Note: This bug is displayed in read-only format because the product is no longer active in Red Hat Bugzilla.

For bugs related to Red Hat Enterprise Linux 5 product line. The current stable release is 5.10. For Red Hat Enterprise Linux 6 and above, please visit Red Hat JIRA https://issues.redhat.com/secure/CreateIssue!default.jspa?pid=12332745 to report new issues.

Bug 592908

Summary:	Memory leak when nfs shares are mounted with option "nolock"
Product:	Red Hat Enterprise Linux 5	Reporter:	Sachin Prabhu <sprabhu>
Component:	kernel	Assignee:	Jeff Layton <jlayton>
Status:	CLOSED ERRATA	QA Contact:	yanfu,wang <yanwang>
Severity:	medium	Docs Contact:
Priority:	low
Version:	5.4	CC:	jlayton, rwheeler, steved, tao, yanwang
Target Milestone:	rc
Target Release:	---
Hardware:	All
OS:	Linux
Whiteboard:
Fixed In Version:		Doc Type:	Bug Fix
Doc Text:		Story Points:	---
Clone Of:
Clones:	973975 1032944 (view as bug list)		Environment:
Last Closed:	2011-01-13 21:32:08 UTC	Type:	---
Regression:	---	Mount Type:	---
Documentation:	---	CRM:
Verified Versions:		Category:	---
oVirt Team:	---	RHEL 7.3 requirements from Atomic Host:
Cloudforms Team:	---	Target Upstream Version:
Embargoed:
Bug Depends On:
Bug Blocks:	973975, 1032944

Description Sachin Prabhu 2010-05-17 10:43:59 UTC

A nfs client which repeatedly mounts shares using the option nolock experiences a memory leak. The slab objects rpc_inode_cache and size-4096 steadily increase. 

This issue was also reported at 
https://bugzilla.novell.com/show_bug.cgi?id=336253#c24


This was also reported upstream
http://kerneltrap.org/mailarchive/linux-nfs/2007/12/11/487982/thread

This is fixed in 2.6.24 in the following commit 

commit 5cef338b30c110daf547fb13d99f0c77f2a79fbc
Author: Trond Myklebust <Trond.Myklebust>
Date:   Tue Dec 11 22:01:56 2007 -0500

    NFSv2/v3: Fix a memory leak when using -onolock
    
    Neil Brown said:
    > Hi Trond,
    >
    > We found that a machine which made moderately heavy use of
    > 'automount' was leaking some nfs data structures - particularly the
    > 4K allocated by rpc_alloc_iostats.
    > It turns out that this only happens with filesystems with -onolock
    > set.
    
    > The problem is that if NFS_MOUNT_NONLM is set, nfs_start_lockd doesn't
    > set server->destroy, so when the filesystem is unmounted, the
    > ->client_acl is not shutdown, and so several resources are still
    > held.  Multiple mount/umount cycles will slowly eat away memory
    > several pages at a time.
    
    Signed-off-by: Trond Myklebust <Trond.Myklebust>
    Acked-by: NeilBrown <neilb>


Reproducer:

We need 2 terminals
1) On first terminal, keep a tab on the slab objects using the command
watch "egrep 'rpc_inode_cache|size-4096'" /proc/slabinfo
2) On the second run a loop of mounts and umounts
for i in {1..10000}; do mount vm23:/exports -o nolock /mnt/m1/; umount /mnt/m1; done

You will see steadily increasing numbers of allocated rpc_inode_cache and size-4096 slab objects.

Comment 1 Jeff Layton 2010-05-17 11:02:45 UTC

Looks pretty straightforward.

Comment 3 RHEL Program Management 2010-06-08 12:39:58 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 5 Jarod Wilson 2010-07-12 15:46:35 UTC

in kernel-2.6.18-206.el5
You can download this test kernel from http://people.redhat.com/jwilson/el5

Detailed testing feedback is always welcomed.

Comment 8 yanfu,wang 2010-10-19 05:45:49 UTC

reproduced on rhel5.5:
# uname -a
Linux amd-ma78gm-02.lab.bos.redhat.com 2.6.18-194.el5 #1 SMP Tue Mar 16 21:52:39 EDT 2010 x86_64 x86_64 x86_64 GNU/Linux

# egrep 'rpc_inode_cache|size-4096' /proc/slabinfo
rpc_inode_cache        6     10    768    5    1 : tunables   54   27    8 : slabdata      2      2      0
size-4096(DMA)         0      0   4096    1    1 : tunables   24   12    8 : slabdata      0      0      0
size-4096            160    160   4096    1    1 : tunables   24   12    8 : slabdata    160    160      0
# egrep 'rpc_inode_cache|size-4096' /proc/slabinfo
rpc_inode_cache    12435  12435    768    5    1 : tunables   54   27    8 : slabdata   2487   2487      0
size-4096(DMA)         0      0   4096    1    1 : tunables   24   12    8 : slabdata      0      0      0
size-4096           6435   6435   4096    1    1 : tunables   24   12    8 : slabdata   6435   6435      0
...
# egrep 'rpc_inode_cache|size-4096' /proc/slabinfo
rpc_inode_cache    37200  37210    768    5    1 : tunables   54   27    8 : slabdata   7442   7442      0
size-4096(DMA)         0      0   4096    1    1 : tunables   24   12    8 : slabdata      0      0      0
size-4096          18779  18779   4096    1    1 : tunables   24   12    8 : slabdata  18779  18779      0


verified on RHEL5.6-Server-20101014.0 on i386 and x86_64, now the slab objects rpc_inode_cache and size-4096 haven't been steadily increased. 
# uname -a
Linux dell-t5500-01.lab.bos.redhat.com 2.6.18-227.el5 #1 SMP Tue Oct 12 18:50:50 EDT 2010 x86_64 x86_64 x86_64 GNU/Linux

# egrep 'rpc_inode_cache|size-4096' /proc/slabinfo
rpc_inode_cache       13     15    768    5    1 : tunables   54   27    8 : slabdata      3      3      0
size-4096(DMA)         0      0   4096    1    1 : tunables   24   12    8 : slabdata      0      0      0
size-4096            409    410   4096    1    1 : tunables   24   12    8 : slabdata    409    410      0

Comment 10 errata-xmlrpc 2011-01-13 21:32:08 UTC

An advisory has been issued which should help the problem
described in this bug report. This report is therefore being
closed with a resolution of ERRATA. For more information
on therefore solution and/or where to find the updated files,
please follow the link below. You may reopen this bug report
if the solution does not work for you.

http://rhn.redhat.com/errata/RHSA-2011-0017.html