From patchwork Mon Mar 23 20:22:49 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Matthew Wilcox X-Patchwork-Id: 11454011 Return-Path: Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 6476015AB for ; Mon, 23 Mar 2020 20:27:37 +0000 (UTC) Received: from userp2130.oracle.com (userp2130.oracle.com [156.151.31.86]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 467A320714 for ; Mon, 23 Mar 2020 20:27:37 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 467A320714 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=infradead.org Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=ocfs2-devel-bounces@oss.oracle.com Received: from pps.filterd (userp2130.oracle.com [127.0.0.1]) by userp2130.oracle.com (8.16.0.42/8.16.0.42) with SMTP id 02NKJ5E7086079; Mon, 23 Mar 2020 20:27:23 GMT Received: from userp3030.oracle.com (userp3030.oracle.com [156.151.31.80]) by userp2130.oracle.com with ESMTP id 2ywabr0utq-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Mon, 23 Mar 2020 20:27:23 +0000 Received: from pps.filterd (userp3030.oracle.com [127.0.0.1]) by userp3030.oracle.com (8.16.0.42/8.16.0.42) with SMTP id 02NKJnds083842; Mon, 23 Mar 2020 20:27:23 GMT Received: from oss.oracle.com (oss-old-reserved.oracle.com [137.254.22.2]) by userp3030.oracle.com with ESMTP id 2yxw4mt4sk-1 (version=TLSv1 cipher=AES256-SHA bits=256 verify=NO); Mon, 23 Mar 2020 20:27:23 +0000 Received: from localhost ([127.0.0.1] helo=lb-oss.oracle.com) by oss.oracle.com with esmtp (Exim 4.63) (envelope-from ) id 1jGTcL-0000EJ-Ba; Mon, 23 Mar 2020 13:24:13 -0700 Received: from userp3020.oracle.com ([156.151.31.79]) by oss.oracle.com with esmtp (Exim 4.63) (envelope-from ) id 1jGTbX-0008QP-Ra for ocfs2-devel@oss.oracle.com; Mon, 23 Mar 2020 13:23:23 -0700 Received: from pps.filterd (userp3020.oracle.com [127.0.0.1]) by userp3020.oracle.com (8.16.0.42/8.16.0.42) with SMTP id 02NKJfSZ020375 for ; Mon, 23 Mar 2020 20:23:23 GMT Received: from userp2030.oracle.com (userp2030.oracle.com [156.151.31.89]) by userp3020.oracle.com with ESMTP id 2yxw6k7ybw-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK) for ; Mon, 23 Mar 2020 20:23:23 +0000 Received: from pps.filterd (userp2030.oracle.com [127.0.0.1]) by userp2030.oracle.com (8.16.0.42/8.16.0.42) with SMTP id 02NKNJE2048478 for ; Mon, 23 Mar 2020 20:23:22 GMT Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) by userp2030.oracle.com with ESMTP id 2yw8yftb7c-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NO) for ; Mon, 23 Mar 2020 20:23:22 +0000 Received: from willy by bombadil.infradead.org with local (Exim 4.92.3 #3 (Red Hat Linux)) id 1jGTbB-0003VP-SE; Mon, 23 Mar 2020 20:23:01 +0000 From: Matthew Wilcox To: Andrew Morton Date: Mon, 23 Mar 2020 13:22:49 -0700 Message-Id: <20200323202259.13363-16-willy@infradead.org> X-Mailer: git-send-email 2.21.1 In-Reply-To: <20200323202259.13363-1-willy@infradead.org> References: <20200323202259.13363-1-willy@infradead.org> MIME-Version: 1.0 X-PDR: PASS X-Source-IP: 198.137.202.133 X-ServerName: bombadil.infradead.org X-Proofpoint-SPF-Result: None X-Proofpoint-Virus-Version: vendor=nai engine=6000 definitions=9569 signatures=668685 X-Proofpoint-Spam-Details: rule=tap_spam_policies_notspam policy=tap_spam_policies score=0 malwarescore=0 spamscore=0 lowpriorityscore=0 mlxlogscore=795 priorityscore=0 phishscore=0 impostorscore=0 mlxscore=0 adultscore=0 