Messages in this thread | | | Date | Wed, 23 Jul 2014 12:20:55 -0700 | Subject | Re: Random panic in load_balance() with 3.16-rc | From | Linus Torvalds <> |
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On Wed, Jul 23, 2014 at 12:02 PM, Peter Zijlstra <peterz@infradead.org> wrote: > > Here goes..
Oh. So this doesn't have CPUMASK_OFFSTACK set at all, so the pointer has never been loaded from memory in the first place. The calculation has been (for me) something like
movq $load_balance_mask, %rax add %gs:this_cpu_off, %rax
and then gcc is being stupid and saving it to the frame and reloading it for no good reason (at least for me it *also* saved the value in %rbx in order to save it into "env.cpus", and the stack spill seems to be just moronic).
In Michel's oops, %rbx doesn't contain the pointer any more, though, so he clearly does have a different compiler. His frame offsets are rather different too ("-136(%rbp)" vs "-168(%rbp)") so looking at whether possibly some stack frame got overwritten is clearly very compiler-specific.
Michel, mind doing
make kernel/sched/fair.s
and sending us the resulting file?
Linus
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