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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 431EDC433FE for ; Mon, 23 May 2022 17:39:16 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S240885AbiEWRjD (ORCPT ); Mon, 23 May 2022 13:39:03 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:43388 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S240617AbiEWRZu (ORCPT ); Mon, 23 May 2022 13:25:50 -0400 Received: from ams.source.kernel.org (ams.source.kernel.org [145.40.68.75]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 2CB3522BD7; Mon, 23 May 2022 10:21:05 -0700 (PDT) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by ams.source.kernel.org (Postfix) with ESMTPS id B09A0B8121A; Mon, 23 May 2022 17:19:13 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id ED80BC385A9; Mon, 23 May 2022 17:19:11 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1653326352; bh=7ORnn3JFvU6w8aQU8L+UaweZmp4SFBZtU6G2YBLCw2A=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=nbTKDHBzxp0MYZSKJP4LJyzCEvvyrvOIQWmufEilzsT+uJosf4pf1/S01vUJiZ4Gq QoXGxz9YK59Sb9Al9c1hOR9KLyKQqbGL0ZJ6gpSwL4NG2k+YUszsZYbkbL+bsaH0ay fY0ikSQogY+uKXFfs7r6sQQ2JRh5Ikb4rq02scJc= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Andreas Gruenbacher , Sasha Levin Subject: [PATCH 5.15 025/132] gfs2: Disable page faults during lockless buffered reads Date: Mon, 23 May 2022 19:03:54 +0200 Message-Id: <20220523165827.674753669@linuxfoundation.org> X-Mailer: git-send-email 2.36.1 In-Reply-To: <20220523165823.492309987@linuxfoundation.org> References: <20220523165823.492309987@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Andreas Gruenbacher [ Upstream commit 52f3f033a5dbd023307520af1ff551cadfd7f037 ] During lockless buffered reads, filemap_read() holds page cache page references while trying to copy data to the user-space buffer. The calling process isn't holding the inode glock, but the page references it holds prevent those pages from being removed from the page cache, and that prevents the underlying inode glock from being moved to another node. Thus, we can end up in the same kinds of distributed deadlock situations as with normal (non-lockless) buffered reads. Fix that by disabling page faults during lockless reads as well. Signed-off-by: Andreas Gruenbacher Signed-off-by: Sasha Levin --- fs/gfs2/file.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) diff --git a/fs/gfs2/file.c b/fs/gfs2/file.c index eb5ea0262f3c..60390f9dc31f 100644 --- a/fs/gfs2/file.c +++ b/fs/gfs2/file.c @@ -963,14 +963,16 @@ static ssize_t gfs2_file_read_iter(struct kiocb *iocb, struct iov_iter *to) return ret; iocb->ki_flags &= ~IOCB_DIRECT; } + pagefault_disable(); iocb->ki_flags |= IOCB_NOIO; ret = generic_file_read_iter(iocb, to); iocb->ki_flags &= ~IOCB_NOIO; + pagefault_enable(); if (ret >= 0) { if (!iov_iter_count(to)) return ret; written = ret; - } else { + } else if (ret != -EFAULT) { if (ret != -EAGAIN) return ret; if (iocb->ki_flags & IOCB_NOWAIT) -- 2.35.1