Re: [mm] 408579cd62: WARNING:suspicious_RCU_usage

[Linus Torvalds]

On Sun, 2 Jul 2023 at 19:04, kernel test robot <oliver.sang@xxxxxxxxx> wrote:
>
> commit: 408579cd627a15bd703fe3eeb8485fd02726e9d3 ("mm: Update do_vmi_align_munmap() return semantics")
> https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git master
>
> in testcase: boot
>
> on test machine: qemu-system-x86_64 -enable-kvm -cpu SandyBridge -smp 2 -m 16G
>
> caused below changes (please refer to attached dmesg/kmsg for entire log/backtrace):
>
>
>
> If you fix the issue, kindly add following tag
> Reported-by: kernel test robot <oliver.sang@xxxxxxxxx>
>
>
> [  215.088258][    T1] WARNING: suspicious RCU usage

I think the

        validate_mm(mm);

call (mm/mmap.c:2561) needs to be moved up to before the

        if (unlock)
                mmap_read_unlock(mm);

that is just a couple of lines earlier.

Can you verify that that fixes the warning?

                 Linus