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Rafael Aquini
30eb170c14
JIRA: https://redhat.atlassian.net/browse/RHEL-227151 CVE: CVE-2026-53153 commit 98733f3f0becb1ae0701d021c1748e974e5fa55c Author: Shakeel Butt <shakeel.butt@linux.dev> Date: Mon Jun 1 09:15:01 2026 -0700 mm/list_lru: drain before clearing xarray entry on reparent memcg_reparent_list_lrus() clears the dying memcg's xarray entry with xas_store(&xas, NULL) before reparenting its per-node lists into the parent. This opens a window where a concurrent list_lru_del() arriving for the dying memcg sees xa_load() == NULL, walks to the parent in lock_list_lru_of_memcg(), takes the parent's per-node lock, and calls list_del_init() on an item still physically linked on the dying memcg's list. If another in-flight thread holds the dying memcg's per-node lock at the same moment (another list_lru_del, or a list_lru_walk_one running an isolate callback), both threads modify ->next/->prev pointers on the same physical list under different locks. Adjacent items can corrupt each other's links. Fix it by reversing the order: reparent each per-node list and mark the child's list lru dead and then clear the xarray entry. Any concurrent list_lru op that finds the still-set xarray entry either takes the dying memcg's per-node lock (synchronizing with the drain) or sees LONG_MIN and walks to the parent, where the items now live. Link: https://lore.kernel.org/20260601161501.1444829-1-shakeel.butt@linux.dev Fixes: fb56fdf8b9a2 ("mm/list_lru: split the lock to per-cgroup scope") Signed-off-by: Shakeel Butt <shakeel.butt@linux.dev> Reported-by: Chris Mason <clm@fb.com> Reviewed-by: Kairui Song <kasong@tencent.com> Acked-by: Muchun Song <muchun.song@linux.dev> Cc: Dave Chinner <david@fromorbit.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Roman Gushchin <roman.gushchin@linux.dev> Cc: <stable@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Rafael Aquini <raquini@redhat.com>