[Bug 486127] [NEW] Not preempt-safe

[Jürgen Kreileder]

Public bug reported:

Binary package hint: apparmor

ii  apparmor                                             2.3.1+1403-0ubuntu27.2                               User-space parser utility for AppArmor
ii  linux-source                                         2.6.31.15.28                                         Linux kernel source with Ubuntu patches

Apparmor in 2.6.31.15.28 (and earlier karmic kernels) apparently is not
safe for use with CONFIG_PREEMPT.  Kernels with CONFIG_PREEMPT_VOLUNTARY
seem to be OK.

With CONFIG_PREEMPT I get "scheduling while atomic".  Sometimes with a non-fatal oops, sometime with a hard crash.
Happens both on i386 and x86-64, both with unicore and multicore machines.

Example from a single-core i386 machine:

[   49.647818] BUG: scheduling while atomic: named/3964/0x00000002
[   49.648030] Pid: 3964, comm: named Not tainted 2.6.31.4 #1Oct 30 03:29:42 server kernel: [   49.648030] Call Trace:Oct 30 03:29:42 server kernel: [   49.648030]  [<c123f255>] ? schedule+0x435/0x4d0
[   49.648030]  [<c103f55a>] ? commit_creds+0xda/0x160
[   49.648030]  [<c100301a>] ? work_resched+0x5/0x1a
[   49.648585] __ratelimit: 9 callbacks suppressed
[   49.648599] named[3964]: segfault at 402480 ip 00402480 sp bfb308ac error 4
[   49.648631] note: named[3964] exited with preempt_count 1
[  365.576949] BUG: scheduling while atomic: named/5101/0x00000003
[  365.577033] Pid: 5101, comm: named Not tainted 2.6.31.4 #1
[  365.577033] Call Trace:
[  365.577033]  [<c123f255>] ? schedule+0x435/0x4d0
[  365.577033]  [<c103f55a>] ? commit_creds+0xda/0x160
[  365.577033]  [<c100301a>] ? work_resched+0x5/0x1a
[  365.577713] named[5101]: segfault at 3f4480 ip 003f4480 sp bf84877c error 4

** Affects: apparmor (Ubuntu)
     Importance: Undecided
         Status: New

-- 
Not preempt-safe
https://bugs.launchpad.net/bugs/486127
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