Hi Frederic,

Thanks for this fix patch.

On Thu, 14 Nov 2019 at 21:26, Leonard Crestez leonard.crestez@nxp.com wrote:

On 13.11.2019 19:12, Frederic Weisbecker wrote:

...

While attempting to clear the buzy bit at the end of a work execution, atomic_cmpxchg() expects the value of the flags with the pending bit cleared as the old value. However we are passing by mistake the value of the flags before we actually cleared the pending bit.

Busy is spelled with an S

...

As a result, clearing the buzy bit fails and irq_work_sync() may stall:

  watchdog: BUG: soft lockup - CPU#0 stuck for 22s! [blktrace:4948]
  CPU: 0 PID: 4948 Comm: blktrace Not tainted 5.4.0-rc7-00003-gfeb4a51323bab #1
  Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.10.2-1 04/01/2014
  RIP: 0010:irq_work_sync+0x4/0x10
  Call Trace:
    relay_close_buf+0x19/0x50
    relay_close+0x64/0x100
    blk_trace_free+0x1f/0x50
    __blk_trace_remove+0x1e/0x30
    blk_trace_ioctl+0x11b/0x140
    blkdev_ioctl+0x6c1/0xa40
    block_ioctl+0x39/0x40
    do_vfs_ioctl+0xa5/0x700
    ksys_ioctl+0x70/0x80
    __x64_sys_ioctl+0x16/0x20
    do_syscall_64+0x5b/0x1d0
    entry_SYSCALL_64_after_hwframe+0x44/0xa9

So clear the appropriate bit before passing the old flags to cmpxchg().

Reported-by: kernel test robot rong.a.chen@intel.com Reported-by: Leonard Crestez leonard.crestez@nxp.com Fixes: feb4a51323ba ("irq_work: Slightly simplify IRQ_WORK_PENDING clearing") Signed-off-by: Frederic Weisbecker frederic@kernel.org Cc: Paul E . McKenney paulmck@linux.vnet.ibm.com Cc: Peter Zijlstra peterz@infradead.org everywhere. Cc: Thomas Gleixner tglx@linutronix.de Cc: Ingo Molnar mingo@kernel.org

Tested-by: Leonard Crestez leonard.crestez@nxp.com

Without this patch switching cpufreq governors hangs on arm64.

Right.

This patch solved two problems, 1) juno-r2 boot pass now 2) rcu_sched self-detected stall on CPU on x86_64 problem is solved now.

Tested-by: Naresh Kamboju naresh.kamboju@linaro.org

Hope this will get merged into linux next.

ref: https://lkft.validation.linaro.org/scheduler/job/1010542#L260 https://lkft.validation.linaro.org/scheduler/job/1010793#L493

- Naresh