lockdep splat: nfsroot on 2.6.39-rc2
diff mbox

Message ID 20110411040209.GA21395@dastard
State New, archived
Headers show

Commit Message

Dave Chinner April 11, 2011, 4:02 a.m. UTC
On Sat, Apr 09, 2011 at 10:55:02PM -0400, Will Simoneau wrote:
> Hi,
> 
> I just got this soft-lockup 3 times in a row and was able to reproduce
> it with lockdep enabled. The kernel is Linus git 94c8a984 plus patches
> to support my hardware. System is a full custom 2-way SMP mipsel/R4K
> clone on an FPGA, I am hoping this is not my fault or the hardware's
> fault though. Root is on NFS (tcp).
> 
> This seems to happen consistently when running "apt-get update". Ideas?
> Known bug?

The bug is in nfs_commit_inode(), where it calls nfs_scan_commit()
with the inode->i_lock held and that calls __mark_inode_dirty()
which takes the inode->i_lock....

The patch below should fix this problem.

Cheers,

Dave.

Comments

Will Simoneau April 11, 2011, 7:23 a.m. UTC | #1
On 14:02 Mon 11 Apr     , Dave Chinner wrote:
> On Sat, Apr 09, 2011 at 10:55:02PM -0400, Will Simoneau wrote:
> > This seems to happen consistently when running "apt-get update". Ideas?
> > Known bug?
> 
> The bug is in nfs_commit_inode(), where it calls nfs_scan_commit()
> with the inode->i_lock held and that calls __mark_inode_dirty()
> which takes the inode->i_lock....
> 
> The patch below should fix this problem.

I can confirm that your patch fixes the issue. Thanks for the fix!

Tested-by: Will Simoneau <simoneau@ele.uri.edu>

Patch
diff mbox

diff --git a/fs/nfs/write.c b/fs/nfs/write.c
index af0c627..e4cbc11 100644
--- a/fs/nfs/write.c
+++ b/fs/nfs/write.c
@@ -542,11 +542,15 @@  nfs_scan_commit(struct inode *inode, struct list_head *dst, pgoff_t idx_start, u
 	if (!nfs_need_commit(nfsi))
 		return 0;
 
+	spin_lock(&inode->i_lock);
 	ret = nfs_scan_list(nfsi, dst, idx_start, npages, NFS_PAGE_TAG_COMMIT);
 	if (ret > 0)
 		nfsi->ncommit -= ret;
+	spin_unlock(&inode->i_lock);
+
 	if (nfs_need_commit(NFS_I(inode)))
 		__mark_inode_dirty(inode, I_DIRTY_DATASYNC);
+
 	return ret;
 }
 #else
@@ -1483,9 +1487,7 @@  int nfs_commit_inode(struct inode *inode, int how)
 	res = nfs_commit_set_lock(NFS_I(inode), may_wait);
 	if (res <= 0)
 		goto out_mark_dirty;
-	spin_lock(&inode->i_lock);
 	res = nfs_scan_commit(inode, &head, 0, 0);
-	spin_unlock(&inode->i_lock);
 	if (res) {
 		int error;