Messages in this thread | | | Date | Wed, 29 Jul 2009 12:32:09 +0900 | From | KAMEZAWA Hiroyuki <> | Subject | Re: [Bugme-new] [Bug 13850] New: reading /proc/kcore causes oops |
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On Tue, 28 Jul 2009 22:46:56 -0400 Mike Smith <scgtrp@gmail.com> wrote:
> > What's layout of memory does your server have ? > The log I gave was from my desktop, so I'll assume you wanted that > instead of the server: > [mike: mike in ~]$ grep "System RAM" /proc/iomem > 00010000-0009efff : System RAM > 00100000-1dedffff : System RAM > From this, your kernel's valid direct-map address range will be
c0010000-c009efff c0100000-ddedffff
And, == unable to handle kernel paging request at e07cf000 == e07cf000 doesn't exist in direct map. It seems this is vmalloc() area.
At looking into mm/vmalloc.c, this area is unmapped under - purge_lock But proc/kcore just access this just under vmlist_lock.
No guards at all. This is _a_ problem. But it seems race is not reproducable easily. I'll think more but is it guaranteed whether vmalloc area(struct vm_struct) linked to vmlist has always valid pages ? Considering get_vm_area(), it's not true I think.
I wonder fs/proc/kcore.c's vmalloc area access needs some fix. let me try.
Thanks, -Kame
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