Messages in this thread | | | Date | Mon, 7 Mar 2022 14:00:20 +0800 | Subject | Re: [PATCH 12/16] mm/migration: fix potential page refcounts leak in migrate_pages | From | Baolin Wang <> |
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On 3/7/2022 1:02 PM, Huang, Ying wrote: > Baolin Wang <baolin.wang@linux.alibaba.com> writes: > >> Hi Miaohe, >> >> On 3/4/2022 5:34 PM, Miaohe Lin wrote: >>> In -ENOMEM case, there might be some subpages of fail-to-migrate THPs >>> left in thp_split_pages list. We should move them back to migration >>> list so that they could be put back to the right list by the caller >>> otherwise the page refcnt will be leaked here. Also adjust nr_failed >>> and nr_thp_failed accordingly to make vm events account more accurate. >>> Fixes: b5bade978e9b ("mm: migrate: fix the return value of >>> migrate_pages()") >>> Signed-off-by: Miaohe Lin <linmiaohe@huawei.com> >>> --- >>> mm/migrate.c | 9 +++++++++ >>> 1 file changed, 9 insertions(+) >>> diff --git a/mm/migrate.c b/mm/migrate.c >>> index e0db06927f02..6c2dfed2ddb8 100644 >>> --- a/mm/migrate.c >>> +++ b/mm/migrate.c >>> @@ -1422,6 +1422,15 @@ int migrate_pages(struct list_head *from, new_page_t get_new_page, >>> } >>> nr_failed_pages += nr_subpages; >>> + /* >>> + * There might be some subpages of fail-to-migrate THPs >>> + * left in thp_split_pages list. Move them back to migration >>> + * list so that they could be put back to the right list by >>> + * the caller otherwise the page refcnt will be leaked. >>> + */ >>> + list_splice_init(&thp_split_pages, from); >>> + nr_failed += retry; >>> + nr_thp_failed += thp_retry; >> >> Yes, I think we missed this case before, and your patch looks >> right. But we should also update the 'rc' to return the correct number >> of pages that were not migrated, right? > > Per my understanding, -ENOMEM should be returned to indicate an fatal > error. >
Ah, right. Sorry for noise. Reviewed-by: Baolin Wang <baolin.wang@linux.alibaba.com>
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