On 5/18/22 4:29 PM, Jens Axboe wrote: > On 5/18/22 1:28 PM, Marek Szyprowski wrote: >> On 16.05.2022 19:39, bh1scw@xxxxxxxxx wrote: >>> From: Fanjun Kong <bh1scw@xxxxxxxxx> >>> >>> spin_lock_irq/spin_unlock_irq contains preempt_disable/enable(). >>> Which can serve as RCU read-side critical region, so remove >>> rcu_read_lock/unlock(). >>> >>> Signed-off-by: Fanjun Kong <bh1scw@xxxxxxxxx> >> >> This patch landed in today's linux next-20220518 as commit 77c570a1ea85 >> ("blk-cgroup: Remove unnecessary rcu_read_lock/unlock()"). >> >> Unfortunately it triggers the following warning on ARM64 based Raspberry >> Pi 4B board:> >> ------------[ cut here ]------------ >> WARNING: CPU: 0 PID: 1 at block/blk-cgroup.c:301 blkg_create+0x398/0x4e0 > > Should this use rcu_read_lock_any_held() rather than > rcu_read_lock_held()? I think the better alternative is just to delete the WARN_ON(), we have a: lockdep_assert_held(&q->queue_lock); right after it. Since the queue_lock is IRQ disabling, having two checks serves no purpose. I'll kill the line. -- Jens Axboe