Re: [PATCH] mm: fix hang on anon_vma->root->lock

From: Hugh Dickins
Date: Fri Aug 27 2010 - 17:33:43 EST


Sorry, I seem to have hit some key which sent the mail off too soon, a
tab perhaps: finishing up...

On Fri, Aug 27, 2010 at 2:28 PM, Hugh Dickins <hughd@xxxxxxxxxx> wrote:
> On Fri, Aug 27, 2010 at 1:56 PM, Christoph Lameter <cl@xxxxxxxxx> wrote:
>>
>>> of that second check, then we know that we got the right anon_vma,
>>
>> I do not see a second check (*after* taking the lock) in the patch

if (page_mapped(page))
return anon_vma;

>> and the way the lock is taken can be a problem in itself.

No, that's what we rely upon SLAB_DESTROY_BY_RCU for.

Hugh
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