FAILED: patch "[PATCH] mm/memory-failure: fix hugetlb_lock AA deadlock in" failed to apply to 6.12-stable tree

PATCH New [email protected] 2 participants 2 messages Jun 15

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[email protected]

author maintainer

2026-06-15 03:52 UTC #0 lore raw

The patch below does not apply to the 6.12-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 <[email protected]>.

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-6.12.y
git checkout FETCH_HEAD
git cherry-pick -x 3c2d42b8ee345b17a4ba56b0f6492d1ff4c1178e
# <resolve conflicts, build, test, etc.>
git commit -s
git send-email --to '<[email protected]>' --in-reply-to '2026061513-catalog-deviant-3f62@gregkh' --subject-prefix 'PATCH 6.12.y' HEAD^..

Possible dependencies:

thanks,

greg k-h

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

From 3c2d42b8ee345b17a4ba56b0f6492d1ff4c1178e Mon Sep 17 00:00:00 2001
From: Wupeng Ma <[email protected]>
Date: Fri, 22 May 2026 09:03:05 +0800
Subject: [PATCH] mm/memory-failure: fix hugetlb_lock AA deadlock in
get_huge_page_for_hwpoison

Two concurrent madvise(MADV_HWPOISON) calls on the same hugetlb page can trigger a recursive spinlock self-deadlock (AA deadlock) on hugetlb_lock when racing with a concurrent unmap:

thread#0 thread#1
-------- --------
madvise(folio, MADV_HWPOISON)

    -> poisons the folio successfully
  madvise(folio, MADV_HWPOISON)         unmap(folio)
    try_memory_failure_hugetlb
      get_huge_page_for_hwpoison
        spin_lock_irq(&hugetlb_lock)    <- held
        __get_huge_page_for_hwpoison
          hugetlb_update_hwpoison()
            -> MF_HUGETLB_FOLIO_PRE_POISONED
          goto out:
            folio_put()
              refcount: 1 -> 0
              free_huge_folio()
                spin_lock_irqsave(&hugetlb_lock)
                  -> AA DEADLOCK!

The out: path in __get_huge_page_for_hwpoison() calls folio_put() to drop the GUP reference while the hugetlb_lock is still held by the hugetlb.c wrapper get_huge_page_for_hwpoison(). If concurrent unmap has released the page table mapping reference, folio_put() drops the folio refcount to zero, triggering free_huge_folio() which attempts to re-acquire the non-recursive hugetlb_lock.

Fix this by moving hugetlb_lock acquisition from the hugetlb.c wrapper into get_huge_page_for_hwpoison(). Place spin_unlock_irq() before the folio_put() at the out: label so the folio is always released outside the lock.

[[email protected]: fix race, rename label per Miaohe]

Link https://sashiko.dev/#/patchset/[email protected]

Link https://lore.kernel.org/[email protected] open here

Fixes 405ce051236c ("mm/hwpoison: fix race between hugetlb free/demotion and memory_failure_hugetlb()")

Signed-off-by Wupeng Ma <[email protected]>

Acked-by Oscar Salvador (SUSE) <[email protected]>

Acked-by Muchun Song <[email protected]>

Reviewed-by Kefeng Wang <[email protected]>

Acked-by Miaohe Lin <[email protected]>

Cc David Hildenbrand <[email protected]>

Cc Liam Howlett <[email protected]>

Cc Lorenzo Stoakes <[email protected]>

Cc Michal Hocko <[email protected]>

Cc Mike Rapoport <[email protected]>

Cc Naoya Horiguchi <[email protected]>

Cc Suren Baghdasaryan <[email protected]>

Cc Vlastimil Babka <[email protected]>

Cc <[email protected]>

Signed-off-by Andrew Morton <[email protected]>

include/linux/hugetlb.h +0 -8

index 5957bc25efa8..2abaf99321e9 100644
@@ -153,8 +153,6 @@ long hugetlb_unreserve_pages(struct inode *inode, long start, long end,
 						long freed);
 bool folio_isolate_hugetlb(struct folio *folio, struct list_head *list);
 int get_hwpoison_hugetlb_folio(struct folio *folio, bool *hugetlb, bool unpoison);
-int get_huge_page_for_hwpoison(unsigned long pfn, int flags,
-				bool *migratable_cleared);
 void folio_putback_hugetlb(struct folio *folio);
 void move_hugetlb_state(struct folio *old_folio, struct folio *new_folio, int reason);
 void hugetlb_fix_reserve_counts(struct inode *inode);

