From cc39c6a9bbdebfcf1a7dee64d83bf302bc38d941 Mon Sep 17 00:00:00 2001
From: Shaohua Li <shaohua.li@intel.com>
Date: Thu, 15 Sep 2011 08:45:19 +0800
Subject: [PATCH] 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: Eric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: Shaohua Li <shaohua.li@intel.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
---
mm/filemap.c | 6 ++++--
1 file changed, 4 insertions(+), 2 deletions(-)
diff --git a/mm/filemap.c b/mm/filemap.c
index 645a080ba4dfb..7771871fa3535 100644
--- a/mm/filemap.c
+++ b/mm/filemap.c
@@ -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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