From patchwork Sat Oct 31 11:36:52 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Greg KH X-Patchwork-Id: 317383 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=-9.8 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED, DKIM_VALID, HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI, SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_GIT 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 85120C388F7 for ; Sat, 31 Oct 2020 11:47:09 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 3F76B20691 for ; Sat, 31 Oct 2020 11:47:09 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1604144829; bh=yBSRb5Pm6ij4DhhXk5+q8ZjX0tNxxnvypfUKoPIA8bE=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=THJLgJDSefyabBiMFRWPfV0CISgpLge/X3Wrg/CduSL74nlOUF9XlbfFaCCTTDoGI 7Z8xOh1ZOodQGpAGRAW8bGCQXOoAHM4JcovNS2mvGhY0yUyefwjLSCo9apXMEfrxEM rSWeTsXD8YGKLuquju+GXOMjvsI0VINXsTOGkO+c= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728322AbgJaLp6 (ORCPT ); Sat, 31 Oct 2020 07:45:58 -0400 Received: from mail.kernel.org ([198.145.29.99]:47156 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728310AbgJaLp5 (ORCPT ); Sat, 31 Oct 2020 07:45:57 -0400 Received: from localhost (83-86-74-64.cable.dynamic.v4.ziggo.nl [83.86.74.64]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 5122520731; Sat, 31 Oct 2020 11:45:56 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1604144756; bh=yBSRb5Pm6ij4DhhXk5+q8ZjX0tNxxnvypfUKoPIA8bE=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=JwPIlW8fIf7fiMX57c1ITp6D/lrHxvbpuyAv6zsHZmsl76rwdfIgYe/1p7kVrwIWt jm0f/SS0hEw+1rVLkoHsHAIl7KhO05fzC6NUXvIiC41B/MT5x5IY3J13IYiTEJF0g+ 74cjSnPIyCKR8NbDwoX+LLOBf/hYumfOqOC+X+BM= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Kent Overstreet , Jens Axboe Subject: [PATCH 5.9 70/74] mm: mark async iocb read as NOWAIT once some data has been copied Date: Sat, 31 Oct 2020 12:36:52 +0100 Message-Id: <20201031113503.388678549@linuxfoundation.org> X-Mailer: git-send-email 2.29.2 In-Reply-To: <20201031113500.031279088@linuxfoundation.org> References: <20201031113500.031279088@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org From: Jens Axboe commit 13bd691421bc191a402d2e0d3da5f248d170a632 upstream. 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. Cc: stable@vger.kernel.org # v5.9 Fixes: 1a0a7853b901 ("mm: support async buffered reads in generic_file_buffered_read()") Reported-by: Kent Overstreet Signed-off-by: Jens Axboe Signed-off-by: Greg Kroah-Hartman --- mm/filemap.c | 8 ++++++++ 1 file changed, 8 insertions(+) --- a/mm/filemap.c +++ b/mm/filemap.c @@ -2179,6 +2179,14 @@ ssize_t generic_file_buffered_read(struc last_index = (*ppos + iter->count + PAGE_SIZE-1) >> PAGE_SHIFT; offset = *ppos & ~PAGE_MASK; + /* + * If we've already successfully copied some data, then we + * can no longer safely return -EIOCBQUEUED. Hence mark + * an async read NOWAIT at that point. + */ + if (written && (iocb->ki_flags & IOCB_WAITQ)) + iocb->ki_flags |= IOCB_NOWAIT; + for (;;) { struct page *page; pgoff_t end_index;