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=-8.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI, SPF_HELO_NONE,SPF_PASS 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 364F3C433E9 for ; Mon, 28 Dec 2020 12:54:48 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 119F122C7B for ; Mon, 28 Dec 2020 12:54:48 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728397AbgL1Myp (ORCPT ); Mon, 28 Dec 2020 07:54:45 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:46680 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728372AbgL1Myg (ORCPT ); Mon, 28 Dec 2020 07:54:36 -0500 Received: from mail-lf1-x134.google.com (mail-lf1-x134.google.com [IPv6:2a00:1450:4864:20::134]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id EF4D2C061794 for ; Mon, 28 Dec 2020 04:53:54 -0800 (PST) Received: by mail-lf1-x134.google.com with SMTP id b26so23631891lff.9 for ; Mon, 28 Dec 2020 04:53:54 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=shutemov-name.20150623.gappssmtp.com; s=20150623; h=date:from:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to; bh=e/ofUiCRRpB4u/ncszNNbx4yVQ41aGMLvWQFS35RvZk=; b=LtOrTYXJm5GCAEJmyygo6av6ilVjte7nrHfuv67gXDpKd+J+pPdTCcxYoIGp1dX2w5 Ihd5Qc2FtGU3gkA9UCXFeBOVXtmF3FnWevd7p76cvCLgY3D+rXxSsU67PTKPx5J3a9zf uElwOP/OCHcUtHiAe6BZzxxUfgrYLg2Z7S38iArnEgsXBm7Vdj8wuG58GjfYodS8aTsq t0CWf/hY4H5bnuF+Baqp67r1D0d25zzn6kMkxzTUWCUgm15TmoKXiO8s6vvrzcjs5BmL 56zSFKosBDPZB9Q+jEXFPoy/z3+8D1EQY1QWh/kndY66e3IQB0KG8w+ANVgwfrdXZJAC 5ZeQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:in-reply-to; bh=e/ofUiCRRpB4u/ncszNNbx4yVQ41aGMLvWQFS35RvZk=; b=fK/EvP64NirrPlF1sZihUHmjJgohGubk2pD9uaqZdSCIq/l8mpH/hCJRTJZaySpC8X 855vBmDaN/0gw5jyZ7ZAttHdCr4WR3h+Z47+nOo+mE9Tb2JBfZQxdAc9/qOTBb7Xq8TK Cf/jvSkUlVfdTHu3IeTQDKzMByHFBv8dDK8xwI/5GUui9oCpAWdHtWAFOl5bIEwxF25t VsrirYmYUCL+KUoSJRdIW3A4NYSC7l6pwUYUVDWTvNVK4HETlCzoDkHBy4F0Ycijcmp+ UXUG1fyIlIl/qdxSp1bEdMBs9fgQoS/g8IPll3GhJ1opSRZoI3brx5m/jcGMT80p7IqU K74A== X-Gm-Message-State: AOAM5331fjUCdkGwUnvxinq8L7i/OHRhGPaa3+Lz5FGFMjatccVRZJ8o vt6iUMO+6K1VhjMexMMItKAdhw== X-Google-Smtp-Source: ABdhPJyF06z1uqFK1T0R7uip1K18Ag78t+cj6KkROGIX8ECc9cTa2pWQCwBOjCm+YlSORX87suNs5A== X-Received: by 2002:a05:651c:205b:: with SMTP id t27mr22712768ljo.368.1609160033448; Mon, 28 Dec 2020 04:53:53 -0800 (PST) Received: from box.localdomain ([86.57.175.117]) by smtp.gmail.com with ESMTPSA id j26sm200426lfh.251.2020.12.28.04.53.52 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 28 Dec 2020 04:53:52 -0800 (PST) Received: by box.localdomain (Postfix, from userid 1000) id 89D9A100F3B; Mon, 28 Dec 2020 15:53:52 +0300 (+03) Date: Mon, 28 Dec 2020 15:53:52 +0300 From: "Kirill A. Shutemov" To: Hugh Dickins Cc: Linus Torvalds , Matthew Wilcox , "Kirill A. Shutemov" , Will Deacon , Linux Kernel Mailing List , Linux-MM , Linux ARM , Catalin Marinas , Jan Kara , Minchan Kim , Andrew Morton , Vinayak Menon , Android Kernel Team Subject: Re: [PATCH 1/2] mm: Allow architectures to request 'old' entries when prefaulting Message-ID: <20201228125352.phnj2x2ci3kwfld5@box> References: <20201226204335.dikqkrkezqet6oqf@box> <20201226224016.dxjmordcfj75xgte@box> <20201227234853.5mjyxcybucts3kbq@box> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Sun, Dec 27, 2020 at 10:43:44PM -0800, Hugh Dickins wrote: > On Sun, 27 Dec 2020, Linus Torvalds wrote: > > On Sun, Dec 27, 2020 at 3:48 PM Kirill A. Shutemov wrote: > > > > > > I did what Hugh proposed and it got clear to my eyes. It gets somewhat > > > large, but take a look. > > > > Ok, it's not that much bigger, and the end result is certainly much > > clearer wrt locking. > > > > So that last version of yours with the fix for the uninitialized 'ret' > > variable looks good to me. > > > > Of course, I've said that before, and have been wrong. So ... > > And guess what... it's broken. > > I folded it into testing rc1: segfault on cc1, systemd > "Journal file corrupted, rotating", seen on more than one machine. > > I've backed it out, rc1 itself seems fine, I'll leave rc1 under > load overnight, then come back to the faultaround patch tomorrow; > won't glance at it tonight, but maybe Kirill will guess what's wrong. So far I only found one more pin leak and always-true check. I don't see how can it lead to crash or corruption. Keep looking. diff --git a/mm/filemap.c b/mm/filemap.c index c5da09f3f363..87671284de62 100644 --- a/mm/filemap.c +++ b/mm/filemap.c @@ -2966,8 +2966,7 @@ vm_fault_t filemap_map_pages(struct vm_fault *vmf, unsigned long address, mmap_miss--; vmf->address += (xas.xa_index - last_pgoff) << PAGE_SHIFT; - if (vmf->pte) - vmf->pte += xas.xa_index - last_pgoff; + vmf->pte += xas.xa_index - last_pgoff; last_pgoff = xas.xa_index; if (!pte_none(*vmf->pte)) diff --git a/mm/memory.c b/mm/memory.c index e51638b92e7c..829f5056dd1c 100644 --- a/mm/memory.c +++ b/mm/memory.c @@ -3785,13 +3785,16 @@ vm_fault_t finish_fault(struct vm_fault *vmf) vmf->pte = pte_offset_map_lock(vma->vm_mm, vmf->pmd, vmf->address, &vmf->ptl); + ret = 0; /* Re-check under ptl */ if (likely(pte_none(*vmf->pte))) do_set_pte(vmf, page); + else + ret = VM_FAULT_NOPAGE; update_mmu_tlb(vma, vmf->address, vmf->pte); pte_unmap_unlock(vmf->pte, vmf->ptl); - return 0; + return ret; } static unsigned long fault_around_bytes __read_mostly = -- Kirill A. Shutemov 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=-8.9 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS 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 1725EC43333 for ; Mon, 28 Dec 2020 12:55:42 +0000 (UTC) Received: from merlin.infradead.org (merlin.infradead.org [205.233.59.134]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id D0DCA22B3B for ; Mon, 28 Dec 2020 12:55:41 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org