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From: Michal Hocko <mhocko@suse.com>
To: Oscar Salvador <osalvador@suse.de>
Cc: Andrew Morton <akpm@linux-foundation.org>,
	Mike Kravetz <mike.kravetz@oracle.com>,
	David Hildenbrand <david@redhat.com>,
	Muchun Song <songmuchun@bytedance.com>,
	linux-mm@kvack.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH v3 2/2] mm: Make alloc_contig_range handle in-use hugetlb pages
Date: Fri, 26 Feb 2021 09:46:57 +0100	[thread overview]
Message-ID: <YDi1gSdDXErJ+SHK@dhcp22.suse.cz> (raw)
In-Reply-To: <20210222135137.25717-3-osalvador@suse.de>

On Mon 22-02-21 14:51:37, Oscar Salvador wrote:
[...]
> @@ -2394,9 +2397,19 @@ bool isolate_or_dissolve_huge_page(struct page *page)
>  	 */
>  	if (hstate_is_gigantic(h))
>  		return ret;
> -
> -	if (!page_count(head) && alloc_and_dissolve_huge_page(h, head))
> +retry:
> +	if (page_count(head) && isolate_huge_page(head, list)) {
>  		ret = true;
> +	} else if (!page_count(head)) {

This is rather head spinning. Do we need to test page_count in the else
branch? Do you want to optimize for a case where the page cannot be
isolated because of page_huge_active?

> +		int err = alloc_and_dissolve_huge_page(h, head);
> +
> +		if (!err) {
> +			ret = true;
> +		} else if (err == -EBUSY && try_again) {
> +			try_again = false;
> +			goto retry;
> +		}

Is this retry once logic really needed? Does it really give us any real
benefit? alloc_and_dissolve_huge_page already retries when the page is
being freed.

-- 
Michal Hocko
SUSE Labs


  parent reply	other threads:[~2021-02-26  8:47 UTC|newest]

Thread overview: 25+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-02-22 13:51 [PATCH v3 0/2] Make alloc_contig_range handle Hugetlb pages Oscar Salvador
2021-02-22 13:51 ` [PATCH v3 1/2] mm: Make alloc_contig_range handle free hugetlb pages Oscar Salvador
2021-02-25 20:03   ` Mike Kravetz
2021-02-26  9:48     ` Oscar Salvador
2021-02-26  8:35   ` Michal Hocko
2021-02-26  8:38     ` Michal Hocko
2021-02-26  9:25       ` David Hildenbrand
2021-02-26  9:47         ` Oscar Salvador
2021-02-26  9:45     ` Oscar Salvador
2021-02-26  9:51       ` Michal Hocko
2021-03-01 14:09   ` David Hildenbrand
2021-03-04 10:19     ` Oscar Salvador
2021-03-04 10:32       ` David Hildenbrand
2021-03-04 10:41         ` Oscar Salvador
2021-02-22 13:51 ` [PATCH v3 2/2] mm: Make alloc_contig_range handle in-use " Oscar Salvador
2021-02-25 23:05   ` Mike Kravetz
2021-02-26  8:46   ` Michal Hocko [this message]
2021-02-26 10:24     ` Oscar Salvador
2021-02-26 10:27       ` Oscar Salvador
2021-02-26 12:46       ` Michal Hocko
2021-02-28 13:43         ` Oscar Salvador
2021-03-05 17:30   ` David Hildenbrand
2021-03-01 12:43 ` [PATCH v3 0/2] Make alloc_contig_range handle Hugetlb pages David Hildenbrand
2021-03-01 12:57   ` Oscar Salvador
2021-03-01 12:59     ` David Hildenbrand

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