The patch titled
Subject: mm: assert mmap write lock held on do_mmap(), mmap_region()
has been added to the -mm mm-unstable branch. Its filename is
mm-assert-mmap-write-lock-held-on-do_mmap-mmap_region.patch
This patch will shortly appear at
https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/mm-assert-mmap-write-lock-held-on-do_mmap-mmap_region.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: Lorenzo Stoakes <lorenzo.stoakes@xxxxxxxxxx>
Subject: mm: assert mmap write lock held on do_mmap(), mmap_region()
Date: Thu, 12 Dec 2024 11:48:41 +0000
Both of these functions can be invoked outside of mm, so it is probably a
good idea to assert that the required lock is held.
Will only have an impact if CONFIG_DEBUG_VM is set, otherwise this amounts
to no change at all.
Link: https://lkml.kernel.org/r/20241212114841.55185-1-lorenzo.stoakes@xxxxxxxxxx
Signed-off-by: Lorenzo Stoakes <lorenzo.stoakes@xxxxxxxxxx>
Cc: Jann Horn <jannh@xxxxxxxxxx>
Cc: Liam R. Howlett <Liam.Howlett@xxxxxxxxxx>
Cc: Vlastimil Babka <vbabka@xxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/mmap.c | 4 ++++
1 file changed, 4 insertions(+)
--- a/mm/mmap.c~mm-assert-mmap-write-lock-held-on-do_mmap-mmap_region
+++ a/mm/mmap.c
@@ -291,6 +291,8 @@ unsigned long do_mmap(struct file *file,
*populate = 0;
+ mmap_assert_write_locked(mm);
+
if (!len)
return -EINVAL;
@@ -1023,6 +1025,8 @@ unsigned long mmap_region(struct file *f
unsigned long ret;
bool writable_file_mapping = false;
+ mmap_assert_write_locked(current->mm);
+
/* Check to see if MDWE is applicable. */
if (map_deny_write_exec(vm_flags, vm_flags))
return -EACCES;
_
Patches currently in -mm which might be from lorenzo.stoakes@xxxxxxxxxx are
docs-mm-add-vma-locks-documentation.patch
mm-reinstate-ability-to-map-write-sealed-memfd-mappings-read-only.patch
selftests-memfd-add-test-for-mapping-write-sealed-memfd-read-only.patch
mm-correctly-reference-merged-vma.patch
fork-avoid-inappropriate-uprobe-access-to-invalid-mm.patch
mm-vma-move-brk-internals-to-mm-vmac.patch
mm-vma-move-brk-internals-to-mm-vmac-fix.patch
mm-vma-move-unmapped_area-internals-to-mm-vmac.patch
mm-abstract-get_arg_page-stack-expansion-and-mmap-read-lock.patch
mm-vma-move-stack-expansion-logic-to-mm-vmac.patch
mm-vma-move-__vm_munmap-to-mm-vmac.patch
selftests-mm-add-fork-cow-guard-page-test.patch
mm-enforce-__must_check-on-vma-merge-and-split.patch
mm-perform-all-memfd-seal-checks-in-a-single-place.patch
mm-perform-all-memfd-seal-checks-in-a-single-place-fix.patch
maintainers-update-memory-mapping-section.patch
mm-assert-mmap-write-lock-held-on-do_mmap-mmap_region.patch
