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From: Andrew Morton <akpm@osdl.org>
To: Eric Dumazet <dada1@cosmosbay.com>
Cc: bcrl@kvack.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH, V2] i386: instead of poisoning .init zone, change protection bits to force a fault
Date: Mon, 6 Feb 2006 02:16:39 -0800	[thread overview]
Message-ID: <20060206021639.2e9d9157.akpm@osdl.org> (raw)
In-Reply-To: <43E71FEC.6020506@cosmosbay.com>

Eric Dumazet <dada1@cosmosbay.com> wrote:
>
> Andrew Morton a écrit :
> 
> > But I'm inclined to drop the whole patch - I don't see how it can detect
> > any bugs which CONFIG_DEBUG_PAGEALLOC won't find.
> > 
> 
> If CONFIG_DEBUG_PAGEALLOC is selected, does a page freed by free_page(addr); 
> guaranted not being reused later ?

No.

So with your patch, any access to the freed page will oops.  With
CONFIG_DEBUG_PAGEALLOC it'll only oops if that page is presently free.

So if enough people run with CONFIG_DEBUG_PAGEALLOC for enough time, we'll
find the same bugs.

> Anyway, the CONFIG_DEBUG_INITDATA was a temporary patch in order to track the 
> accesses to non possible cpus percpu data. So if you feel all such accesses 
> were cleaned, we can drop the patch...

I think so..

      reply	other threads:[~2006-02-06 10:17 UTC|newest]

Thread overview: 20+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2006-01-29  6:26 [PATCH] i386: Add a temporary to make put_user more type safe Eric W. Biederman
2006-01-29  6:39 ` Andrew Morton
2006-01-29  6:49   ` Eric W. Biederman
2006-01-29  7:51     ` Andrew Morton
     [not found]       ` <200601291620.28291.ioe-lkml@rameria.de>
2006-01-29 19:33         ` Andrew Morton
2006-01-29 20:04           ` [PATCH] i386: instead of poisoning .init zone, change protection bits to force a fault Eric Dumazet
2006-01-29 20:05             ` Benjamin LaHaise
2006-01-29 20:28               ` Eric Dumazet
2006-01-29 20:56               ` [PATCH, V2] " Eric Dumazet
2006-01-30  9:03                 ` Questions about alloc_large_system_hash() and TLB entries Eric Dumazet
2006-01-30  9:22                   ` David S. Miller
2006-01-30 10:22                     ` Eric Dumazet
2006-02-04 22:41                 ` [PATCH, V2] i386: instead of poisoning .init zone, change protection bits to force a fault Andrew Morton
2006-02-05 17:03                   ` Eric Dumazet
2006-02-05 19:42                     ` Andrew Morton
2006-02-06  8:53                       ` Eric Dumazet
2006-02-06  9:02                   ` Eric Dumazet
2006-02-06  9:28                     ` Andrew Morton
2006-02-06 10:07                       ` Eric Dumazet
2006-02-06 10:16                         ` Andrew Morton [this message]

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