linux-kernel - Re: [PATCH V6] panic: Move panic

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 for Android: free password hash cracker in your pocket

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

Message-ID: <YgvRe92hEvj5mEUS@alley>
Date:   Tue, 15 Feb 2022 17:14:51 +0100
From:   Petr Mladek <pmladek@...e.com>
To:     "Guilherme G. Piccoli" <gpiccoli@...lia.com>
Cc:     linux-kernel@...r.kernel.org, bhe@...hat.com,
        akpm@...ux-foundation.org, anton@...msg.org, ccross@...roid.com,
        dyoung@...hat.com, feng.tang@...el.com, john.ogness@...utronix.de,
        keescook@...omium.org, kernel@...ccoli.net,
        kexec@...ts.infradead.org, rostedt@...dmis.org,
        senozhatsky@...omium.org, tony.luck@...el.com, vgoyal@...hat.com
Subject: Re: [PATCH V6] panic: Move panic_print before kmsg dumpers

On Mon 2022-02-14 11:13:09, Guilherme G. Piccoli wrote:
> The panic_print setting allows users to collect more information in a
> panic event, like memory stats, tasks, CPUs backtraces, etc.
> This is an interesting debug mechanism, but currently the print event
> happens *after* kmsg_dump(), meaning that pstore, for example, cannot
> collect a dmesg with the panic_print extra information.
> 
> This patch changes that in 2 steps:
> 
> (a) The panic_print setting allows to replay the existing kernel log
> buffer to the console (bit 5), besides the extra information dump.
> This functionality makes sense only at the end of the panic() function.
> So, we hereby allow to distinguish the two situations by a new boolean
> parameter in the function panic_print_sys_info().
> 
> (b) With the above change, we can safely call panic_print_sys_info()
> before kmsg_dump(), allowing to dump the extra information when using
> pstore or other kmsg dumpers.
> 
> The additional messages from panic_print could overwrite the oldest
> messages when the buffer is full. The only reasonable solution is to
> use a large enough log buffer, hence we added an advice into the kernel
> parameters documentation about that.
> 
> Cc: Feng Tang <feng.tang@...el.com>
> Cc: Petr Mladek <pmladek@...e.com>
> Acked-by: Baoquan He <bhe@...hat.com>
> Signed-off-by: Guilherme G. Piccoli <gpiccoli@...lia.com>

Makes sense and looks good to me.

Reviewed-by: Petr Mladek <pmladek@...e.com>

Best Regards,
Petr