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From: David Hildenbrand <david@redhat.com>
To: Mike Rapoport <rppt@kernel.org>
Cc: linux-kernel@vger.kernel.org,
	Andrew Morton <akpm@linux-foundation.org>,
	"Michael S. Tsirkin" <mst@redhat.com>,
	Jason Wang <jasowang@redhat.com>,
	Alexey Dobriyan <adobriyan@gmail.com>,
	"Matthew Wilcox (Oracle)" <willy@infradead.org>,
	Oscar Salvador <osalvador@suse.de>,
	Michal Hocko <mhocko@suse.com>, Roman Gushchin <guro@fb.com>,
	Alex Shi <alex.shi@linux.alibaba.com>,
	Steven Price <steven.price@arm.com>,
	Mike Kravetz <mike.kravetz@oracle.com>,
	Aili Yao <yaoaili@kingsoft.com>, Jiri Bohac <jbohac@suse.cz>,
	"K. Y. Srinivasan" <kys@microsoft.com>,
	Haiyang Zhang <haiyangz@microsoft.com>,
	Stephen Hemminger <sthemmin@microsoft.com>,
	Wei Liu <wei.liu@kernel.org>,
	Naoya Horiguchi <naoya.horiguchi@nec.com>,
	linux-hyperv@vger.kernel.org,
	virtualization@lists.linux-foundation.org,
	linux-fsdevel@vger.kernel.org, linux-mm@kvack.org
Subject: Re: [PATCH v1 5/7] mm: introduce page_offline_(begin|end|freeze|unfreeze) to synchronize setting PageOffline()
Date: Mon, 3 May 2021 10:11:29 +0200	[thread overview]
Message-ID: <4aa55978-c224-7ead-f00d-df1a6c3dfda4@redhat.com> (raw)
In-Reply-To: <YI5Hp49AmWgfTzNy@kernel.org>

On 02.05.21 08:33, Mike Rapoport wrote:
> On Thu, Apr 29, 2021 at 02:25:17PM +0200, David Hildenbrand wrote:
>> A driver might set a page logically offline -- PageOffline() -- and
>> turn the page inaccessible in the hypervisor; after that, access to page
>> content can be fatal. One example is virtio-mem; while unplugged memory
>> -- marked as PageOffline() can currently be read in the hypervisor, this
>> will no longer be the case in the future; for example, when having
>> a virtio-mem device backed by huge pages in the hypervisor.
>>
>> Some special PFN walkers -- i.e., /proc/kcore -- read content of random
>> pages after checking PageOffline(); however, these PFN walkers can race
>> with drivers that set PageOffline().
>>
>> Let's introduce page_offline_(begin|end|freeze|unfreeze) for
> 
> Bikeshed: freeze|thaw?
>

Sure :)


-- 
Thanks,

David / dhildenb


WARNING: multiple messages have this Message-ID (diff)
From: David Hildenbrand <david@redhat.com>
To: Mike Rapoport <rppt@kernel.org>
Cc: Aili Yao <yaoaili@kingsoft.com>, Michal Hocko <mhocko@suse.com>,
	"Michael S. Tsirkin" <mst@redhat.com>,
	linux-hyperv@vger.kernel.org,
	virtualization@lists.linux-foundation.org, linux-mm@kvack.org,
	Wei Liu <wei.liu@kernel.org>,
	Alex Shi <alex.shi@linux.alibaba.com>,
	Stephen Hemminger <sthemmin@microsoft.com>,
	"Matthew Wilcox \(Oracle\)" <willy@infradead.org>,
	Steven Price <steven.price@arm.com>,
	Alexey Dobriyan <adobriyan@gmail.com>,
	Jiri Bohac <jbohac@suse.cz>,
	Haiyang Zhang <haiyangz@microsoft.com>,
	Oscar Salvador <osalvador@suse.de>,
	Naoya Horiguchi <naoya.horiguchi@nec.com>,
	linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org,
	Andrew Morton <akpm@linux-foundation.org>,
	Roman Gushchin <guro@fb.com>,
	Mike Kravetz <mike.kravetz@oracle.com>
Subject: Re: [PATCH v1 5/7] mm: introduce page_offline_(begin|end|freeze|unfreeze) to synchronize setting PageOffline()
Date: Mon, 3 May 2021 10:11:29 +0200	[thread overview]
Message-ID: <4aa55978-c224-7ead-f00d-df1a6c3dfda4@redhat.com> (raw)
In-Reply-To: <YI5Hp49AmWgfTzNy@kernel.org>

