Re: .17rc5 cfq slab corruption.

[Jens Axboe]

On Tue, May 30 2006, Jens Axboe wrote:
> On Tue, May 30 2006, Dave Jones wrote:
> > On Tue, May 30, 2006 at 06:49:18PM +0200, Jens Axboe wrote:
> > 
> >  > > List corruption. next->prev should be f74a5e2c, but was ea7ed31c
> >  > > Pointing at cfq_set_request.
> >  > 
> >  > I think I'm missing a piece of this - what list was corrupted, in what
> >  > function did it trigger?
> > 
> > If you look at the attachment in the bugzilla url in my previous msg,
> > you'll see this:
> > 
> > ay 30 05:31:33 mandril kernel: List corruption. next->prev should be f74a5e2c, but was ea7ed31c
> > May 30 05:31:33 mandril kernel: ------------[ cut here ]------------
> > May 30 05:31:33 mandril kernel: kernel BUG at include/linux/list.h:58!
> > May 30 05:31:33 mandril kernel: invalid opcode: 0000 [#1]
> > May 30 05:31:33 mandril kernel: SMP
> > May 30 05:31:33 mandril kernel: last sysfs file: /devices/pci0000:00/0000:00:1f.3/i2c-0/0-002e/pwm3
> > May 30 05:31:33 mandril kernel: Modules linked in: iptable_filter ipt_DSCP iptable_mangle ip_tables x_tables eeprom lm85 hwmon_vid hwmon i2c_isa ipv6 nls_utf8 loop dm_mirror dm_mod video button battery ac lp parport_pc parport ehci_hcd uhci_hcd floppy snd_intel8x0 snd_ac97_codec snd_ac97_bus sg snd_seq_dummy matroxfb_base snd_seq_oss snd_seq_midi_event matroxfb_DAC1064 snd_seq matroxfb_accel matroxfb_Ti3026 3w_9xxx matroxfb_g450 snd_seq_device g450_pll matroxfb_misc snd_pcm_oss snd_mixer_oss snd_pcm snd_timer snd e1000 soundcore snd_page_alloc i2c_i801 i2c_core ext3 jbd 3w_xxxx ata_piix libata sd_mod scsi_mod
> > May 30 05:31:33 mandril kernel: CPU:    0
> > May 30 05:31:33 mandril kernel: EIP:    0060:[<c04e3310>]    Not tainted VLI
> > May 30 05:31:33 mandril kernel: EFLAGS: 00210292   (2.6.16-1.2227_FC6 #1)
> > May 30 05:31:33 mandril kernel: EIP is at cfq_set_request+0x202/0x3ff
> 
> Just do a l *cfq_set_request+0x202 from gdb if you have
> CONFIG_DEBUG_INFO enabled in your vmlinux.

Doh, found it. Dave, please try and reproduce with this applied:

---

[PATCH] cfq-iosched: kill list entry on dead cic

We must remember to drop the cic circular list when we prune
a dead entry.

Signed-off-by: Jens Axboe <axboe@xxxxxxx>

diff --git a/block/cfq-iosched.c b/block/cfq-iosched.c
index 2540dfa..309e0f4 100644
--- a/block/cfq-iosched.c
+++ b/block/cfq-iosched.c
@@ -1477,6 +1477,7 @@ cfq_drop_dead_cic(struct io_context *ioc
 {
 	read_lock(&cfq_exit_lock);
 	rb_erase(&cic->rb_node, &ioc->cic_root);
+	list_del_init(&cic->queue_list);
 	read_unlock(&cfq_exit_lock);
 	kmem_cache_free(cfq_ioc_pool, cic);
 	atomic_dec(&ioc_count);

-- 
Jens Axboe

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