e37386abdf1967927f78ff1167d179a99cb867e4
[openwrt/staging/xback.git] /
1 From c7dfefd4bdfba3d5171038d1cc2d4160288e6ee4 Mon Sep 17 00:00:00 2001
2 From: Yu Zhao <yuzhao@google.com>
3 Date: Sun, 15 Jan 2023 20:44:05 -0700
4 Subject: [PATCH 16/29] mm: multi-gen LRU: fix crash during cgroup migration
5
6 lru_gen_migrate_mm() assumes lru_gen_add_mm() runs prior to itself. This
7 isn't true for the following scenario:
8
9 CPU 1 CPU 2
10
11 clone()
12 cgroup_can_fork()
13 cgroup_procs_write()
14 cgroup_post_fork()
15 task_lock()
16 lru_gen_migrate_mm()
17 task_unlock()
18 task_lock()
19 lru_gen_add_mm()
20 task_unlock()
21
22 And when the above happens, kernel crashes because of linked list
23 corruption (mm_struct->lru_gen.list).
24
25 Link: https://lore.kernel.org/r/20230115134651.30028-1-msizanoen@qtmlabs.xyz/
26 Link: https://lkml.kernel.org/r/20230116034405.2960276-1-yuzhao@google.com
27 Fixes: bd74fdaea146 ("mm: multi-gen LRU: support page table walks")
28 Signed-off-by: Yu Zhao <yuzhao@google.com>
29 Reported-by: msizanoen <msizanoen@qtmlabs.xyz>
30 Tested-by: msizanoen <msizanoen@qtmlabs.xyz>
31 Cc: <stable@vger.kernel.org> [6.1+]
32 Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
33 ---
34 mm/vmscan.c | 5 ++++-
35 1 file changed, 4 insertions(+), 1 deletion(-)
36
37 --- a/mm/vmscan.c
38 +++ b/mm/vmscan.c
39 @@ -3024,13 +3024,16 @@ void lru_gen_migrate_mm(struct mm_struct
40 if (mem_cgroup_disabled())
41 return;
42
43 + /* migration can happen before addition */
44 + if (!mm->lru_gen.memcg)
45 + return;
46 +
47 rcu_read_lock();
48 memcg = mem_cgroup_from_task(task);
49 rcu_read_unlock();
50 if (memcg == mm->lru_gen.memcg)
51 return;
52
53 - VM_WARN_ON_ONCE(!mm->lru_gen.memcg);
54 VM_WARN_ON_ONCE(list_empty(&mm->lru_gen.list));
55
56 lru_gen_del_mm(mm);