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Subject: Re: introducing __GFP_PANIC
From: Pekka Enberg <penberg@cs.helsinki.fi>
To: Cyrill Gorcunov <gorcunov@gmail.com>
Cc: David Rientjes <rientjes@google.com>, Ingo Molnar <mingo@elte.hu>,
       Jack Steiner <steiner@sgi.com>,
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Date: Mon, 04 May 2009 12:56:09 +0300
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On Mon, 2009-05-04 at 12:49 +0400, Cyrill Gorcunov wrote:
> | __GFP_PANIC is an annotation saying that it's okay for a particular
> | call-site not to check for NULL because we never expect to run out of
> | memory at that point. But we don't really need to panic() for all the
> | possible *errors*, just for the out-of-memory case.
> | 
> | 			Pekka
> | 
> 
> Which means, __GFP_PANIC will not grant the guarantee to a caller
> that he will not get NULL deref even with __GFP_PANIC specified?

Yes, __GFP_PANIC will guarantee that you never return NULL for
_out-of-memory_ but makes no guarantees what happens if you pass bogus
size or order.