From: Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com>
To: Petr Mladek <pmladek@suse.com>
Cc: Steven Rostedt <rostedt@goodmis.org>,
Sergey Senozhatsky <sergey.senozhatsky@gmail.com>,
Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>,
Peter Zijlstra <peterz@infradead.org>,
Andrew Morton <akpm@linux-foundation.org>,
Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
Jiri Slaby <jslaby@suse.cz>,
linux-fbdev@vger.kernel.org, linux-kernel@vger.kernel.org,
ergey Senozhatsky <sergey.senozhatsky.work@gmail.com>
Subject: Re: [PATCH] printk: Correctly handle preemption in console_unlock()
Date: Wed, 18 Jan 2017 07:21:41 +0000 [thread overview]
Message-ID: <20170118072141.GB881@jagdpanzerIV.localdomain> (raw)
In-Reply-To: <20170118054551.GA881@jagdpanzerIV.localdomain>
On (01/18/17 14:45), Sergey Senozhatsky wrote:
[..]
>
> there is a function that clears @console_may_schedule out of
> console_sem scope - console_flush_on_panic().
> so I *may be* can think about a worst case scenario of race
> condition between
> console_flush_on_panic()->console_may_schedule = 0 on panic CPU
> and
> console_unlock()->console_may_schedule = 1 from CPU that panic CPU
> failed to stop (smp_send_stop() can return with secondary CPUs still being
> online).
what I mean, is that we can have, let's say, 2 CPUs spinning in
console_unlock(), both with @console_may_schedule = 1 (because secondary
CPU restores global @console_may_schedule value). now, suppose, we have
misbehaving scheduler (well, we are in panic after all). secondary CPU
will cond_resched() and may be lockup somewhere in the scheduler. which is
fine, we don't care about that secondary CPU anyway. but the same can happen
to panic CPU as well.
what do you think?
-ss
next prev parent reply other threads:[~2017-01-18 7:21 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-01-13 13:15 [PATCH] printk: Correctly handle preemption in console_unlock() Petr Mladek
2017-01-13 16:05 ` Steven Rostedt
2017-01-16 11:00 ` Petr Mladek
2017-01-18 5:45 ` Sergey Senozhatsky
2017-01-18 7:21 ` Sergey Senozhatsky [this message]
2017-01-25 12:34 ` Petr Mladek
2017-01-14 6:28 ` Sergey Senozhatsky
2017-01-16 11:38 ` Petr Mladek
2017-01-16 11:58 ` Sergey Senozhatsky
2017-01-16 12:48 ` Petr Mladek
2017-01-16 13:26 ` Sergey Senozhatsky
2017-01-16 13:43 ` Sergey Senozhatsky
2017-01-16 14:14 ` Petr Mladek
2017-01-16 15:19 ` Sergey Senozhatsky
2017-01-16 15:43 ` Sergey Senozhatsky
2017-01-16 16:35 ` Petr Mladek
2017-01-16 13:41 ` Tetsuo Handa
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20170118072141.GB881@jagdpanzerIV.localdomain \
--to=sergey.senozhatsky.work@gmail.com \
--cc=akpm@linux-foundation.org \
--cc=gregkh@linuxfoundation.org \
--cc=jslaby@suse.cz \
--cc=linux-fbdev@vger.kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=penguin-kernel@I-love.SAKURA.ne.jp \
--cc=peterz@infradead.org \
--cc=pmladek@suse.com \
--cc=rostedt@goodmis.org \
--cc=sergey.senozhatsky@gmail.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).