Re: Re: cfq-iosched.c: panic in cfq_dispatch_requests
From: Vivek Goyal
Date: Tue Mar 22 2011 - 11:39:56 EST
On Tue, Mar 22, 2011 at 11:32:47PM +0800, Lina Lu wrote:
> On 2011-03-21 22:08:19, Vivek Goyal wrote:
> >On Sun, Mar 20, 2011 at 03:23:23PM +0800, Lina Lu wrote:
> >> Hi Vivek,
> >> I did some test with blkio weight policy these days. The kernel panic
> >> once in a while.
> >> From the calltrace, It 's in func cfq_dispatch_requests(+0x058D).
> >> And I caught a divide by zero error with system monitor tools.
> >Hi Lina,
> >Can you please paste the full backtrace here.
> >> The panic happens when I first set 100 weight to two IO pids, then
> >> change the weight to 200, and begin to perform IO. The kernel panic
> >> accurately when the IO begin.
> >So you notice this only if weights are changed otherwise not?
> Hi Vivek
> Thanks for this patch! I did objdump and find place that divide by zero.
> It's in cfq_group_slice function, the st->total_weight is zero in my issue.
> As described in the patch, this is because I change the weight when the
> group on service tree.
Ok, so this patch did solve the issue you are facing?
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