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From: David Hildenbrand <david@redhat.com>
To: Oscar Salvador <osalvador@suse.de>,
	Muchun Song <songmuchun@bytedance.com>
Cc: corbet@lwn.net, mike.kravetz@oracle.com, tglx@linutronix.de,
	mingo@redhat.com, bp@alien8.de, x86@kernel.org, hpa@zytor.com,
	dave.hansen@linux.intel.com, luto@kernel.org,
	peterz@infradead.org, viro@zeniv.linux.org.uk,
	akpm@linux-foundation.org, paulmck@kernel.org,
	mchehab+huawei@kernel.org, pawan.kumar.gupta@linux.intel.com,
	rdunlap@infradead.org, oneukum@suse.com,
	anshuman.khandual@arm.com, jroedel@suse.de,
	almasrymina@google.com, rientjes@google.com, willy@infradead.org,
	mhocko@suse.com, song.bao.hua@hisilicon.com,
	naoya.horiguchi@nec.com, duanxiongchun@bytedance.com,
	linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org,
	linux-mm@kvack.org, linux-fsdevel@vger.kernel.org
Subject: Re: [PATCH v13 05/12] mm: hugetlb: allocate the vmemmap pages associated with each HugeTLB page
Date: Tue, 26 Jan 2021 10:36:21 +0100	[thread overview]
Message-ID: <6fe52a7e-ebd8-f5ce-1fcd-5ed6896d3797@redhat.com> (raw)
In-Reply-To: <20210126092942.GA10602@linux>

On 26.01.21 10:29, Oscar Salvador wrote:
> On Sun, Jan 17, 2021 at 11:10:46PM +0800, Muchun Song wrote:
>> When we free a HugeTLB page to the buddy allocator, we should allocate the
>> vmemmap pages associated with it. We can do that in the __free_hugepage()
>> before freeing it to buddy.
>>
>> Signed-off-by: Muchun Song <songmuchun@bytedance.com>
> 
> This series has grown a certain grade of madurity and improvment, but it seems
> to me that we have been stuck in this patch (and patch#4) for quite some time.
> 
> Would it be acceptable for a first implementation to not let hugetlb pages to
> be freed when this feature is in use?
> This would simplify things for now, as we could get rid of patch#4 and patch#5.
> We can always extend functionality once this has been merged, right?

I think either keep it completely simple (only free vmemmap of hugetlb
pages allocated early during boot - which is what's not sufficient for
some use cases) or implement the full thing properly (meaning, solve
most challenging issues to get the basics running).

I don't want to have some easy parts of complex features merged (e.g.,
breaking other stuff as you indicate below), and later finding out "it's
not that easy" again and being stuck with it forever.

> 
> Of course, this means that e.g: memory-hotplug (hot-remove) will not fully work
> when this in place, but well.

Can you elaborate? Are we're talking about having hugepages in
ZONE_MOVABLE that are not migratable (and/or dissolvable) anymore? Than
a clear NACK from my side.

-- 
Thanks,

David / dhildenb


  reply	other threads:[~2021-01-26 14:52 UTC|newest]

