The patch titled
Subject: mm/huge_memory: skip invalid debugfs new_order input for folio split
has been added to the -mm mm-unstable branch. Its filename is
mm-huge_memory-skip-invalid-debugfs-new_order-input-for-folio-split.patch
This patch will shortly appear at
https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/mm-huge_memory-skip-invalid-debugfs-new_order-input-for-folio-split.patch
This patch will later appear in the mm-unstable branch at
git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
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------------------------------------------------------
From: Zi Yan <ziy@xxxxxxxxxx>
Subject: mm/huge_memory: skip invalid debugfs new_order input for folio split
Date: Thu, 7 Mar 2024 13:18:54 -0500
User can put arbitrary new_order via debugfs for folio split test.
Although new_order check is added to split_huge_page_to_list_order() in
the prior commit, these two additional checks can avoid unnecessary folio
locking and split_folio_to_order() calls.
Link: https://lkml.kernel.org/r/20240307181854.138928-2-zi.yan@xxxxxxxx
Signed-off-by: Zi Yan <ziy@xxxxxxxxxx>
Reported-by: Dan Carpenter <dan.carpenter@xxxxxxxxxx>
Closes: https://lore.kernel.org/linux-mm/7dda9283-b437-4cf8-ab0d-83c330deb9c0@moroto.mountain/
Cc: David Hildenbrand <david@xxxxxxxxxx>
Cc: Kirill A. Shutemov <kirill.shutemov@xxxxxxxxxxxxxxx>
Cc: Matthew Wilcox (Oracle) <willy@xxxxxxxxxxxxx>
Cc: Ryan Roberts <ryan.roberts@xxxxxxx>
Cc: Yang Shi <shy828301@xxxxxxxxx>
Cc: Yu Zhao <yuzhao@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/huge_memory.c | 6 ++++++
1 file changed, 6 insertions(+)
--- a/mm/huge_memory.c~mm-huge_memory-skip-invalid-debugfs-new_order-input-for-folio-split
+++ a/mm/huge_memory.c
@@ -3486,6 +3486,9 @@ static int split_huge_pages_pid(int pid,
if (!is_transparent_hugepage(folio))
goto next;
+ if (new_order >= folio_order(folio))
+ goto next;
+
total++;
/*
* For folios with private, split_huge_page_to_list_to_order()
@@ -3553,6 +3556,9 @@ static int split_huge_pages_in_file(cons
total++;
nr_pages = folio_nr_pages(folio);
+ if (new_order >= folio_order(folio))
+ goto next;
+
if (!folio_trylock(folio))
goto next;
_
Patches currently in -mm which might be from ziy@xxxxxxxxxx are
mm-huge_memory-check-new-folio-order-when-split-a-folio.patch
mm-huge_memory-skip-invalid-debugfs-new_order-input-for-folio-split.patch
