Re: [PATCH sched_ext/for-6.13-fixes] sched_ext: Fix invalid irq restore in scx_ops_bypass()

Tejun Heo
2024-12-11T21:03:05Z

On Wed, Dec 11, 2024 at 11:01:51AM -1000, Tejun Heo wrote:
> While adding outer irqsave/restore locking, 0e7ffff1b811 ("scx: Fix raciness
> in scx_ops_bypass()") forgot to convert an inner rq_unlock_irqrestore() to
> rq_unlock() which could re-enable IRQ prematurely leading to the following
> warning:
>
> raw_local_irq_restore() called with IRQs enabled
> WARNING: CPU: 1 PID: 96 at kernel/locking/irqflag-debug.c:10 warn_bogus_irq_restore+0x30/0x40
> ...
> Sched_ext: create_dsq (enabling)
> pstate: 60400005 (nZCv daif +PAN -UAO -TCO -DIT -SSBS BTYPE=--)
> pc : warn_bogus_irq_restore+0x30/0x40
> lr : warn_bogus_irq_restore+0x30/0x40
> ...
> Call trace:
> warn_bogus_irq_restore+0x30/0x40 (P)
> warn_bogus_irq_restore+0x30/0x40 (L)
> scx_ops_bypass+0x224/0x3b8
> scx_ops_enable.isra.0+0x2c8/0xaa8
> bpf_scx_reg+0x18/0x30
> ...
> irq event stamp: 33739
> hardirqs last enabled at (33739): [<ffff8000800b699c>] scx_ops_bypass+0x174/0x3b8
> hardirqs last disabled at (33738): [<ffff800080d48ad4>] _raw_spin_lock_irqsave+0xb4/0xd8
>
> Drop the stray _irqrestore().
>
> Signed-off-by: Tejun Heo <tj@kernel.org>
> Reported-by: Ihor Solodrai <ihor.solodrai@pm.me>
> Link: http://lkml.kernel.org/r/qC39k3UsonrBYD_SmuxHnZIQLsuuccoCrkiqb_BT7DvH945A1_LZwE4g-5Pu9FcCtqZt4lY1HhIPi0homRuNWxkgo1rgP3bkxa0donw8kV4=@pm.me
> Fixes: 0e7ffff1b811 ("scx: Fix raciness in scx_ops_bypass()")
> Cc: stable@vger.kernel.org # v6.12

Applying to sched_ext/for-6.13-fixes.

Thanks.

--
tejun