From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-qk1-f197.google.com (mail-qk1-f197.google.com [209.85.222.197]) by kanga.kvack.org (Postfix) with ESMTP id 87CCC8E0001 for ; Sun, 30 Sep 2018 09:10:32 -0400 (EDT) Received: by mail-qk1-f197.google.com with SMTP id 17-v6so11705896qkj.19 for ; Sun, 30 Sep 2018 06:10:32 -0700 (PDT) Received: from out3-smtp.messagingengine.com (out3-smtp.messagingengine.com. [66.111.4.27]) by mx.google.com with ESMTPS id y68-v6si5221156qkd.226.2018.09.30.06.10.31 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Sun, 30 Sep 2018 06:10:31 -0700 (PDT) Date: Sun, 30 Sep 2018 06:10:26 -0700 From: Greg KH Subject: Re: [STABLE PATCH] slub: make ->cpu_partial unsigned int Message-ID: <20180930131026.GA25677@kroah.com> References: <1538303301-61784-1-git-send-email-zhongjiang@huawei.com> <20180930125038.GA2533@bombadil.infradead.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20180930125038.GA2533@bombadil.infradead.org> Sender: owner-linux-mm@kvack.org List-ID: To: Matthew Wilcox Cc: zhong jiang , cl@linux.com, penberg@kernel.org, rientjes@google.com, iamjoonsoo.kim@lge.com, akpm@linux-foundation.org, mhocko@kernel.org, mgorman@suse.de, vbabka@suse.cz, andrea@kernel.org, kirill@shutemov.name, linux-mm@kvack.org, linux-kernel@vger.kernel.org On Sun, Sep 30, 2018 at 05:50:38AM -0700, Matthew Wilcox wrote: > On Sun, Sep 30, 2018 at 06:28:21PM +0800, zhong jiang wrote: > > From: Alexey Dobriyan > > > > [ Upstream commit e5d9998f3e09359b372a037a6ac55ba235d95d57 ] > > > > /* > > * cpu_partial determined the maximum number of objects > > * kept in the per cpu partial lists of a processor. > > */ > > > > Can't be negative. > > > > I hit a real issue that it will result in a large number of memory leak. > > Becuase Freeing slabs are in interrupt context. So it can trigger this issue. > > put_cpu_partial can be interrupted more than once. > > due to a union struct of lru and pobjects in struct page, when other core handles > > page->lru list, for eaxmple, remove_partial in freeing slab code flow, It will > > result in pobjects being a negative value(0xdead0000). Therefore, a large number > > of slabs will be added to per_cpu partial list. > > > > I had posted the issue to community before. The detailed issue description is as follows. > > > > https://www.spinics.net/lists/kernel/msg2870979.html > > > > After applying the patch, The issue is fixed. So the patch is a effective bugfix. > > It should go into stable. > > > > Link: http://lkml.kernel.org/r/20180305200730.15812-15-adobriyan@gmail.com > > Signed-off-by: Alexey Dobriyan > > Acked-by: Christoph Lameter > > Hang on. Christoph acked the _original_ patch going into upstream. > When he reviewed this patch for _stable_ last week, he asked for more > investigation. Including this patch in stable is misleading. But the original patch has been in upstream for a long time now (it went into 4.17-rc1). If there was a real problem here, whouldn't it have been resolved already? And the patch in mainline has Christoph's ack... thanks, greg k-h