Nikolay Borisov <[email protected]> writes: > On 20.01.2017 20:05, Eric W. Biederman wrote: >> Nikolay Borisov <[email protected]> writes: >> >>> On 20.01.2017 15:07, Dmitry Vyukov wrote: >>>> Hello, >>>> >>>> I've got the following deadlock report while running syzkaller fuzzer >>>> on eec0d3d065bfcdf9cd5f56dd2a36b94d12d32297 of linux-next (on odroid >>>> device if it matters): >> >> I am puzzled I thought we had fixed this with: >> add7c65ca426 ("pid: fix lockdep deadlock warning due to ucount_lock") >> But apparently not. We just moved it from hardirq to softirq context. Bah. >> >> Thank you very much for the report. >> >> Nikolay can you make your change use spinlock_irq? And have put_ucounts >> do spin_lock_irqsave? That way we just don't care where we call this. > > Like the one attached?
Exactly thank you. Dmitry if you have time to test that patch and verify it fixes your issue I would appreciate it. > I haven't really taken careful look as to whether > the function where _irq versions do fiddle with irq state, since this > might cause a problem if we unconditionally enable them. In code paths where we can sleep irqs must come in enabled or it's a bug. spin_lock_irq which unconditionally disables irqs is thus safe on the allocation path. Similary spin_unlock_irq which unconditionally enables irqs is also safe on the allocation path. Eric