@@ -421,12 +419,6 @@ static inline int get_hwpoison_hugetlb_folio(struct folio *folio, bool *hugetlb,
 	return 0;
 }
 
-static inline int get_huge_page_for_hwpoison(unsigned long pfn, int flags,
-					bool *migratable_cleared)
-{
-	return 0;
-}
-
 static inline void folio_putback_hugetlb(struct folio *folio)
 {
 }

include/linux/mm.h +0 -8

index 06bbe9eba636..fc2acedf0b76 100644
@@ -4975,8 +4975,6 @@ extern int soft_offline_page(unsigned long pfn, int flags);
  */
 extern const struct attribute_group memory_failure_attr_group;
 extern void memory_failure_queue(unsigned long pfn, int flags);
-extern int __get_huge_page_for_hwpoison(unsigned long pfn, int flags,
-					bool *migratable_cleared);
 void num_poisoned_pages_inc(unsigned long pfn);
 void num_poisoned_pages_sub(unsigned long pfn, long i);
 #else

@@ -4984,12 +4982,6 @@ static inline void memory_failure_queue(unsigned long pfn, int flags)
 {
 }
 
-static inline int __get_huge_page_for_hwpoison(unsigned long pfn, int flags,
-					bool *migratable_cleared)
-{
-	return 0;
-}
-
 static inline void num_poisoned_pages_inc(unsigned long pfn)
 {
 }

mm/hugetlb.c +0 ~~-11~~

index 1b1d4f87a3a4..c921287489de 100644
@@ -7161,17 +7161,6 @@ int get_hwpoison_hugetlb_folio(struct folio *folio, bool *hugetlb, bool unpoison
 	return ret;
 }
 
-int get_huge_page_for_hwpoison(unsigned long pfn, int flags,
-				bool *migratable_cleared)
-{
-	int ret;
-
-	spin_lock_irq(&hugetlb_lock);
-	ret = __get_huge_page_for_hwpoison(pfn, flags, migratable_cleared);
-	spin_unlock_irq(&hugetlb_lock);
-	return ret;
-}
-
 /**
  * folio_putback_hugetlb - unisolate a hugetlb folio
  * @folio: the isolated hugetlb folio

mm/memory-failure.c +10 -9

index ee42d4361309..d47aef256a32 100644
@@ -1966,20 +1966,19 @@ void folio_clear_hugetlb_hwpoison(struct folio *folio)
 	folio_free_raw_hwp(folio, true);
 }
 
-/*
- * Called from hugetlb code with hugetlb_lock held.
- */
-int __get_huge_page_for_hwpoison(unsigned long pfn, int flags,
+static int get_huge_page_for_hwpoison(unsigned long pfn, int flags,
 				 bool *migratable_cleared)
 {
 	struct page *page = pfn_to_page(pfn);
-	struct folio *folio = page_folio(page);
+	struct folio *folio;
 	bool count_increased = false;
 	int ret, rc;
 
+	spin_lock_irq(&hugetlb_lock);
+	folio = page_folio(page);
 	if (!folio_test_hugetlb(folio)) {
 		ret = MF_HUGETLB_NON_HUGEPAGE;
-		goto out;
+		goto out_unlock;
 	} else if (flags & MF_COUNT_INCREASED) {
 		ret = MF_HUGETLB_IN_USED;
 		count_increased = true;

@@ -1995,13 +1994,13 @@ int __get_huge_page_for_hwpoison(unsigned long pfn, int flags,
 	} else {
 		ret = MF_HUGETLB_RETRY;
 		if (!(flags & MF_NO_RETRY))
-			goto out;
+			goto out_unlock;
 	}
 
 	rc = hugetlb_update_hwpoison(folio, page);
 	if (rc >= MF_HUGETLB_FOLIO_PRE_POISONED) {
 		ret = rc;
-		goto out;
+		goto out_unlock;
 	}
 
 	/*

@@ -2013,8 +2012,10 @@ int __get_huge_page_for_hwpoison(unsigned long pfn, int flags,
 		*migratable_cleared = true;
 	}
 
+	spin_unlock_irq(&hugetlb_lock);
 	return ret;
-out:
+out_unlock:
+	spin_unlock_irq(&hugetlb_lock);
 	if (count_increased)
 		folio_put(folio);
 	return ret;

Sasha Levin

maintainer

2026-06-15 13:29 UTC #1 lore raw

PATCH 1/1 mm/memory-failure: fix hugetlb_lock AA deadlock in get_huge_page_for_hwpoison

From: Wupeng Ma <[email protected]>

[ Upstream commit 3c2d42b8ee345b17a4ba56b0f6492d1ff4c1178e ]