FAILED: patch "[PATCH] mm/hugetlb: fix two comments related to huge_pmd_unshare()" failed to apply to 6.18-stable tree

FAILED: patch "[PATCH] mm/hugetlb: fix two comments related to huge_pmd_unshare()" failed to apply to 6.18-stable tree

[gregkh]

The patch below does not apply to the 6.18-stable tree.
If someone wants it applied there, or to any other stable or longterm
tree, then please email the backport, including the original git commit
id to <stable@vger.kernel.org>.

To reproduce the conflict and resubmit, you may use the following commands:

git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-6.18.y
git checkout FETCH_HEAD
git cherry-pick -x 3937027caecb4f8251e82dd857ba1d749bb5a428
# <resolve conflicts, build, test, etc.>
git commit -s
git send-email --to '<stable@vger.kernel.org>' --in-reply-to '2026012615-emblaze-unified-1aeb@gregkh' --subject-prefix 'PATCH 6.18.y' HEAD^..

Possible dependencies:



thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From 3937027caecb4f8251e82dd857ba1d749bb5a428 Mon Sep 17 00:00:00 2001
From: "David Hildenbrand (Red Hat)" <david@kernel.org>
Date: Tue, 23 Dec 2025 22:40:35 +0100
Subject: [PATCH] mm/hugetlb: fix two comments related to huge_pmd_unshare()

Ever since we stopped using the page count to detect shared PMD page
tables, these comments are outdated.

The only reason we have to flush the TLB early is because once we drop the
i_mmap_rwsem, the previously shared page table could get freed (to then
get reallocated and used for other purpose).  So we really have to flush
the TLB before that could happen.

So let's simplify the comments a bit.

The "If we unshared PMDs, the TLB flush was not recorded in mmu_gather."
part introduced as in commit a4a118f2eead ("hugetlbfs: flush TLBs
correctly after huge_pmd_unshare") was confusing: sure it is recorded in
the mmu_gather, otherwise tlb_flush_mmu_tlbonly() wouldn't do anything.
So let's drop that comment while at it as well.

We'll centralize these comments in a single helper as we rework the code
next.

Link: https://lkml.kernel.org/r/20251223214037.580860-3-david@kernel.org
Fixes: 59d9094df3d7 ("mm: hugetlb: independent PMD page table shared count")
Signed-off-by: David Hildenbrand (Red Hat) <david@kernel.org>
Reviewed-by: Rik van Riel <riel@surriel.com>
Tested-by: Laurence Oberman <loberman@redhat.com>
Reviewed-by: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Acked-by: Oscar Salvador <osalvador@suse.de>
Reviewed-by: Harry Yoo <harry.yoo@oracle.com>
Cc: Liu Shixin <liushixin2@huawei.com>
Cc: Lance Yang <lance.yang@linux.dev>
Cc: "Uschakow, Stanislav" <suschako@amazon.de>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

diff --git a/mm/hugetlb.c b/mm/hugetlb.c
index e0ab14020513..67131aa24d77 100644
--- a/mm/hugetlb.c
+++ b/mm/hugetlb.c
@@ -5320,17 +5320,10 @@ void __unmap_hugepage_range(struct mmu_gather *tlb, struct vm_area_struct *vma,
 	tlb_end_vma(tlb, vma);
 
