Re: [PATCH resend] mm/memory-failure: fix hugetlb_lock AA deadlock in get_huge_page_for_hwpoison

[Andrew Morton <akpm@linux-foundation.org>]

On Fri, 22 May 2026 09:03:05 +0800 Wupeng Ma <mawupeng1@huawei.com> wrote:

> 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:

Well we don't want that.

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

So I'll add cc:stable here.

AI review didn't like the unlocked page_folio():

	https://sashiko.dev/#/patchset/20260522010305.4099834-1-mawupeng1@huawei.com

So I'll add a followup patch which addresses that (and which addresses
Miaohe's naming nit).

Please let's check this - perhaps the locking alteration isn't needed.


From: Andrew Morton <akpm@linux-foundation.org>
Subject: mm-memory-failure-fix-hugetlb_lock-aa-deadlock-in-get_huge_page_for_hwpoison-fix
Date: Fri May 22 08:44:25 PM PDT 2026

- address possible race identified by Sashiko

- s/out/out_unlock/, per Miaohe

Link: https://sashiko.dev/#/patchset/20260522010305.4099834-1-mawupeng1@huawei.com
Link: https://lore.kernel.org/f39f405e-4b4b-8f79-70fe-a2b5b62114eb@huawei.com
Cc: David Hildenbrand <david@kernel.org>
Cc: Kefeng Wang <wangkefeng.wang@huawei.com>
Cc: Liam Howlett <liam.howlett@oracle.com>
Cc: Lorenzo Stoakes <ljs@kernel.org>
Cc: Miaohe Lin <linmiaohe@huawei.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Mike Rapoport <rppt@kernel.org>
Cc: Muchun Song <muchun.song@linux.dev>
Cc: Naoya Horiguchi <nao.horiguchi@gmail.com>
Cc: Oscar Salvador (SUSE) <osalvador@kernel.org>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Vlastimil Babka <vbabka@kernel.org>
Cc: Wupeng Ma <mawupeng1@huawei.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 mm/memory-failure.c |   11 ++++++-----
 1 file changed, 6 insertions(+), 5 deletions(-)

--- a/mm/memory-failure.c~mm-memory-failure-fix-hugetlb_lock-aa-deadlock-in-get_huge_page_for_hwpoison-fix
+++ a/mm/memory-failure.c
@@ -1970,14 +1970,15 @@ static int get_huge_page_for_hwpoison(un
 				 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;
@@ -1993,13 +1994,13 @@ static int get_huge_page_for_hwpoison(un
 	} 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;
 	}
 
 	/*
@@ -2013,7 +2014,7 @@ static int get_huge_page_for_hwpoison(un
 
 	spin_unlock_irq(&hugetlb_lock);
 	return ret;
-out:
+out_unlock:
 	spin_unlock_irq(&hugetlb_lock);
 	if (count_increased)
 		folio_put(folio);
_