invalidate_mapping_pages(): add cond_resched

invalidate_mapping_pages() can sometimes take a long time (millions of pages
to free).  Long enough for the softlockup detector to trigger.

We used to have a cond_resched() in there but I took it out because the
drop_caches code calls invalidate_mapping_pages() under inode_lock.

The patch adds a nasty flag and puts the cond_resched() back.

Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 1 insertions, 1 deletions

diff --git a/fs/drop_caches.c b/fs/drop_caches.c
index 03ea7696fe39..59375efcf39d 100644
--- a/fs/drop_caches.c
+++ b/fs/drop_caches.c
@@ -20,7 +20,7 @@ static void drop_pagecache_sb(struct super_block *sb)
         list_for_each_entry(inode, &sb->s_inodes, i_sb_list) {
                 if (inode->i_state & (I_FREEING|I_WILL_FREE))
                         continue;
-                invalidate_mapping_pages(inode->i_mapping, 0, -1);
+                __invalidate_mapping_pages(inode->i_mapping, 0, -1, true);
         }
         spin_unlock(&inode_lock);
 }