 	/*
-	 * If we unshared PMDs, the TLB flush was not recorded in mmu_gather. We
-	 * could defer the flush until now, since by holding i_mmap_rwsem we
-	 * guaranteed that the last reference would not be dropped. But we must
-	 * do the flushing before we return, as otherwise i_mmap_rwsem will be
-	 * dropped and the last reference to the shared PMDs page might be
-	 * dropped as well.
-	 *
-	 * In theory we could defer the freeing of the PMD pages as well, but
-	 * huge_pmd_unshare() relies on the exact page_count for the PMD page to
-	 * detect sharing, so we cannot defer the release of the page either.
-	 * Instead, do flush now.
+	 * There is nothing protecting a previously-shared page table that we
+	 * unshared through huge_pmd_unshare() from getting freed after we
+	 * release i_mmap_rwsem, so flush the TLB now. If huge_pmd_unshare()
+	 * succeeded, flush the range corresponding to the pud.
 	 */
 	if (force_flush)
 		tlb_flush_mmu_tlbonly(tlb);
@@ -6552,11 +6545,10 @@ long hugetlb_change_protection(struct vm_area_struct *vma,
 		cond_resched();
 	}
 	/*
-	 * Must flush TLB before releasing i_mmap_rwsem: x86's huge_pmd_unshare
-	 * may have cleared our pud entry and done put_page on the page table:
-	 * once we release i_mmap_rwsem, another task can do the final put_page
-	 * and that page table be reused and filled with junk.  If we actually
-	 * did unshare a page of pmds, flush the range corresponding to the pud.
+	 * There is nothing protecting a previously-shared page table that we
+	 * unshared through huge_pmd_unshare() from getting freed after we
+	 * release i_mmap_rwsem, so flush the TLB now. If huge_pmd_unshare()
+	 * succeeded, flush the range corresponding to the pud.
 	 */
 	if (shared_pmd)
 		flush_hugetlb_tlb_range(vma, range.start, range.end);

[PATCH 6.18.y 1/2] mm: fix some typos in mm module

[Sasha Levin]

From: "jianyun.gao" <jianyungao89@gmail.com>

[ Upstream commit b6c46600bfb28b4be4e9cff7bad4f2cf357e0fb7 ]

Below are some typos in the code comments:

  intevals ==> intervals
  addesses ==> addresses
  unavaliable ==> unavailable
  facor ==> factor
  droping ==> dropping
  exlusive ==> exclusive
  decription ==> description
  confict ==> conflict
  desriptions ==> descriptions
  otherwize ==> otherwise
  vlaue ==> value
  cheching ==> checking
  exisitng ==> existing
  modifed ==> modified
  differenciate ==> differentiate
  refernece ==> reference
  permissons ==> permissions
  indepdenent ==> independent
  spliting ==> splitting

Just fix it.

Link: https://lkml.kernel.org/r/20250929002608.1633825-1-jianyungao89@gmail.com
Signed-off-by: jianyun.gao <jianyungao89@gmail.com>
Reviewed-by: SeongJae Park <sj@kernel.org>
Reviewed-by: Wei Yang <richard.weiyang@gmail.com>
Reviewed-by: Dev Jain <dev.jain@arm.com>
Reviewed-by: Liam R. Howlett <Liam.Howlett@oracle.com>
Acked-by: Chris Li <chrisl@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Stable-dep-of: 3937027caecb ("mm/hugetlb: fix two comments related to huge_pmd_unshare()")
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 mm/damon/sysfs.c     | 2 +-
 mm/gup.c             | 2 +-
 mm/hugetlb.c         | 6 +++---
 mm/hugetlb_vmemmap.c | 6 +++---
 mm/kmsan/core.c      | 2 +-
 mm/ksm.c             | 2 +-
 mm/memory-tiers.c    | 2 +-
 mm/memory.c          | 4 ++--
 mm/secretmem.c       | 2 +-
 mm/slab_common.c     | 2 +-
 mm/slub.c            | 2 +-
 mm/swapfile.c        | 2 +-
 mm/userfaultfd.c     | 2 +-
 mm/vma.c             | 4 ++--
 14 files changed, 20 insertions(+), 20 deletions(-)

