mm: memcg: fix split queue list crash when large folio migration

When running autonuma with enabling multi-size THP, I encountered the
following kernel crash issue:

[  134.290216] list_del corruption. prev->next should be fffff9ad42e1c490,
but was dead000000000100. (prev=fffff9ad42399890)
[  134.290877] kernel BUG at lib/list_debug.c:62!
[  134.291052] invalid opcode: 0000 [#1] PREEMPT SMP NOPTI
[  134.291210] CPU: 56 PID: 8037 Comm: numa01 Kdump: loaded Tainted:
G            E      6.7.0-rc4+ #20
[  134.291649] RIP: 0010:__list_del_entry_valid_or_report+0x97/0xb0
......
[  134.294252] Call Trace:
[  134.294362]  <TASK>
[  134.294440]  ? die+0x33/0x90
[  134.294561]  ? do_trap+0xe0/0x110
......
[  134.295681]  ? __list_del_entry_valid_or_report+0x97/0xb0
[  134.295842]  folio_undo_large_rmappable+0x99/0x100
[  134.296003]  destroy_large_folio+0x68/0x70
[  134.296172]  migrate_folio_move+0x12e/0x260
[  134.296264]  ? __pfx_remove_migration_pte+0x10/0x10
[  134.296389]  migrate_pages_batch+0x495/0x6b0
[  134.296523]  migrate_pages+0x1d0/0x500
[  134.296646]  ? __pfx_alloc_misplaced_dst_folio+0x10/0x10
[  134.296799]  migrate_misplaced_folio+0x12d/0x2b0
[  134.296953]  do_numa_page+0x1f4/0x570
[  134.297121]  __handle_mm_fault+0x2b0/0x6c0
[  134.297254]  handle_mm_fault+0x107/0x270
[  134.300897]  do_user_addr_fault+0x167/0x680
[  134.304561]  exc_page_fault+0x65/0x140
[  134.307919]  asm_exc_page_fault+0x22/0x30

The reason for the crash is that, the commit 85ce2c517ade ("memcontrol:
only transfer the memcg data for migration") removed the charging and
uncharging operations of the migration folios and cleared the memcg data
of the old folio.

During the subsequent release process of the old large folio in
destroy_large_folio(), if the large folio needs to be removed from the
split queue, an incorrect split queue can be obtained (which is
pgdat->deferred_split_queue) because the old folio's memcg is NULL now. 
This can lead to list operations being performed under the wrong split
queue lock protection, resulting in a list crash as above.

After the migration, the old folio is going to be freed, so we can remove
it from the split queue in mem_cgroup_migrate() a bit earlier before
clearing the memcg data to avoid getting incorrect split queue.

[akpm@linux-foundation.org: fix comment, per Zi Yan]
Link: https://lkml.kernel.org/r/61273e5e9b490682388377c20f52d19de4a80460.1703054559.git.baolin.wang@linux.alibaba.com
Fixes: 85ce2c517ade ("memcontrol: only transfer the memcg data for migration")
Signed-off-by: Baolin Wang <baolin.wang@linux.alibaba.com>
Reviewed-by: Nhat Pham <nphamcs@gmail.com>
Reviewed-by: Yang Shi <shy828301@gmail.com>
Reviewed-by: Zi Yan <ziy@nvidia.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: "Huang, Ying" <ying.huang@intel.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Muchun Song <muchun.song@linux.dev>
Cc: Roman Gushchin <roman.gushchin@linux.dev>
Cc: Shakeel Butt <shakeelb@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

2 files changed, 12 insertions, 1 deletions

diff --git a/mm/huge_memory.c b/mm/huge_memory.c
index 4f542444a91f..86ee29b5c39c 100644
--- a/mm/huge_memory.c
+++ b/mm/huge_memory.c
@@ -2823,7 +2823,7 @@ void folio_undo_large_rmappable(struct folio *folio)
 	spin_lock_irqsave(&ds_queue->split_queue_lock, flags);
 	if (!list_empty(&folio->_deferred_list)) {
 		ds_queue->split_queue_len--;
-		list_del(&folio->_deferred_list);
+		list_del_init(&folio->_deferred_list);
 	}
 	spin_unlock_irqrestore(&ds_queue->split_queue_lock, flags);
 }
diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index b226090fd906..651b86ff03dd 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -7543,6 +7543,17 @@ void mem_cgroup_migrate(struct folio *old, struct folio *new)
 
 	/* Transfer the charge and the css ref */
 	commit_charge(new, memcg);
+	/*
+	 * If the old folio is a large folio and is in the split queue, it needs
+	 * to be removed from the split queue now, in case getting an incorrect
+	 * split queue in destroy_large_folio() after the memcg of the old folio
+	 * is cleared.
+	 *
+	 * In addition, the old folio is about to be freed after migration, so
+	 * removing from the split queue a bit earlier seems reasonable.
+	 */
+	if (folio_test_large(old) && folio_test_large_rmappable(old))
+		folio_undo_large_rmappable(old);
 	old->memcg_data = 0;
 }