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=-2.5 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, USER_AGENT_SANE_1 autolearn=no 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 942FAC49ED6 for ; Wed, 11 Sep 2019 15:23:41 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 5119B2085B for ; Wed, 11 Sep 2019 15:23:41 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=shutemov-name.20150623.gappssmtp.com header.i=@shutemov-name.20150623.gappssmtp.com header.b="poetBkUA" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728368AbfIKPXk (ORCPT ); Wed, 11 Sep 2019 11:23:40 -0400 Received: from mail-ed1-f67.google.com ([209.85.208.67]:38675 "EHLO mail-ed1-f67.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727581AbfIKPXk (ORCPT ); Wed, 11 Sep 2019 11:23:40 -0400 Received: by mail-ed1-f67.google.com with SMTP id a23so18776004edv.5 for ; Wed, 11 Sep 2019 08:23:39 -0700 (PDT) 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:user-agent; bh=bdRXlyq4l4A8bpgzomm6eF1x1mYYtVmO70wKMu77KXc=; b=poetBkUAgbyDnI3y/qa1TcPN6avL7jZvYR1xuvOR4FYgMjSzY40Ez86GbhxUHGeiuV OV3euIHts64HIU4Xzlj4S+3jIbtb7oDOg19eORR5vIx6G6RInuzBwciIB60mpznuxeSh yKBvY/OePNkSFcqk+zwRD1MpMpVVcYY1Q/bjXb7Fomelex8GuamZMdzf06WyyAD55m9J VnuuqSnc1+vy32kWxUhtQgIU4Hh4to4oylRr9XbWJn4dB4R2N+FXadF7FTR7TaA85m0a NPy0XKaEmseSM4oumr3Zb5qkaTDI/6BBRiApwIvibKuiJFeGdKJkWki4mmBwygxDeNZ8 nFFg== 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:user-agent; bh=bdRXlyq4l4A8bpgzomm6eF1x1mYYtVmO70wKMu77KXc=; b=t0ryBz252KD/7ExIT/cXXHB6sJclXydZjauOzRkT9O5PvZzUDDjIBSsNkVkBxIhHL5 PtAAmZKQj+oleAjlZxjsHcOCwtgL6UpnNa8H4RaIgfDV2/3KDXVql5eKnBA/w0z8AwYD yod6vBPDvA1OcvyQ4donnjeRBdg0LM0tNkm5Xu5s5+dFS/QD59hIW2UVq2jyBXJ0kVPr gzoUAHv9IZ2Bi/NjigopHmLL33mpO23WzfvMGRzMYfAkaH0uUhMfITUSxn+XIPFDARY/ Olq/wuWkLMKZsGUhsIdwNc0mEXy4GW4T2Ym9Eps5LFpiBDlYZYAb0zypC5qJm6E7SUjF 5+9A== X-Gm-Message-State: APjAAAUIhGO5cUKxWC1enzu8MUoJYIWPy7t4p8G7m/Wo/8OocWt0iNQh SuT8V70ILZfLJKZpY9gsssjWvErsEII= X-Google-Smtp-Source: APXvYqwYuTgslFkpD3GVu+/ZtjWa6+TgqNSXkaGo/8pTyfEMxmrTMrRhfUjxMtUOPKOTQwdqzarKOQ== X-Received: by 2002:a50:9734:: with SMTP id c49mr37498960edb.93.1568215418672; Wed, 11 Sep 2019 08:23:38 -0700 (PDT) Received: from box.localdomain ([86.57.175.117]) by smtp.gmail.com with ESMTPSA id d24sm4264007edp.88.2019.09.11.08.23.37 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Wed, 11 Sep 2019 08:23:38 -0700 (PDT) Received: by box.localdomain (Postfix, from userid 1000) id A385D10416F; Wed, 11 Sep 2019 18:23:38 +0300 (+03) Date: Wed, 11 Sep 2019 18:23:38 +0300 From: "Kirill A. Shutemov" To: Matthew Wilcox Cc: Josef Bacik , linux-mm@kvack.org, linux-fsdevel@vger.kernel.org Subject: Re: filemap_fault can lose errors Message-ID: <20190911152338.gqqgxrmqycodfocb@box> References: <20190911025158.GG29434@bombadil.infradead.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20190911025158.GG29434@bombadil.infradead.org> User-Agent: NeoMutt/20180716 Sender: linux-fsdevel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org On Tue, Sep 10, 2019 at 07:51:58PM -0700, Matthew Wilcox wrote: > > If we encounter an error on a page, we can lose the error if we've > dropped the mmap_sem while we wait for the I/O. That can result in > taking the fault multiple times, and retrying the read multiple times. > Spotted by inspection. But does the patch make any difference? Looking into x86 code, VM_FAULT_RETRY makes it retry the fault or return to userspace before it checks for VM_FAULT_SIGBUS bit. -- Kirill A. Shutemov