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Subject: Re: double fault
From: Martin Hunt <hunt@redhat.com>
To: Mathieu Desnoyers <compudj@krystal.dyndns.org>
Cc: "Stone, Joshua I" <joshua.i.stone@intel.com>,         "systemtap@sources.redhat.com" <systemtap@sources.redhat.com>
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Date: Wed, 23 Nov 2005 17:54:00 -0000
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On Wed, 2005-11-23 at 12:21 -0500, Mathieu Desnoyers wrote:
> * Martin Hunt (hunt@redhat.com) wrote:
> > I changed the code to use
> > vmalloc (we really want vmalloc_node() but RHEL4 doesn't have it) and
> > all the crashes stopped on every machine.
> > 
> 
> What are the flags used for the memory allocated by vmalloc ?

>From mm/vmalloc.c:
void *vmalloc(unsigned long size)
{
       return __vmalloc(size, GFP_KERNEL | __GFP_HIGHMEM, PAGE_KERNEL);
}


> Did you try : 
> 
> - allocating the memory with kmalloc instead of vmalloc ?

Why would I do that?  What would I look for?  vmalloc already works.

> - to see if there is a code path that goes from do_page_fault to sys_open ? I
>   would be surprised about it, but we never know...
I think we can assume that files aren't being opened in do_page_fault.
But I checked anyway and I don't see anything like that.

Martin