Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752861AbcKHEXx (ORCPT ); Mon, 7 Nov 2016 23:23:53 -0500 Received: from mail-yw0-f181.google.com ([209.85.161.181]:35214 "EHLO mail-yw0-f181.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752419AbcKHEXw (ORCPT ); Mon, 7 Nov 2016 23:23:52 -0500 MIME-Version: 1.0 In-Reply-To: <20161107144931.edcf151a04f1af6d230b8a8a@linux-foundation.org> References: <1478553075-120242-1-git-send-email-thgarnie@google.com> <20161107141919.fe50cef419918c7a4660f3c2@linux-foundation.org> <20161107144931.edcf151a04f1af6d230b8a8a@linux-foundation.org> From: Thomas Garnier Date: Mon, 7 Nov 2016 20:23:50 -0800 Message-ID: Subject: Re: [PATCH v3 1/2] memcg: Prevent memcg caches to be both OFF_SLAB & OBJFREELIST_SLAB To: Andrew Morton Cc: Christoph Lameter , Pekka Enberg , David Rientjes , Joonsoo Kim , Linux-MM , LKML , Greg Thelen , Vladimir Davydov , Michal Hocko Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1917 Lines: 52 On Mon, Nov 7, 2016 at 2:49 PM, Andrew Morton wrote: > On Mon, 7 Nov 2016 14:32:56 -0800 Thomas Garnier wrote: > >> On Mon, Nov 7, 2016 at 2:19 PM, Andrew Morton wrote: >> > On Mon, 7 Nov 2016 13:11:14 -0800 Thomas Garnier wrote: >> > >> >> From: Greg Thelen >> >> >> >> While testing OBJFREELIST_SLAB integration with pagealloc, we found a >> >> bug where kmem_cache(sys) would be created with both CFLGS_OFF_SLAB & >> >> CFLGS_OBJFREELIST_SLAB. >> >> >> >> The original kmem_cache is created early making OFF_SLAB not possible. >> >> When kmem_cache(sys) is created, OFF_SLAB is possible and if pagealloc >> >> is enabled it will try to enable it first under certain conditions. >> >> Given kmem_cache(sys) reuses the original flag, you can have both flags >> >> at the same time resulting in allocation failures and odd behaviors. >> > >> > Can we please have a better description of the problems which this bug >> > causes? Without this info it's unclear to me which kernel version(s) >> > need the fix. >> > >> > Given that the bug is 6 months old I'm assuming "not very urgent". >> > >> >> I will add more details and send another round. > > Please simply send the additional changelog text in this thread - > processing an entire v4 patch just for a changelog fiddle is rather > heavyweight. > Got it, here is the diff of the previous commit message: 9,10c9 < CFLGS_OBJFREELIST_SLAB. When it happened, critical allocations needed < for loading drivers or creating new caches will fail. --- > CFLGS_OBJFREELIST_SLAB. 16c15 < at the same time. --- > at the same time resulting in allocation failures and odd behaviors. 21,23d19 < The bug exists since 4.6-rc1 and affects testing debug pagealloc < configurations. < 26d21 < Signed-off-by: Thomas Garnier -- Thomas