
+		perror("ioctl UFFDIO_API");
+		success = false;
+		goto out_close_uffd;
+	}
+
+	ptr = mmap(NULL, size, PROT_READ | PROT_WRITE,
+		   MAP_PRIVATE | MAP_ANON, -1, 0);
+	if (ptr == MAP_FAILED) {
+		perror("mmap");
+		success = false;
+		goto out_close_uffd;
+	}
+
+	tgt_ptr = mmap(NULL, size, PROT_NONE, MAP_PRIVATE | MAP_ANON, -1, 0);
+	if (tgt_ptr == MAP_FAILED) {
+		perror("mmap");
+		success = false;
+		goto out_close_uffd;
+	}
+	if (munmap(tgt_ptr, size)) {
+		perror("munmap");
+		success = false;
+		goto out_unmap;
+	}
+
+	/*
+	 * Unmap so we end up with:
+	 *
+	 *  0   2   4   6   8   10 offset in buffer
+	 * |*| |*| |*| |*| |*|
+	 * |*| |*| |*| |*| |*|
+	 *
+	 * Additionally, register each with UFFD.
+	 */
+	for (i = 0; i < 10; i += 2) {
+		void *unmap_ptr = &ptr[(i + 1) * page_size];
+		unsigned long start = (unsigned long)&ptr[i * page_size];
+		struct uffdio_register reg = {
+			.range = {
+				.start = start,
+				.len = page_size,
+			},
+			.mode = UFFDIO_REGISTER_MODE_MISSING,
+		};
+
+		if (ioctl(uffd, UFFDIO_REGISTER, &reg) == -1) {
+			perror("ioctl UFFDIO_REGISTER");
+			success = false;
+			goto out_unmap;
+		}
+		if (munmap(unmap_ptr, page_size)) {
+			perror("munmap");
+			success = false;
+			goto out_unmap;
+		}
+	}
+
+	/*
+	 * Now try to move the entire range which is invalid for multi VMA move.
+	 *
+	 * This will fail, and no VMA should be moved, as we check this ahead of
+	 * time.
+	 */
+	res = mremap(ptr, size, size, MREMAP_MAYMOVE | MREMAP_FIXED, tgt_ptr);
+	err = errno;
+	if (res != MAP_FAILED) {
+		fprintf(stderr, "mremap() succeeded for multi VMA uffd armed\n");
+		success = false;
+		goto out_unmap;
+	}
+	if (err != EFAULT) {
+		errno = err;
+		perror("mrmeap() unexpected error");
+		success = false;
+		goto out_unmap;
+	}
+	if (is_ptr_mapped(maps_fp, tgt_ptr, page_size)) {
+		fprintf(stderr,
+			"Invalid uffd-armed VMA at start of multi range moved\n");
+		success = false;
+		goto out_unmap;
+	}
+
+	/*
+	 * Now try to move a single VMA, this should succeed as not multi VMA
+	 * move.
+	 */
+	res = mremap(ptr, page_size, page_size,
+		     MREMAP_MAYMOVE | MREMAP_FIXED, tgt_ptr);
+	if (res == MAP_FAILED) {
+		perror("mremap single invalid-multi VMA");
+		success = false;
+		goto out_unmap;
+	}
+
+	/*
+	 * Unmap the VMA, and remap a non-uffd registered (therefore, multi VMA
+	 * move valid) VMA at the start of ptr range.
+	 */
+	if (munmap(tgt_ptr, page_size)) {
+		perror("munmap");
+		success = false;
+		goto out_unmap;
+	}
+	res = mmap(ptr, page_size, PROT_READ | PROT_WRITE,
+		   MAP_PRIVATE | MAP_ANON | MAP_FIXED, -1, 0);
+	if (res == MAP_FAILED) {
+		perror("mmap");
+		success = false;
+		goto out_unmap;
+	}
+
+	/*
+	 * Now try to move the entire range, we should succeed in moving the
+	 * first VMA, but no others, and report a failure.
+	 */
+	res = mremap(ptr, size, size, MREMAP_MAYMOVE | MREMAP_FIXED, tgt_ptr);
+	err = errno;
+	if (res != MAP_FAILED) {
+		fprintf(stderr, "mremap() succeeded for multi VMA uffd armed\n");
+		success = false;
+		goto out_unmap;
+	}
+	if (err != EFAULT) {
+		errno = err;
+		perror("mrmeap() unexpected error");
+		success = false;
+		goto out_unmap;
+	}
+	if (!is_ptr_mapped(maps_fp, tgt_ptr, page_size)) {
+		fprintf(stderr, "Valid VMA not moved\n");
+		success = false;
+		goto out_unmap;
+	}
+
+	/*
+	 * Unmap the VMA, and map valid VMA at start of ptr range, and replace
