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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>,
	akpm@linux-foundation.org, mingo@kernel.org,
	linux-kernel@vger.kernel.org, akinobu.mita@gmail.com,
	jack@suse.cz, peter@hurleysoftware.com,
	torvalds@linux-foundation.org
Subject: Re: [PATCH v5] lib/spinlock_debug.c: prevent a recursive cycle in the debug code
Date: Mon, 1 Feb 2016 11:13:17 +0900	[thread overview]
Message-ID: <20160201021317.GB1033@swordfish> (raw)
In-Reply-To: <20160201014536.GA29804@X58A-UD3R>

On (02/01/16 10:45), Byungchul Park wrote:
> But avoiding an unnecessary recursive cycle is better than panic(). What I handled
> in this patch is the warning case which causes unnecessary lockup and don't need to
> happen.

Hello,

correct, that was one of the reasons why I proposed to
return back to discussion. it's a bit hard to tell if
we have any chance to survive a "lockup suspected"
spin_dump() recursion; even if we have one, it's a race
spin_unlock on CPUA vs. stack overflow on CPUB. we can
be more certain with ->magic mismatch, for example, but
"lockup suspected" is tricky.

	-ss

  reply	other threads:[~2016-02-01  2:12 UTC|newest]

Thread overview: 9+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2016-01-29 12:43 [PATCH v5] lib/spinlock_debug.c: prevent a recursive cycle in the debug code Byungchul Park
2016-01-29 12:54 ` Byungchul Park
2016-01-31 12:40   ` Sergey Senozhatsky
2016-02-01  1:45     ` Byungchul Park
2016-02-01  2:13       ` Sergey Senozhatsky [this message]
2016-01-30  9:27 ` Ingo Molnar
2016-02-02  2:34   ` Byungchul Park
2016-02-01  2:31 ` Sergey Senozhatsky
2016-02-01  6:28   ` Byungchul Park

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