linux-kernel - Re: [PATCH] mm: dump page when hitting a VM_BUG_ON using VM_BUG_ON

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Date:	Fri, 27 Dec 2013 18:19:02 -0500
From:	Sasha Levin <sasha.levin@...cle.com>
To:	akpm@...ux-foundation.org
CC:	linux-mm@...ck.org, linux-kernel@...r.kernel.org,
	Sasha Levin <sasha.levin@...cle.com>
Subject: Re: [PATCH] mm: dump page when hitting a VM_BUG_ON using VM_BUG_ON_PAGE

On 12/26/2013 10:20 PM, Sasha Levin wrote:
> Most of the VM_BUG_ON assertions are performed on a page. Usually, when
> one of these assertions fails we'll get a BUG_ON with a call stack and
> the registers.
>
> I've recently noticed based on the requests to add a small piece of code
> that dumps the page to various VM_BUG_ON sites that the page dump is quite
> useful to people debugging issues in mm.
>
> This patch adds a VM_BUG_ON_PAGE(cond, page) which beyond doing what
> VM_BUG_ON() does, also dumps the page before executing the actual BUG_ON.

Somewhat related to that, I've tried adding a VM_BUG_ON_PAGE in SetPageXXX()
and ClearPageXXX macros to catch cases where page flags are being set or
cleared twice.

There seems to be a lot of those...

Is that a valid use? Or should it be fixed?


Thanks,
Sasha
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