On 01/21/2015 12:29 PM, Christoph Hellwig wrote:
On Wed, Jan 21, 2015 at 12:17:07PM -0700, Jens Axboe wrote:
Christoph,
Ran into this one while testing. Looks like mapping->host is NULL, off
the shmem_writepage().
Hmm. Not sure how this can happen, but for a NULL inode we can
always just return noop_backing_dev_info safely, I'll cook up a patch.
I got 8 of them in a row. Current kernel is running with the attached,
just to see if I can reproduce it.
--
Jens Axboe
diff --git a/fs/fs-writeback.c b/fs/fs-writeback.c
index a20b1145f4d5..4f03e33365e1 100644
--- a/fs/fs-writeback.c
+++ b/fs/fs-writeback.c
@@ -68,7 +68,12 @@ EXPORT_SYMBOL(writeback_in_progress);
struct backing_dev_info *inode_to_bdi(struct inode *inode)
{
- struct super_block *sb = inode->i_sb;
+ struct super_block *sb;
+
+ if (WARN_ON(!inode))
+ return &noop_backing_dev_info;
+
+ sb = inode->i_sb;
#ifdef CONFIG_BLOCK
if (sb_is_blkdev_sb(sb))
return blk_get_backing_dev_info(I_BDEV(inode));
