On 04/29/2014 06:22 PM, Oleg Nesterov wrote:
> On 04/29, Srivatsa S. Bhat wrote:
>>
>> I guess I'll hold off on testing this fix until I get to reproduce
>> the bug more reliably..
>
> perhaps the patch below can help a bit?
>
> -------------------------------------------------------------------------------
> Subject: [PATCH] vmacache: change vmacache_find() to always check ->vm_mm
>
> If ->vmacache was corrupted it would be better to detect and report
> the problem asap, check vma->vm_mm before vm_start/vm_end.
>
> Signed-off-by: Oleg Nesterov <o...@redhat.com>
> ---
> mm/vmacache.c | 5 +++--
> 1 files changed, 3 insertions(+), 2 deletions(-)
>
> diff --git a/mm/vmacache.c b/mm/vmacache.c
> index d4224b3..952a324 100644
> --- a/mm/vmacache.c
> +++ b/mm/vmacache.c
> @@ -81,9 +81,10 @@ struct vm_area_struct *vmacache_find(struct mm_struct *mm,
> unsigned long addr)
> for (i = 0; i < VMACACHE_SIZE; i++) {
> struct vm_area_struct *vma = current->vmacache[i];
>
> - if (vma && vma->vm_start <= addr && vma->vm_end > addr) {
> + if (vma) {
> BUG_ON(vma->vm_mm != mm);
> - return vma;
> + if (vma->vm_start <= addr && vma->vm_end > addr)
> + return vma;
> }
> }
>
IIUC, this is similar to commit 50f5aa8a9b2 (mm: don't pointlessly use
BUG_ON() for sanity check). But even with that commit included I was
not able to reproduce the bug again, as reported here:
https://lkml.org/lkml/2014/4/29/187
Regards,
Srivatsa S. Bhat
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