The quilt patch titled
Subject: mm: multi-gen LRU: fix crash during cgroup migration
has been removed from the -mm tree. Its filename was
mm-multi-gen-lru-fix-crash-during-cgroup-migration.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: Yu Zhao <yuzhao@xxxxxxxxxx>
Subject: mm: multi-gen LRU: fix crash during cgroup migration
Date: Sun, 15 Jan 2023 20:44:05 -0700
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>
---
mm/vmscan.c | 5 ++++-
1 file changed, 4 insertions(+), 1 deletion(-)
--- a/mm/vmscan.c~mm-multi-gen-lru-fix-crash-during-cgroup-migration
+++ a/mm/vmscan.c
@@ -3323,13 +3323,16 @@ 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 -mm which might be from yuzhao@xxxxxxxxxx are
