Messages in this thread | | | Date | Wed, 4 May 2011 14:57:13 +0200 | From | Ingo Molnar <> | Subject | Re: [block IO crash] Re: 2.6.39-rc5-git2 boot crashs |
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* Pekka Enberg <penberg@kernel.org> wrote:
> Hi Tejun, > > On Wed, May 4, 2011 at 2:27 PM, Tejun Heo <tj@kernel.org> wrote: > > Hmmm... if it's a race caused by preemtion enabled where it shouldn't > > be, it's most likely the wrong type of this_cpu_cmpxchg_double() being > > used in SLUB? ie. __this_cpu_cmpxchg_double() where it should have > > been this_cpu_cmpxchg_double()? Christoph? > > There's no __this_cpu_cmpxchg_double() usage in mm/slub.c so I don't > think it's that simple.
Well, AFAICS the problem is:
earth4:~/tip> grep cmpxchg mm/slub.c
if (unlikely(!this_cpu_cmpxchg_double( if (unlikely(!this_cpu_cmpxchg_double(
Where this macro resolves to:
# define this_cpu_cmpxchg_double_8(pcp1, pcp2, oval1, oval2, nval1, nval2) \ _this_cpu_generic_cmpxchg_double(pcp1, pcp2, oval1, oval2, nval1, nval2)
where:
#define _this_cpu_generic_cmpxchg_double(pcp1, pcp2, oval1, oval2, nval1, nval2) \ ({ \ int ret__; \ preempt_disable(); \ ret__ = __this_cpu_generic_cmpxchg_double(pcp1, pcp2, \ oval1, oval2, nval1, nval2); \ preempt_enable(); where:
#define __this_cpu_generic_cmpxchg_double(pcp1, pcp2, oval1, oval2, nval1, nval2) \ ({ \ int __ret = 0; \ if (__this_cpu_read(pcp1) == (oval1) && \ __this_cpu_read(pcp2) == (oval2)) { \ __this_cpu_write(pcp1, (nval1)); \ __this_cpu_write(pcp2, (nval2)); \ __ret = 1; \ } \ (__ret); \ })
With is both IRQ and SMP unsafe.
Thanks,
Ingo -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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