D0DCA22B3B Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=shutemov.name Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=merlin.20170209; h=Sender:Content-Transfer-Encoding: Content-Type:Cc:List-Subscribe:List-Help:List-Post:List-Archive: List-Unsubscribe:List-Id:In-Reply-To:MIME-Version:References:Message-ID: Subject:To:From:Date:Reply-To:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=kTxhAWxtezkjgQqcZss06SoZOW2JT4NylI/lNLd2b5I=; b=wlD2I0CJL5uOleMHf+TASf8mg qfbBR0SXA7PS/4MuM4Sln8F08Cp4N216FNCVmMegeLfijMBBLC5Hj8yMYTjThMxU1uFvCboRzIi9m 9G9VM52hZBAnXc137mCRBCNtK+KYG1Su6KG7oVTx1ATzn1vylh2SrkbFW9zIHMyBB9Ss/DWOnymBA 19Rjd5H8kSql6Y/wJ1nVs9rtiA/abNQ/pXBODuuqGBW+XMBWVnXOb5fgNM5Ly0Wo8cDW1LLs+JTJR 1ErRDWRLwWhWsHvXAW02vjTuZHvu0iIh0JCLExV0wotN//E6W4/buxTKX5XTQa77xSarlKtS2/w/H MTlptdIOA==; Received: from localhost ([::1] helo=merlin.infradead.org) by merlin.infradead.org with esmtp (Exim 4.92.3 #3 (Red Hat Linux)) id 1kts2B-0003Rq-Sr; Mon, 28 Dec 2020 12:53:59 +0000 Received: from mail-lf1-x12e.google.com ([2a00:1450:4864:20::12e]) by merlin.infradead.org with esmtps (Exim 4.92.3 #3 (Red Hat Linux)) id 1kts28-0003Qj-2q for linux-arm-kernel@lists.infradead.org; Mon, 28 Dec 2020 12:53:57 +0000 Received: by mail-lf1-x12e.google.com with SMTP id x20so23600258lfe.12 for ; Mon, 28 Dec 2020 04:53:54 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=shutemov-name.20150623.gappssmtp.com; s=20150623; h=date:from:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to; bh=e/ofUiCRRpB4u/ncszNNbx4yVQ41aGMLvWQFS35RvZk=; b=LtOrTYXJm5GCAEJmyygo6av6ilVjte7nrHfuv67gXDpKd+J+pPdTCcxYoIGp1dX2w5 Ihd5Qc2FtGU3gkA9UCXFeBOVXtmF3FnWevd7p76cvCLgY3D+rXxSsU67PTKPx5J3a9zf uElwOP/OCHcUtHiAe6BZzxxUfgrYLg2Z7S38iArnEgsXBm7Vdj8wuG58GjfYodS8aTsq t0CWf/hY4H5bnuF+Baqp67r1D0d25zzn6kMkxzTUWCUgm15TmoKXiO8s6vvrzcjs5BmL 56zSFKosBDPZB9Q+jEXFPoy/z3+8D1EQY1QWh/kndY66e3IQB0KG8w+ANVgwfrdXZJAC 5ZeQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:in-reply-to; bh=e/ofUiCRRpB4u/ncszNNbx4yVQ41aGMLvWQFS35RvZk=; b=Vr7FemXErMpVdCl4wie/7v5tFc6S9NKg9Mwt359KDpxHeWgRMO818rDfd5XPl3nk1n BrcXQPWjzLLmM1XGoSyd5MBYcu/A4sgxs+2wz9jNryecuG513NMxHjxAWpZiD0OmZAFi uY2FwbJq6hhUzbh2a6CvyAgx2kjn1HKM2Hw0MaNKcMZCtzHazEoSqVBduVLJOJlc4Duv 4DvWxrG6Ef8ngghbDc2HdK6LW4jD5ogblLAqiM2yhhSlpuATXdGWZGLJSbSUv4xG/Zpz jFxd3bhoTVFIYFmnCJViR0ba9W9w4zqBhahCr3+O0QQPlVcH+ij3veyMCK+xi7G/Qw0J KcXw== X-Gm-Message-State: AOAM531pG04MXEdCK1pFczMiegYczAD5L0LgtJmJ80UwTK+rmaVeroZS R4PeCmrEenf7uyyETFPZTsrSIA== X-Google-Smtp-Source: ABdhPJyF06z1uqFK1T0R7uip1K18Ag78t+cj6KkROGIX8ECc9cTa2pWQCwBOjCm+YlSORX87suNs5A== X-Received: by 2002:a05:651c:205b:: with SMTP id t27mr22712768ljo.368.1609160033448; Mon, 28 Dec 2020 04:53:53 -0800 (PST) Received: from box.localdomain ([86.57.175.117]) by smtp.gmail.com with ESMTPSA id j26sm200426lfh.251.2020.12.28.04.53.52 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 28 Dec 2020 04:53:52 -0800 (PST) Received: by box.localdomain (Postfix, from userid 1000) id 89D9A100F3B; Mon, 28 Dec 2020 15:53:52 +0300 (+03) Date: Mon, 28 Dec 2020 15:53:52 +0300 From: "Kirill A. Shutemov" To: Hugh Dickins Subject: Re: [PATCH 1/2] mm: Allow architectures to request 'old' entries when prefaulting Message-ID: <20201228125352.phnj2x2ci3kwfld5@box> References: <20201226204335.dikqkrkezqet6oqf@box> <20201226224016.dxjmordcfj75xgte@box> <20201227234853.5mjyxcybucts3kbq@box> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20201228_075356_326250_D714F5D9 X-CRM114-Status: GOOD ( 21.44 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Android Kernel Team , Jan Kara , Minchan Kim , Linus Torvalds , Linux Kernel Mailing List , Matthew Wilcox , Linux-MM , Vinayak Menon , Linux ARM , Catalin Marinas , Andrew Morton , Will Deacon , "Kirill A. Shutemov" Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org On Sun, Dec 27, 2020 at 10:43:44PM -0800, Hugh Dickins wrote: > On Sun, 27 Dec 2020, Linus Torvalds wrote: > > On Sun, Dec 27, 2020 at 3:48 PM Kirill A. Shutemov wrote: > > > > > > I did what Hugh proposed and it got clear to my eyes. It gets somewhat > > > large, but take a look. > > > > Ok, it's not that much bigger, and the end result is certainly much > > clearer wrt locking. > > > > So that last version of yours with the fix for the uninitialized 'ret' > > variable looks good to me. > > > > Of course, I've said that before, and have been wrong. So ... > > And guess what... it's broken. > > I folded it into testing rc1: segfault on cc1, systemd > "Journal file corrupted, rotating", seen on more than one machine. > > I've backed it out, rc1 itself seems fine, I'll leave rc1 under > load overnight, then come back to the faultaround patch tomorrow; > won't glance at it tonight, but maybe Kirill will guess what's wrong. So far I only found one more pin leak and always-true check. I don't see how can it lead to crash or corruption. Keep looking. diff --git a/mm/filemap.c b/mm/filemap.c index c5da09f3f363..87671284de62 100644 --- a/mm/filemap.c +++ b/mm/filemap.c @@ -2966,8 +2966,7 @@ vm_fault_t filemap_map_pages(struct vm_fault *vmf, unsigned long address, mmap_miss--; vmf->address += (xas.xa_index - last_pgoff) << PAGE_SHIFT; - if (vmf->pte) - vmf->pte += xas.xa_index - last_pgoff; + vmf->pte += xas.xa_index - last_pgoff; last_pgoff = xas.xa_index; if (!pte_none(*vmf->pte)) diff --git a/mm/memory.c b/mm/memory.c index e51638b92e7c..829f5056dd1c 100644 --- a/mm/memory.c +++ b/mm/memory.c @@ -3785,13 +3785,16 @@ vm_fault_t finish_fault(struct vm_fault *vmf) vmf->pte = pte_offset_map_lock(vma->vm_mm, vmf->pmd, vmf->address, &vmf->ptl); + ret = 0; /* Re-check under ptl */ if (likely(pte_none(*vmf->pte))) do_set_pte(vmf, page); + else + ret = VM_FAULT_NOPAGE; update_mmu_tlb(vma, vmf->address, vmf->pte); pte_unmap_unlock(vmf->pte, vmf->ptl); - return 0; + return ret; } static unsigned long fault_around_bytes __read_mostly = -- Kirill A. Shutemov _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel