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=-8.2 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE, SPF_PASS,URIBL_BLOCKED,USER_AGENT_SANE_1 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 B0873C43463 for ; Fri, 18 Sep 2020 19:33:06 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 7B16F21734 for ; Fri, 18 Sep 2020 19:33:06 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726361AbgIRTdF (ORCPT ); Fri, 18 Sep 2020 15:33:05 -0400 Received: from lobo.ruivo.org ([173.14.175.98]:40946 "EHLO lobo.ruivo.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726156AbgIRTdE (ORCPT ); Fri, 18 Sep 2020 15:33:04 -0400 X-Greylist: delayed 406 seconds by postgrey-1.27 at vger.kernel.org; Fri, 18 Sep 2020 15:33:03 EDT Received: by lobo.ruivo.org (Postfix, from userid 1011) id B329C5315F; Fri, 18 Sep 2020 15:27:40 -0400 (EDT) Received: from jake.ruivo.org (bob.qemu.ruivo [192.168.72.19]) by lobo.ruivo.org (Postfix) with ESMTPA id 2410E52EBB; Fri, 18 Sep 2020 15:27:24 -0400 (EDT) Received: by jake.ruivo.org (Postfix, from userid 1000) id 1D7401A52B6; Fri, 18 Sep 2020 15:27:24 -0400 (EDT) Date: Fri, 18 Sep 2020 15:27:24 -0400 From: Aristeu Rozanski To: Oscar Salvador Cc: akpm@linux-foundation.org, naoya.horiguchi@nec.com, mhocko@kernel.org, tony.luck@intel.com, cai@lca.pw, linux-kernel@vger.kernel.org, linux-mm@kvack.org Subject: Re: [PATCH v4 3/7] mm,hwpoison: Try to narrow window race for free pages Message-ID: <20200918192724.GD18315@cathedrallabs.org> References: <20200917081049.27428-1-osalvador@suse.de> <20200917081049.27428-4-osalvador@suse.de> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20200917081049.27428-4-osalvador@suse.de> User-Agent: Mutt/1.10.1 (2018-07-13) Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Sep 17, 2020 at 10:10:45AM +0200, Oscar Salvador wrote: > Aristeu Rozanski reported that a customer test case started > to report -EBUSY after the hwpoison report patchset. > > There is a race window between spotting a free page and taking it off > its buddy freelist, so it might be that by the time we try to take it off, > the page has been already allocated. > > This patch tries to handle such race window by trying to handle the new > type of page again if the page was allocated under us. > > After this patch, Aristeu said the test cases work properly. > > Signed-off-by: Oscar Salvador > Reported-by: Aristeu Rozanski Tested-by: Aristeu Rozanski -- Aristeu