FAILED: patch "[PATCH] mm/hugetlb: fix potential race in" failed to apply to 6.9-stable tree

FAILED: patch "[PATCH] mm/hugetlb: fix potential race in" failed to apply to 6.9-stable tree

[gregkh]

The patch below does not apply to the 6.9-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-6.9.y
git checkout FETCH_HEAD
git cherry-pick -x 5596d9e8b553dacb0ac34bcf873cbbfb16c3ba3e
# <resolve conflicts, build, test, etc.>
git commit -s
git send-email --to '<stable@vger.kernel.org>' --in-reply-to '2024071558-unbundle-resize-a6d4@gregkh' --subject-prefix 'PATCH 6.9.y' HEAD^..

Possible dependencies:

5596d9e8b553 ("mm/hugetlb: fix potential race in __update_and_free_hugetlb_folio()")
bd225530a4c7 ("mm/hugetlb_vmemmap: fix race with speculative PFN walkers")
51718e25c53f ("mm: convert arch_clear_hugepage_flags to take a folio")

thanks,

greg k-h

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

From 5596d9e8b553dacb0ac34bcf873cbbfb16c3ba3e Mon Sep 17 00:00:00 2001
From: Miaohe Lin <linmiaohe@huawei.com>
Date: Mon, 8 Jul 2024 10:51:27 +0800
Subject: [PATCH] mm/hugetlb: fix potential race in
 __update_and_free_hugetlb_folio()

There is a potential race between __update_and_free_hugetlb_folio() and
try_memory_failure_hugetlb():

 CPU1					CPU2
 __update_and_free_hugetlb_folio	try_memory_failure_hugetlb
					 folio_test_hugetlb
					  -- It's still hugetlb folio.
  folio_clear_hugetlb_hwpoison
  					  spin_lock_irq(&hugetlb_lock);
					   __get_huge_page_for_hwpoison
					    folio_set_hugetlb_hwpoison
					  spin_unlock_irq(&hugetlb_lock);
  spin_lock_irq(&hugetlb_lock);
  __folio_clear_hugetlb(folio);
   -- Hugetlb flag is cleared but too late.
  spin_unlock_irq(&hugetlb_lock);

When the above race occurs, raw error page info will be leaked.  Even
worse, raw error pages won't have hwpoisoned flag set and hit
pcplists/buddy.  Fix this issue by deferring
folio_clear_hugetlb_hwpoison() until __folio_clear_hugetlb() is done.  So
all raw error pages will have hwpoisoned flag set.

Link: https://lkml.kernel.org/r/20240708025127.107713-1-linmiaohe@huawei.com
Fixes: 32c877191e02 ("hugetlb: do not clear hugetlb dtor until allocating vmemmap")
Signed-off-by: Miaohe Lin <linmiaohe@huawei.com>
Acked-by: Muchun Song <muchun.song@linux.dev>
Reviewed-by: Oscar Salvador <osalvador@suse.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 2afb70171b76..fe44324d6383 100644
--- a/mm/hugetlb.c
+++ b/mm/hugetlb.c
@@ -1725,13 +1725,6 @@ static void __update_and_free_hugetlb_folio(struct hstate *h,
 		return;
 	}
 
-	/*
-	 * Move PageHWPoison flag from head page to the raw error pages,
-	 * which makes any healthy subpages reusable.
-	 */
-	if (unlikely(folio_test_hwpoison(folio)))
-		folio_clear_hugetlb_hwpoison(folio);
-
 	/*
 	 * If vmemmap pages were allocated above, then we need to clear the
 	 * hugetlb flag under the hugetlb lock.
@@ -1742,6 +1735,13 @@ static void __update_and_free_hugetlb_folio(struct hstate *h,
 		spin_unlock_irq(&hugetlb_lock);
 	}
 
