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From: Martin Schwidefsky <schwidefsky@de.ibm.com>
To: Andreas Krebbel1 <Andreas.Krebbel@de.ibm.com>
Cc: mschwid2@linux.vnet.ibm.com,
	Andrew Morton <akpm@linux-foundation.org>,
	Christoph Lameter <cl@linux-foundation.org>,
	kbuild test robot <fengguang.wu@intel.com>,
	heicars2@linux.vnet.ibm.com, kbuild-all@01.org,
	Linux Memory Management List <linux-mm@kvack.org>
Subject: Re: [linux-next:master 12891/13017] mm/slub.c:2396:1: warning: '___slab_alloc' uses dynamic stack allocation
Date: Mon, 16 Nov 2015 09:47:37 +0100	[thread overview]
Message-ID: <20151116094737.270168cc@mschwide> (raw)
In-Reply-To: <201511131414.tADEE1co028795@d06av10.portsmouth.uk.ibm.com>

On Fri, 13 Nov 2015 16:13:46 +0100
"Andreas Krebbel1" <Andreas.Krebbel@de.ibm.com> wrote:

> this appears to be the result of aligning struct page to more than 8 bytes 
> and putting it onto the stack - wich is only 8 bytes aligned.  The 
> compiler has to perform runtime alignment to achieve that. It allocates 
> memory using *alloca* and does the math with the returned pointer. Our 
> dynamic stack allocation option basically only checks if there is an 
> alloca user.

I can confirm that this is caused by the struct page alignment, if I
force HAVE_ALIGNED_STRUCT_PAGE=n the warning vanishes.

-- 
blue skies,
   Martin.

"Reality continues to ruin my life." - Calvin.

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      parent reply	other threads:[~2015-11-16  8:47 UTC|newest]

Thread overview: 8+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2015-11-11  6:34 [linux-next:master 12891/13017] mm/slub.c:2396:1: warning: '___slab_alloc' uses dynamic stack allocation kbuild test robot
2015-11-11 20:41 ` Andrew Morton
2015-11-13 11:52   ` Martin Schwidefsky
2015-11-13 15:13     ` Andreas Krebbel1
     [not found]     ` <201511131513.tADFDwJN030997@d06av03.portsmouth.uk.ibm.com>
2015-11-13 15:22       ` Christoph Lameter
2015-11-13 15:32         ` Andreas Krebbel1
     [not found]         ` <201511131532.tADFWgYs000305@d06av09.portsmouth.uk.ibm.com>
2015-11-13 17:05           ` Christoph Lameter
     [not found]     ` <201511131414.tADEE1co028795@d06av10.portsmouth.uk.ibm.com>
2015-11-16  8:47       ` Martin Schwidefsky [this message]

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