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mm/migration: fix potential page refcounts leak in migrate_pages

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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.

Link: https://lkml.kernel.org/r/20220318111709.60311-10-linmiaohe@huawei.com
Fixes: b5bade978e ("mm: migrate: fix the return value of migrate_pages()")
Signed-off-by: Miaohe Lin <linmiaohe@huawei.com>
Reviewed-by: Zi Yan <ziy@nvidia.com>
Reviewed-by: "Huang, Ying" <ying.huang@intel.com>
Reviewed-by: Baolin Wang <baolin.wang@linux.alibaba.com>
Reviewed-by: Muchun Song <songmuchun@bytedance.com>
Cc: Alistair Popple <apopple@nvidia.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
This commit is contained in:
Miaohe Lin 2022-04-28 23:16:08 -07:00 committed by akpm
parent f430893b01
commit 69a041ff50
1 changed files with 8 additions and 0 deletions
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8
mm/migrate.c
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@ -1434,6 +1434,14 @@ retry:
}
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_thp_failed += thp_retry;
goto out;
case -EAGAIN:
if (is_thp)