From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752077AbbCHAxZ (ORCPT ); Sat, 7 Mar 2015 19:53:25 -0500 Received: from mail-ig0-f171.google.com ([209.85.213.171]:37270 "EHLO mail-ig0-f171.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751109AbbCHAxW (ORCPT ); Sat, 7 Mar 2015 19:53:22 -0500 Date: Sat, 7 Mar 2015 16:53:20 -0800 (PST) From: David Rientjes X-X-Sender: rientjes@chino.kir.corp.google.com To: Jens Axboe cc: Lars Ellenberg , linux-kernel@vger.kernel.org, drbd-user@lists.linbit.com Subject: Re: [patch 1/2] block, drbd: fix drbd_req_new() initialization In-Reply-To: <54FB98F3.2050308@fb.com> Message-ID: References: <54FB98F3.2050308@fb.com> User-Agent: Alpine 2.10 (DEB 1266 2009-07-14) MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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.