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From: Michal Hocko <mhocko@kernel.org>
To: Mikhail Zaslonko <zaslonko@linux.ibm.com>,
	Mikhail Gavrilov <mikhail.v.gavrilov@gmail.com>
Cc: Andrew Morton <akpm@linux-foundation.org>,
	Pavel Tatashin <pasha.tatashin@soleen.com>,
	schwidefsky@de.ibm.com, heiko.carstens@de.ibm.com,
	gerald.schaefer@de.ibm.com, linux-mm@kvack.org,
	LKML <linux-kernel@vger.kernel.org>
Subject: [PATCH 0/2] mm, memory_hotplug: fix uninitialized pages fallouts.
Date: Mon, 28 Jan 2019 15:45:04 +0100	[thread overview]
Message-ID: <20190128144506.15603-1-mhocko@kernel.org> (raw)

Hi,
Mikhail has posted fixes for the two bugs quite some time ago [1]. I
have pushed back on those fixes because I believed that it is much
better to plug the problem at the initialization time rather than play
whack-a-mole all over the hotplug code and find all the places which
expect the full memory section to be initialized. We have ended up with
2830bf6f05fb ("mm, memory_hotplug: initialize struct pages for the full
memory section") merged and cause a regression [2][3]. The reason is
that there might be memory layouts when two NUMA nodes share the same
memory section so the merged fix is simply incorrect.

In order to plug this hole we really have to be zone range aware in
those handlers. I have split up the original patch into two. One is
unchanged (patch 2) and I took a different approach for `removable'
crash. It would be great if Mikhail could test it still works for his
memory layout.

[1] http://lkml.kernel.org/r/20181105150401.97287-2-zaslonko@linux.ibm.com
[2] https://bugzilla.redhat.com/show_bug.cgi?id=1666948
[3] http://lkml.kernel.org/r/20190125163938.GA20411@dhcp22.suse.cz

WARNING: multiple messages have this Message-ID (diff)
From: Michal Hocko <mhocko@kernel.org>
To: Mikhail Zaslonko <zaslonko@linux.ibm.com>,
	Mikhail Gavrilov <mikhail.v.gavrilov@gmail.com>
Cc: Andrew Morton <akpm@linux-foundation.org>,
	Pavel Tatashin <pasha.tatashin@soleen.com>,
	schwidefsky@de.ibm.com, heiko.carstens@de.ibm.com,
	gerald.schaefer@de.ibm.com, <linux-mm@kvack.org>,
	LKML <linux-kernel@vger.kernel.org>
Subject: [PATCH 0/2] mm, memory_hotplug: fix uninitialized pages fallouts.
Date: Mon, 28 Jan 2019 15:45:04 +0100	[thread overview]
Message-ID: <20190128144506.15603-1-mhocko@kernel.org> (raw)
Message-ID: <20190128144504.HSsPhVgCd8uzSWjRIFNcqTkZTrO1tUx_GpMmL3clqkI@z> (raw)

Hi,
Mikhail has posted fixes for the two bugs quite some time ago [1]. I
have pushed back on those fixes because I believed that it is much
better to plug the problem at the initialization time rather than play
whack-a-mole all over the hotplug code and find all the places which
expect the full memory section to be initialized. We have ended up with
2830bf6f05fb ("mm, memory_hotplug: initialize struct pages for the full
memory section") merged and cause a regression [2][3]. The reason is
that there might be memory layouts when two NUMA nodes share the same
memory section so the merged fix is simply incorrect.

In order to plug this hole we really have to be zone range aware in
those handlers. I have split up the original patch into two. One is
unchanged (patch 2) and I took a different approach for `removable'
crash. It would be great if Mikhail could test it still works for his
memory layout.

[1] http://lkml.kernel.org/r/20181105150401.97287-2-zaslonko@linux.ibm.com
[2] https://bugzilla.redhat.com/show_bug.cgi?id=1666948
[3] http://lkml.kernel.org/r/20190125163938.GA20411@dhcp22.suse.cz



             reply	other threads:[~2019-01-28 14:45 UTC|newest]

Thread overview: 21+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-01-28 14:45 Michal Hocko [this message]
2019-01-28 14:45 ` [PATCH 0/2] mm, memory_hotplug: fix uninitialized pages fallouts Michal Hocko
2019-01-28 14:45 ` [PATCH 1/2] mm, memory_hotplug: is_mem_section_removable do not pass the end of a zone Michal Hocko
2019-01-28 14:45   ` Michal Hocko
2019-01-29  9:06   ` Oscar Salvador
2019-01-29  9:12     ` Michal Hocko
2019-01-30  7:54       ` Oscar Salvador
2019-01-28 14:45 ` [PATCH 2/2] mm, memory_hotplug: test_pages_in_a_zone do not pass the end of zone Michal Hocko
2019-01-28 14:45   ` Michal Hocko
2019-01-29  9:09   ` Oscar Salvador
2019-01-29  9:13     ` Michal Hocko
2019-01-28 17:50 ` [PATCH 0/2] mm, memory_hotplug: fix uninitialized pages fallouts Andrew Morton
2019-01-28 17:50   ` Andrew Morton
2019-01-28 18:41   ` Michal Hocko
2019-01-28 18:45     ` Michal Hocko
2019-01-29 13:14 ` Gerald Schaefer
2019-01-29 13:49   ` Michal Hocko
2019-01-29 14:08     ` Gerald Schaefer
2019-01-29 17:38     ` Mikhail Gavrilov
2019-01-29 20:24       ` Michal Hocko
2019-01-29 20:56         ` Mikhail Gavrilov

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