On Wed, May 2, 2018 at 1:23 PM, Dmitry Vyukov <dvyu...@google.com> wrote: > On Wed, May 2, 2018 at 12:30 PM, Tetsuo Handa > <penguin-ker...@i-love.sakura.ne.jp> wrote: >> Dmitry Vyukov wrote: >>> > syzbot is reporting various bugs which involve /dev/loopX. >>> > Two of them >>> > >>> > INFO: rcu detected stall in lo_ioctl >>> > >>> > https://syzkaller.appspot.com/bug?id=7b49fb610af9cca78c24e9f796f2e8b0d5573997 >>> > >>> > general protection fault in lo_ioctl (2) >>> > >>> > https://syzkaller.appspot.com/bug?id=f3cfe26e785d85f9ee259f385515291d21bd80a3 >>> >>> /\/\/\/\/\/\/\/\/\/\/\/\/\/\/\ >>> >>> Now there is a repro for this one. I've pushed it to kernel mailing lists: >>> >>> https://groups.google.com/d/msg/syzkaller-bugs/c8KUcTAzTvA/3o_7g6-tAwAJ >> >> OK, thanks. But among loop related reports, this will be a dup of >> "INFO: rcu detected stall in blkdev_ioctl" which already has C reproducer. >> Should we merge them? > > Yes, sure, I will take care of it.
1. I forgot to take care of it. 2. "INFO: rcu detected stall in blkdev_ioctl" was fixed 3 months ago: https://syzkaller.appspot.com/bug?id=1f7b710f4110f225aed1f4263ec2b98b8dbd472e but this bug still happens up until now: https://syzkaller.appspot.com/bug?id=bf154052f0eea4bc7712499e4569505907d15889 So this is a different bug. >> INFO: rcu detected stall in blkdev_ioctl >> >> https://syzkaller.appspot.com/bug?id=1f7b710f4110f225aed1f4263ec2b98b8dbd472e >> >> general protection fault in lo_ioctl (2) >> >> https://syzkaller.appspot.com/bug?id=f3cfe26e785d85f9ee259f385515291d21bd80a3 >> #syz dup: INFO: rcu detected stall in blkdev_ioctl >> >> INFO: rcu detected stall in lo_compat_ioctl >> >> https://syzkaller.appspot.com/bug?id=6299555c4e252b53f7a2ae2b8216cc9456c56ac0 >> #syz dup: INFO: rcu detected stall in blkdev_ioctl >> >> INFO: rcu detected stall in lo_ioctl >> >> https://syzkaller.appspot.com/bug?id=7b49fb610af9cca78c24e9f796f2e8b0d5573997 >> #syz dup: INFO: rcu detected stall in blkdev_ioctl >> >> INFO: task hung in lo_ioctl >> >> https://syzkaller.appspot.com/bug?id=608144371e7fc2cb6285b9ed871fb1eb817a61ce >> >> INFO: task hung in lo_open (2) >> >> https://syzkaller.appspot.com/bug?id=1f93b57f496d969efb9fb24167f6f9de5ee068fd >> >> possible deadlock in blkdev_reread_part >> >> https://syzkaller.appspot.com/bug?id=bf154052f0eea4bc7712499e4569505907d15889 >> >> INFO: task hung in loop_control_ioctl >> >> https://syzkaller.appspot.com/bug?id=61fe32c77ea00412c5149bd34649a65b7f672b5e >> >> WARNING in sysfs_remove_group >> >> https://syzkaller.appspot.com/bug?id=3f86c0edf75c86d2633aeb9dd69eccc70bc7e90b >> >>> >>> > suggest that loop module is not thread safe. The former suggests that >>> > l->lo_backing_file is forming circular loop and the latter suggests that >>> > l->lo_backing_file became NULL.
