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From: Manfred Spraul <manfred@colorfullife.com>
To: Ingo Molnar <mingo@elte.hu>
Cc: linux-kernel@vger.kernel.org, Andrew Morton <akpm@osdl.org>,
	Alexander Viro <viro@math.psu.edu>
Subject: Re: 4GB+DEBUG_PAGEALLOC oopses with 2.6.0-test3-mm1
Date: Mon, 11 Aug 2003 17:22:31 +0200	[thread overview]
Message-ID: <3F37B4B7.9010108@colorfullife.com> (raw)
In-Reply-To: <Pine.LNX.4.56.0308111024330.19887@localhost.localdomain>

Ingo Molnar wrote:

>(in theory it's possible that kernel-internal mounts pass in a pointer
>where pointer + PAGE_SIZE is not a valid kernel address - if this happens
>then we'd get a hard crash.)
>  
>
Exactly that happens.
I'm running with CONFIG_PAGE_DEBUG, i.e. unallocated pages are marked as 
non-present in the linear mapping.

Regarding the i386 trap handler: show_registers tries to hexdump the 
current instructions. It did a __get_user, to avoid causing a fault when 
%eip is invalid.
Now it contains:

>      if ((user_mode(regs) && get_user(c, eip)) ||
>           (!user_mode(regs) && __direct_get_user(c, eip))) {
>              printk(" Bad EIP value.");
>              break;
>      }

I.e. it's already fixed.

--
    Manfred


  reply	other threads:[~2003-08-11 15:23 UTC|newest]

Thread overview: 8+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2003-08-10 10:33 4GB+DEBUG_PAGEALLOC oopses with 2.6.0-test3-mm1 Manfred Spraul
2003-08-11  8:56 ` Ingo Molnar
2003-08-11 15:22   ` Manfred Spraul [this message]
2003-08-11 15:24     ` Ingo Molnar
2003-08-11 16:05       ` Manfred Spraul
2003-08-11 17:19         ` Ingo Molnar
2003-08-11 18:01           ` Manfred Spraul
2003-08-11  9:00 ` Ingo Molnar

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