mm/thp: do not wait for lock_page() in deferred_split_scan()

deferred_split_scan() gets called from reclaim path.  Waiting for page
lock may lead to deadlock there.

Replace lock_page() with trylock_page() and skip the page if we failed
to lock it.  We will get to the page on the next scan.

Link: http://lkml.kernel.org/r/20180315150747.31945-1-kirill.shutemov@linux.intel.com
Fixes: 9a982250f7 ("thp: introduce deferred_split_huge_page()")
Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Kirill A. Shutemov 2018-03-22 16:17:31 -07:00 committed by Linus Torvalds
parent fece2029a9
commit fa41b900c3

View file

@ -2783,11 +2783,13 @@ static unsigned long deferred_split_scan(struct shrinker *shrink,
list_for_each_safe(pos, next, &list) {
page = list_entry((void *)pos, struct page, mapping);
lock_page(page);
if (!trylock_page(page))
goto next;
/* split_huge_page() removes page from list on success */
if (!split_huge_page(page))
split++;
unlock_page(page);
next:
put_page(page);
}