+ mm-huge_memory-skip-invalid-debugfs-new_order-input-for-folio-split.patch added to mm-unstable branch

+ mm-huge_memory-skip-invalid-debugfs-new_order-input-for-folio-split.patch added to mm-unstable branch

[Andrew Morton]

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@nvidia.com>
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@sent.com
Signed-off-by: Zi Yan <ziy@nvidia.com>
Reported-by: Dan Carpenter <dan.carpenter@linaro.org>
Closes: https://lore.kernel.org/linux-mm/7dda9283-b437-4cf8-ab0d-83c330deb9c0@moroto.mountain/
Cc: David Hildenbrand <david@redhat.com>
Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Ryan Roberts <ryan.roberts@arm.com>
Cc: Yang Shi <shy828301@gmail.com>
Cc: Yu Zhao <yuzhao@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 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@nvidia.com 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