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=-10.0 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=ham 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 363B7C433DF for ; Mon, 3 Aug 2020 12:45:19 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 04B8C206D4 for ; Mon, 3 Aug 2020 12:45:19 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1596458719; bh=5zeqietPhyhUpjpUe2K3zAjtmebUM/EY9MObnePZxdw=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=gW+RM1hLLGNrwzVHD2B7hH2DYHvph/1xM7+jyCnqvf0MrknE4xPkQs9XV1c3fr1kU bShxfdYKQnoJI89R/BTtDy8Uy1pf3wPKOR/6DjErXBykjTW0ljoU0MmzyDdQvTCoka fuvSMwVBOSghn1CIGc1nHXOFOzwK/XMlRxdttVag= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729262AbgHCMpR (ORCPT ); Mon, 3 Aug 2020 08:45:17 -0400 Received: from mail.kernel.org ([198.145.29.99]:53596 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726725AbgHCM1n (ORCPT ); Mon, 3 Aug 2020 08:27:43 -0400 Received: from localhost (83-86-89-107.cable.dynamic.v4.ziggo.nl [83.86.89.107]) (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 0DC98207FC; Mon, 3 Aug 2020 12:27:41 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1596457662; bh=5zeqietPhyhUpjpUe2K3zAjtmebUM/EY9MObnePZxdw=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=tC7suW3kc6NUDhSfWM2FfA2nTwpRT8xLHzDJf2s+Yxo6+HqcMffnLv2a4/HovODWF 4r1dug6vaRex083LFvRJBH3yHmfQd7XOlNwFfy/kFsyYIdPod4J18L8+y4+L6GdPAr Q92RHI/+hSvRRk9l5/VOY/rLagSvZH7uqnBkfq/g= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Minchan Kim , Robert Stupp , Jan Kara , Andrew Morton , Josef Bacik , Linus Torvalds , SeongJae Park Subject: [PATCH 5.4 06/90] mm/filemap.c: dont bother dropping mmap_sem for zero size readahead Date: Mon, 3 Aug 2020 14:18:28 +0200 Message-Id: <20200803121857.853351983@linuxfoundation.org> X-Mailer: git-send-email 2.28.0 In-Reply-To: <20200803121857.546052424@linuxfoundation.org> References: <20200803121857.546052424@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Jan Kara commit 5c72feee3e45b40a3c96c7145ec422899d0e8964 upstream. When handling a page fault, we drop mmap_sem to start async readahead so that we don't block on IO submission with mmap_sem held. However there's no point to drop mmap_sem in case readahead is disabled. Handle that case to avoid pointless dropping of mmap_sem and retrying the fault. This was actually reported to block mlockall(MCL_CURRENT) indefinitely. Fixes: 6b4c9f446981 ("filemap: drop the mmap_sem for all blocking operations") Reported-by: Minchan Kim Reported-by: Robert Stupp Signed-off-by: Jan Kara Signed-off-by: Andrew Morton Reviewed-by: Josef Bacik Reviewed-by: Minchan Kim Link: http://lkml.kernel.org/r/20200212101356.30759-1-jack@suse.cz Signed-off-by: Linus Torvalds Cc: SeongJae Park Signed-off-by: Greg Kroah-Hartman --- mm/filemap.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) --- a/mm/filemap.c +++ b/mm/filemap.c @@ -2438,7 +2438,7 @@ static struct file *do_async_mmap_readah pgoff_t offset = vmf->pgoff; /* If we don't want any read-ahead, don't bother */ - if (vmf->vma->vm_flags & VM_RAND_READ) + if (vmf->vma->vm_flags & VM_RAND_READ || !ra->ra_pages) return fpin; if (ra->mmap_miss > 0) ra->mmap_miss--;