[LU-2370] ldiskfs / ext4 panic with accessing to mb_groups procfs file

• Status: Resolved
• Project: Lustre
• Fix Version/s: Lustre 2.4.0
• Type: Bug
• Priority: Minor
• Reporter: Alexey Lyashkov
• Assignee: WC Triage
• Resolution: Fixed
• Labels: patch

Environment

any ext4 based ldiskfs (may be ext3 based also)

• Severity: 3

Description

fixed in valina kernel as
commit 95599968d19db175829fb580baa6b68939b320fb
Author: Salman Qazi <[e-mail]>
Date: Thu May 31 23:52:14 2012 -0400
ext4: remove mb_groups before tearing down the buddy_cache
We can't have references held on pages in the s_buddy_cache while we are
trying to truncate its pages and put the inode. All the pages must be
gone before we reach clear_inode. This can only be gauranteed if we
can prevent new users from grabbing references to s_buddy_cache's pages.
The original bug can be reproduced and the bug fix can be verified by:
while true; do mount -t ext4 /dev/ram0 /export/hda3/ram0; \
umount /export/hda3/ram0; done &
while true; do cat /proc/fs/ext4/ram0/mb_groups; done
Signed-off-by: Salman Qazi <[e-mail]>
Signed-off-by: "Theodore Ts'o" <[e-mail]>
Cc: [e-mail]

Comments

[Alexey Lyashkov]

also RHEL6 (and may be other distro) have a bug with unhandled memory allocation error caused a null pointer deference.

[Keith Mannthey (Inactive)]

Will this patch be present in RHEL7?

[Alexey Lyashkov]

if you will provide a link to RHEL7 sources i may check it, i don't see that is on ftp.redhat.com.

[Peter Jones]

Landed for 2.4

[Keith Mannthey (Inactive)]

I think the best checks for RHEL7 are if it is in Current Fedora.

Is there a bug open for RHEL6 and the other Distros?

[Alexey Lyashkov]

Keith,

I have no time to check it in other distro`s, but last RHEL6.4 beta (2.6.32-343) have that bug fixed.
except second part of patch with error memory allocation check, that is don't fixed for now.
If you want - you may create a ticket in RH bugzilla.

corresponded commit is one before 95599968d19db175829fb580baa6b68939b320fb in mainstream + one in past.