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From: Michal Hocko <mhocko@kernel.org>
To: David Hildenbrand <david@redhat.com>
Cc: "Vlastimil Babka" <vbabka@suse.cz>,
	linux-mm@kvack.org, linux-kernel@vger.kernel.org,
	"Andrew Morton" <akpm@linux-foundation.org>,
	"Baoquan He" <bhe@redhat.com>, "Dave Young" <dyoung@redhat.com>,
	"Greg Kroah-Hartman" <gregkh@linuxfoundation.org>,
	"Hari Bathini" <hbathini@linux.vnet.ibm.com>,
	"Huang Ying" <ying.huang@intel.com>,
	"Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>,
	"Marc-André Lureau" <marcandre.lureau@redhat.com>,
	"Matthew Wilcox" <mawilcox@microsoft.com>,
	"Miles Chen" <miles.chen@mediatek.com>,
	"Pavel Tatashin" <pasha.tatashin@oracle.com>,
	"Petr Tesarik" <ptesarik@suse.cz>
Subject: Re: [PATCH v1 0/2] mm/kdump: exclude reserved pages in dumps
Date: Wed, 25 Jul 2018 15:51:47 +0200	[thread overview]
Message-ID: <20180725135147.GN28386@dhcp22.suse.cz> (raw)
In-Reply-To: <6c753cae-f8b6-5563-e5ba-7c1fefdeb74e@redhat.com>

On Tue 24-07-18 16:13:09, David Hildenbrand wrote:
[...]
> So I see right now:
> 
> - Pg_reserved + e.g. new page type (or some other unique identifier in
>   combination with Pg_reserved)
>  -> Avoid reads of pages we know are offline
> - extend is_ram_page()
>  -> Fake zero memory for pages we know are offline
> 
> Or even both (avoid reading and don't crash the kernel if it is being done).

I really fail to see how that can work without kernel being aware of
PageOffline. What will/should happen if you run an old kdump tool on a
kernel with this partially offline memory?
-- 
Michal Hocko
SUSE Labs

  reply	other threads:[~2018-07-25 13:51 UTC|newest]

Thread overview: 33+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-07-20 12:34 [PATCH v1 0/2] mm/kdump: exclude reserved pages in dumps David Hildenbrand
2018-07-20 12:34 ` [PATCH v1 1/2] mm: clarify semantics of reserved pages David Hildenbrand
2018-07-23 10:48   ` Michal Hocko
2018-07-20 12:34 ` [PATCH v1 2/2] kdump: include PG_reserved value in VMCOREINFO David Hildenbrand
2018-07-23 11:45 ` [PATCH v1 0/2] mm/kdump: exclude reserved pages in dumps Vlastimil Babka
2018-07-23 12:30   ` Michal Hocko
2018-07-23 17:20     ` David Hildenbrand
2018-07-24  7:25       ` Michal Hocko
2018-07-24  8:46         ` David Hildenbrand
2018-07-24  8:53           ` Michal Hocko
2018-07-24  9:18             ` David Hildenbrand
2018-07-24 12:17         ` David Hildenbrand
2018-07-24 13:13           ` Michal Hocko
2018-07-24 13:27             ` David Hildenbrand
2018-07-24 13:35               ` Michal Hocko
2018-07-24 14:13                 ` David Hildenbrand
2018-07-25 13:51                   ` Michal Hocko [this message]
2018-07-25 14:20                     ` David Hildenbrand
2018-07-26  8:27                       ` Michal Hocko
2018-07-26  8:37                         ` David Hildenbrand
2018-07-24  9:47     ` Vlastimil Babka
2018-07-24 11:19       ` Michal Hocko
2018-07-24 12:22         ` Vlastimil Babka
2018-07-24 12:33           ` David Hildenbrand
2018-07-24 13:06           ` Michal Hocko
2018-07-23 17:12   ` David Hildenbrand
2018-07-24  7:22     ` Michal Hocko
2018-07-24  9:48       ` Vlastimil Babka
2018-07-26  8:22       ` David Hildenbrand
2018-07-26  8:30         ` Michal Hocko
2018-07-26  8:45           ` David Hildenbrand
2018-07-26 19:50             ` Andrew Morton
2018-07-30  8:17               ` David Hildenbrand

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