Bug 729434

Summary: nfs sillyrename can call d_move without holding the i_mutex
Product: Red Hat Enterprise Linux 6 Reporter: Jeff Layton <jlayton>
Component: kernelAssignee: Jeff Layton <jlayton>
Status: CLOSED ERRATA QA Contact: Petr Be┼łas <pbenas>
Severity: high Docs Contact:
Priority: high    
Version: 6.2CC: aviro, bfields, dhowells, kzhang, pbenas, pstehlik, rwheeler, sprabhu, steved, yanwang
Target Milestone: rc   
Target Release: ---   
Hardware: Unspecified   
OS: Unspecified   
Whiteboard:
Fixed In Version: kernel-2.6.32-188.el6 Doc Type: Bug Fix
Doc Text:
Story Points: ---
Clone Of:
: 729446 (view as bug list) Environment:
Last Closed: 2011-12-06 14:01:08 UTC Type: ---
Regression: --- Mount Type: ---
Documentation: --- CRM:
Verified Versions: Category: ---
oVirt Team: --- RHEL 7.3 requirements from Atomic Host:
Cloudforms Team: ---
Bug Depends On:    
Bug Blocks: 729446    

Description Jeff Layton 2011-08-09 18:22:26 UTC
As Al pointed out recently, if a process doing a sillyrename ends up getting issued a SIGKILL then it can end up returning back up to userspace while the RENAME operation is still going on the wire. When this happens, it will release the parent's i_mutex prematurely, and nfs_async_rename_done will call d_move without holding the it.

Holding the i_mutex is required to prevent dcache corruption. I sent a patch to Trond to fix this recently by simply unhashing the old and new dentries in this situation, and he has pushed it to Linus for 3.1. I think we'll also want this in 6.2 as well:

commit 73ca1001ed6881b476e8252adcd0eede1ea368ea
Author: Jeff Layton <jlayton@redhat.com>
Date:   Mon Jul 18 11:26:30 2011 -0400

    nfs: don't use d_move in nfs_async_rename_done

Comment 1 RHEL Product and Program Management 2011-08-09 18:40:08 UTC
This request was evaluated by Red Hat Product Management for inclusion
in a Red Hat Enterprise Linux maintenance release. Product Management has 
requested further review of this request by Red Hat Engineering, for potential
inclusion in a Red Hat Enterprise Linux Update release for currently deployed 
products. This request is not yet committed for inclusion in an Update release.

Comment 3 yanfu,wang 2011-08-12 05:28:09 UTC
hi Jeff,
QE need to know how to reproduce and verify the problem by run some test steps, so could you point out it? thanks.

Comment 4 Jeff Layton 2011-08-12 11:15:31 UTC
There's no reproducer that I'm aware of. This was noticed by inspection. The thing to do here is just to test that sillyrenames still work after the patch. I think the connectathon suite already tests this so making sure that it doesn't regress is probably the best you can do for this.

Comment 5 Kyle McMartin 2011-08-15 12:50:21 UTC
Patch(es) available on kernel-2.6.32-188.el6

Comment 10 errata-xmlrpc 2011-12-06 14:01:08 UTC
Since the problem described in this bug report should be
resolved in a recent advisory, it has been closed with a
resolution of ERRATA.

For information on the advisory, and where to find the updated
files, follow the link below.

If the solution does not work for you, open a new bug report.

http://rhn.redhat.com/errata/RHSA-2011-1530.html