mm/migrate.c | 5 +++++ 1 file changed, 5 insertions(+)
From: Zi Yan <ziy@nvidia.com>
As Ying pointed out in [1], stats->nr_thp_failed needs to be updated to
avoid stats inconsistency between MIGRATE_SYNC and MIGRATE_ASYNC when
calling migrate_pages_batch().
[1] https://lore.kernel.org/linux-mm/87msnq7key.fsf@yhuang6-desk2.ccr.corp.intel.com/
Suggested-by: "Huang, Ying" <ying.huang@intel.com>
Signed-off-by: Zi Yan <ziy@nvidia.com>
---
mm/migrate.c | 5 +++++
1 file changed, 5 insertions(+)
diff --git a/mm/migrate.c b/mm/migrate.c
index 2cc5a68f6843..20cb9f5f7446 100644
--- a/mm/migrate.c
+++ b/mm/migrate.c
@@ -1659,6 +1659,10 @@ static int migrate_pages_batch(struct list_head *from,
* migrate_pages() may report success with (split but
* unmigrated) pages still on its fromlist; whereas it
* always reports success when its fromlist is empty.
+ * stats->nr_thp_failed should be increased too,
+ * otherwise stats inconsistency will happen when
+ * migrate_pages_batch is called via migrate_pages()
+ * with MIGRATE_SYNC and MIGRATE_ASYNC.
*
* Only check it without removing it from the list.
* Since the folio can be on deferred_split_scan()
@@ -1675,6 +1679,7 @@ static int migrate_pages_batch(struct list_head *from,
!list_empty(&folio->_deferred_list)) {
if (try_split_folio(folio, split_folios) == 0) {
nr_failed++;
+ stats->nr_thp_failed += is_thp;
stats->nr_thp_split += is_thp;
stats->nr_split++;
continue;
base-commit: 14d7c92f8df9c0964ae6f8b813c1b3ac38120825
--
2.43.0Zi Yan <zi.yan@sent.com> writes: > From: Zi Yan <ziy@nvidia.com> > > As Ying pointed out in [1], stats->nr_thp_failed needs to be updated to > avoid stats inconsistency between MIGRATE_SYNC and MIGRATE_ASYNC when > calling migrate_pages_batch(). > > [1] https://lore.kernel.org/linux-mm/87msnq7key.fsf@yhuang6-desk2.ccr.corp.intel.com/ IMHO, we shouldn't ask people to use link to understand the patch description or commit message. If so, we can make the link less outstanding and maybe add more words about the issue. > Suggested-by: "Huang, Ying" <ying.huang@intel.com> > Signed-off-by: Zi Yan <ziy@nvidia.com> Otherwise, LGTM, Thanks! [snip] -- Best Regards, Huang, Ying
On 19 Jun 2024, at 3:25, Huang, Ying wrote: > Zi Yan <zi.yan@sent.com> writes: > >> From: Zi Yan <ziy@nvidia.com> >> >> As Ying pointed out in [1], stats->nr_thp_failed needs to be updated to >> avoid stats inconsistency between MIGRATE_SYNC and MIGRATE_ASYNC when >> calling migrate_pages_batch(). Because if not, when migrate_pages_batch() is called via migrate_pages(MIGRATE_ASYNC), nr_thp_failed will not be increased and when migrate_pages_batch() is called via migrate_pages(MIGRATE_SYNC*), nr_thp_failed will be increase in migrate_pages_sync() by stats->nr_thp_failed += astats.nr_thp_split. >> >> [1] https://lore.kernel.org/linux-mm/87msnq7key.fsf@yhuang6-desk2.ccr.corp.intel.com/ > > IMHO, we shouldn't ask people to use link to understand the patch > description or commit message. If so, we can make the link less > outstanding and maybe add more words about the issue. I summarized your explanation from the link. You think the summary is not enough? I can add more text. Let me know if the above text looks good to you, then I can resend the patch. Thanks. -- Best Regards, Yan, Zi
Zi Yan <ziy@nvidia.com> writes: > On 19 Jun 2024, at 3:25, Huang, Ying wrote: > >> Zi Yan <zi.yan@sent.com> writes: >> >>> From: Zi Yan <ziy@nvidia.com> >>> >>> As Ying pointed out in [1], stats->nr_thp_failed needs to be updated to >>> avoid stats inconsistency between MIGRATE_SYNC and MIGRATE_ASYNC when >>> calling migrate_pages_batch(). > > Because if not, when migrate_pages_batch() is called via > migrate_pages(MIGRATE_ASYNC), nr_thp_failed will not be increased and > when migrate_pages_batch() is called via migrate_pages(MIGRATE_SYNC*), > nr_thp_failed will be increase in migrate_pages_sync() by > stats->nr_thp_failed += astats.nr_thp_split. > >>> >>> [1] https://lore.kernel.org/linux-mm/87msnq7key.fsf@yhuang6-desk2.ccr.corp.intel.com/ >> >> IMHO, we shouldn't ask people to use link to understand the patch >> description or commit message. If so, we can make the link less >> outstanding and maybe add more words about the issue. > > I summarized your explanation from the link. You think the summary is not > enough? I can add more text. Let me know if the above text looks > good to you, then I can resend the patch. Thanks. It looks good to me, Thanks! -- Best Regards, Huang, Ying
On Tue, 18 Jun 2024 09:41:51 -0400 Zi Yan <zi.yan@sent.com> wrote:
> From: Zi Yan <ziy@nvidia.com>
>
> As Ying pointed out in [1], stats->nr_thp_failed needs to be updated to
> avoid stats inconsistency between MIGRATE_SYNC and MIGRATE_ASYNC when
> calling migrate_pages_batch().
>
Thanks. I'll add
Fixes: 7262f208ca68 ("mm/migrate: split source folio if it is on deferred split list")
and shall queue it for 6.10-rcX.
Please don't forget such details.
On 18 Jun 2024, at 15:44, Andrew Morton wrote:
> On Tue, 18 Jun 2024 09:41:51 -0400 Zi Yan <zi.yan@sent.com> wrote:
>
>> From: Zi Yan <ziy@nvidia.com>
>>
>> As Ying pointed out in [1], stats->nr_thp_failed needs to be updated to
>> avoid stats inconsistency between MIGRATE_SYNC and MIGRATE_ASYNC when
>> calling migrate_pages_batch().
>>
>
> Thanks. I'll add
>
> Fixes: 7262f208ca68 ("mm/migrate: split source folio if it is on deferred split list")
>
> and shall queue it for 6.10-rcX.
>
> Please don't forget such details.
I thought about the Fixes tag. Since Hugh's patch fixes the
BUG_ON and VM_BUG_ON, I did not add it here. But yeah stats inconsistency
is something needs to be fixed. Thanks for adding it.
--
Best Regards,
Yan, Zi
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