Re: [patch 1/2] block, drbd: fix drbd_req_new() initialization
From: David Rientjes
Date: Sat Mar 07 2015 - 19:53:29 EST
On Sat, 7 Mar 2015, Jens Axboe wrote:
> > mempool_alloc() does not support __GFP_ZERO since elements may come from
> > memory that has already been released by mempool_free().
> >
> > Remove __GFP_ZERO from mempool_alloc() in drbd_req_new() and properly
> > initialize it to 0.
>
> You should add it to mempool instead, avoid having this issue show up for
> other folks as well. It'd be trivial to do. Normal ->alloc() should honor
> __GFP_ZERO, just do the same manually for removing an item from the internal
> pool.
>
Umm, it's not trivial to do and wouldn't make sense to do it. Mempools
don't know the element size, in other words it wouldn't know the length to
memset() to 0 for mempool_alloc(). It shouldn't be modified to know the
element size since elements are allocated by the implementation of
mempool_alloc_t and they could easily become inconsistent. This patch is
what you want to merge, really.
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