Messages in this thread | | | Date | Mon, 7 Mar 2022 09:57:30 +0800 | Subject | Re: [PATCH 12/16] mm/migration: fix potential page refcounts leak in migrate_pages | From | Baolin Wang <> |
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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?
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