From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-2.3 required=3.0 tests=DKIM_INVALID,DKIM_SIGNED, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_PASS,USER_AGENT_MUTT autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 45BB0C43381 for ; Wed, 27 Mar 2019 18:22:11 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 0D49F2070B for ; Wed, 27 Mar 2019 18:22:11 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b="GsP1PSkK" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2391262AbfC0SWJ (ORCPT ); Wed, 27 Mar 2019 14:22:09 -0400 Received: from bombadil.infradead.org ([198.137.202.133]:53876 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2403816AbfC0SWE (ORCPT ); Wed, 27 Mar 2019 14:22:04 -0400 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=bombadil.20170209; h=In-Reply-To:Content-Type:MIME-Version :References:Message-ID:Subject:Cc:To:From:Date:Sender:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Id: List-Help:List-Unsubscribe:List-Subscribe:List-Post:List-Owner:List-Archive; bh=p7uJNRLkzeeNJQDM4SyzmPlQbirmlbL45c4zuRXPsDc=; b=GsP1PSkKCM3pKHBQoPlZ6U28O p7kN3WPwHv2Ayga/YUdwllSSRNfrRZDjXDr6XKNHjs72DF8Bq71fI7ZJ5tqFi8MTOO+xsM6nvRqEt yphYGTt3bEDJAUcNFhtBV50f4zqN9fzKU9pyTlijQCa+r5YDvSvtZjz1e4EkPCQG5GrreXvXQBDwv rGhTGKVG545O5Gx1e9+8nIQyoP/5Hjg/mFm/V/gatooBIn2wADh+sz8/qcqinBr91u+VLItmb6kWb StTLEYhh50ngqYJ9fhOZhgCmFzZgBAYd9ZsyVBZtXNJqEm6AMp185aMwJaTHmYhc5wgPihAYpuiq3 39u185IDg==; Received: from willy by bombadil.infradead.org with local (Exim 4.90_1 #2 (Red Hat Linux)) id 1h9DBW-0001Q1-GP; Wed, 27 Mar 2019 18:21:58 +0000 Date: Wed, 27 Mar 2019 11:21:58 -0700 From: Matthew Wilcox To: Catalin Marinas Cc: Michal Hocko , Qian Cai , akpm@linux-foundation.org, cl@linux.com, penberg@kernel.org, rientjes@google.com, iamjoonsoo.kim@lge.com, linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH v4] kmemleak: survive in a low-memory situation Message-ID: <20190327182158.GS10344@bombadil.infradead.org> References: <20190327005948.24263-1-cai@lca.pw> <20190327084432.GA11927@dhcp22.suse.cz> <20190327172955.GB17247@arrakis.emea.arm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20190327172955.GB17247@arrakis.emea.arm.com> User-Agent: Mutt/1.9.2 (2017-12-15) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Mar 27, 2019 at 05:29:57PM +0000, Catalin Marinas wrote: > On Wed, Mar 27, 2019 at 09:44:32AM +0100, Michal Hocko wrote: > > As long as there is an implicit __GFP_NOFAIL then kmemleak is simply > > broken no matter what other gfp flags you play with. Has anybody looked > > at some sort of preallocation where gfpflags_allow_blocking context > > allocate objects into a pool that non-sleeping allocations can eat from? > > Quick attempt below and it needs some more testing (pretty random pick > of the EMERGENCY_POOL_SIZE value). Also, with __GFP_NOFAIL removed, are > the other flags safe or we should trim them further? Why not use mempool? > #define gfp_kmemleak_mask(gfp) (((gfp) & (GFP_KERNEL | GFP_ATOMIC)) | \ > __GFP_NORETRY | __GFP_NOMEMALLOC | \ > - __GFP_NOWARN | __GFP_NOFAIL) > + __GFP_NOWARN) Why GFP_NORETRY? And if I have specified one of the other retry policies in my gfp flags, you should presumably clear that off before setting GFP_NORETRY.