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Commit cc39c6a9 authored by Shaohua Li's avatar Shaohua Li Committed by Linus Torvalds
Browse files

mm: account skipped entries to avoid looping in find_get_pages 



The found entries by find_get_pages() could be all swap entries.  In
this case we skip the entries, but make sure the skipped entries are
accounted, so we don't keep looping.

Using nr_found > nr_skip to simplify code as suggested by Eric.

Reported-and-tested-by: default avatarEric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: default avatarShaohua Li <shaohua.li@intel.com>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 4f5b0480

mm/filemap.c

+4 −2
Original line number Diff line number Diff line
@@ -827,13 +827,14 @@ unsigned find_get_pages(struct address_space *mapping, pgoff_t start, 
{

	unsigned int i;

	unsigned int ret;

	unsigned int nr_found;

	unsigned int nr_found, nr_skip;



	rcu_read_lock();

restart:

	nr_found = radix_tree_gang_lookup_slot(&mapping->page_tree,

				(void ***)pages, NULL, start, nr_pages);

	ret = 0;

	nr_skip = 0;

	for (i = 0; i < nr_found; i++) {

		struct page *page;

repeat:
@@ -856,6 +857,7 @@ repeat: 
			 * here as an exceptional entry: so skip over it -

			 * we only reach this from invalidate_mapping_pages().

			 */

			nr_skip++;

			continue;

		}
@@ -876,7 +878,7 @@ repeat: 
	 * If all entries were removed before we could secure them,

	 * try again, because callers stop trying once 0 is returned.

	 */

	if (unlikely(!ret && nr_found))

	if (unlikely(!ret && nr_found > nr_skip))

		goto restart;

	rcu_read_unlock();

	return ret;