Re: [PROBLEM] 2.6.22-rc2 panics on x86-64 with slub

[Srihari Vijayaraghavan <sriharivijayaraghavan@yahoo.com.au>]

--- Ingo Molnar <mingo@elte.hu> wrote:
> * Srihari Vijayaraghavan <sriharivijayaraghavan@yahoo.com.au> wrote:
> > Yup, with CONFIG_SMP=n, I'm unable to reproduce the problem. It's 
> > quite stable actually (having completed a dozen kernel compile 
> > sessions so far).

[...]

> could you enable CONFIG_PROVE_LOCKING - does it spit out any warning 
> into the syslog?

Compiled slub with SMP & CONFIG_PROVE_LOCKING. No luck. It still hangs solid
after the second spinlock lockup call trace.

Here's the relevant sections of the kernel logs:

...
Freeing unused kernel memory: 228k freed
BUG: spinlock bad magic on CPU#1, init/1
 lock: ffff81011f5f1100, .magic: ffff8101, .owner: <none>/-1, .owner_cpu: -1

Call Trace:
 [<ffffffff802f326a>] _raw_spin_lock+0x22/0xf6
 [<ffffffff8026b2d5>] vma_adjust+0x21c/0x446
 [<ffffffff8026b2d5>] vma_adjust+0x21c/0x446
 [<ffffffff8026b9d4>] vma_merge+0x10c/0x195
 [<ffffffff8026c757>] do_mmap_pgoff+0x3f5/0x794
 [<ffffffff803fff0c>] _spin_unlock_irq+0x24/0x27
 [<ffffffff8020f414>] sys_mmap+0xe5/0x110
 [<ffffffff80209dde>] system_call+0x7e/0x83
...
PM: Adding info for No Bus:vcsa1
BUG: spinlock lockup on CPU#1, hostname/369, ffff81011f5f1fc0

Call Trace:
 [<ffffffff802f3317>] _raw_spin_lock+0xcf/0xf6
 [<ffffffff8026ec9c>] anon_vma_unlink+0x1c/0x68
 [<ffffffff8026ec9c>] anon_vma_unlink+0x1c/0x68
 [<ffffffff80269aa0>] free_pgtables+0x69/0xc4
 [<ffffffff8026ad0e>] exit_mmap+0x91/0xeb
 [<ffffffff80228cea>] mmput+0x2c/0x9f
 [<ffffffff8022df72>] do_exit+0x22e/0x82e
 [<ffffffff8022e5f4>] sys_exit_group+0x0/0xe
 [<ffffffff80209dde>] system_call+0x7e/0x83


Surprisingly, with CONFIG_SMP=n, CONFIG_PROVE_LOCKING produces this with slub
(then hangs solid):

Freeing unused kernel memory: 188k freed
BUG: spinlock lockup on CPU#0, init/1, ffff81011e9d3160

Call Trace:
 [<ffffffff802eca20>] _raw_spin_lock+0xca/0xe8
 [<ffffffff80265d6d>] vma_adjust+0x218/0x442
 [<ffffffff80265d6d>] vma_adjust+0x218/0x442
 [<ffffffff8026646b>] vma_merge+0x10c/0x195
 [<ffffffff802671d5>] do_mmap_pgoff+0x3f5/0x790
 [<ffffffff803f6e84>] _spin_unlock_irq+0x24/0x27
 [<ffffffff8020ead0>] sys_mmap+0xe5/0x110
 [<ffffffff80209cce>] system_call+0x7e/0x83

To recap:
1. No problems with slub on CONFIG_SMP=n & CONFIG_PROVE_LOCKING=n
2. Problem with slub on CONFIG_SMP=n & CONFIG_PROVE_LOCKING=y (perhaps a. some
locking issue when slub is activated or b. something is wrong with 'prove
locking' mechanism when slub is activated or c. something else I don't see) 
3. Problem with slub on CONFIG_SMP=y (even without CONFIG_PROVE_LOCKING=y)

Thanks



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