From: Jan Kara Fix longstanding lock inversion in drop_pagecache_sb by dropping inode_lock before calling __invalidate_mapping_pages(). We just have to make sure inode won't go away from under us by keeping reference to it and putting the reference only after we have safely resumed the scan of the inode list. A bit tricky but not too bad... Signed-off-by: Jan Kara Cc: Fengguang Wu Cc: David Chinner Signed-off-by: Andrew Morton --- fs/drop_caches.c | 8 +++++++- 1 file changed, 7 insertions(+), 1 deletion(-) diff -puN fs/drop_caches.c~vfs-fix-lock-inversion-in-drop_pagecache_sb fs/drop_caches.c --- a/fs/drop_caches.c~vfs-fix-lock-inversion-in-drop_pagecache_sb +++ a/fs/drop_caches.c @@ -14,15 +14,21 @@ int sysctl_drop_caches; static void drop_pagecache_sb(struct super_block *sb) { - struct inode *inode; + struct inode *inode, *toput_inode = NULL; spin_lock(&inode_lock); list_for_each_entry(inode, &sb->s_inodes, i_sb_list) { if (inode->i_state & (I_FREEING|I_WILL_FREE)) continue; + __iget(inode); + spin_unlock(&inode_lock); __invalidate_mapping_pages(inode->i_mapping, 0, -1, true); + iput(toput_inode); + toput_inode = inode; + spin_lock(&inode_lock); } spin_unlock(&inode_lock); + iput(toput_inode); } static void drop_pagecache(void) _