+ mm-vma-correctly-unaccount-on-mmap_prepare-failure.patch added to mm-hotfixes-unstable branch

+ mm-vma-correctly-unaccount-on-mmap_prepare-failure.patch added to mm-hotfixes-unstable branch

[Andrew Morton]

The patch titled
     Subject: mm/vma: correctly unaccount on mmap_prepare() failure
has been added to the -mm mm-hotfixes-unstable branch.  Its filename is
     mm-vma-correctly-unaccount-on-mmap_prepare-failure.patch

This patch will shortly appear at
     https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/mm-vma-correctly-unaccount-on-mmap_prepare-failure.patch

This patch will later appear in the mm-hotfixes-unstable branch at
    git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm

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------------------------------------------------------
From: "Lorenzo Stoakes (ARM)" <ljs@kernel.org>
Subject: mm/vma: correctly unaccount on mmap_prepare() failure
Date: Wed, 02 Sep 2026 19:08:08 +0100

__mmap_setup() accounts memory for relevant mappings via:

security_vm_enough_memory_mm()
  -> __vm_enough_memory()
    -> vm_acct_memory()

If __mmap_setup() fails, this indicates that this accounting did not take
place, and thus it's appropriate for __mmap_region() to jump to
abort_munmap.

However if call_mmap_prepare() fails, it also jumps there and any accounted
memory is not correctly unaccounted.

Fix this by handling each error separately.

Link: https://lore.kernel.org/20260902-fix-unaccount-mmap_prepare-v1-1-ea070189fdfb@kernel.org
Fixes: c84bf6dd2b83 ("mm: introduce new .mmap_prepare() file callback")
Signed-off-by: Lorenzo Stoakes (ARM) <ljs@kernel.org>
Cc: Jann Horn <jannh@google.com>
Cc: Liam R. Howlett <liam@infradead.org>
Cc: Pedro Falcato <pfalcato@suse.de>
Cc: Vlastimil Babka <vbabka@kernel.org>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 mm/vma.c |    6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

--- a/mm/vma.c~mm-vma-correctly-unaccount-on-mmap_prepare-failure
+++ a/mm/vma.c
@@ -2859,10 +2859,12 @@ static unsigned long __mmap_region(struc
 	map.check_ksm_early = can_set_ksm_flags_early(&map);
 
 	error = __mmap_setup(&map, &desc, uf);
-	if (!error && have_mmap_prepare)
-		error = call_mmap_prepare(&map, &desc);
 	if (error)
 		goto abort_munmap;
+	if (have_mmap_prepare)
+		error = call_mmap_prepare(&map, &desc);
+	if (error)
+		goto unacct_error;
 
 	if (map.check_ksm_early)
 		update_ksm_flags(&map);
_

Patches currently in -mm which might be from ljs@kernel.org are

mm-mremap-reset-unfaulted-vma-page-offset-for-mremap_dontunmap.patch
mm-secretmem-properly-account-locked-pages.patch
mm-huge_memory-bypass-thp-tuneables-for-huge-pfnmap-mappings.patch
mm-mremap-account-mm-locked_vm-correctly-for-mremap_dontunmap.patch
mm-vma-correctly-unaccount-on-mmap_prepare-failure.patch
mm-vmpressure-remove-window-size-todo.patch
tools-testing-selftests-mm-add-missing-gitignore-entries.patch