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

JIRA: https://issues.redhat.com/browse/RHEL-84184

This patch is a backport of the following upstream commit:
commit 9bcef59
Author: Baolin Wang <[email protected]>
Date:   Wed Dec 20 14:51:40 2023 +0800

    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 85ce2c5 ("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.

    [[email protected]: fix comment, per Zi Yan]
    Link: https://lkml.kernel.org/r/61273e5e9b490682388377c20f52d19de4a80460.1703054559.git.baolin.wang@linux.alibaba.com
    Fixes: 85ce2c5 ("memcontrol: only transfer the memcg data for migration")
    Signed-off-by: Baolin Wang <[email protected]>
    Reviewed-by: Nhat Pham <[email protected]>
    Reviewed-by: Yang Shi <[email protected]>
    Reviewed-by: Zi Yan <[email protected]>
    Cc: David Hildenbrand <[email protected]>
    Cc: "Huang, Ying" <[email protected]>
    Cc: Johannes Weiner <[email protected]>
    Cc: Michal Hocko <[email protected]>
    Cc: Muchun Song <[email protected]>
    Cc: Roman Gushchin <[email protected]>
    Cc: Shakeel Butt <[email protected]>
    Signed-off-by: Andrew Morton <[email protected]>

Signed-off-by: Rafael Aquini <[email protected]>

Author: Rafael Aquini

mm/huge_memory.c

@@ -2801,7 +2801,7 @@ 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);
 }

mm/memcontrol.c

@@ -7695,6 +7695,17 @@ 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;
 }