+	 * all existing multi-move invalid VMAs, except the last, with valid
+	 * multi-move VMAs.
+	 */
+	if (munmap(tgt_ptr, page_size)) {
+		perror("munmap");
+		success = false;
+		goto out_unmap;
+	}
+	if (munmap(ptr, size - 2 * page_size)) {
+		perror("munmap");
+		success = false;
+		goto out_unmap;
+	}
+	for (i = 0; i < 8; i += 2) {
+		res = mmap(&ptr[i * page_size], page_size,
+			   PROT_READ | PROT_WRITE,
+			   MAP_PRIVATE | MAP_ANON | MAP_FIXED, -1, 0);
+		if (res == MAP_FAILED) {
+			perror("mmap");
+			success = false;
+			goto out_unmap;
+		}
+	}
+
+	/*
+	 * Now try to move the entire range, we should succeed in moving all but
+	 * the last VMA, and report a failure.
+	 */
+	res = mremap(ptr, size, size, MREMAP_MAYMOVE | MREMAP_FIXED, tgt_ptr);
+	err = errno;
+	if (res != MAP_FAILED) {
+		fprintf(stderr, "mremap() succeeded for multi VMA uffd armed\n");
+		success = false;
+		goto out_unmap;
+	}
+	if (err != EFAULT) {
+		errno = err;
+		perror("mrmeap() unexpected error");
+		success = false;
+		goto out_unmap;
+	}
+
+	for (i = 0; i < 10; i += 2) {
+		bool is_mapped = is_ptr_mapped(maps_fp,
+				&tgt_ptr[i * page_size], page_size);
+
+		if (i < 8 && !is_mapped) {
+			fprintf(stderr, "Valid VMA not moved at %d\n", i);
+			success = false;
+			goto out_unmap;
+		} else if (i == 8 && is_mapped) {
+			fprintf(stderr, "Invalid VMA moved at %d\n", i);
+			success = false;
+			goto out_unmap;
+		}
+	}
+
+out_unmap:
+	if (munmap(tgt_ptr, size))
+		perror("munmap tgt");
+	if (munmap(ptr, size))
+		perror("munmap src");
+out_close_uffd:
+	close(uffd);
+out:
+	if (success)
+		ksft_test_result_pass("%s\n", test_name);
+	else
+		ksft_test_result_fail("%s\n", test_name);
+}
+#else
+static void mremap_move_multi_invalid_vmas(FILE *maps_fp, unsigned long page_size)
+{
+	char *test_name = "mremap move multiple invalid vmas";
+
+	ksft_test_result_skip("%s - missing uffd", test_name);
+}
+#endif /* __NR_userfaultfd */
+
 /* Returns the time taken for the remap on success else returns -1. */
 static long long remap_region(struct config c, unsigned int threshold_mb,
 			      char *rand_addr)
@@ -1074,7 +1331,7 @@ int main(int argc, char **argv)
 	char *rand_addr;
 	size_t rand_size;
 	int num_expand_tests = 2;
-	int num_misc_tests = 8;
+	int num_misc_tests = 9;
 	struct test test_cases[MAX_TEST] = {};
 	struct test perf_test_cases[MAX_PERF_TEST];
 	int page_size;
@@ -1197,8 +1454,6 @@ int main(int argc, char **argv)
 	mremap_expand_merge(maps_fp, page_size);
 	mremap_expand_merge_offset(maps_fp, page_size);
 
-	fclose(maps_fp);
-
 	mremap_move_within_range(pattern_seed, rand_addr);
 	mremap_move_1mb_from_start(pattern_seed, rand_addr);
 	mremap_shrink_multiple_vmas(page_size, /* inplace= */true);
@@ -1207,6 +1462,9 @@ int main(int argc, char **argv)
 	mremap_move_multiple_vmas(pattern_seed, page_size, /* dontunmap= */ true);
 	mremap_move_multiple_vmas_split(pattern_seed, page_size, /* dontunmap= */ false);
 	mremap_move_multiple_vmas_split(pattern_seed, page_size, /* dontunmap= */ true);
+	mremap_move_multi_invalid_vmas(maps_fp, page_size);
+
+	fclose(maps_fp);
 
 	if (run_perf_tests) {
 		ksft_print_msg("\n%s\n",

tools/testing/shared/linux/idr.h

@@ -1 +1,5 @@
+/* Avoid duplicate definitions due to system headers. */
+#ifdef __CONCAT
+#undef __CONCAT
+#endif
 #include "../../../../include/linux/idr.h"