From: Yu Zhao Date: Mon, 16 Jan 2023 03:44:05 +0000 (-0700) Subject: mm: multi-gen LRU: fix crash during cgroup migration X-Git-Tag: baikal/aarch64/sdk6.1~54 X-Git-Url: https://git.baikalelectronics.ru/sdk/?a=commitdiff_plain;h=ff6687d35babb256984cfa9989d1a37f2b3f5a9a;p=kernel.git mm: multi-gen LRU: fix crash during cgroup migration 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@qtmlabs.xyz/ Link: https://lkml.kernel.org/r/20230116034405.2960276-1-yuzhao@google.com Fixes: d6cb17c5af77 ("mm: multi-gen LRU: support page table walks") Signed-off-by: Yu Zhao Reported-by: msizanoen Tested-by: msizanoen Cc: [6.1+] Signed-off-by: Andrew Morton Signed-off-by: Greg Kroah-Hartman --- diff --git a/mm/vmscan.c b/mm/vmscan.c index 8fcc5fa768c07..96eb9da372cd7 100644 --- a/mm/vmscan.c +++ b/mm/vmscan.c @@ -3290,13 +3290,16 @@ void lru_gen_migrate_mm(struct mm_struct *mm) 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);