diff --git a/mm/damon/sysfs.c b/mm/damon/sysfs.c
index 2caeca5624ce8..dec9f5d0d5123 100644
--- a/mm/damon/sysfs.c
+++ b/mm/damon/sysfs.c
@@ -1267,7 +1267,7 @@ enum damon_sysfs_cmd {
 	DAMON_SYSFS_CMD_UPDATE_SCHEMES_EFFECTIVE_QUOTAS,
 	/*
 	 * @DAMON_SYSFS_CMD_UPDATE_TUNED_INTERVALS: Update the tuned monitoring
-	 * intevals.
+	 * intervals.
 	 */
 	DAMON_SYSFS_CMD_UPDATE_TUNED_INTERVALS,
 	/*
diff --git a/mm/gup.c b/mm/gup.c
index a8ba5112e4d09..d2524fe09338f 100644
--- a/mm/gup.c
+++ b/mm/gup.c
@@ -2710,7 +2710,7 @@ EXPORT_SYMBOL(get_user_pages_unlocked);
  *
  *  *) ptes can be read atomically by the architecture.
  *
- *  *) valid user addesses are below TASK_MAX_SIZE
+ *  *) valid user addresses are below TASK_MAX_SIZE
  *
  * The last two assumptions can be relaxed by the addition of helper functions.
  *
diff --git a/mm/hugetlb.c b/mm/hugetlb.c
index 0455119716ec0..4e016433e32e5 100644
--- a/mm/hugetlb.c
+++ b/mm/hugetlb.c
@@ -2934,7 +2934,7 @@ typedef enum {
 	 * NOTE: This is mostly identical to MAP_CHG_NEEDED, except
 	 * that currently vma_needs_reservation() has an unwanted side
 	 * effect to either use end() or commit() to complete the
-	 * transaction.	 Hence it needs to differenciate from NEEDED.
+	 * transaction. Hence it needs to differentiate from NEEDED.
 	 */
 	MAP_CHG_ENFORCED = 2,
 } map_chg_state;
@@ -6007,7 +6007,7 @@ void __unmap_hugepage_range(struct mmu_gather *tlb, struct vm_area_struct *vma,
 	/*
 	 * If we unshared PMDs, the TLB flush was not recorded in mmu_gather. We
 	 * could defer the flush until now, since by holding i_mmap_rwsem we
-	 * guaranteed that the last refernece would not be dropped. But we must
+	 * guaranteed that the last reference would not be dropped. But we must
 	 * do the flushing before we return, as otherwise i_mmap_rwsem will be
 	 * dropped and the last reference to the shared PMDs page might be
 	 * dropped as well.
@@ -7193,7 +7193,7 @@ long hugetlb_change_protection(struct vm_area_struct *vma,
 		} else if (unlikely(is_pte_marker(pte))) {
 			/*
 			 * Do nothing on a poison marker; page is
-			 * corrupted, permissons do not apply.  Here
+			 * corrupted, permissions do not apply. Here
 			 * pte_marker_uffd_wp()==true implies !poison
 			 * because they're mutual exclusive.
 			 */
diff --git a/mm/hugetlb_vmemmap.c b/mm/hugetlb_vmemmap.c
index ba0fb1b6a5a8e..96ee2bd16ee15 100644
--- a/mm/hugetlb_vmemmap.c
+++ b/mm/hugetlb_vmemmap.c
@@ -75,7 +75,7 @@ static int vmemmap_split_pmd(pmd_t *pmd, struct page *head, unsigned long start,
 	if (likely(pmd_leaf(*pmd))) {
 		/*
 		 * Higher order allocations from buddy allocator must be able to
-		 * be treated as indepdenent small pages (as they can be freed
+		 * be treated as independent small pages (as they can be freed
 		 * individually).
 		 */
 		if (!PageReserved(head))
@@ -684,7 +684,7 @@ static void __hugetlb_vmemmap_optimize_folios(struct hstate *h,
 		ret = hugetlb_vmemmap_split_folio(h, folio);
 
 		/*
-		 * Spliting the PMD requires allocating a page, thus lets fail
+		 * Splitting the PMD requires allocating a page, thus let's fail
 		 * early once we encounter the first OOM. No point in retrying
 		 * as it can be dynamically done on remap with the memory
 		 * we get back from the vmemmap deduplication.
@@ -715,7 +715,7 @@ static void __hugetlb_vmemmap_optimize_folios(struct hstate *h,
 		/*
 		 * Pages to be freed may have been accumulated.  If we
 		 * encounter an ENOMEM,  free what we have and try again.
-		 * This can occur in the case that both spliting fails
+		 * This can occur in the case that both splitting fails
 		 * halfway and head page allocation also failed. In this
 		 * case __hugetlb_vmemmap_optimize_folio() would free memory
 		 * allowing more vmemmap remaps to occur.
diff --git a/mm/kmsan/core.c b/mm/kmsan/core.c
index 35ceaa8adb41e..90f427b95a213 100644
--- a/mm/kmsan/core.c
+++ b/mm/kmsan/core.c
@@ -33,7 +33,7 @@ bool kmsan_enabled __read_mostly;
 
