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=-10.1 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,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 46935C3B187 for ; Wed, 12 Feb 2020 22:16:25 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 1B3FB2082F for ; Wed, 12 Feb 2020 22:16:25 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1581545785; bh=nh/fCuQsemp1ev5seT2rEzpA0w2JnCg+BtPxs4P4pjE=; h=From:To:Cc:Subject:Date:List-ID:From; b=ZskFyi61mKOR6LU4PqbxC/GMIOO2gyKpBxIZTJ8DxrqJG4ZJlNgVq4MSi8OVOHot9 bzngXnK9WU3+VFyl8cdnkiw00dClOnM+9VemLIAFRDzyvKpg1m0Wybq20UWVbnWh8S VO1XLHEHFMRIDr4u/rMrpjwShJFWLc8CAM7lnWxc= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729171AbgBLWQY (ORCPT ); Wed, 12 Feb 2020 17:16:24 -0500 Received: from mail-pg1-f195.google.com ([209.85.215.195]:36145 "EHLO mail-pg1-f195.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727692AbgBLWQX (ORCPT ); Wed, 12 Feb 2020 17:16:23 -0500 Received: by mail-pg1-f195.google.com with SMTP id d9so1944193pgu.3 for ; Wed, 12 Feb 2020 14:16:22 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=sender:from:to:cc:subject:date:message-id:mime-version :content-transfer-encoding; bh=IRbfdGWqcwmnNp2DnvQOXpGpDdlJdzZpC1N7ZpXf7R4=; b=m2+iclFGS8CzBhvrLeUiObRXq+BHsUSMMB7Vj20hZbpVGnjh/++VyGUTYt2woRJvbz L/tFb9D7IjjcHYxbU1p16n0jDAd49fMG5fydr961+y1BEXCfEkYgb+tn1HlwvBfA7Bk6 I9/cVK87OWQEVxTu8l4ZyYDMQ3fRJlGRnfAe3+Uf2t0Ncu/tzwbO7i0xk8enb/Cjcv1w YZOPvQVFwN9Joc3PLsZNieDH1S0lhbebYGRgZGijwZTApsCTAiSfFZDmWBpfV/IwAcQj AFrnPWicOYux0+P25+pC2SJAJIkuHnqMOCaXq8aQ1oa0O+S29vcTAOFJYlxuEeemPoyc /RsA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:sender:from:to:cc:subject:date:message-id :mime-version:content-transfer-encoding; bh=IRbfdGWqcwmnNp2DnvQOXpGpDdlJdzZpC1N7ZpXf7R4=; b=fJpAjIRLRLzjyB5TN3IlKUPaDSKAqDb20rbW1gQnTn6thq7Kb2VkyJpBt7hDKxaREv aSRyUzXnhWd6gZh9R+rVmxdrTCLi+lbrCh0C4GZbbxEAb5Xh6ToiZfwlA0X3OYqmUkrO DdjgkHUatx1vRszskpJE7amDS4ICzEILvl7DKLlJppuOHu25+bEOo6ka5PNAG3FDKkx4 vyxmzs+87rteOoo2pBy9OZZFZPOCFmqlR9SkK6/3HX8r7sqDO2Cvz1jqLcMKQt9kfU53 mvbJuudKEH65bQ7uz3BSjU1ScXtquIIeY5UZThaEs1JPZptzob42HBjexRfT3NDdGDpj o1qQ== X-Gm-Message-State: APjAAAVSS9pbTkLN4wsC/tRcYyLwBbCqo+YVcRzgiIWPMxKHiaVXrbiw YMgHXCTavgc/pTPujw2lm+Kn6uxi X-Google-Smtp-Source: APXvYqzIIedGxf8nZB9JoeCmITqMhnSUr9gnQJ8hlq9gR2gywKw1M3NDG//Z/TKJd6Spy2jGjOp+xw== X-Received: by 2002:aa7:9808:: with SMTP id e8mr14135402pfl.32.1581545781691; Wed, 12 Feb 2020 14:16:21 -0800 (PST) Received: from bbox-1.mtv.corp.google.com ([2620:15c:211:1:3e01:2939:5992:52da]) by smtp.gmail.com with ESMTPSA id o10sm117683pgq.68.2020.02.12.14.16.19 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 12 Feb 2020 14:16:20 -0800 (PST) From: Minchan Kim To: Andrew Morton Cc: linux-mm , LKML , Jan Kara , Matthew Wilcox , Josef Bacik , Johannes Weiner , Minchan Kim , Robert Stupp Subject: [PATCH 1/3] mm: Don't bother dropping mmap_sem for zero size readahead Date: Wed, 12 Feb 2020 14:16:12 -0800 Message-Id: <20200212221614.215302-1-minchan@kernel.org> X-Mailer: git-send-email 2.25.0.225.g125e21ebc7-goog MIME-Version: 1.0 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 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 Reviewed-by: Minchan Kim Reviewed-by: Josef Bacik Signed-off-by: Jan Kara Signed-off-by: Minchan Kim --- mm/filemap.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/mm/filemap.c b/mm/filemap.c index 1784478270e1..5bffaa2176cd 100644 --- a/mm/filemap.c +++ b/mm/filemap.c @@ -2416,7 +2416,7 @@ static struct file *do_async_mmap_readahead(struct vm_fault *vmf, 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--; -- 2.25.0.225.g125e21ebc7-goog