From: Petr Mladek <pmladek@suse.com>
To: Bradley Morgan <brads@mainlining.org>
Cc: Andrew Morton <akpm@linux-foundation.org>,
Jinchao Wang <wangjinchao600@gmail.com>,
Craig Lamparter <craig.lamparter@hpe.com>,
Wim Van Sebroeck <wim@linux-watchdog.org>,
Guenter Roeck <linux@roeck-us.net>,
linux-watchdog@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH v7 6/6] panic: kill the "buffer unavailable" redirect fallback
Date: Tue, 22 Sep 2026 14:28:52 +0200 [thread overview]
Message-ID: <arJ0hE0bKWoIzYyG@pathway.suse.cz> (raw)
In-Reply-To: <20260916182957.7788-7-brads@mainlining.org>
On Wed 2026-09-16 18:29:57, Bradley Morgan wrote:
> The redirect buffer is a disgusting terrible hack. panic_force_buf is
> kmalloc'ed in a late_initcall, and until then the redirect delivers
> this as the panic message:
>
> Redirected panic (buffer unavailable)
>
> The whole point of the redirect is to hand the panic message to the
> target CPU, so the crash kernel boots knowing it panicked and not why.
> And that window is the entire boot, from the early_param to the
> late_initcall, which is exactly when you most want the message.
>
> Make it a static 1KB buffer and kill the initcall. The cost is 1KB of
> .bss in SMP crash dump builds, and it is only ever touched when
> panic_force_cpu= is set anyway. The local msg variable is gone too,
> the buffer goes directly to panic_smp_redirect_cpu().
>
> Suggested-by: Petr Mladek <pmladek@suse.com>
> Signed-off-by: Bradley Morgan <brads@mainlining.org>
Look good to me:
Reviewed-by: Petr Mladek <pmladek@suse.com>
Best Regards,
Petr
next prev parent reply other threads:[~2026-09-22 12:28 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-09-16 18:29 [PATCH v7 0/6] panic: fix panic_force_cpu= redirect races and NMI bypass Bradley Morgan
2026-09-16 18:29 ` [PATCH v7 1/6] panic: fix redirect CPU race in panic_try_force_cpu() Bradley Morgan
2026-09-16 18:29 ` [PATCH v7 2/6] panic: flatten nmi_panic control flow Bradley Morgan
2026-09-16 18:29 ` [PATCH v7 3/6] panic: fix va_list reuse in panic_try_force_cpu() Bradley Morgan
2026-09-16 18:29 ` [PATCH v7 4/6] panic: restore variable arguments to nmi_panic() Bradley Morgan
2026-09-22 12:14 ` Petr Mladek
2026-09-16 18:29 ` [PATCH v7 5/6] panic: allow force_cpu redirect from an NMI Bradley Morgan
2026-09-16 18:29 ` [PATCH v7 6/6] panic: kill the "buffer unavailable" redirect fallback Bradley Morgan
2026-09-22 12:28 ` Petr Mladek [this message]
2026-09-22 12:35 ` [PATCH v7 0/6] panic: fix panic_force_cpu= redirect races and NMI bypass Petr Mladek
2026-09-22 14:41 ` Bradley Morgan
2026-09-22 23:22 ` Andrew Morton
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