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=-3.8 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED 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 76142C43331 for ; Thu, 2 Apr 2020 04:04:43 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 37EA720747 for ; Thu, 2 Apr 2020 04:04:43 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=kernel.org header.i=@kernel.org header.b="kXQ+z7PY" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 37EA720747 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=linux-foundation.org Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id C57998E001D; Thu, 2 Apr 2020 00:04:42 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id C085A8E000D; Thu, 2 Apr 2020 00:04:42 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id B21218E001D; Thu, 2 Apr 2020 00:04:42 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0152.hostedemail.com [216.40.44.152]) by kanga.kvack.org (Postfix) with ESMTP id 935A88E000D for ; Thu, 2 Apr 2020 00:04:42 -0400 (EDT) Received: from smtpin08.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay03.hostedemail.com (Postfix) with ESMTP id 555B68248047 for ; Thu, 2 Apr 2020 04:04:42 +0000 (UTC) X-FDA: 76661573604.08.stick84_290af71630a63 X-HE-Tag: stick84_290af71630a63 X-Filterd-Recvd-Size: 2808 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by imf09.hostedemail.com (Postfix) with ESMTP for ; Thu, 2 Apr 2020 04:04:41 +0000 (UTC) Received: from localhost.localdomain (c-73-231-172-41.hsd1.ca.comcast.net [73.231.172.41]) (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 0A554206E9; Thu, 2 Apr 2020 04:04:41 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1585800281; bh=0dA1BKhiGeC/IRzc3HTKBJHqi5tNb0J/H/+Qgqi1CRE=; h=Date:From:To:Subject:In-Reply-To:From; b=kXQ+z7PYLBJYHaXGY+1xRn+wvAYG7BHXpNHGKZv4i2vKM8JAAiCy3l3e4udKrUdRi tmkme4U9626T4Rp0VdhRg/74yQ+lT7/Tmef28EcbDEhUtoc0sevg5y2b9qzN7+SIVk SMRqzrDPpMqushs3rJjUnXF84ePkeJ8ot+azb6LY= Date: Wed, 01 Apr 2020 21:04:40 -0700 From: Andrew Morton To: akpm@linux-foundation.org, jack@suse.cz, josef@toxicpanda.com, linux-mm@kvack.org, minchan@kernel.org, mm-commits@vger.kernel.org, snazy@gmx.de, torvalds@linux-foundation.org Subject: [patch 029/155] mm/filemap.c: don't bother dropping mmap_sem for zero size readahead Message-ID: <20200402040440.RCDEWJbKc%akpm@linux-foundation.org> In-Reply-To: <20200401210155.09e3b9742e1c6e732f5a7250@linux-foundation.org> User-Agent: s-nail v14.8.16 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: From: Jan Kara Subject: mm/filemap.c: don't bother dropping mmap_sem for zero size readahead 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. Link: http://lkml.kernel.org/r/20200212101356.30759-1-jack@suse.cz Fixes: 6b4c9f446981 ("filemap: drop the mmap_sem for all blocking operations") Signed-off-by: Jan Kara Reported-by: Minchan Kim Reported-by: Robert Stupp Reviewed-by: Josef Bacik Reviewed-by: Minchan Kim Signed-off-by: Andrew Morton --- mm/filemap.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) --- a/mm/filemap.c~mm-dont-bother-dropping-mmap_sem-for-zero-size-readahead +++ a/mm/filemap.c @@ -2416,7 +2416,7 @@ 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--; _