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=-3.5 required=3.0 tests=BAYES_00,DKIM_INVALID, DKIM_SIGNED,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS 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 E39D2C433DF for ; Sat, 17 Oct 2020 16:28:28 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 1F9BD20760 for ; Sat, 17 Oct 2020 16:28:27 +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="htnJXS/P" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 1F9BD20760 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=infradead.org Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id 9544A940007; Sat, 17 Oct 2020 12:28:26 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 90543900002; Sat, 17 Oct 2020 12:28:26 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 81B60940007; Sat, 17 Oct 2020 12:28:26 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0060.hostedemail.com [216.40.44.60]) by kanga.kvack.org (Postfix) with ESMTP id 52095900002 for ; Sat, 17 Oct 2020 12:28:26 -0400 (EDT) Received: from smtpin25.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay05.hostedemail.com (Postfix) with ESMTP id E036D181AEF0B for ; Sat, 17 Oct 2020 16:28:25 +0000 (UTC) X-FDA: 77381950170.25.dress95_210365127227 Received: from filter.hostedemail.com (10.5.16.251.rfc1918.com [10.5.16.251]) by smtpin25.hostedemail.com (Postfix) with ESMTP id BC1881804E3A0 for ; Sat, 17 Oct 2020 16:28:25 +0000 (UTC) X-HE-Tag: dress95_210365127227 X-Filterd-Recvd-Size: 2587 Received: from casper.infradead.org (casper.infradead.org [90.155.50.34]) by imf26.hostedemail.com (Postfix) with ESMTP for ; Sat, 17 Oct 2020 16:28:24 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=casper.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; bh=6mXfPhMnu+roSNkFrv07dky78OHMusb7Dgd7GmBrx/4=; b=htnJXS/PhGkzvmiN6ZOXEAAUYt SjZw82JyeciN+YhJvRPyaKvoRQN0s8/sqzfzC46sE/LyFP8sDzDMm6c0Sk3M/EsRzUKZw+UDzWb6p vboGDs+WWAHXTIVZ9Sw11FvhZfBTgET3o4x7IloFL+BFa2+jgGxtpmluJ5Ocj0QdBbfsqDQ8LwtIJ UkmB3bNovQostdCZqeTUkmxsh9lXlGrjfg2R1cmvdBRYPtHYQPtF/dy61tguFwKBTXauHvEk4P7lg ZmYx1vocIK9cpLhj7Tf72KvJa/2bgvfUU5vsyI1e/bON1L6V5lb9zn2ItWzl9k5mTj+UJ+dOKANid d+XzKVXA==; Received: from willy by casper.infradead.org with local (Exim 4.92.3 #3 (Red Hat Linux)) id 1kTp48-0008It-KA; Sat, 17 Oct 2020 16:28:20 +0000 Date: Sat, 17 Oct 2020 17:28:20 +0100 From: Matthew Wilcox To: Jens Axboe Cc: linux-mm , Andrew Morton , Johannes Weiner , Kent Overstreet Subject: Re: [PATCH] mm: mark async iocb read as NOWAIT once some data has been, copied Message-ID: <20201017162820.GI20115@casper.infradead.org> References: <59eae433-9b30-f094-534d-eb5cf0a40a80@kernel.dk> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <59eae433-9b30-f094-534d-eb5cf0a40a80@kernel.dk> X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Sat, Oct 17, 2020 at 09:30:59AM -0600, Jens Axboe wrote: > Once we've copied some data for an iocb that is marked with IOCB_WAITQ, > we should no longer attempt to async lock a new page. Instead make sure > we return the copied amount, and let the caller retry, instead of > returning -EIOCBQUEUED for a new page. > > This should only be possible with read-ahead disabled on the below > device, and multiple threads racing on the same file. Haven't been able > to reproduce on anything else. Wouldn't this do the job just as well? @@ -2211,6 +2211,8 @@ ssize_t generic_file_buffered_read(struct kiocb *iocb, put_page(page); written += ret; + if (iocb->ki_flags & IOCB_WAITQ) + iocb->ki_flags |= IOCB_NOWAIT; if (!iov_iter_count(iter)) goto out; if (ret < nr) {