From: David Hildenbrand <david@redhat.com>
To: Michal Hocko <mhocko@suse.com>
Cc: Dan Williams <dan.j.williams@intel.com>,
linux-mm@kvack.org, LKML <linux-kernel@vger.kernel.org>,
Oscar Salvador <osalvador@suse.de>
Subject: Re: uninitialized pmem struct pages
Date: Mon, 4 Jan 2021 17:30:48 +0100 [thread overview]
Message-ID: <a2e8f11a-24b0-5d30-2d8f-1940b268392c@redhat.com> (raw)
In-Reply-To: <20210104155931.GN13207@dhcp22.suse.cz>
>> Let's assume this is indeed a reserved pfn in the altmap. What's the
>> actual address of the memmap?
>
> Not sure what exactly you are asking for but crash says
> crash> kmem -p 6060000
> PAGE PHYSICAL MAPPING INDEX CNT FLAGS
> fffff8c600181800 6060000 0 0 0 fffffc0000000
^ this looks like it was somewhat initialized. All flags zero, nid/zone
set to -1 (wild guess) and thus the crash? weird
>
>> I do wonder what hosts pfn_to_page(PHYS_PFN(0x6060000)) - is it actually
>> part of the actual altmap (i.e. > 0x6060000) or maybe even self-hosted?
>
> I am not really familiar with the pmem so I would need more assistance
> here. I've tried this (shot into the dark):
> crash> struct page.pgmap fffff8c600181800
> pgmap = 0xfffff8c600181808
That's weird. If the memmap is at fffff8c600181800, why should the pgmap
be at an offset of 8 bytes from there. The "pgmap" field is actually at
an offset of 8 bytes within the memmap ...
Assuming the memmap is not actually ZONE_DEVICE, fffff8c600181800 really
only contains garbage, including the pgmap pointer :(
> crash> struct -x dev_pagemap 0xfffff8c600181808
> struct dev_pagemap {
> altmap = {
> base_pfn = 0xfffff8c600181808,
> end_pfn = 0xfffff8c600181808,
^ because this is very weird
> reserve = 0x0,
^ and this indicates nothing was actually reserved.
--
Thanks,
David / dhildenb
next prev parent reply other threads:[~2021-01-04 16:31 UTC|newest]
Thread overview: 32+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-01-04 10:03 Michal Hocko
2021-01-04 10:45 ` David Hildenbrand
2021-01-04 14:26 ` Michal Hocko
2021-01-04 14:51 ` David Hildenbrand
2021-01-04 15:10 ` Michal Hocko
2021-01-04 15:15 ` David Hildenbrand
2021-01-04 15:33 ` Michal Hocko
2021-01-04 15:43 ` David Hildenbrand
2021-01-04 15:44 ` David Hildenbrand
2021-01-05 8:00 ` Michal Hocko
2021-01-05 8:16 ` Michal Hocko
2021-01-05 8:27 ` Dan Williams
2021-01-05 8:42 ` Michal Hocko
2021-01-05 8:57 ` Dan Williams
2021-01-05 9:05 ` Michal Hocko
2021-01-05 9:13 ` David Hildenbrand
2021-01-05 9:25 ` Michal Hocko
2021-01-05 9:27 ` David Hildenbrand
2021-01-04 15:59 ` Michal Hocko
2021-01-04 16:30 ` David Hildenbrand [this message]
2021-01-05 7:44 ` Michal Hocko
2021-01-05 9:56 ` David Hildenbrand
2021-01-05 5:33 ` Dan Williams
2021-01-05 7:40 ` Michal Hocko
2021-01-05 5:17 ` Dan Williams
2021-01-05 7:50 ` Michal Hocko
2021-01-05 9:16 ` David Hildenbrand
2021-01-05 9:25 ` David Hildenbrand
2021-01-05 9:33 ` Dan Williams
2021-01-05 9:37 ` David Hildenbrand
2021-01-05 9:56 ` Dan Williams
2021-01-05 9:58 ` David Hildenbrand
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