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Tue, 13 Oct 2020 03:09:13 +0000 Received: from localhost (unknown [104.132.1.66]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 4859020797; Tue, 13 Oct 2020 03:08:46 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1602558526; bh=AJHpKMUJIcw11Gyz1KpytJxDA6dnO7UshnzQjlHsm/M=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=y0LmppGGwxqV3x7CInRGNW3xlTfPR9OZEQcWkKmoTH6PZYTZjHGmf/uefQ93XxMwE dK6fPi99zf1pqhnRd6esaK2yAkfu8YVppx+JNKImx6W3JDIMuMqzxRxbAf+CzgxwVe qMbwrTpWgGLNw193WY27hv1YU/Ejyzd4DE3r2IqA= Date: Mon, 12 Oct 2020 20:08:45 -0700 From: jaegeuk@kernel.org To: Chao Yu Message-ID: <20201013030845.GA3373865@google.com> References: <000000000000432c5405b1113296@google.com> <20201007213253.GD1530638@gmail.com> <20201007215305.GA714500@google.com> <20201009015015.GA1931838@google.com> <8fa4f9fe-5ca5-f3a3-c8f4-e800373c1e46@huawei.com> <20201009043237.GB1973455@google.com> <20201009145626.GA2186792@google.com> <70faa161-bcd7-64a3-4a6c-04963c0784b6@huawei.com> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <70faa161-bcd7-64a3-4a6c-04963c0784b6@huawei.com> X-Headers-End: 1kSAgM-00Cx08-QS Subject: Re: [f2fs-dev] [f2fs bug] infinite loop in f2fs_get_meta_page_nofail() X-BeenThere: linux-f2fs-devel@lists.sourceforge.net X-Mailman-Version: 2.1.21 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Eric Biggers , syzbot+ee250ac8137be41d7b13@syzkaller.appspotmail.com, syzkaller-bugs@googlegroups.com, linux-kernel@vger.kernel.org, linux-f2fs-devel@lists.sourceforge.net Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Errors-To: linux-f2fs-devel-bounces@lists.sourceforge.net On 10/13, Chao Yu wrote: > Jaegeuk, > > I guess you missed sending last applied patch to mailing list? I was testing locally and supposed to post it soon before pull request. Putting it in -dev can give some soak time in -next. No worries. Thanks, > > Thanks, > > On 2020/10/9 22:56, jaegeuk@kernel.org wrote: > > On 10/09, Chao Yu wrote: > > > On 2020/10/9 12:32, jaegeuk@kernel.org wrote: > > > > On 10/09, Chao Yu wrote: > > > > > On 2020/10/9 9:50, jaegeuk@kernel.org wrote: > > > > > > On 10/09, Chao Yu wrote: > > > > > > > On 2020/10/8 5:53, jaegeuk@kernel.org wrote: > > > > > > > > On 10/07, Eric Biggers wrote: > > > > > > > > > [moved linux-fsdevel to Bcc] > > > > > > > > > > > > > > > > > > On Wed, Oct 07, 2020 at 02:18:19AM -0700, syzbot wrote: > > > > > > > > > > Hello, > > > > > > > > > > > > > > > > > > > > syzbot found the following issue on: > > > > > > > > > > > > > > > > > > > > HEAD commit: a804ab08 Add linux-next specific files for 20201006 > > > > > > > > > > git tree: linux-next > > > > > > > > > > console output: https://syzkaller.appspot.com/x/log.txt?x=17fe30bf900000 > > > > > > > > > > kernel config: https://syzkaller.appspot.com/x/.config?x=26c1b4cc4a62ccb > > > > > > > > > > dashboard link: https://syzkaller.appspot.com/bug?extid=ee250ac8137be41d7b13 > > > > > > > > > > compiler: gcc (GCC) 10.1.0-syz 20200507 > > > > > > > > > > syz repro: https://syzkaller.appspot.com/x/repro.syz?x=1336413b900000 > > > > > > > > > > C reproducer: https://syzkaller.appspot.com/x/repro.c?x=12f7392b900000 > > > > > > > > > > > > > > > > > > > > The issue was bisected to: > > > > > > > > > > > > > > > > > > > > commit eede846af512572b1f30b34f9889d7df64c017d4 > > > > > > > > > > Author: Jaegeuk Kim > > > > > > > > > > Date: Fri Oct 2 21:17:35 2020 +0000 > > > > > > > > > > > > > > > > > > > > f2fs: f2fs_get_meta_page_nofail should not be failed > > > > > > > > > > > > > > > > > > > > > > > > > > > > Jaegeuk, it looks like the loop you added in the above commit doesn't terminate > > > > > > > > > if the requested page is beyond the end of the device. > > > > > > > > > > > > > > > > Yes, that will go infinite loop. Otherwise, it will trigger a panic during > > > > > > > > the device reboot. Let me think how to avoid that before trying to get the > > > > > > > > wrong lba access. > > > > > > > > > > > > > > Delivering f2fs_get_sum_page()'s return value needs a lot of codes change, I think > > > > > > > we can just zeroing sum_page in error case, as we have already shutdown f2fs via > > > > > > > calling f2fs_stop_checkpoint(), then f2fs_cp_error() will stop all updates to > > > > > > > filesystem data including summary pages. > > > > > > > > > > > > That sounds like one solution tho, I'm afraid of getting another panic by > > > > > > wrong zero'ed summary page. > > > > > > > > > > What case do you mean? maybe I missed some corner cases? > > > > > > > > I sent v2 to fix syzbot issue, which fixes wrong use of > > > > f2fs_get_meta_page_nofail. > > > > > > I agreed to fix that case, however we may encounter deadloop in other > > > places where we call f2fs_get_meta_page_nofail()? like the case that > > > filesystem will always see EIO after we shutdown device via dmflakey? > > > > We may need another option to deal with this. At least, however, it's literally > > _nofail function which should guarantee no error, instead of hiding the error > > with zero'ed page. > > > > > > > > Thanks, > > > > > > > > > > > > > > > > > Thanks, > > > > > > > > > > > > > > > > > > > > > > > > > Thoughts? > > > > > > > > > > > > > > Thanks, > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > - Eric > > > > > > > > > > > > > > > > > > > > > > > > _______________________________________________ > > > > > > > > Linux-f2fs-devel mailing list > > > > > > > > Linux-f2fs-devel@lists.sourceforge.net > > > > > > > > https://lists.sourceforge.net/lists/listinfo/linux-f2fs-devel > > > > > > > > . > > > > > > > > > > > > > > . > > > > > > > > > > . > > > > > > . > > _______________________________________________ Linux-f2fs-devel mailing list Linux-f2fs-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/linux-f2fs-devel