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Old 02-28-2011, 09:15 PM
Dave Anderson
 
Default Crash physical search on live session not recommended :-)

----- Original Message -----
>
> crash> help -v
> ... [ cut ] ...
> numnodes: 1
> nr_zones: 4
> nr_free_areas: 11
> node_table[0]:
> id: 0
> pgdat: ffff81000000b000
> size: 261642
> present: 256704
> mem_map: ffff8100006e6000
> start_paddr: 0
> start_mapnr: 0
> dump_free_pages: dump_free_pages_zones_v2()
> dump_kmem_cache: dump_kmem_cache_percpu_v2()
> ...

>
> But doing the phys_to_page() before the read seems reasonable.

Although, it may not make a difference at all. On the system
above, all of the pages in the node have page structures
associated with them, even with SPARSEMEM_EX, so it doesn't
make a difference. And if I search just the unity-map region,
the CRASHDEBUG(1) output is identical with respect to the
number of pages read vs. checked.

Dave

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Old 03-01-2011, 12:05 AM
Bob Montgomery
 
Default Crash physical search on live session not recommended :-)

On Tue, 2011-03-01 at 00:13 +0000, Montgomery, Bob wrote:
> On Mon, 2011-02-28 at 21:59 +0000, Dave Anderson wrote:
> >
> > ----- Original Message -----
> > > On Thu, 2011-02-24 at 15:18 +0000, Dave Anderson wrote:
> > > >
> > > > ----- Original Message -----
> > > > > While testing my search patch, I kicked off an unconstrained physical
> > > > > search on a live session and hung the machine so thoroughly that it
> > > > > required a visit to the machine room to physically unplug it to get the
> > > > > remote console back up. Coincidence? Or should physical address search
> > > > > on a live session be constrained somehow for safety?

>
> I'm guessing that's bad :-) I'll implement the rejector code in the
> physical search, and see if I can avoid a trip to the machine room.

Something like this? It seems to be surviving physical searches on my
live session now. Any reason this would thwart the purpose of the
physical search in any way? "But I wanted to search pci space..."

Bob Montgomery
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Old 03-01-2011, 01:08 PM
Dave Anderson
 
Default Crash physical search on live session not recommended :-)

----- Original Message -----
> On Tue, 2011-03-01 at 00:13 +0000, Montgomery, Bob wrote:
> > On Mon, 2011-02-28 at 21:59 +0000, Dave Anderson wrote:
> > >
> > > ----- Original Message -----
> > > > On Thu, 2011-02-24 at 15:18 +0000, Dave Anderson wrote:
> > > > >
> > > > > ----- Original Message -----
> > > > > > While testing my search patch, I kicked off an unconstrained physical
> > > > > > search on a live session and hung the machine so thoroughly that it
> > > > > > required a visit to the machine room to physically unplug it to get the
> > > > > > remote console back up. Coincidence? Or should physical address search
> > > > > > on a live session be constrained somehow for safety?
>
> >
> > I'm guessing that's bad :-) I'll implement the rejector code in the
> > physical search, and see if I can avoid a trip to the machine room.
>
> Something like this? It seems to be surviving physical searches on my
> live session now. Any reason this would thwart the purpose of the
> physical search in any way? "But I wanted to search pci space..."

Nah -- it's meant for physical memory only.

Queued for version 5.1.3.

Thanks,
Dave

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