 /*
  * Per-CPU KMSAN context to be used in interrupts, where current->kmsan is
- * unavaliable.
+ * unavailable.
  */
 DEFINE_PER_CPU(struct kmsan_ctx, kmsan_percpu_ctx);
 
diff --git a/mm/ksm.c b/mm/ksm.c
index ba97828f32903..4f672f4f21407 100644
--- a/mm/ksm.c
+++ b/mm/ksm.c
@@ -389,7 +389,7 @@ static unsigned long ewma(unsigned long prev, unsigned long curr)
  * exponentially weighted moving average. The new pages_to_scan value is
  * multiplied with that change factor:
  *
- *      new_pages_to_scan *= change facor
+ *      new_pages_to_scan *= change factor
  *
  * The new_pages_to_scan value is limited by the cpu min and max values. It
  * calculates the cpu percent for the last scan and calculates the new
diff --git a/mm/memory-tiers.c b/mm/memory-tiers.c
index 0ea5c13f10a23..864811fff4093 100644
--- a/mm/memory-tiers.c
+++ b/mm/memory-tiers.c
@@ -519,7 +519,7 @@ static inline void __init_node_memory_type(int node, struct memory_dev_type *mem
 	 * for each device getting added in the same NUMA node
 	 * with this specific memtype, bump the map count. We
 	 * Only take memtype device reference once, so that
-	 * changing a node memtype can be done by droping the
+	 * changing a node memtype can be done by dropping the
 	 * only reference count taken here.
 	 */
 
diff --git a/mm/memory.c b/mm/memory.c
index b59ae7ce42ebc..61748b762876f 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -4328,7 +4328,7 @@ static inline bool should_try_to_free_swap(struct folio *folio,
 	 * If we want to map a page that's in the swapcache writable, we
 	 * have to detect via the refcount if we're really the exclusive
 	 * user. Try freeing the swapcache to get rid of the swapcache
-	 * reference only in case it's likely that we'll be the exlusive user.
+	 * reference only in case it's likely that we'll be the exclusive user.
 	 */
 	return (fault_flags & FAULT_FLAG_WRITE) && !folio_test_ksm(folio) &&
 		folio_ref_count(folio) == (1 + folio_nr_pages(folio));
@@ -5405,7 +5405,7 @@ vm_fault_t do_set_pmd(struct vm_fault *vmf, struct folio *folio, struct page *pa
 
 /**
  * set_pte_range - Set a range of PTEs to point to pages in a folio.
- * @vmf: Fault decription.
+ * @vmf: Fault description.
  * @folio: The folio that contains @page.
  * @page: The first page to create a PTE for.
  * @nr: The number of PTEs to create.
diff --git a/mm/secretmem.c b/mm/secretmem.c
index b59350daffe31..9b0f5d9ec6f4b 100644
--- a/mm/secretmem.c
+++ b/mm/secretmem.c
@@ -227,7 +227,7 @@ SYSCALL_DEFINE1(memfd_secret, unsigned int, flags)
 	struct file *file;
 	int fd, err;
 
