linux-kernel - Re: [PATCH 2/4] printk: disable optimistic spin during 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: Windows password security audit tool. GUI, reports in PDF.

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

Message-ID: <87r18un83x.fsf@jogness.linutronix.de>
Date:   Wed, 26 Jan 2022 10:51:22 +0106
From:   John Ogness <john.ogness@...utronix.de>
To:     Sergey Senozhatsky <senozhatsky@...omium.org>,
        Stephen Brennan <stephen.s.brennan@...cle.com>
Cc:     Petr Mladek <pmladek@...e.com>,
        Sergey Senozhatsky <senozhatsky@...omium.org>,
        Steven Rostedt <rostedt@...dmis.org>,
        Sergey Senozhatsky <sergey.senozhatsky@...il.com>,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH 2/4] printk: disable optimistic spin during panic

> Is there something that prevents panic CPU from NMI hlt CPU which is
> in console_trylock() under raw_spin_lock_irqsave()?
>
>  CPU0				CPU1
> 				console_trylock_spinnning()
> 				 console_trylock()
> 				  down_trylock()
> 				   raw_spin_lock_irqsave(&sem->lock)
>
>  panic()
>   crash_smp_send_stop()
>    NMI 			-> 		HALT

This is a good point. I wonder if console_flush_on_panic() should
perform a sema_init() before it does console_trylock().

John