From: Michal Hocko <mhocko@kernel.org>
To: Baoquan He <bhe@redhat.com>
Cc: linux-kernel@vger.kernel.org, linux-mm@kvack.org,
akpm@linux-foundation.org, richardw.yang@linux.intel.com,
david@redhat.com, osalvador@suse.de, dan.j.williams@intel.com,
rppt@linux.ibm.com, robin.murphy@arm.com
Subject: Re: [PATCH v2 0/7] mm/hotplug: Only use subsection map in VMEMMAP case
Date: Thu, 20 Feb 2020 11:38:49 +0100 [thread overview]
Message-ID: <20200220103849.GG20509@dhcp22.suse.cz> (raw)
In-Reply-To: <20200220043316.19668-1-bhe@redhat.com>
On Thu 20-02-20 12:33:09, Baoquan He wrote:
> Memory sub-section hotplug was added to fix the issue that nvdimm could
> be mapped at non-section aligned starting address. A subsection map is
> added into struct mem_section_usage to implement it. However, sub-section
> is only supported in VMEMMAP case.
Why? Is there any fundamental reason or just a lack of implementation?
VMEMMAP should be really only an implementation detail unless I am
missing something subtle.
> Hence there's no need to operate
> subsection map in SPARSEMEM|!VMEMMAP case. In this patchset, change
> codes to make sub-section map and the relevant operation only available
> in VMEMMAP case.
>
> And since sub-section hotplug added, the hot add/remove functionality
> have been broken in SPARSEMEM|!VMEMMAP case. Wei Yang and I, each of us
> make one patch to fix one of the failures. In this patchset, the patch
> 1/7 from me is used to fix the hot remove failure. Wei Yang's patch has
> been merged by Andrew.
Not sure I understand. Are there more issues to be fixed?
> include/linux/mmzone.h | 2 +
> mm/sparse.c | 178 +++++++++++++++++++++++++++++------------
> 2 files changed, 127 insertions(+), 53 deletions(-)
Why do we need to add so much code to remove a functionality from one
memory model?
--
Michal Hocko
SUSE Labs
next prev parent reply other threads:[~2020-02-20 10:38 UTC|newest]
Thread overview: 46+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-02-20 4:33 [PATCH v2 0/7] mm/hotplug: Only use subsection map in VMEMMAP case Baoquan He
2020-02-20 4:33 ` [PATCH v2 1/7] mm/hotplug: fix hot remove failure in SPARSEMEM|!VMEMMAP case Baoquan He
2020-02-20 6:11 ` Wei Yang
2020-02-20 12:07 ` David Hildenbrand
2020-02-26 12:31 ` David Hildenbrand
2020-02-26 13:07 ` Baoquan He
2020-02-26 18:09 ` Dan Williams
2020-02-26 18:09 ` Dan Williams
2020-03-03 8:34 ` David Hildenbrand
2020-03-03 8:39 ` Baoquan He
2020-02-20 4:33 ` [PATCH v2 2/7] mm/sparse.c: introduce new function fill_subsection_map() Baoquan He
2020-02-20 6:14 ` Wei Yang
2020-02-28 14:27 ` David Hildenbrand
2020-03-01 4:59 ` Baoquan He
2020-02-20 4:33 ` [PATCH v2 3/7] mm/sparse.c: introduce a new function clear_subsection_map() Baoquan He
2020-02-20 6:15 ` Wei Yang
2020-02-28 14:36 ` David Hildenbrand
2020-03-01 5:20 ` Baoquan He
2020-03-02 15:43 ` David Hildenbrand
2020-03-03 1:53 ` Baoquan He
2020-03-03 8:22 ` Baoquan He
2020-03-03 8:33 ` David Hildenbrand
2020-03-03 8:38 ` Baoquan He
2020-02-20 4:33 ` [PATCH v2 4/7] mm/sparse.c: only use subsection map in VMEMMAP case Baoquan He
2020-02-20 6:17 ` Wei Yang
2020-02-25 9:57 ` Michal Hocko
2020-02-26 3:53 ` Baoquan He
2020-02-26 9:10 ` Michal Hocko
2020-02-28 7:25 ` Baoquan He
2020-02-20 4:33 ` [PATCH v2 5/7] mm/sparse.c: add code comment about sub-section hotplug Baoquan He
2020-02-20 4:33 ` [PATCH v2 6/7] mm/sparse.c: move subsection_map related codes together Baoquan He
2020-02-20 6:18 ` Wei Yang
2020-02-20 7:04 ` Baoquan He
2020-02-20 7:12 ` Wei Yang
2020-02-20 8:55 ` Baoquan He
2020-02-20 21:52 ` Wei Yang
2020-02-20 4:33 ` [PATCH v2 7/7] mm/sparse.c: Use __get_free_pages() instead in populate_section_memmap() Baoquan He
2020-02-20 10:38 ` Michal Hocko [this message]
2020-02-21 14:28 ` [PATCH v2 0/7] mm/hotplug: Only use subsection map in VMEMMAP case Baoquan He
2020-02-25 9:10 ` David Hildenbrand
2020-02-25 10:02 ` Michal Hocko
2020-02-26 3:42 ` Baoquan He
2020-02-26 9:14 ` Michal Hocko
2020-02-26 12:30 ` Baoquan He
2020-02-25 10:03 ` Michal Hocko
2020-02-26 3:44 ` Baoquan He
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