-	/* make sure local flags do not confict with global fcntl.h */
+	/* make sure local flags do not conflict with global fcntl.h */
 	BUILD_BUG_ON(SECRETMEM_FLAGS_MASK & O_CLOEXEC);
 
 	if (!secretmem_enable || !can_set_direct_map())
diff --git a/mm/slab_common.c b/mm/slab_common.c
index 29be54153fa91..87bde1d8916be 100644
--- a/mm/slab_common.c
+++ b/mm/slab_common.c
@@ -259,7 +259,7 @@ static struct kmem_cache *create_cache(const char *name,
  * @object_size: The size of objects to be created in this cache.
  * @args: Additional arguments for the cache creation (see
  *        &struct kmem_cache_args).
- * @flags: See the desriptions of individual flags. The common ones are listed
+ * @flags: See the descriptions of individual flags. The common ones are listed
  *         in the description below.
  *
  * Not to be called directly, use the kmem_cache_create() wrapper with the same
diff --git a/mm/slub.c b/mm/slub.c
index 507f346102256..e4c47a6b726ad 100644
--- a/mm/slub.c
+++ b/mm/slub.c
@@ -2533,7 +2533,7 @@ bool slab_free_hook(struct kmem_cache *s, void *x, bool init,
 		memset((char *)kasan_reset_tag(x) + inuse, 0,
 		       s->size - inuse - rsize);
 		/*
-		 * Restore orig_size, otherwize kmalloc redzone overwritten
+		 * Restore orig_size, otherwise kmalloc redzone overwritten
 		 * would be reported
 		 */
 		set_orig_size(s, x, orig_size);
diff --git a/mm/swapfile.c b/mm/swapfile.c
index 82524f8595eda..89746abc47373 100644
--- a/mm/swapfile.c
+++ b/mm/swapfile.c
@@ -1703,7 +1703,7 @@ static bool swap_entries_put_map_nr(struct swap_info_struct *si,
 
 /*
  * Check if it's the last ref of swap entry in the freeing path.
- * Qualified vlaue includes 1, SWAP_HAS_CACHE or SWAP_MAP_SHMEM.
+ * Qualified value includes 1, SWAP_HAS_CACHE or SWAP_MAP_SHMEM.
  */
 static inline bool __maybe_unused swap_is_last_ref(unsigned char count)
 {
diff --git a/mm/userfaultfd.c b/mm/userfaultfd.c
index af61b95c89e4e..0630f188c847c 100644
--- a/mm/userfaultfd.c
+++ b/mm/userfaultfd.c
@@ -1578,7 +1578,7 @@ static int validate_move_areas(struct userfaultfd_ctx *ctx,
 
 	/*
 	 * For now, we keep it simple and only move between writable VMAs.
-	 * Access flags are equal, therefore cheching only the source is enough.
+	 * Access flags are equal, therefore checking only the source is enough.
 	 */
 	if (!(src_vma->vm_flags & VM_WRITE))
 		return -EINVAL;
diff --git a/mm/vma.c b/mm/vma.c
index abe0da33c8446..9127eaeea93ff 100644
--- a/mm/vma.c
+++ b/mm/vma.c
@@ -109,7 +109,7 @@ static inline bool is_mergeable_vma(struct vma_merge_struct *vmg, bool merge_nex
 static bool is_mergeable_anon_vma(struct vma_merge_struct *vmg, bool merge_next)
 {
 	struct vm_area_struct *tgt = merge_next ? vmg->next : vmg->prev;
-	struct vm_area_struct *src = vmg->middle; /* exisitng merge case. */
+	struct vm_area_struct *src = vmg->middle; /* existing merge case. */
 	struct anon_vma *tgt_anon = tgt->anon_vma;
 	struct anon_vma *src_anon = vmg->anon_vma;
 
@@ -798,7 +798,7 @@ static bool can_merge_remove_vma(struct vm_area_struct *vma)
  * Returns: The merged VMA if merge succeeds, or NULL otherwise.
  *
  * ASSUMPTIONS:
- * - The caller must assign the VMA to be modifed to @vmg->middle.
+ * - The caller must assign the VMA to be modified to @vmg->middle.
  * - The caller must have set @vmg->prev to the previous VMA, if there is one.
  * - The caller must not set @vmg->next, as we determine this.
  * - The caller must hold a WRITE lock on the mm_struct->mmap_lock.
-- 
2.51.0

[PATCH 6.18.y 2/2] mm/hugetlb: fix two comments related to huge_pmd_unshare()

[Sasha Levin]

From: "David Hildenbrand (Red Hat)" <david@kernel.org>

[ Upstream commit 3937027caecb4f8251e82dd857ba1d749bb5a428 ]

Ever since we stopped using the page count to detect shared PMD page
tables, these comments are outdated.

