[Xen-devel] Re: Kernel BUG at arch/x86/mm/tlb.c:61

[Jeremy Fitzhardinge <jeremy@xxxxxxxx>]

On 04/15/2011 05:23 AM, MaoXiaoyun wrote:
> Hi：
>
> Could the crash related to this patch ?
> http://git.kernel.org/?p=linux/kernel/git/jeremy/xen.git;a=commitdiff;h=45bfd7bfc6cf32f8e60bb91b32349f0b5090eea3
>
> Since now TLB state change to TLBSTATE_OK(mmu_context.h:40) is before
> cpumask_clear_cpu(line 49).
> Could it possible that right after execute line 40 of mmu_context.h,
> CPU revice IPI from other CPU to
> flush the mm, and when in interrupt, find the TLB state happened to be
> TLBSTATE_OK. Which conflicts.

Does reverting it help?

J

>
> Thanks.
>
> arch/x86/include/asm/mmu_context.h
>
> 33 static inline void switch_mm(struct mm_struct *prev, struct
> mm_struct *next,
> 34 <+++<+++<+++ struct task_struct *tsk)
> 35 {
> 36 <+++unsigned cpu = smp_processor_id();
> 37
> 38 <+++if (likely(prev != next)) {
> 39 #ifdef CONFIG_SMP
> 40 <+++<+++percpu_write(cpu_tlbstate.state, TLBSTATE_OK);
> 41 <+++<+++percpu_write(cpu_tlbstate.active_mm, next);
> 42 #endif
> 43 <+++<+++cpumask_set_cpu(cpu, mm_cpumask(next));
> 44
> 45 <+++<+++/* Re-load page tables */
> 46 <+++<+++load_cr3(next->pgd);
> 47
> 48 <+++<+++/* stop flush ipis for the previous mm */
> 49 <+++<+++cpumask_clear_cpu(cpu, mm_cpumask(prev));
>
>


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