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From: Mike Kravetz <mike.kravetz@oracle.com>
To: Oscar Salvador <osalvador@suse.de>
Cc: Andrew Morton <akpm@linux-foundation.org>,
	Vlastimil Babka <vbabka@suse.cz>,
	David Hildenbrand <david@redhat.com>,
	Michal Hocko <mhocko@kernel.org>,
	Muchun Song <songmuchun@bytedance.com>,
	linux-mm@kvack.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH v7 6/7] mm: Make alloc_contig_range handle in-use hugetlb pages
Date: Wed, 14 Apr 2021 10:07:54 -0700
Message-ID: <681fac27-9684-48cd-daec-fb82057f2253@oracle.com> (raw)
In-Reply-To: <YHZ1A8Wi43DcEv98@localhost.localdomain>

On 4/13/21 9:52 PM, Oscar Salvador wrote:
> On Tue, Apr 13, 2021 at 03:48:53PM -0700, Mike Kravetz wrote:
>> The label free_new is:
>>
>> free_new:
>>         spin_unlock_irq(&hugetlb_lock);
>>         __free_pages(new_page, huge_page_order(h));
>>
>>         return ret;
>>
>> So, we are locking and immediately unlocking without any code in
>> between.  Usually, I don't like like multiple labels before return.
>> However, perhaps we should add another to avoid this unnecessary
>> cycle.  On the other hand, this is an uncommon race condition so the
>> simple code may be acceptable.
> 
> I guess we could have something like:
> 
>  free_new:
>          spin_unlock_irq(&hugetlb_lock);
>  free_new_nolock:
>          __free_pages(new_page, huge_page_order(h));
>  
>          return ret;
> 
> And let the retry go to there without locking. But as you said, the
> racecondition is rare enough, so I am not sure if this buys us much.
> But I can certainly add it if you feel strong about it.

No strong feelings.  I am fine with it as is.

-- 
Mike Kravetz

  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
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 [this message]
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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