The only reason we have to flush the TLB early is because once we drop the
i_mmap_rwsem, the previously shared page table could get freed (to then
get reallocated and used for other purpose).  So we really have to flush
the TLB before that could happen.

So let's simplify the comments a bit.

The "If we unshared PMDs, the TLB flush was not recorded in mmu_gather."
part introduced as in commit a4a118f2eead ("hugetlbfs: flush TLBs
correctly after huge_pmd_unshare") was confusing: sure it is recorded in
the mmu_gather, otherwise tlb_flush_mmu_tlbonly() wouldn't do anything.
So let's drop that comment while at it as well.

We'll centralize these comments in a single helper as we rework the code
next.

Link: https://lkml.kernel.org/r/20251223214037.580860-3-david@kernel.org
Fixes: 59d9094df3d7 ("mm: hugetlb: independent PMD page table shared count")
Signed-off-by: David Hildenbrand (Red Hat) <david@kernel.org>
Reviewed-by: Rik van Riel <riel@surriel.com>
Tested-by: Laurence Oberman <loberman@redhat.com>
Reviewed-by: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Acked-by: Oscar Salvador <osalvador@suse.de>
Reviewed-by: Harry Yoo <harry.yoo@oracle.com>
Cc: Liu Shixin <liushixin2@huawei.com>
Cc: Lance Yang <lance.yang@linux.dev>
Cc: "Uschakow, Stanislav" <suschako@amazon.de>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 mm/hugetlb.c | 24 ++++++++----------------
 1 file changed, 8 insertions(+), 16 deletions(-)

diff --git a/mm/hugetlb.c b/mm/hugetlb.c
index 4e016433e32e5..6a60af4798bee 100644
--- a/mm/hugetlb.c
+++ b/mm/hugetlb.c
@@ -6005,17 +6005,10 @@ void __unmap_hugepage_range(struct mmu_gather *tlb, struct vm_area_struct *vma,
 	tlb_end_vma(tlb, vma);
 
 	/*
-	 * If we unshared PMDs, the TLB flush was not recorded in mmu_gather. We
-	 * could defer the flush until now, since by holding i_mmap_rwsem we
-	 * guaranteed that the last reference would not be dropped. But we must
-	 * do the flushing before we return, as otherwise i_mmap_rwsem will be
-	 * dropped and the last reference to the shared PMDs page might be
-	 * dropped as well.
-	 *
-	 * In theory we could defer the freeing of the PMD pages as well, but
-	 * huge_pmd_unshare() relies on the exact page_count for the PMD page to
-	 * detect sharing, so we cannot defer the release of the page either.
-	 * Instead, do flush now.
+	 * There is nothing protecting a previously-shared page table that we
+	 * unshared through huge_pmd_unshare() from getting freed after we
+	 * release i_mmap_rwsem, so flush the TLB now. If huge_pmd_unshare()
+	 * succeeded, flush the range corresponding to the pud.
 	 */
 	if (force_flush)
 		tlb_flush_mmu_tlbonly(tlb);
@@ -7226,11 +7219,10 @@ long hugetlb_change_protection(struct vm_area_struct *vma,
 		cond_resched();
 	}
 	/*
-	 * Must flush TLB before releasing i_mmap_rwsem: x86's huge_pmd_unshare
-	 * may have cleared our pud entry and done put_page on the page table:
-	 * once we release i_mmap_rwsem, another task can do the final put_page
-	 * and that page table be reused and filled with junk.  If we actually
-	 * did unshare a page of pmds, flush the range corresponding to the pud.
+	 * There is nothing protecting a previously-shared page table that we
+	 * unshared through huge_pmd_unshare() from getting freed after we
+	 * release i_mmap_rwsem, so flush the TLB now. If huge_pmd_unshare()
+	 * succeeded, flush the range corresponding to the pud.
 	 */
 	if (shared_pmd)
 		flush_hugetlb_tlb_range(vma, range.start, range.end);
-- 
2.51.0