From: Vlastimil Babka <vbabka@suse.cz>
To: Michal Hocko <mhocko@kernel.org>
Cc: Andrew Morton <akpm@linux-foundation.org>,
linux-mm@kvack.org, Mel Gorman <mgorman@suse.de>,
Andrea Arcangeli <aarcange@redhat.com>,
Jerome Glisse <jglisse@redhat.com>,
Reza Arbab <arbab@linux.vnet.ibm.com>,
Yasuaki Ishimatsu <yasu.isimatu@gmail.com>,
qiuxishi@huawei.com, Kani Toshimitsu <toshi.kani@hpe.com>,
slaoub@gmail.com, Joonsoo Kim <js1304@gmail.com>,
Andi Kleen <ak@linux.intel.com>,
David Rientjes <rientjes@google.com>,
Daniel Kiper <daniel.kiper@oracle.com>,
Igor Mammedov <imammedo@redhat.com>,
Vitaly Kuznetsov <vkuznets@redhat.com>,
LKML <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH 07/14] mm: consider zone which is not fully populated to have holes
Date: Fri, 19 May 2017 09:21:20 +0200 [thread overview]
Message-ID: <3d5d4d0b-bc5e-dbb5-de68-f4ea31abb38c@suse.cz> (raw)
In-Reply-To: <20170518164210.GD18333@dhcp22.suse.cz>
On 05/18/2017 06:42 PM, Michal Hocko wrote:
> On Thu 18-05-17 18:14:39, Vlastimil Babka wrote:
>> On 05/15/2017 10:58 AM, Michal Hocko wrote:
> [...]
>>> #ifdef CONFIG_MEMORY_HOTPLUG
>>> +/*
>>> + * Return page for the valid pfn only if the page is online. All pfn
>>> + * walkers which rely on the fully initialized page->flags and others
>>> + * should use this rather than pfn_valid && pfn_to_page
>>> + */
>>> +#define pfn_to_online_page(pfn) \
>>> +({ \
>>> + struct page *___page = NULL; \
>>> + \
>>> + if (online_section_nr(pfn_to_section_nr(pfn))) \
>>> + ___page = pfn_to_page(pfn); \
>>> + ___page; \
>>> +})
>>
>> This seems to be already assuming pfn_valid() to be true. There's no
>> "pfn_to_section_nr(pfn) >= NR_MEM_SECTIONS" check and the comment
>> suggests as such, but...
>
> Yes, we should check the validity of the section number. We do not have
> to check whether the section is valid because online sections are a
> subset of those that are valid.
>
>>> diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c
>>> index 05796ee974f7..c3a146028ba6 100644
>>> --- a/mm/memory_hotplug.c
>>> +++ b/mm/memory_hotplug.c
>>> @@ -929,6 +929,9 @@ static int online_pages_range(unsigned long start_pfn, unsigned long nr_pages,
>>> unsigned long i;
>>> unsigned long onlined_pages = *(unsigned long *)arg;
>>> struct page *page;
>>> +
>>> + online_mem_sections(start_pfn, start_pfn + nr_pages);
>>
>> Shouldn't this be moved *below* the loop that initializes struct pages?
>> In the offline case you do mark sections offline before "tearing" struct
>> pages, so that should be symmetric.
>
> You are right! Andrew, could you fold the following intot the patch?
> ---
> From 0550b61203d6970b47fd79f5e6372dccd143cbec Mon Sep 17 00:00:00 2001
> From: Michal Hocko <mhocko@suse.com>
> Date: Thu, 18 May 2017 18:38:24 +0200
> Subject: [PATCH] fold me "mm: consider zone which is not fully populated to
> have holes"
>
> - check valid section number in pfn_to_online_page - Vlastimil
> - mark sections online after all struct pages are initialized in
> online_pages_range - Vlastimil
>
> Signed-off-by: Michal Hocko <mhocko@suse.com>
Both the patch and fix:
Acked-by: Vlastimil Babka <vbabka@suse.cz>
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next prev parent reply other threads:[~2017-05-19 7:21 UTC|newest]
Thread overview: 41+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-05-15 8:58 [PATCH -v4 0/14] mm: make movable onlining suck less Michal Hocko
2017-05-15 8:58 ` [PATCH 01/14] mm: remove return value from init_currently_empty_zone Michal Hocko
2017-05-15 8:58 ` [PATCH 02/14] mm, memory_hotplug: use node instead of zone in can_online_high_movable Michal Hocko
2017-05-15 8:58 ` [PATCH 03/14] mm: drop page_initialized check from get_nid_for_pfn Michal Hocko
2017-05-15 8:58 ` [PATCH 04/14] mm, memory_hotplug: get rid of is_zone_device_section Michal Hocko
2017-06-10 9:56 ` Wei Yang
2017-06-10 14:58 ` Wei Yang
2017-06-12 6:49 ` Michal Hocko
2017-06-14 6:17 ` Wei Yang
2017-06-14 6:12 ` Wei Yang
2017-06-14 6:32 ` Michal Hocko
2017-06-14 9:12 ` Wei Yang
2017-06-14 9:24 ` Michal Hocko
2017-06-15 1:02 ` Wei Yang
2017-05-15 8:58 ` [PATCH 05/14] mm, memory_hotplug: split up register_one_node Michal Hocko
2017-05-15 8:58 ` [PATCH 06/14] mm, memory_hotplug: consider offline memblocks removable Michal Hocko
2017-05-15 8:58 ` [PATCH 07/14] mm: consider zone which is not fully populated to have holes Michal Hocko
2017-05-18 16:14 ` Vlastimil Babka
2017-05-18 16:42 ` Michal Hocko
2017-05-19 7:21 ` Vlastimil Babka [this message]
2017-05-15 8:58 ` [PATCH 08/14] mm, compaction: skip over holes in __reset_isolation_suitable Michal Hocko
2017-05-19 7:23 ` Vlastimil Babka
2017-05-15 8:58 ` [PATCH 09/14] mm: __first_valid_page skip over offline pages Michal Hocko
2017-05-19 8:05 ` Vlastimil Babka
2017-05-15 8:58 ` [PATCH 10/14] mm, vmstat: skip reporting offline pages in pagetypeinfo Michal Hocko
2017-05-19 8:17 ` Vlastimil Babka
2017-05-15 8:58 ` [PATCH 11/14] mm, memory_hotplug: do not associate hotadded memory to zones until online Michal Hocko
2017-05-19 8:56 ` Vlastimil Babka
2017-06-16 4:20 ` Wei Yang
2017-06-16 8:05 ` Michal Hocko
2017-06-16 8:11 ` Wei Yang
2017-06-16 8:45 ` Michal Hocko
2017-06-16 9:11 ` Wei Yang
2017-06-25 0:14 ` Wei Yang
2017-06-26 5:38 ` Michal Hocko
2017-05-15 8:58 ` [PATCH 12/14] mm, memory_hotplug: replace for_device by want_memblock in arch_add_memory Michal Hocko
2017-05-15 8:58 ` [PATCH 13/14] mm, memory_hotplug: fix the section mismatch warning Michal Hocko
2017-05-15 8:58 ` [PATCH 14/14] mm, memory_hotplug: remove unused cruft after memory hotplug rework Michal Hocko
2017-06-09 9:51 ` [PATCH -v4 0/14] mm: make movable onlining suck less Wei Yang
2017-06-09 10:49 ` Michal Hocko
2017-06-10 2:20 ` Wei Yang
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