+	/*
+	 * Move PageHWPoison flag from head page to the raw error pages,
+	 * which makes any healthy subpages reusable.
+	 */
+	if (unlikely(folio_test_hwpoison(folio)))
+		folio_clear_hugetlb_hwpoison(folio);
+
 	folio_ref_unfreeze(folio, 1);
 
 	/*

[PATCH 6.9.y] mm/hugetlb: fix potential race in __update_and_free_hugetlb_folio()

[Miaohe Lin]

There is a potential race between __update_and_free_hugetlb_folio() and
try_memory_failure_hugetlb():

 CPU1					CPU2
 __update_and_free_hugetlb_folio	try_memory_failure_hugetlb
					 folio_test_hugetlb
					  -- It's still hugetlb folio.
  folio_clear_hugetlb_hwpoison
  					  spin_lock_irq(&hugetlb_lock);
					   __get_huge_page_for_hwpoison
					    folio_set_hugetlb_hwpoison
					  spin_unlock_irq(&hugetlb_lock);
  spin_lock_irq(&hugetlb_lock);
  __folio_clear_hugetlb(folio);
   -- Hugetlb flag is cleared but too late.
  spin_unlock_irq(&hugetlb_lock);

When the above race occurs, raw error page info will be leaked.  Even
worse, raw error pages won't have hwpoisoned flag set and hit
pcplists/buddy.  Fix this issue by deferring
folio_clear_hugetlb_hwpoison() until __folio_clear_hugetlb() is done.  So
all raw error pages will have hwpoisoned flag set.

Link: https://lkml.kernel.org/r/20240708025127.107713-1-linmiaohe@huawei.com
Fixes: 32c877191e02 ("hugetlb: do not clear hugetlb dtor until allocating vmemmap")
Signed-off-by: Miaohe Lin <linmiaohe@huawei.com>
Acked-by: Muchun Song <muchun.song@linux.dev>
Reviewed-by: Oscar Salvador <osalvador@suse.de>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
(cherry picked from commit 5596d9e8b553dacb0ac34bcf873cbbfb16c3ba3e)
Signed-off-by: Miaohe Lin <linmiaohe@huawei.com>
---
 mm/hugetlb.c | 14 +++++++-------
 1 file changed, 7 insertions(+), 7 deletions(-)

diff --git a/mm/hugetlb.c b/mm/hugetlb.c
index c445e6fd8579..0cefa9f82c47 100644
--- a/mm/hugetlb.c
+++ b/mm/hugetlb.c
@@ -1770,13 +1770,6 @@ static void __update_and_free_hugetlb_folio(struct hstate *h,
 		return;
 	}
 
-	/*
-	 * Move PageHWPoison flag from head page to the raw error pages,
-	 * which makes any healthy subpages reusable.
-	 */
-	if (unlikely(folio_test_hwpoison(folio)))
-		folio_clear_hugetlb_hwpoison(folio);
-
 	/*
 	 * If vmemmap pages were allocated above, then we need to clear the
 	 * hugetlb destructor under the hugetlb lock.
@@ -1787,6 +1780,13 @@ static void __update_and_free_hugetlb_folio(struct hstate *h,
 		spin_unlock_irq(&hugetlb_lock);
 	}
 
+	/*
+	 * Move PageHWPoison flag from head page to the raw error pages,
+	 * which makes any healthy subpages reusable.
+	 */
+	if (unlikely(folio_test_hwpoison(folio)))
+		folio_clear_hugetlb_hwpoison(folio);
+
 	/*
 	 * Non-gigantic pages demoted from CMA allocated gigantic pages
 	 * need to be given back to CMA in free_gigantic_folio.
-- 
2.33.0

Re: [PATCH 6.9.y] mm/hugetlb: fix potential race in __update_and_free_hugetlb_folio()

[Greg KH]

On Wed, Aug 07, 2024 at 11:49:49AM +0800, Miaohe Lin wrote:
> There is a potential race between __update_and_free_hugetlb_folio() and
> try_memory_failure_hugetlb():
> 

6.9.y is end-of-life now, sorry.

greg k-h