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Date: Wed, 10 Apr 2019 10:02:24 +0200 From: Petr Mladek <pmladek@...e.com> To: Sergey Senozhatsky <sergey.senozhatsky.work@...il.com> Cc: Feng Tang <feng.tang@...el.com>, Andrew Morton <akpm@...ux-foundation.org>, Steven Rostedt <rostedt@...dmis.org>, linux-kernel@...r.kernel.org, Kees Cook <keescook@...omium.org>, Borislav Petkov <bp@...e.de> Subject: Re: [PATCH 2/2] panic: Enable to print out all printk msg in buffer On Wed 2019-04-10 10:59:26, Sergey Senozhatsky wrote: > On (04/09/19 16:14), Petr Mladek wrote: > > We should: > > > > + Flush the latest messages before we replay the log. > > Do you mean the pending messages? When we replay the log we also should > print "header line" and panic-cpu backtrace. So we will print panic-cpu > oops twice console_flush_on_panic() is just the last resort. I believe that the panic header and backtrace reach the console even without it in most cases. Explicit flush before reply would just make it consistent. > // from panic-cpu flush_on_panic > [header] > backtrace > [end of header] > > // from console_replay > then all logbuf messages > and then the same header/backtrace one more time > > [header] > backtrace] > [end of backtrace] > > Is there any particular reason to flush pending messages before > we play the buffer? Replaying the logbuf can take some time, so > my guess would be that you want to print panic-cpu backtrace as > soon as possible. Is there something else? The panic() message is usually the most important one for debugging. I feel a bit uneasy that we would delay it until full replay that might get killed from several reasons: + external monitoring system would force reboot + user might realize, e.g. after 20 minutes, that the full log reply was probably not worth it. I understand that people enabling this option would most likely wait but still. I do not see it as a big deal to repeat the messages. Best Regards, Petr
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