On 02.05.21 08:33, Mike Rapoport wrote:
> On Thu, Apr 29, 2021 at 02:25:17PM +0200, David Hildenbrand wrote:
>> A driver might set a page logically offline -- PageOffline() -- and
>> turn the page inaccessible in the hypervisor; after that, access to page
>> content can be fatal. One example is virtio-mem; while unplugged memory
>> -- marked as PageOffline() can currently be read in the hypervisor, this
>> will no longer be the case in the future; for example, when having
>> a virtio-mem device backed by huge pages in the hypervisor.
>>
>> Some special PFN walkers -- i.e., /proc/kcore -- read content of random
>> pages after checking PageOffline(); however, these PFN walkers can race
>> with drivers that set PageOffline().
>>
>> Let's introduce page_offline_(begin|end|freeze|unfreeze) for
> 
> Bikeshed: freeze|thaw?
>

Sure :)


-- 
Thanks,

David / dhildenb

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Virtualization@lists.linux-foundation.org
https://lists.linuxfoundation.org/mailman/listinfo/virtualization

  reply	other threads:[~2021-05-03  8:11 UTC|newest]

Thread overview: 54+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-04-29 12:25 [PATCH v1 0/7] fs/proc/kcore: don't read offline sections, logically offline pages and hwpoisoned pages David Hildenbrand
2021-04-29 12:25 ` David Hildenbrand
2021-04-29 12:25 ` [PATCH v1 1/7] fs/proc/kcore: drop KCORE_REMAP and KCORE_OTHER David Hildenbrand
2021-04-29 12:25   ` David Hildenbrand
2021-05-02  6:31   ` Mike Rapoport
2021-04-29 12:25 ` [PATCH v1 2/7] fs/proc/kcore: pfn_is_ram check only applies to KCORE_RAM David Hildenbrand
2021-04-29 12:25   ` David Hildenbrand
2021-05-02  6:31   ` Mike Rapoport
2021-04-29 12:25 ` [PATCH v1 3/7] mm: rename and move page_is_poisoned() David Hildenbrand
2021-04-29 12:25   ` David Hildenbrand
2021-05-02  6:32   ` Mike Rapoport
2021-05-05 13:13   ` Michal Hocko
2021-05-05 13:17     ` David Hildenbrand
2021-05-05 13:17       ` David Hildenbrand
2021-05-05 13:27       ` Michal Hocko
2021-05-05 13:39         ` David Hildenbrand
2021-05-05 13:39           ` David Hildenbrand
2021-05-05 13:45           ` Michal Hocko
2021-05-06  1:08             ` Aili Yao
2021-05-06  0:56         ` Aili Yao
2021-05-06  7:06           ` Michal Hocko
2021-05-06  7:28             ` Aili Yao
2021-05-06  7:55               ` Michal Hocko
2021-05-06  8:52                 ` Aili Yao
2021-04-29 12:25 ` [PATCH v1 4/7] fs/proc/kcore: don't read offline sections, logically offline pages and hwpoisoned pages David Hildenbrand
2021-04-29 12:25   ` David Hildenbrand
2021-05-02  6:32   ` Mike Rapoport
2021-04-29 12:25 ` [PATCH v1 5/7] mm: introduce page_offline_(begin|end|freeze|unfreeze) to synchronize setting PageOffline() David Hildenbrand
2021-04-29 12:25   ` David Hildenbrand
2021-05-02  6:33   ` Mike Rapoport
2021-05-03  8:11     ` David Hildenbrand [this message]
2021-05-03  8:11       ` David Hildenbrand
2021-05-05 13:24   ` Michal Hocko
2021-05-05 15:10     ` David Hildenbrand
2021-05-05 15:10       ` David Hildenbrand
2021-05-05 17:41       ` Mike Rapoport
2021-04-29 12:25 ` [PATCH v1 6/7] virtio-mem: use page_offline_(start|end) when " David Hildenbrand
2021-04-29 12:25   ` David Hildenbrand
2021-05-02  6:33   ` Mike Rapoport
2021-05-03  8:16     ` David Hildenbrand
2021-05-03  8:16       ` David Hildenbrand
2021-05-03  8:23   ` Michael S. Tsirkin
2021-05-03  8:23     ` Michael S. Tsirkin
2021-04-29 12:25 ` [PATCH v1 7/7] fs/proc/kcore: use page_offline_(freeze|unfreeze) David Hildenbrand
2021-04-29 12:25   ` David Hildenbrand
2021-05-02  6:34   ` Mike Rapoport
2021-05-03  8:28     ` David Hildenbrand
2021-05-03  8:28       ` David Hildenbrand
2021-05-03  9:28       ` Mike Rapoport
2021-05-03 10:13         ` David Hildenbrand
2021-05-03 10:13           ` David Hildenbrand
2021-05-03 11:33           ` Mike Rapoport
2021-05-03 11:35             ` David Hildenbrand
2021-05-03 11:35               ` David Hildenbrand

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