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From: David Hildenbrand <david@redhat.com>
To: Michal Hocko <mhocko@suse.com>, Oscar Salvador <osalvador@suse.de>
Cc: Mike Kravetz <mike.kravetz@oracle.com>,
	Andrew Morton <akpm@linux-foundation.org>,
	Vlastimil Babka <vbabka@suse.cz>,
	Muchun Song <songmuchun@bytedance.com>,
	linux-mm@kvack.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH v7 3/7] mm,hugetlb: Clear HPageFreed outside of the lock
Date: Wed, 14 Apr 2021 14:02:45 +0200
Message-ID: <f8d86f84-b354-cdaf-e1c6-4707dbe33dd9@redhat.com> (raw)
In-Reply-To: <YHbNUjU1Y4sqMVBd@dhcp22.suse.cz>

On 14.04.21 13:09, Michal Hocko wrote:
> On Wed 14-04-21 12:49:53, Oscar Salvador wrote:
>> On Wed, Apr 14, 2021 at 12:32:58PM +0200, Michal Hocko wrote:
> [...]
>>>> I checked, and when we get there in __alloc_bootmem_huge_page, page->private is
>>>> still zeroed, so I guess it should be safe to assume that we do not really need
>>>> to clear the flag in __prep_new_huge_page() routine?
>>>
>>> It would be quite nasty if the struct pages content would be undefined.
>>> Maybe that is possible but then I would rather stick the initialization
>>> into __alloc_bootmem_huge_page.
>>
>> Yes, but I do not think that is really possible unless I missed something.
> 
> Yeah, it should be fine. I was thinking of a alloc, modify struct pages,
> free back to the bootmem allocator sequence. But I do not remember ever
> seeing sequence like that.

We do have code like that, though.

Take a look at arch/x86/mm/init_64.c:free_pagetable() as one example.

But in general, we assume freeing code (buddy, but also memblock) 
restores the state of the memmap to the original state it obtained the 
memmap. So if it's properly initialized when coming from the allocator 
the first time, it should remain properly initialized when re-entering 
and re-leaving the allocator.

-- 
Thanks,

David / dhildenb


  reply index

Thread overview: 40+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-04-13 10:47 [PATCH v7 0/7] Make alloc_contig_range handle Hugetlb pages Oscar Salvador
2021-04-13 10:47 ` [PATCH v7 1/7] mm,page_alloc: Bail out earlier on -ENOMEM in alloc_contig_migrate_range Oscar Salvador
2021-04-13 17:00   ` Mike Kravetz
2021-04-13 10:47 ` [PATCH v7 2/7] mm,compaction: Let isolate_migratepages_{range,block} return error codes Oscar Salvador
2021-04-13 17:52   ` Mike Kravetz
2021-04-14 11:54   ` David Hildenbrand
2021-04-15  8:42     ` Oscar Salvador
2021-04-13 10:47 ` [PATCH v7 3/7] mm,hugetlb: Clear HPageFreed outside of the lock Oscar Salvador
2021-04-13 13:23   ` Michal Hocko
2021-04-13 21:19     ` Mike Kravetz
2021-04-14  6:04       ` Michal Hocko
2021-04-14  7:41         ` Oscar Salvador
2021-04-14  8:28           ` Michal Hocko
2021-04-14 10:01             ` Oscar Salvador
2021-04-14 10:03               ` Oscar Salvador
2021-04-14 10:32               ` Michal Hocko
2021-04-14 10:49                 ` Oscar Salvador
2021-04-14 11:09                   ` Michal Hocko
2021-04-14 12:02                     ` David Hildenbrand [this message]
2021-04-14 16:45                   ` Mike Kravetz
2021-04-13 10:47 ` [PATCH v7 4/7] mm,hugetlb: Split prep_new_huge_page functionality Oscar Salvador
2021-04-13 13:24   ` Michal Hocko
2021-04-13 13:26     ` Michal Hocko
2021-04-13 21:33   ` Mike Kravetz
2021-04-14  4:59     ` Oscar Salvador
2021-04-14 12:15       ` David Hildenbrand
2021-04-14 17:03       ` Mike Kravetz
2021-04-13 10:47 ` [PATCH v7 5/7] mm: Make alloc_contig_range handle free hugetlb pages Oscar Salvador
2021-04-13 13:40   ` Michal Hocko
2021-04-15  8:29     ` Oscar Salvador
2021-04-13 22:29   ` Mike Kravetz
2021-04-14  4:54     ` Oscar Salvador
2021-04-14 12:26   ` David Hildenbrand
2021-04-15  8:28     ` Oscar Salvador
2021-04-13 10:47 ` [PATCH v7 6/7] mm: Make alloc_contig_range handle in-use " Oscar Salvador
2021-04-13 22:48   ` Mike Kravetz
2021-04-14  4:52     ` Oscar Salvador
2021-04-14 17:07       ` Mike Kravetz
2021-04-13 10:47 ` [PATCH v7 7/7] mm,page_alloc: Drop unnecessary checks from pfn_range_valid_contig Oscar Salvador
2021-04-13 22:53   ` Mike Kravetz

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