From: Michal Hocko <mhocko@suse.com>
To: Mike Kravetz <mike.kravetz@oracle.com>
Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org,
Shakeel Butt <shakeelb@google.com>,
Oscar Salvador <osalvador@suse.de>,
David Hildenbrand <david@redhat.com>,
Muchun Song <songmuchun@bytedance.com>,
David Rientjes <rientjes@google.com>,
Miaohe Lin <linmiaohe@huawei.com>,
Peter Zijlstra <peterz@infradead.org>,
Matthew Wilcox <willy@infradead.org>,
HORIGUCHI NAOYA <naoya.horiguchi@nec.com>,
"Aneesh Kumar K . V" <aneesh.kumar@linux.ibm.com>,
Waiman Long <longman@redhat.com>, Peter Xu <peterx@redhat.com>,
Mina Almasry <almasrymina@google.com>,
Andrew Morton <akpm@linux-foundation.org>
Subject: Re: [RFC PATCH 4/8] hugetlb: call update_and_free_page without hugetlb_lock
Date: Mon, 22 Mar 2021 15:19:21 +0100 [thread overview]
Message-ID: <YFinaZoTVR0MbYxo@dhcp22.suse.cz> (raw)
In-Reply-To: <20210319224209.150047-5-mike.kravetz@oracle.com>
On Fri 19-03-21 15:42:05, Mike Kravetz wrote:
> With the introduction of remove_hugetlb_page(), there is no need for
> update_and_free_page to hold the hugetlb lock. Change all callers to
> drop the lock before calling.
>
> With additional code modifications, this will allow loops which decrease
> the huge page pool to drop the hugetlb_lock with each page to reduce
> long hold times.
>
> The ugly unlock/lock cycle in free_pool_huge_page will be removed in
> a subsequent patch which restructures free_pool_huge_page.
>
> Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com>
Looks good to me. I will not ack it right now though. I am still
crawling through the series and want to get a full picture. So far it
looks promising ;).
> ---
> mm/hugetlb.c | 21 +++++++++++++--------
> 1 file changed, 13 insertions(+), 8 deletions(-)
>
> diff --git a/mm/hugetlb.c b/mm/hugetlb.c
> index ae185d3315e0..3028cf10d504 100644
> --- a/mm/hugetlb.c
> +++ b/mm/hugetlb.c
> @@ -1362,14 +1362,8 @@ static void update_and_free_page(struct hstate *h, struct page *page)
> 1 << PG_writeback);
> }
> if (hstate_is_gigantic(h)) {
> - /*
> - * Temporarily drop the hugetlb_lock, because
> - * we might block in free_gigantic_page().
> - */
> - spin_unlock(&hugetlb_lock);
> destroy_compound_gigantic_page(page, huge_page_order(h));
> free_gigantic_page(page, huge_page_order(h));
> - spin_lock(&hugetlb_lock);
> } else {
> __free_pages(page, huge_page_order(h));
> }
> @@ -1435,16 +1429,18 @@ static void __free_huge_page(struct page *page)
>
> if (HPageTemporary(page)) {
> remove_hugetlb_page(h, page, false);
> + spin_unlock(&hugetlb_lock);
> update_and_free_page(h, page);
> } else if (h->surplus_huge_pages_node[nid]) {
> /* remove the page from active list */
> remove_hugetlb_page(h, page, true);
> + spin_unlock(&hugetlb_lock);
> update_and_free_page(h, page);
> } else {
> arch_clear_hugepage_flags(page);
> enqueue_huge_page(h, page);
> + spin_unlock(&hugetlb_lock);
> }
> - spin_unlock(&hugetlb_lock);
> }
>
> /*
> @@ -1725,7 +1721,13 @@ static int free_pool_huge_page(struct hstate *h, nodemask_t *nodes_allowed,
> list_entry(h->hugepage_freelists[node].next,
> struct page, lru);
> remove_hugetlb_page(h, page, acct_surplus);
> + /*
> + * unlock/lock around update_and_free_page is temporary
> + * and will be removed with subsequent patch.
