FAILED: patch "[PATCH] mm/huge_memory: drop beyond-EOF folios with the right number" failed to apply to 6.12-stable tree

FAILED: patch "[PATCH] mm/huge_memory: drop beyond-EOF folios with the right number" failed to apply to 6.12-stable tree

[gregkh]

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 <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-6.12.y
git checkout FETCH_HEAD
git cherry-pick -x 14efb4793519d73fb2902bb0ece319b886e4b4b9
# <resolve conflicts, build, test, etc.>
git commit -s
git send-email --to '<stable@vger.kernel.org>' --in-reply-to '2025032430-granny-hunter-c6a5@gregkh' --subject-prefix 'PATCH 6.12.y' HEAD^..

Possible dependencies:



thanks,

greg k-h

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

From 14efb4793519d73fb2902bb0ece319b886e4b4b9 Mon Sep 17 00:00:00 2001
From: Zi Yan <ziy@nvidia.com>
Date: Mon, 10 Mar 2025 11:57:27 -0400
Subject: [PATCH] mm/huge_memory: drop beyond-EOF folios with the right number
 of refs

When an after-split folio is large and needs to be dropped due to EOF,
folio_put_refs(folio, folio_nr_pages(folio)) should be used to drop all
page cache refs.  Otherwise, the folio will not be freed, causing memory
leak.

This leak would happen on a filesystem with blocksize > page_size and a
truncate is performed, where the blocksize makes folios split to >0 order
ones, causing truncated folios not being freed.

Link: https://lkml.kernel.org/r/20250310155727.472846-1-ziy@nvidia.com
Fixes: c010d47f107f ("mm: thp: split huge page to any lower order pages")
Signed-off-by: Zi Yan <ziy@nvidia.com>
Reported-by: Hugh Dickins <hughd@google.com>
Closes: https://lore.kernel.org/all/fcbadb7f-dd3e-21df-f9a7-2853b53183c4@google.com/
Cc: Baolin Wang <baolin.wang@linux.alibaba.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: John Hubbard <jhubbard@nvidia.com>
Cc: Kefeng Wang <wangkefeng.wang@huawei.com>
Cc: Kirill A. Shuemov <kirill.shutemov@linux.intel.com>
Cc: Luis Chamberalin <mcgrof@kernel.org>
Cc: Matthew Wilcow (Oracle) <willy@infradead.org>
Cc: Miaohe Lin <linmiaohe@huawei.com>
Cc: Pankaj Raghav <p.raghav@samsung.com>
Cc: Ryan Roberts <ryan.roberts@arm.com>
Cc: Yang Shi <yang@os.amperecomputing.com>
Cc: Yu Zhao <yuzhao@google.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

diff --git a/mm/huge_memory.c b/mm/huge_memory.c
index 3d3ebdc002d5..373781b21e5c 100644
--- a/mm/huge_memory.c
+++ b/mm/huge_memory.c
@@ -3304,7 +3304,7 @@ static void __split_huge_page(struct page *page, struct list_head *list,
 				folio_account_cleaned(tail,
 					inode_to_wb(folio->mapping->host));
 			__filemap_remove_folio(tail, NULL);
-			folio_put(tail);
+			folio_put_refs(tail, folio_nr_pages(tail));
 		} else if (!folio_test_anon(folio)) {
 			__xa_store(&folio->mapping->i_pages, tail->index,
 					tail, 0);

[PATCH 6.12.y] mm/huge_memory: drop beyond-EOF folios with the right number of refs

[Zi Yan]

When an after-split folio is large and needs to be dropped due to EOF,
folio_put_refs(folio, folio_nr_pages(folio)) should be used to drop all
page cache refs.  Otherwise, the folio will not be freed, causing memory
leak.

This leak would happen on a filesystem with blocksize > page_size and a
truncate is performed, where the blocksize makes folios split to >0 order
ones, causing truncated folios not being freed.

Link: https://lkml.kernel.org/r/20250310155727.472846-1-ziy@nvidia.com
Fixes: c010d47f107f ("mm: thp: split huge page to any lower order pages")
Signed-off-by: Zi Yan <ziy@nvidia.com>
Reported-by: Hugh Dickins <hughd@google.com>
Closes: https://lore.kernel.org/all/fcbadb7f-dd3e-21df-f9a7-2853b53183c4@google.com/
Cc: Baolin Wang <baolin.wang@linux.alibaba.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: John Hubbard <jhubbard@nvidia.com>
Cc: Kefeng Wang <wangkefeng.wang@huawei.com>
Cc: Kirill A. Shuemov <kirill.shutemov@linux.intel.com>
Cc: Luis Chamberalin <mcgrof@kernel.org>
Cc: Matthew Wilcow (Oracle) <willy@infradead.org>
Cc: Miaohe Lin <linmiaohe@huawei.com>
Cc: Pankaj Raghav <p.raghav@samsung.com>
Cc: Ryan Roberts <ryan.roberts@arm.com>
Cc: Yang Shi <yang@os.amperecomputing.com>
Cc: Yu Zhao <yuzhao@google.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
(cherry picked from commit 14efb4793519d73fb2902bb0ece319b886e4b4b9)
---
 mm/huge_memory.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/mm/huge_memory.c b/mm/huge_memory.c
index f127b61f04a8..40ac11e29423 100644
--- a/mm/huge_memory.c
+++ b/mm/huge_memory.c
@@ -3224,7 +3224,7 @@ static void __split_huge_page(struct page *page, struct list_head *list,
 				folio_account_cleaned(tail,
 					inode_to_wb(folio->mapping->host));
 			__filemap_remove_folio(tail, NULL);
-			folio_put(tail);
+			folio_put_refs(tail, folio_nr_pages(tail));
 		} else if (!PageAnon(page)) {
 			__xa_store(&folio->mapping->i_pages, head[i].index,
 					head + i, 0);
-- 
2.47.2

Re: [PATCH 6.12.y] mm/huge_memory: drop beyond-EOF folios with the right number of refs

[Sasha Levin]

[ Sasha's backport helper bot ]

Hi,

Summary of potential issues:
⚠️ Found matching upstream commit but patch is missing proper reference to it

Found matching upstream commit: 14efb4793519d73fb2902bb0ece319b886e4b4b9

Status in newer kernel trees:
6.13.y | Not found

Note: The patch differs from the upstream commit:
---
1:  14efb4793519d ! 1:  8e2adc6066c3d mm/huge_memory: drop beyond-EOF folios with the right number of refs
    @@ Commit message
         Cc: Yu Zhao <yuzhao@google.com>
         Cc: <stable@vger.kernel.org>
         Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
    +    (cherry picked from commit 14efb4793519d73fb2902bb0ece319b886e4b4b9)
     
      ## mm/huge_memory.c ##
     @@ mm/huge_memory.c: static void __split_huge_page(struct page *page, struct list_head *list,
    @@ mm/huge_memory.c: static void __split_huge_page(struct page *page, struct list_h
      			__filemap_remove_folio(tail, NULL);
     -			folio_put(tail);
     +			folio_put_refs(tail, folio_nr_pages(tail));
    - 		} else if (!folio_test_anon(folio)) {
    - 			__xa_store(&folio->mapping->i_pages, tail->index,
    - 					tail, 0);
    + 		} else if (!PageAnon(page)) {
    + 			__xa_store(&folio->mapping->i_pages, head[i].index,
    + 					head + i, 0);
---

Results of testing on various branches:

| Branch                    | Patch Apply | Build Test |
|---------------------------|-------------|------------|
| stable/linux-6.12.y       |  Success    |  Success   |