Messages in this thread | | | Subject | Re: INFO: task hung in __get_super | From | Tetsuo Handa <> | Date | Wed, 15 May 2019 20:32:27 +0900 |
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On 2019/05/15 19:21, Jan Kara wrote: > The question is how to fix this problem. The simplest fix I can see is that > we'd just refuse to do LOOP_SET_FD if someone has the block device > exclusively open as there are high chances such user will be unpleasantly > surprised by the device changing under him. OTOH this has some potential > for userspace visible regressions. But I guess it's worth a try. Something > like attached patch?
(1) If I understand correctly, FMODE_EXCL is set at blkdev_open() only if O_EXCL is specified. How can we detect if O_EXCL was not used, for the reproducer ( https://syzkaller.appspot.com/text?tag=ReproC&x=135385a8a00000 ) is not using O_EXCL ?
(2) There seems to be no serialization. What guarantees that mount_bdev() does not start due to preempted after the check added by this patch?
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