linux-kernel - Re: [PATCH] [v2] mm: pass VM_BUG_ON() reason to dump

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Message-ID: <1397251420.2503.25.camel@buesod1.americas.hpqcorp.net>
Date:	Fri, 11 Apr 2014 14:23:40 -0700
From:	Davidlohr Bueso <davidlohr@...com>
To:	Dave Hansen <dave@...1.net>
Cc:	akpm@...ux-foundation.org, linux-kernel@...r.kernel.org,
	linux-mm@...ck.org, dave.hansen@...ux.intel.com,
	kirill.shutemov@...ux.intel.com
Subject: Re: [PATCH] [v2] mm: pass VM_BUG_ON() reason to dump_page()

On Fri, 2014-04-11 at 13:42 -0700, Dave Hansen wrote:
> Changes from v1:
>  * Fix tabs before spaces in the multi-line #define
> 
> --
> From: Dave Hansen <dave.hansen@...ux.intel.com>
> 
> I recently added a patch to let folks pass a "reason" string
> dump_page() which gets dumped out along with the page's data.
> This essentially saves the bug-reader a trip in to the source
> to figure out why we BUG_ON()'d.
> 
> The new VM_BUG_ON_PAGE() passes in NULL for "reason".  It seems
> like we might as well pass the BUG_ON() condition if we have it.
> This will bloat kernels a bit with ~160 new strings, but this
> is all under a debugging option anyway.
> 
> 	page:ffffea0008560280 count:1 mapcount:0 mapping:(null) index:0x0
> 	page flags: 0xbfffc0000000001(locked)
> 	page dumped because: VM_BUG_ON_PAGE(PageLocked(page))
> 	------------[ cut here ]------------
> 	kernel BUG at /home/davehans/linux.git/mm/filemap.c:464!
> 	invalid opcode: 0000 [#1] SMP
> 	CPU: 0 PID: 1 Comm: swapper/0 Not tainted 3.14.0+ #251
> 	Hardware name: Bochs Bochs, BIOS Bochs 01/01/2011
> 	...
> 
> 
> Signed-off-by: Dave Hansen <dave.hansen@...ux.intel.com>
> Acked-by: Kirill A. Shutemov <kirill.shutemov@...ux.intel.com>

Acked-by: Davidlohr Bueso <davidlohr@...com>

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