Messages in this thread | | | Date | Wed, 30 Mar 2022 08:51:21 +0900 | From | Dominique Martinet <> | Subject | Re: [syzbot] possible deadlock in p9_write_work |
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Tetsuo Handa wrote on Wed, Mar 30, 2022 at 07:35:47AM +0900: > This seems to be an example of > https://lkml.kernel.org/r/49925af7-78a8-a3dd-bce6-cfc02e1a9236@I-love.SAKURA.ne.jp > introduced by "ext4: truncate during setxattr leads to kernel panic".
Thanks for the pointer
> Please don't use schedule_work() if you need to use flush_scheduled_work().
In this case we don't call flush_scheduled_work -- ext4 does. The problem is mixing in the two subsystems when someone (e.g. syzbot) opens an ext4 file and passes that fd to 9p when mounting with e.g. mount -t 9p -o rfdno=<no>,wfdno=<no>
Frankly that's just not something I consider useful, interacting through 9p to a local file doesn't make sense except for testing.
If that is a real problem, the simplest way out would be to just forbid non-socket FDs if it's something we can check. -- Dominique
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