linux-kernel - Re: 6.11/regression/bisected - The commit c1385c1f0ba3 caused a new possible recursive locking detected warning at computer boot.

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <CABXGCsOYHJKix6aEMf1VoVDfdqncvDy5r-PDg=Lv5hkpaxvifw@mail.gmail.com>
Date: Fri, 26 Jul 2024 03:30:14 +0500
From: Mikhail Gavrilov <mikhail.v.gavrilov@...il.com>
To: Jonathan Cameron <Jonathan.Cameron@...wei.com>
Cc: linuxarm@...wei.com, rafael.j.wysocki@...el.com, guohanjun@...wei.com, 
	gshan@...hat.com, miguel.luis@...cle.com, catalin.marinas@....com, 
	Linux List Kernel Mailing <linux-kernel@...r.kernel.org>, 
	Linux regressions mailing list <regressions@...ts.linux.dev>, Thomas Gleixner <tglx@...utronix.de>, 
	Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>, 
	Dave Hansen <dave.hansen@...ux.intel.com>, x86@...nel.org, 
	"H. Peter Anvin" <hpa@...or.com>, "Bowman, Terry" <Terry.bowman@....com>
Subject: Re: 6.11/regression/bisected - The commit c1385c1f0ba3 caused a new
 possible recursive locking detected warning at computer boot.

On Thu, Jul 25, 2024 at 10:13 PM Jonathan Cameron
<Jonathan.Cameron@...wei.com> wrote:
>
> Hi Mikhail.
>
> So the short story, ignoring the journey (which should only be described
> with beer in hand), is that I now have an emulated test setup in QEMU
> that fakes enough of the previously missing bits to bring up this path
> and can trigger the splat you shared.  With the below fix I can get to
> something approaching a running system.
>
> However, without more work the emulation isn't actually doing any control
> of frequency etc so I have no idea if the code actually works after this
> patch.
>
> If you are in a position to test a patch, could you try the following?
>
> One bit I need to check out tomorrow is to make sure this doesn't race with the
> workfn that is used to tear down the same static key on error.
>
> From 8f7ad4c73954aae74265a3ec50a1d56e0c56050d Mon Sep 17 00:00:00 2001
> From: Jonathan Cameron <Jonathan.Cameron@...wei.com>
> Date: Thu, 25 Jul 2024 17:56:00 +0100
> Subject: [RFC PATCH] x86/aperfmperf: Push static_branch_enable(&arch_scale_freq_key) onto work queue
>
> This to avoid a deadlock reported by lockdep.
>
> TODO: Fix up this commit message before posting to actually give
> some details and tags etc.
>
> Reported-by: Mikhail Gavrilov <mikhail.v.gavrilov@...il.com>
> Signed-off-by: Jonathan Cameron <Jonathan.Cameron@...wei.com>
> ---
>  arch/x86/kernel/cpu/aperfmperf.c | 13 ++++++++++---
>  1 file changed, 10 insertions(+), 3 deletions(-)
>
> diff --git a/arch/x86/kernel/cpu/aperfmperf.c b/arch/x86/kernel/cpu/aperfmperf.c
> index b3fa61d45352..41c729d3517c 100644
> --- a/arch/x86/kernel/cpu/aperfmperf.c
> +++ b/arch/x86/kernel/cpu/aperfmperf.c
> @@ -300,15 +300,22 @@ static void register_freq_invariance_syscore_ops(void)
>  static inline void register_freq_invariance_syscore_ops(void) {}
>  #endif
>
> +static void enable_freq_invariance_workfn(struct work_struct *work)
> +{
> +       static_branch_enable(&arch_scale_freq_key);
> +       register_freq_invariance_syscore_ops();
> +       pr_info("Estimated ratio of average max frequency by base frequency (times 1024): %llu\n", arch_max_freq_ratio);
> +}
> +static DECLARE_WORK(enable_freq_invariance_work,
> +                   enable_freq_invariance_workfn);
> +
>  static void freq_invariance_enable(void)
>  {
>         if (static_branch_unlikely(&arch_scale_freq_key)) {
>                 WARN_ON_ONCE(1);
>                 return;
>         }
> -       static_branch_enable(&arch_scale_freq_key);
> -       register_freq_invariance_syscore_ops();
> -       pr_info("Estimated ratio of average max frequency by base frequency (times 1024): %llu\n", arch_max_freq_ratio);
> +       schedule_work(&enable_freq_invariance_work);
>  }
>
>  void freq_invariance_set_perf_ratio(u64 ratio, bool turbo_disabled)
> --
> 2.43.0
>
>

Jonathan, thanks a lot.
With this patch, the issue has gone.
Tested-by: Mikhail Gavrilov <mikhail.v.gavrilov@...il.com>

-- 
Best Regards,
Mike Gavrilov.

Download attachment "6.10.0-d67978318827-with-enable-onto-work-queue-patch.zip" of type "application/zip" (105097 bytes)