[merged mm-hotfixes-stable] mm-cma_debug-fix-invalid-accesses-for-inactive-cma-areas.patch removed from -mm tree

[merged mm-hotfixes-stable] mm-cma_debug-fix-invalid-accesses-for-inactive-cma-areas.patch removed from -mm tree

[Andrew Morton]

The quilt patch titled
     Subject: mm/cma_debug: fix invalid accesses for inactive CMA areas
has been removed from the -mm tree.  Its filename was
     mm-cma_debug-fix-invalid-accesses-for-inactive-cma-areas.patch

This patch was dropped because it was merged into the mm-hotfixes-stable branch
of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm

------------------------------------------------------
From: Muchun Song <songmuchun@bytedance.com>
Subject: mm/cma_debug: fix invalid accesses for inactive CMA areas
Date: Wed, 20 May 2026 14:10:25 +0800

cma_activate_area() can fail after allocating range bitmaps.  Its cleanup
path frees those bitmaps, but only clears cma->count and
cma->available_count.  It leaves cma->nranges and each range's count in
place, so cma_debugfs_init() can still register debugfs files for an area
that never activated successfully.

That exposes two problems.  Reading the bitmap file can make debugfs walk
a freed range bitmap and trigger an invalid memory access.  Reading
maxchunk can also take cma->lock even though that lock is initialized only
on the successful activation path.

Fix this by creating debugfs entries only for CMA areas that reached
CMA_ACTIVATED.

c009da4258f9 introduced the invalid access to bitmap file.  2e32b947606d
introduced the invalid access to cma->lock.  This change applies to both
issues.  So I added two Fixes tags.

Link: https://lore.kernel.org/20260520061025.3971821-1-songmuchun@bytedance.com
Fixes: c009da4258f9 ("mm, cma: support multiple contiguous ranges, if requested")
Fixes: 2e32b947606d ("mm: cma: add functions to get region pages counters")
Signed-off-by: Muchun Song <songmuchun@bytedance.com>
Acked-by: Mike Rapoport (Microsoft) <rppt@kernel.org>
Acked-by: Oscar Salvador (SUSE) <osalvador@kernel.org>
Acked-by: David Hildenbrand (Arm) <david@kernel.org>
Cc: Dmitry Safonov <0x7f454c46@gmail.com>
Cc: Frank van der Linden <fvdl@google.com>
Cc: Liam R. Howlett <liam@infradead.org>
Cc: Lorenzo Stoakes <ljs@kernel.org>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Michal Nazarewicz <mina86@mina86.com>
Cc: Stefan Strogin <stefan.strogin@gmail.com>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Vlastimil Babka <vbabka@kernel.org>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 mm/cma_debug.c |    3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

--- a/mm/cma_debug.c~mm-cma_debug-fix-invalid-accesses-for-inactive-cma-areas
+++ a/mm/cma_debug.c
@@ -205,7 +205,8 @@ static int __init cma_debugfs_init(void)
 	cma_debugfs_root = debugfs_create_dir("cma", NULL);
 
 	for (i = 0; i < cma_area_count; i++)
-		cma_debugfs_add_one(&cma_areas[i], cma_debugfs_root);
+		if (test_bit(CMA_ACTIVATED, &cma_areas[i].flags))
+			cma_debugfs_add_one(&cma_areas[i], cma_debugfs_root);
 
 	return 0;
 }
_

Patches currently in -mm which might be from songmuchun@bytedance.com are

mm-hugetlb_vmemmap-fix-incorrect-vmemmap-restore-in-rollback.patch
mm-sparse-remove-sparse-buffer-pre-allocation-mechanism.patch
mm-sparse-vmemmap-fix-vmemmap-accounting-underflow.patch
mm-memory_hotplug-fix-incorrect-altmap-passing-in-error-path.patch
mm-sparse-vmemmap-pass-pgmap-argument-to-memory-deactivation-paths.patch
mm-sparse-vmemmap-fix-dax-vmemmap-accounting-with-optimization.patch
mm-mm_init-fix-pageblock-migratetype-for-zone_device-compound-pages.patch
mm-mm_init-fix-uninitialized-struct-pages-for-zone_device.patch
mm-memory_hotplug-factor-out-altmap-freeing-checks.patch
drivers-base-memory-make-memory-block-get-put-explicit.patch