Messages in this thread | | | Subject | Re: [f2fs-dev] [f2fs bug] infinite loop in f2fs_get_meta_page_nofail() | From | Chao Yu <> | Date | Tue, 13 Oct 2020 10:30:36 +0800 |
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Jaegeuk,
I guess you missed sending last applied patch to mailing list?
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 <jaegeuk@kernel.org> >>>>>>>>> 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 >>>>>>> . >>>>>>> >>>>> . >>>>> >>> . >>> > . >
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