+ mm-assert-mmap-write-lock-held-on-do_mmap-mmap_region.patch added to mm-unstable branch

+ mm-assert-mmap-write-lock-held-on-do_mmap-mmap_region.patch added to mm-unstable branch

[Andrew Morton]

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@oracle.com>
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@oracle.com
Signed-off-by: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Cc: Jann Horn <jannh@google.com>
Cc: Liam R. Howlett <Liam.Howlett@Oracle.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 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@oracle.com 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