> + */
> + spin_unlock(&hugetlb_lock);
> update_and_free_page(h, page);
> + spin_lock(&hugetlb_lock);
> ret = 1;
> break;
> }
> @@ -1794,8 +1796,9 @@ int dissolve_free_huge_page(struct page *page)
> }
> remove_hugetlb_page(h, page, false);
> h->max_huge_pages--;
> + spin_unlock(&hugetlb_lock);
> update_and_free_page(h, head);
> - rc = 0;
> + return 0;
> }
> out:
> spin_unlock(&hugetlb_lock);
> @@ -2572,7 +2575,9 @@ static void try_to_free_low(struct hstate *h, unsigned long count,
> remove_hugetlb_page(h, page, false);
> h->free_huge_pages--;
> h->free_huge_pages_node[page_to_nid(page)]--;
> + spin_unlock(&hugetlb_lock);
> update_and_free_page(h, page);
> + spin_lock(&hugetlb_lock);
>
> /*
> * update_and_free_page could have dropped lock so
> --
> 2.30.2
>
--
Michal Hocko
SUSE Labs
next prev parent reply other threads:[~2021-03-22 14:20 UTC|newest]
Thread overview: 44+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-03-19 22:42 [RFC PATCH 0/8] make hugetlb put_page safe for all calling contexts Mike Kravetz
2021-03-19 22:42 ` [RFC PATCH 1/8] hugetlb: add per-hstate mutex to synchronize user adjustments Mike Kravetz
2021-03-22 13:59 ` Michal Hocko
2021-03-22 16:57 ` Mike Kravetz
2021-03-23 7:48 ` Michal Hocko
2021-03-19 22:42 ` [RFC PATCH 2/8] hugetlb: recompute min_count when dropping hugetlb_lock Mike Kravetz
2021-03-22 14:07 ` Michal Hocko
2021-03-22 23:07 ` Mike Kravetz
2021-03-23 7:50 ` Michal Hocko
2021-03-23 8:01 ` Peter Zijlstra
2021-03-23 8:14 ` Michal Hocko
2021-03-23 23:18 ` Mike Kravetz
2021-03-24 8:36 ` Michal Hocko
2021-03-24 16:43 ` Mike Kravetz
2021-03-19 22:42 ` [RFC PATCH 3/8] hugetlb: create remove_hugetlb_page() to separate functionality Mike Kravetz
2021-03-22 14:15 ` Michal Hocko
2021-03-22 17:01 ` Mike Kravetz
2021-03-19 22:42 ` [RFC PATCH 4/8] hugetlb: call update_and_free_page without hugetlb_lock Mike Kravetz
2021-03-22 14:19 ` Michal Hocko [this message]
2021-03-19 22:42 ` [RFC PATCH 5/8] hugetlb: change free_pool_huge_page to remove_pool_huge_page Mike Kravetz
2021-03-22 14:31 ` Michal Hocko
2021-03-22 23:28 ` Mike Kravetz
2021-03-23 7:57 ` Michal Hocko
2021-03-24 1:03 ` Mike Kravetz
2021-03-24 8:40 ` Michal Hocko
2021-03-24 16:38 ` Mike Kravetz
2021-03-24 16:50 ` Michal Hocko
2021-03-19 22:42 ` [RFC PATCH 6/8] hugetlb: make free_huge_page irq safe Mike Kravetz
2021-03-21 19:55 ` Mike Kravetz
2021-03-22 13:36 ` [hugetlb] cd190f60f9: BUG:sleeping_function_called_from_invalid_context_at_mm/hugetlb.c kernel test robot
2021-03-22 14:35 ` [RFC PATCH 6/8] hugetlb: make free_huge_page irq safe Michal Hocko
2021-03-19 22:42 ` [RFC PATCH 7/8] hugetlb: add update_and_free_page_no_sleep for irq context Mike Kravetz
2021-03-22 8:41 ` Peter Zijlstra
2021-03-22 17:42 ` Mike Kravetz
2021-03-22 18:10 ` Roman Gushchin
2021-03-23 18:51 ` Mike Kravetz
2021-03-23 19:07 ` Roman Gushchin
2021-03-24 8:43 ` Michal Hocko
2021-03-24 16:53 ` Mike Kravetz
2021-03-22 20:43 ` Peter Zijlstra
2021-03-22 14:42 ` Michal Hocko
2021-03-22 14:46 ` Michal Hocko
2021-03-19 22:42 ` [RFC PATCH 8/8] hugetlb: track hugetlb pages allocated via cma_alloc Mike Kravetz
[not found] ` <20210320011857.2004-1-hdanton@sina.com>
2021-03-25 0:26 ` [RFC PATCH 7/8] hugetlb: add update_and_free_page_no_sleep for irq context Mike Kravetz
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