arm64: WARN_ON_ONCE issue when resuming from hibernation

[Kunihiko Hayashi <hayashi.kunihiko@socionext.com>]

Hello all,

I found that a WARN_ON_ONCE dump occured in the resuming sequence from
hibernation on arm64 SoC (I use UniPhier LD20 environment).

    ...
    Disabling non-boot CPUs ...
    CPU1: shutdown
    psci: CPU1 killed.
    CPU2: shutdown
    psci: CPU2 killed.
    CPU3: shutdown
    psci: CPU3 killed.
    WARNING: CPU: 0 PID: 1 at ../kernel/smp.c:416 smp_call_function_many+0xd4/0x350
    Modules linked in:
    CPU: 0 PID: 1 Comm: swapper/0 Not tainted 4.20.0-rc4 #1
    ...

I show the result of reading the code, however,
I'm not sure that this issue occurs in other arm64 SoC.

In the resuming sequence, once all CPUs are stopped and local IRQs
are disabled [1].

[1] https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/kernel/power/hibernate.c?h=v4.20-rc4#n450

In case of arm64, flush_icache_range() will be called after that.
This calls kick_all_cpus_sync() to sync all CPUs with IPI, and
since local IRQs are disabled, WARN_ON_ONCE() will be called in
smp_call_function_many() [2].

[2] https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/kernel/smp.c?h=v4.20-rc4#n415

The following tree shows a part of the callgraph.

    resume_target_kernel()
    +- local_irq_disable()
    +- swsusp_arch_resume()				/* for arm64 */
       +- create_safe_exec_page()			/* for arm64 */
          +- flush_icache_range()			/* for arm64 */
             +- kick_all_cpus_sync()
                +- smp_call_function()
                   +- smp_call_function_many()
                      +- WARN_ON_ONCE(irq_disabled())

What is the possible way to solve this issue?

Thank you,

---
Best Regards,
Kunihiko Hayashi



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