linux-kernel - Re: [PATCH] x86/mce: drop cpu_missing since we have more capable mce_missing

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Message-ID: <4d526023.3cde.17cff097bab.Coremail.zhangzl2013@126.com>
Date:   Mon, 8 Nov 2021 18:13:04 +0800 (CST)
From:   "Zhaolong Zhang" <zhangzl2013@....com>
To:     "Borislav Petkov" <bp@...en8.de>
Cc:     "Tony Luck" <tony.luck@...el.com>, x86@...nel.org,
        linux-edac@...r.kernel.org, linux-kernel@...r.kernel.org,
        "Paul E . McKenney" <paulmck@...nel.org>
Subject: Re: [PATCH] x86/mce: drop cpu_missing since we have more capable
 mce_missing_cpus

At 2021-11-08 17:31:52, "Borislav Petkov" <bp@...en8.de> wrote:
>On Mon, Nov 08, 2021 at 04:28:32PM +0800, Zhaolong Zhang wrote:
>> move mce_missing_cpus checking into mce_panic() as well, because we don't want
>> to lose the cpu missing information in case mca_cfg.tolerant > 1 and there is
>> no_way_out.
>> 
>> Signed-off-by: Zhaolong Zhang <zhangzl2013@....com>
>> ---
>>  arch/x86/kernel/cpu/mce/core.c | 38 ++++++++++++++++++++--------------
>>  1 file changed, 22 insertions(+), 16 deletions(-)
>
>I was actually expecting to see something like this:

Hi Boris,

I was concerning that if I simply remove the cpu_missing code, we will lose the log in the
situation where mca_cfg.tolerant > 1 and no_way_out is set afterwards.

Do you think we can safely ignore that situation?

Regards,
Zhaolong


>
>diff --git a/arch/x86/kernel/cpu/mce/core.c b/arch/x86/kernel/cpu/mce/core.c
>index 6ed365337a3b..30de00fe0d7a 100644
>--- a/arch/x86/kernel/cpu/mce/core.c
>+++ b/arch/x86/kernel/cpu/mce/core.c
>@@ -99,7 +99,6 @@ struct mca_config mca_cfg __read_mostly = {
> 
> static DEFINE_PER_CPU(struct mce, mces_seen);
> static unsigned long mce_need_notify;
>-static int cpu_missing;
> 
> /*
>  * MCA banks polled by the period polling timer for corrected events.
>@@ -314,8 +313,6 @@ static void mce_panic(const char *msg, struct mce *final, char *exp)
> 		if (!apei_err)
> 			apei_err = apei_write_mce(final);
> 	}
>-	if (cpu_missing)
>-		pr_emerg(HW_ERR "Some CPUs didn't answer in synchronization\n");
> 	if (exp)
> 		pr_emerg(HW_ERR "Machine check: %s\n", exp);
> 	if (!fake_panic) {
>@@ -891,7 +888,6 @@ static int mce_timed_out(u64 *t, const char *msg)
> 					 cpumask_pr_args(&mce_missing_cpus));
> 			mce_panic(msg, NULL, NULL);
> 		}
>-		cpu_missing = 1;
> 		return 1;
> 	}
> 	*t -= SPINUNIT;
>@@ -2702,7 +2698,6 @@ struct dentry *mce_get_debugfs_dir(void)
> 
> static void mce_reset(void)
> {
>-	cpu_missing = 0;
> 	atomic_set(&mce_fake_panicked, 0);
> 	atomic_set(&mce_executing, 0);
> 	atomic_set(&mce_callin, 0);
>
>-- 
>Regards/Gruss,
>    Boris.
>
>https://people.kernel.org/tglx/notes-about-netiquette