Red Hat Bugzilla – Bug 190611
Race condition between i_mapping and iput() causes system panic
Last modified: 2010-03-16 14:52:17 EDT
Description of problem:
Related People Group Security
Assignee: Thorsten Kukuk <email@example.com> Bug Insecure
Reporter: PolyServe Employee <firstname.lastname@example.org> Reporter Accessible
QA Contact: E-mail List <email@example.com>
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2006-05-03 15:52:22 2 172493
Race condition between ->i_mapping and iput() causes system panic.
Our product does direct I/O to block devices to monitor filesystem status and
because of this bug our system will panic if we hit the race. The stack from
the panic is included below. It appears in the thread:
that others are having this issue as well. The thread above has the first
version of a patch that later made it into 2.6.17-rc2-mm at kernel.org.
Stack traceback for pid 11950
0xc8585980 11950 11947 1 0 R 0xc8585c40 *stress
EBP EIP Function (args)
0xd3d41d60 0xc01643ca find_get_pages_tag+0x1a (0x10, 0xd3d41db0, 0xf8aaf880,
0xd3d41d78 0xc01740d9 pagevec_lookup_tag+0x29 (0x1, 0x10, 0x0, 0xd3d41dd4,
0xd3d41e04 0xc01669f4 wait_on_page_writeback_range_wq+0x84 (0x0)
0xd3d41e10 0xc0166cb9 filemap_fdatawait+0x19 (0xdb018980, 0xc8585b54,
, 0xf8d6e681, 0x0)
0xd3d41e50 0xc01bcaa8 __writeback_single_inode+0x258 (0x40, 0x8, 0xf6ee4e88,
0xd3d41e8c 0xc01bd206 sync_sb_inodes+0x136 (0xd3d41f14, 0xd3d41ec4,
0xd3d41f84 0xc01bd4b9 sync_inodes_sb+0x99 (0x1, 0x0)
0xd3d41f94 0xc01bd573 sync_inodes+0x53 (0x0, 0x0)
0xd3d41fa4 0xc01959cd do_sync+0x3d (0x0, 0x0, 0x0, 0xbb8)
0xd3d41fbc 0xc0195a30 sys_sync+0x40
Version-Release number of selected component (if applicable):
The shell code below does the trick.
Steps to Reproduce:
while true; do
dd if=/dev/zero of=/dev/hdg1 bs=512 count=1000 & sync
Folks, this bug has been sitting here for a long time with an easy reproduction
case. Do you have any plans to address it ? We would appreciate an update.
BTW - we have a patch for this. I will post it to the bug.
Created attachment 146716 [details]
Patch to eliminate the i_mapping race in bd_acquire().
upstream commit at
Looks like there have been no further changes to these functions since then.
For what it's worth, I have not yet been able to reproduce with the
Bob, I see that the original report looks pasted from a SuSE bug report. I
still have not been able to reproduce this on a RHEL4 kernel, and while it is
not an absolute requirement before we include this patch (since it does appear
that RHEL4 has this same problem), it's always best if we can demonstrate the
problem before we go fixing it.
Have you actually been able to reproduce this on a RHEL4 machine?
polyserv, ping? Have you actually seen or reproduced this on RHEL?
If this is still an issue, please reopen the bug.