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From: Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com>
To: Byungchul Park <byungchul.park@lge.com>
Cc: Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com>,
	Sergey Senozhatsky <sergey.senozhatsky@gmail.com>,
	Andrew Morton <akpm@linux-foundation.org>,
	Jan Kara <jack@suse.com>, Petr Mladek <pmladek@suse.com>,
	Tejun Heo <tj@kernel.org>,
	Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>,
	linux-kernel@vger.kernel.org, Jan Kara <jack@suse.cz>
Subject: Re: [RFC][PATCH v5 1/2] printk: Make printk() completely async
Date: Tue, 22 Mar 2016 14:52:43 +0900	[thread overview]
Message-ID: <20160322055243.GA1759@swordfish> (raw)
In-Reply-To: <20160322021343.GC2279@X58A-UD3R>

On (03/22/16 11:13), Byungchul Park wrote:
[..]

what about a "normal" case, when things are not going to explode printk(),
but we have several lockups on the same lock (which is probably more
likely than printk recursion)?

suppose:
- there are 8 CPUs on the system
- 1 cpus owns the spin_lock for too long
- 4 cpus are trying to lock the spin_lock w/o any success
- so all 4 trigger spin_dump.

what we have at the moment, is that all 4 CPUs will report a lockup,
but with this static pointer only X (between 1 and 4, depending on the
timing; on how fast spin_dump() will return (logbuf lock can
be busy for a while); etc.) CPUs will do so.

	-ss

  reply	other threads:[~2016-03-22  5:51 UTC|newest]

Thread overview: 20+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2016-03-20 14:13 [RFC][PATCH v5 0/2] printk: Make printk() completely async Sergey Senozhatsky
2016-03-20 14:13 ` [RFC][PATCH v5 1/2] " Sergey Senozhatsky
2016-03-21  0:06   ` Byungchul Park
2016-03-21  0:43     ` Sergey Senozhatsky
2016-03-21  0:56       ` Byungchul Park
2016-03-21  7:35         ` Sergey Senozhatsky
2016-03-21  8:07           ` Byungchul Park
2016-03-21  8:47             ` Byungchul Park
2016-03-21  9:28               ` Sergey Senozhatsky
2016-03-21 14:32                 ` Jan Kara
2016-03-21 14:58                   ` Sergey Senozhatsky
2016-03-21 15:33                     ` Jan Kara
2016-03-21 17:11                       ` Sergey Senozhatsky
2016-03-22  2:18                         ` Byungchul Park
2016-03-22  2:13                 ` Byungchul Park
2016-03-22  5:52                   ` Sergey Senozhatsky [this message]
2016-03-22  6:57                     ` Byungchul Park
2016-03-22  7:43                       ` Sergey Senozhatsky
2016-03-21  8:51             ` Sergey Senozhatsky
2016-03-20 14:13 ` [RFC][PATCH v5 2/2] printk: Make wake_up_klogd_work_func() async Sergey Senozhatsky

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