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From: Michal Hocko <mhocko@suse.com>
To: David Hildenbrand <david@redhat.com>
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>,
	Mike Rapoport <rppt@kernel.org>,
	"Matthew Wilcox (Oracle)" <willy@infradead.org>,
	Oscar Salvador <osalvador@suse.de>, 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 3/7] mm: rename and move page_is_poisoned()
Date: Wed, 5 May 2021 15:13:11 +0200	[thread overview]
Message-ID: <YJKZ5yXdl18m9YSM@dhcp22.suse.cz> (raw)
In-Reply-To: <20210429122519.15183-4-david@redhat.com>

On Thu 29-04-21 14:25:15, David Hildenbrand wrote:
> Commit d3378e86d182 ("mm/gup: check page posion status for coredump.")
> introduced page_is_poisoned(), however, v5 [1] of the patch used
> "page_is_hwpoison()" and something went wrong while upstreaming. Rename the
> function and move it to page-flags.h, from where it can be used in other
> -- kcore -- context.
> 
> Move the comment to the place where it belongs and simplify.
> 
> [1] https://lkml.kernel.org/r/20210322193318.377c9ce9@alex-virtual-machine
> 
> Signed-off-by: David Hildenbrand <david@redhat.com>

I do agree that being explicit about hwpoison is much better. Poisoned
page can be also an unitialized one and I believe this is the reason why
you are bringing that up.

But you've made me look at d3378e86d182 and I am wondering whether this
is really a valid patch. First of all it can leak a reference count
AFAICS. Moreover it doesn't really fix anything because the page can be
marked hwpoison right after the check is done. I do not think the race
is feasible to be closed. So shouldn't we rather revert it?

-- 
Michal Hocko
SUSE Labs

  parent reply	other threads:[~2021-05-05 13:13 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 [this message]
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
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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