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

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
......@@ -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 @@ unsigned find_get_pages(struct address_space *mapping, pgoff_t start,
* here as an exceptional entry: so skip over it -
* we only reach this from invalidate_mapping_pages().
*/
nr_skip++;
continue;
}
......@@ -876,7 +878,7 @@ unsigned find_get_pages(struct address_space *mapping, pgoff_t start,
* 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;
......
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