Thread overview: 62+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-01-17 15:10 [PATCH v13 00/12] Free some vmemmap pages of HugeTLB page Muchun Song
2021-01-17 15:10 ` [PATCH v13 01/12] mm: memory_hotplug: factor out bootmem core functions to bootmem_info.c Muchun Song
2021-01-25  2:48   ` Miaohe Lin
2021-01-17 15:10 ` [PATCH v13 02/12] mm: hugetlb: introduce a new config HUGETLB_PAGE_FREE_VMEMMAP Muchun Song
2021-01-24 23:58   ` David Rientjes
2021-01-25  3:16     ` Randy Dunlap
2021-01-25  4:06     ` [External] " Muchun Song
2021-01-25  4:08       ` Randy Dunlap
2021-01-25  5:06         ` Muchun Song
2021-01-25 18:47           ` David Rientjes
2021-01-26  2:45             ` Muchun Song
2021-01-26 20:13               ` David Rientjes
2021-01-26  2:07   ` Miaohe Lin
2021-01-17 15:10 ` [PATCH v13 03/12] mm: hugetlb: free the vmemmap pages associated with each HugeTLB page Muchun Song
2021-01-17 15:29   ` Muchun Song
2021-01-23  0:59   ` Mike Kravetz
2021-01-23  3:22     ` [External] " Muchun Song
2021-01-23 17:52   ` Oscar Salvador
2021-01-24  6:48     ` [External] " Muchun Song
2021-01-17 15:10 ` [PATCH v13 04/12] mm: hugetlb: defer freeing of HugeTLB pages Muchun Song
2021-01-24 23:55   ` David Rientjes
2021-01-25  3:58     ` [External] " Muchun Song
2021-01-17 15:10 ` [PATCH v13 05/12] mm: hugetlb: allocate the vmemmap pages associated with each HugeTLB page Muchun Song
2021-01-25  0:05   ` David Rientjes
2021-01-25  6:40     ` [External] " Muchun Song
2021-01-25  7:41       ` Muchun Song
2021-01-25  9:15         ` David Hildenbrand
2021-01-25  9:34           ` Muchun Song
2021-01-25 23:25             ` Mike Kravetz
2021-01-26  7:48               ` Oscar Salvador
2021-01-26  9:29   ` Oscar Salvador
2021-01-26  9:36     ` David Hildenbrand [this message]
2021-01-26 14:58       ` Oscar Salvador
2021-01-26 15:10         ` David Hildenbrand
2021-01-26 15:34           ` Oscar Salvador
2021-01-26 15:56             ` David Hildenbrand
2021-01-27 10:36               ` David Hildenbrand
2021-01-28 12:37                 ` [External] " Muchun Song
2021-01-28 13:08                   ` Muchun Song
2021-01-29  1:04                   ` Mike Kravetz
2021-01-29  6:56                     ` Muchun Song
2021-02-01 16:10                     ` David Hildenbrand
2021-02-02  0:05                       ` Mike Kravetz
2021-01-28 22:29                 ` Oscar Salvador
2021-01-29  6:16                   ` [External] " Muchun Song
2021-02-01 15:50                   ` David Hildenbrand
2021-01-17 15:10 ` [PATCH v13 06/12] mm: hugetlb: set the PageHWPoison to the raw error page Muchun Song
2021-01-25  0:06   ` David Rientjes
2021-01-25  5:06     ` [External] " Muchun Song
2021-01-17 15:10 ` [PATCH v13 07/12] mm: hugetlb: flush work when dissolving a HugeTLB page Muchun Song
2021-01-17 15:10 ` [PATCH v13 08/12] mm: hugetlb: introduce PageHugeInflight Muchun Song
2021-01-17 15:10 ` [PATCH v13 09/12] mm: hugetlb: add a kernel parameter hugetlb_free_vmemmap Muchun Song
2021-01-25 11:43   ` David Hildenbrand
2021-01-25 12:08     ` Oscar Salvador
2021-01-25 12:31       ` [External] " Muchun Song
2021-01-25 12:30     ` Muchun Song
2021-01-17 15:10 ` [PATCH v13 10/12] mm: hugetlb: introduce nr_free_vmemmap_pages in the struct hstate Muchun Song
2021-01-17 15:10 ` [PATCH v13 11/12] mm: hugetlb: gather discrete indexes of tail page Muchun Song
2021-01-17 15:10 ` [PATCH v13 12/12] mm: hugetlb: optimize the code with the help of the compiler Muchun Song
2021-01-20 12:52 ` [PATCH v13 00/12] Free some vmemmap pages of HugeTLB page Muchun Song
2021-01-20 13:10   ` Oscar Salvador
2021-01-20 14:22     ` [External] " Muchun Song

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