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=-9.8 required=3.0 tests=DKIM_INVALID,DKIM_SIGNED, 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 F32DAC352A4 for ; Wed, 12 Feb 2020 22:16:24 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 8FD132082F for ; Wed, 12 Feb 2020 22:16:24 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="m2+iclFG" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 8FD132082F Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=kernel.org Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id E3B2D6B049A; Wed, 12 Feb 2020 17:16:23 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id DEBC56B049B; Wed, 12 Feb 2020 17:16:23 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id D01946B049C; Wed, 12 Feb 2020 17:16:23 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0091.hostedemail.com [216.40.44.91]) by kanga.kvack.org (Postfix) with ESMTP id B69376B049A for ; Wed, 12 Feb 2020 17:16:23 -0500 (EST) Received: from smtpin20.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay05.hostedemail.com (Postfix) with ESMTP id 55F6E181AC9CC for ; Wed, 12 Feb 2020 22:16:23 +0000 (UTC) X-FDA: 76482884646.20.grade58_71f052435e926 X-HE-Tag: grade58_71f052435e926 X-Filterd-Recvd-Size: 4382 Received: from mail-pf1-f195.google.com (mail-pf1-f195.google.com [209.85.210.195]) by imf14.hostedemail.com (Postfix) with ESMTP for ; Wed, 12 Feb 2020 22:16:22 +0000 (UTC) Received: by mail-pf1-f195.google.com with SMTP id i6so1934619pfc.1 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=UCJQaMGeD55Pcr6OFoFwW6JiMq91leTnf5nSUvZMu6L/rQszwStrsCQIgnAxac+DvE HldvRzqm9307yaz0R/2EA2fqr5gHl11xW6kWZbvLSmyWgEzT5fJ++vi9gYyuMBTQGOlB 2FbgnGZ2otWkS+mVypQgxRPi+0e47/EJPlGsREqwDNBevg4zfCzf7uz+jC2wf/6dx11x PBR9BuswFw/OLWblTeiRU6P5sVyHDLuCzjxjn3Dtax51yXjZRkY6n1k2qs0lNZa1hCRQ XtxTYA7w6RXkBptbiCItDTH1KIHXzg7Xkmu+0JHZYbnnr4kdkwHGSONfw/4gOJpjWhq4 qe1w== X-Gm-Message-State: APjAAAXhPPmRXPpKm+uHfkxrMIRs02KuKsd2jkrkE8KV/VAyG0+6hUAv AudBDr64kQL/LSzmxZnFN8s= 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: quoted-printable 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 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 operati= ons") 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 =3D vmf->pgoff; =20 /* 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--; --=20 2.25.0.225.g125e21ebc7-goog