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From:   Linus Torvalds <torvalds@linux-foundation.org>
Date:   Sun, 2 Jul 2023 21:34:35 -0700
Message-ID: <CAHk-=wg1_8L+e09_RuX=Z_49oLn8=w82YzCk+kybS-ymSd_zbA@mail.gmail.com>
Subject: Re: [mm] 408579cd62: WARNING:suspicious_RCU_usage
To:     lkp <oliver.sang@intel.com>
Cc:     "Liam R. Howlett" <Liam.Howlett@oracle.com>,
        LKML <linux-kernel@vger.kernel.org>, lkp@lists.01.org,
        lkp@intel.com
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On Sun, 2 Jul 2023 at 19:04, kernel test robot <oliver.sang@intel.com> 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@intel.com>
>
>
> [  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