On 6/27/2022 12:23 PM, Huang, Ying wrote:
Baolin Wang <baolin.wang@xxxxxxxxxxxxxxxxx> writes:
On 6/27/2022 9:46 AM, Huang, Ying wrote:
Baolin Wang <baolin.wang@xxxxxxxxxxxxxxxxx> writes:
On 6/24/2022 10:53 AM, Huang Ying wrote:
If THP is failed to be migrated for -ENOSYS and -ENOMEM, the THP will
be split into thp_split_pages, and after other pages are migrated,
pages in thp_split_pages will be migrated with no_subpage_counting ==
true, because its failure have been counted already. If some pages in
thp_split_pages are retried during migration, we should not count
their failure if no_subpage_counting == true too. This is done this
patch to fix the failure counting for THP subpages retrying.
Good catch. Totally agree with you. It seems we can move the condition
into -EAGAIN case like other cases did?
diff --git a/mm/migrate.c b/mm/migrate.c
index 1ece23d80bc4..491c2d07402b 100644
--- a/mm/migrate.c
+++ b/mm/migrate.c
@@ -1463,7 +1463,7 @@ int migrate_pages(struct list_head *from,
new_page_t get_new_page,
case -EAGAIN:
if (is_thp)
thp_retry++;
- else
+ else if (!no_subpage_counting)
retry++;
break;
This has another effect except fixing the failure counting. That
is,
the split subpages of THP will not be retried for 10 times for -EAGAIN.
Ah, yes.
TBH, I think that we should do that. But because this has some behavior
OK. So you afraid that 10 times retry for each subpage of THP will
waste lots of time?
I just think that it's unnecessary. We have already regarded the
migration as failed. And for the worst case, we will try 512 * 10 =
5120 times in total.
change, it's better to be done in a separate patch? Do you have
interest to do that on top of this patchset?
Sure. I can send a patch which can be folded into your series. Is this
OK for you?
By the way, if I do like I said, the patch 4 can be avoided.
I tend to keep both. [4/7] is just a fix. You patch will introduce the
behavior change. And your patch needn't to be folded into this series.
You can send it and push it separately.
OK. Thanks.
