On Tue, Dec 19, 2023 at 10:52 PM Baolin Wang
<baolin.wang@xxxxxxxxxxxxxxxxx> wrote:
>
> 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.
Ah this is tricky. I think you're right - the old folio's memcg is
used to get the deferred split queue, and we cleared it here :)
>
> 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.
>
> Fixes: 85ce2c517ade ("memcontrol: only transfer the memcg data for migration")
> Signed-off-by: Baolin Wang <baolin.wang@xxxxxxxxxxxxxxxxx>
> ---
> mm/huge_memory.c | 2 +-
> mm/memcontrol.c | 11 +++++++++++
> 2 files changed, 12 insertions(+), 1 deletion(-)
>
> diff --git a/mm/huge_memory.c b/mm/huge_memory.c
> index 6be1a380a298..c50dc2e1483f 100644
> --- a/mm/huge_memory.c
> +++ b/mm/huge_memory.c
> @@ -3124,7 +3124,7 @@ 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 ae8c62c7aa53..e66e0811cccc 100644
> --- a/mm/memcontrol.c
> +++ b/mm/memcontrol.c
> @@ -7575,6 +7575,17 @@ 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 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);
This looks reasonable to me :)
Reviewed-by: Nhat Pham <nphamcs@xxxxxxxxx>
> old->memcg_data = 0;
> }
>
> --
> 2.39.3
>
