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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 3/8] hugetlb: create remove_hugetlb_page() to separate functionality
Date: Mon, 22 Mar 2021 15:15:43 +0100	[thread overview]
Message-ID: <YFimj4UGBat8Tp/C@dhcp22.suse.cz> (raw)
In-Reply-To: <20210319224209.150047-4-mike.kravetz@oracle.com>

On Fri 19-03-21 15:42:04, Mike Kravetz wrote:
> The new remove_hugetlb_page() routine is designed to remove a hugetlb
> page from hugetlbfs processing.  It will remove the page from the active
> or free list, update global counters and set the compound page
> destructor to NULL so that PageHuge() will return false for the 'page'.
> After this call, the 'page' can be treated as a normal compound page or
> a collection of base size pages.
> 
> remove_hugetlb_page is to be called with the hugetlb_lock held.
> 
> Creating this routine and separating functionality is in preparation for
> restructuring code to reduce lock hold times.

I like this! Counters handling both in __free_huge_page and
update_and_free_page is really confusing.


> Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com>
> ---
>  mm/hugetlb.c | 70 ++++++++++++++++++++++++++++++++++------------------
>  1 file changed, 46 insertions(+), 24 deletions(-)
> 
> diff --git a/mm/hugetlb.c b/mm/hugetlb.c
> index c537274c2a38..ae185d3315e0 100644
> --- a/mm/hugetlb.c
> +++ b/mm/hugetlb.c
> @@ -1306,6 +1306,46 @@ static inline void destroy_compound_gigantic_page(struct page *page,
>  						unsigned int order) { }
>  #endif
>  
> +/*
> + * Remove hugetlb page from lists, and update dtor so that page appears
> + * as just a compound page.  A reference is held on the page.
> + * NOTE: hugetlb specific page flags stored in page->private are not
> + *	 automatically cleared.  These flags may be used in routines
> + *	 which operate on the resulting compound page.
> + *
> + * Must be called with hugetlb lock held.
> + */
> +static void remove_hugetlb_page(struct hstate *h, struct page *page,
> +							bool adjust_surplus)
> +{
> +	int nid = page_to_nid(page);
> +

I think we want lockdep_assert_held here. Lockdep asserts are not used
in this code but now that you are touching it then it is probably better
to start adding them. What do you think?

> +	if (hstate_is_gigantic(h) && !gigantic_page_runtime_supported())
> +		return;
> +
> +	list_del(&page->lru);
> +
> +	if (HPageFreed(page)) {
> +		h->free_huge_pages--;
> +		h->free_huge_pages_node[nid]--;
> +		ClearHPageFreed(page);
> +	}
> +	if (adjust_surplus) {
> +		h->surplus_huge_pages--;
> +		h->surplus_huge_pages_node[nid]--;
> +	}
> +
> +	VM_BUG_ON_PAGE(hugetlb_cgroup_from_page(page), page);
> +	VM_BUG_ON_PAGE(hugetlb_cgroup_from_page_rsvd(page), page);
> +
> +	ClearHPageTemporary(page);
> +	set_page_refcounted(page);
> +	set_compound_page_dtor(page, NULL_COMPOUND_DTOR);
> +
> +	h->nr_huge_pages--;
> +	h->nr_huge_pages_node[nid]--;
> +}

-- 
Michal Hocko
SUSE Labs


  reply	other threads:[~2021-03-22 14:15 UTC|newest]

Thread overview: 45+ 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 [this message]
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
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
2021-03-20  1:18   ` Hillf Danton
2021-03-25  0:26     ` 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

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