This is a note to let you know that I've just added the patch titled mm: multi-gen LRU: fix crash during cgroup migration to the 6.1-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary The filename of the patch is: mm-multi-gen-lru-fix-crash-during-cgroup-migration.patch and it can be found in the queue-6.1 subdirectory. If you, or anyone else, feels it should not be added to the stable tree, please let <stable@xxxxxxxxxxxxxxx> know about it. >From de08eaa6156405f2e9369f06ba5afae0e4ab3b62 Mon Sep 17 00:00:00 2001 From: Yu Zhao <yuzhao@xxxxxxxxxx> Date: Sun, 15 Jan 2023 20:44:05 -0700 Subject: mm: multi-gen LRU: fix crash during cgroup migration From: Yu Zhao <yuzhao@xxxxxxxxxx> commit de08eaa6156405f2e9369f06ba5afae0e4ab3b62 upstream. lru_gen_migrate_mm() assumes lru_gen_add_mm() runs prior to itself. This isn't true for the following scenario: CPU 1 CPU 2 clone() cgroup_can_fork() cgroup_procs_write() cgroup_post_fork() task_lock() lru_gen_migrate_mm() task_unlock() task_lock() lru_gen_add_mm() task_unlock() And when the above happens, kernel crashes because of linked list corruption (mm_struct->lru_gen.list). Link: https://lore.kernel.org/r/20230115134651.30028-1-msizanoen@xxxxxxxxxxx/ Link: https://lkml.kernel.org/r/20230116034405.2960276-1-yuzhao@xxxxxxxxxx Fixes: bd74fdaea146 ("mm: multi-gen LRU: support page table walks") Signed-off-by: Yu Zhao <yuzhao@xxxxxxxxxx> Reported-by: msizanoen <msizanoen@xxxxxxxxxxx> Tested-by: msizanoen <msizanoen@xxxxxxxxxxx> Cc: <stable@xxxxxxxxxxxxxxx> [6.1+] Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- mm/vmscan.c | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-) --- a/mm/vmscan.c +++ b/mm/vmscan.c @@ -3290,13 +3290,16 @@ void lru_gen_migrate_mm(struct mm_struct if (mem_cgroup_disabled()) return; + /* migration can happen before addition */ + if (!mm->lru_gen.memcg) + return; + rcu_read_lock(); memcg = mem_cgroup_from_task(task); rcu_read_unlock(); if (memcg == mm->lru_gen.memcg) return; - VM_WARN_ON_ONCE(!mm->lru_gen.memcg); VM_WARN_ON_ONCE(list_empty(&mm->lru_gen.list)); lru_gen_del_mm(mm); Patches currently in stable-queue which might be from yuzhao@xxxxxxxxxx are queue-6.1/mm-multi-gen-lru-fix-crash-during-cgroup-migration.patch