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 A35D3C4332F for ; Fri, 11 Nov 2022 09:08:21 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233540AbiKKJIU (ORCPT ); Fri, 11 Nov 2022 04:08:20 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:57164 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233033AbiKKJIT (ORCPT ); Fri, 11 Nov 2022 04:08:19 -0500 Received: from out30-54.freemail.mail.aliyun.com (out30-54.freemail.mail.aliyun.com [115.124.30.54]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id EC8502AEC for ; Fri, 11 Nov 2022 01:08:17 -0800 (PST) X-Alimail-AntiSpam: AC=PASS;BC=-1|-1;BR=01201311R301e4;CH=green;DM=||false|;DS=||;FP=0|-1|-1|-1|0|-1|-1|-1;HT=ay29a033018046051;MF=jefflexu@linux.alibaba.com;NM=1;PH=DS;RN=6;SR=0;TI=SMTPD_---0VUWtHXK_1668157693; Received: from localhost(mailfrom:jefflexu@linux.alibaba.com fp:SMTPD_---0VUWtHXK_1668157693) by smtp.aliyun-inc.com; Fri, 11 Nov 2022 17:08:14 +0800 From: Jingbo Xu To: xiang@kernel.org, chao@kernel.org, yinxin.x@bytedance.com, linux-erofs@lists.ozlabs.org Cc: linux-kernel@vger.kernel.org, dhowells@redhat.com Subject: [PATCH] erofs: fix missing xas_retry() in fscache mode Date: Fri, 11 Nov 2022 17:08:13 +0800 Message-Id: <20221111090813.72068-1-jefflexu@linux.alibaba.com> X-Mailer: git-send-email 2.19.1.6.gb485710b MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org The xarray iteration only holds RCU and thus may encounter XA_RETRY_ENTRY if there's process modifying the xarray concurrently. This will cause oops when referring to the invalid entry. Fix this by adding the missing xas_retry(), which will make the iteration wind back to the root node if XA_RETRY_ENTRY is encountered. Fixes: d435d53228dd ("erofs: change to use asynchronous io for fscache readpage/readahead") Signed-off-by: Jingbo Xu --- fs/erofs/fscache.c | 10 +++++++--- 1 file changed, 7 insertions(+), 3 deletions(-) diff --git a/fs/erofs/fscache.c b/fs/erofs/fscache.c index fe05bc51f9f2..458c1c70ef30 100644 --- a/fs/erofs/fscache.c +++ b/fs/erofs/fscache.c @@ -75,11 +75,15 @@ static void erofs_fscache_rreq_unlock_folios(struct netfs_io_request *rreq) rcu_read_lock(); xas_for_each(&xas, folio, last_page) { - unsigned int pgpos = - (folio_index(folio) - start_page) * PAGE_SIZE; - unsigned int pgend = pgpos + folio_size(folio); + unsigned int pgpos, pgend; bool pg_failed = false; + if (xas_retry(&xas, folio)) + continue; + + pgpos = (folio_index(folio) - start_page) * PAGE_SIZE; + pgend = pgpos + folio_size(folio); + for (;;) { if (!subreq) { pg_failed = true; -- 2.19.1.6.gb485710b