suspectscore=0 bulkscore=0 clxscore=297 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2003020000 definitions=main-2003230102 X-Spam: Clean X-Proofpoint-Spam-Details: rule=notspam policy=default score=0 suspectscore=0 adultscore=0 malwarescore=0 mlxscore=0 spamscore=0 mlxlogscore=921 bulkscore=0 phishscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2003020000 definitions=main-2003230101 Cc: linux-xfs@vger.kernel.org, Michal Hocko , William Kucharski , linux-kernel@vger.kernel.org, linux-f2fs-devel@lists.sourceforge.net, cluster-devel@redhat.com, linux-mm@kvack.org, ocfs2-devel@oss.oracle.com, linux-fsdevel@vger.kernel.org, Cong Wang , linux-ext4@vger.kernel.org, linux-erofs@lists.ozlabs.org, linux-btrfs@vger.kernel.org Subject: [Ocfs2-devel] [PATCH v10 15/25] mm: Use memalloc_nofs_save in readahead path X-BeenThere: ocfs2-devel@oss.oracle.com X-Mailman-Version: 2.1.9 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: ocfs2-devel-bounces@oss.oracle.com Errors-To: ocfs2-devel-bounces@oss.oracle.com X-Proofpoint-Virus-Version: vendor=nai engine=6000 definitions=9569 signatures=668685 X-Proofpoint-Spam-Details: rule=notspam policy=default score=0 malwarescore=0 suspectscore=0 spamscore=0 mlxlogscore=999 adultscore=0 phishscore=0 mlxscore=0 bulkscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2003020000 definitions=main-2003230101 X-Proofpoint-Virus-Version: vendor=nai engine=6000 definitions=9569 signatures=668685 X-Proofpoint-Spam-Details: rule=notspam policy=default score=0 spamscore=0 suspectscore=0 lowpriorityscore=0 malwarescore=0 phishscore=0 priorityscore=1501 clxscore=1034 adultscore=0 mlxscore=0 mlxlogscore=999 bulkscore=0 impostorscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2003020000 definitions=main-2003230101 From: "Matthew Wilcox (Oracle)" Ensure that memory allocations in the readahead path do not attempt to reclaim file-backed pages, which could lead to a deadlock. It is possible, though unlikely this is the root cause of a problem observed by Cong Wang. Signed-off-by: Matthew Wilcox (Oracle) Reported-by: Cong Wang Suggested-by: Michal Hocko Reviewed-by: William Kucharski --- mm/readahead.c | 14 ++++++++++++++ 1 file changed, 14 insertions(+) diff --git a/mm/readahead.c b/mm/readahead.c index 73cb59ed5cff..3c9a8dd7c56c 100644 --- a/mm/readahead.c +++ b/mm/readahead.c @@ -22,6 +22,7 @@ #include #include #include +#include #include "internal.h" @@ -185,6 +186,18 @@ void page_cache_readahead_unbounded(struct address_space *mapping, }; unsigned long i; + /* + * Partway through the readahead operation, we will have added + * locked pages to the page cache, but will not yet have submitted + * them for I/O. Adding another page may need to allocate memory, + * which can trigger memory reclaim. Telling the VM we're in + * the middle of a filesystem operation will cause it to not + * touch file-backed pages, preventing a deadlock. Most (all?) + * filesystems already specify __GFP_NOFS in their mapping's + * gfp_mask, but let's be explicit here. + */ + unsigned int nofs = memalloc_nofs_save(); + /* * Preallocate as many pages as we will need. */ @@ -229,6 +242,7 @@ void page_cache_readahead_unbounded(struct address_space *mapping, * will then handle the error. */ read_pages(&rac, &page_pool, false); + memalloc_nofs_restore(nofs); } EXPORT_SYMBOL_GPL(page_cache_readahead_unbounded);