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Sun, 13 Nov 2022 22:27:55 -0800 (PST) Received: from [10.3.156.122] ([63.216.146.190]) by smtp.gmail.com with ESMTPSA id 23-20020a621617000000b0056b6a22d6c9sm5781388pfw.212.2022.11.13.22.27.52 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Sun, 13 Nov 2022 22:27:55 -0800 (PST) Message-ID: <1bcb11ad-e2e0-6c0d-659e-1b20b6b99fb1@bytedance.com> Date: Mon, 14 Nov 2022 14:27:50 +0800 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.15; rv:102.0) Gecko/20100101 Thunderbird/102.4.1 Subject: Re: [Phishing Risk] [External] [PATCH] erofs: fix missing xas_retry() in fscache mode To: Jingbo Xu , xiang@kernel.org, chao@kernel.org, yinxin.x@bytedance.com, linux-erofs@lists.ozlabs.org Cc: dhowells@redhat.com, linux-kernel@vger.kernel.org References: <20221111090813.72068-1-jefflexu@linux.alibaba.com> From: Jia Zhu In-Reply-To: <20221111090813.72068-1-jefflexu@linux.alibaba.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 在 2022/11/11 17:08, Jingbo Xu 写道: > 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 Reviewed-by: Jia Zhu > --- > 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;