From cc39c6a9bbdebfcf1a7dee64d83bf302bc38d941 Mon Sep 17 00:00:00 2001 From: Shaohua Li 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 Signed-off-by: Shaohua Li Signed-off-by: Linus Torvalds --- mm/filemap.c | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-) diff --git a/mm/filemap.c b/mm/filemap.c index 645a080ba4df..7771871fa353 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 @@ 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;