From: "David Hildenbrand (Red Hat)" <david@kernel.org>
To: Zi Yan <ziy@nvidia.com>, Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Cc: Andrew Morton <akpm@linux-foundation.org>,
Baolin Wang <baolin.wang@linux.alibaba.com>,
"Liam R. Howlett" <Liam.Howlett@oracle.com>,
Nico Pache <npache@redhat.com>,
Ryan Roberts <ryan.roberts@arm.com>, Dev Jain <dev.jain@arm.com>,
Barry Song <baohua@kernel.org>, Lance Yang <lance.yang@linux.dev>,
Miaohe Lin <linmiaohe@huawei.com>,
Naoya Horiguchi <nao.horiguchi@gmail.com>,
Wei Yang <richard.weiyang@gmail.com>,
Balbir Singh <balbirs@nvidia.com>,
linux-mm@kvack.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH v3 2/4] mm/huge_memory: replace can_split_folio() with direct refcount calculation
Date: Wed, 26 Nov 2025 10:56:35 +0100 [thread overview]
Message-ID: <71b8c4ab-3f4f-4b45-a9ea-706871463a83@kernel.org> (raw)
In-Reply-To: <20251126035008.1919461-3-ziy@nvidia.com>
> static int __folio_freeze_and_split_unmapped(struct folio *folio, unsigned int new_order,
> struct page *split_at, struct xa_state *xas,
> struct address_space *mapping, bool do_lru,
> struct list_head *list, enum split_type split_type,
> - pgoff_t end, int *nr_shmem_dropped, int extra_pins)
> + pgoff_t end, int *nr_shmem_dropped)
> {
> struct folio *end_folio = folio_next(folio);
> struct folio *new_folio, *next;
> @@ -3782,7 +3773,7 @@ static int __folio_freeze_and_split_unmapped(struct folio *folio, unsigned int n
> VM_WARN_ON_ONCE(!mapping && end);
> /* Prevent deferred_split_scan() touching ->_refcount */
> ds_queue = folio_split_queue_lock(folio);
> - if (folio_ref_freeze(folio, 1 + extra_pins)) {
> + if (folio_ref_freeze(folio, folio_cache_ref_count(folio) + 1)) {
> struct swap_cluster_info *ci = NULL;
> struct lruvec *lruvec;
> int expected_refs;
> @@ -3853,7 +3844,7 @@ static int __folio_freeze_and_split_unmapped(struct folio *folio, unsigned int n
>
> zone_device_private_split_cb(folio, new_folio);
>
> - expected_refs = folio_expected_ref_count(new_folio) + 1;
> + expected_refs = folio_cache_ref_count(new_folio) + 1;
> folio_ref_unfreeze(new_folio, expected_refs);
>
> if (do_lru)
> @@ -3897,7 +3888,7 @@ static int __folio_freeze_and_split_unmapped(struct folio *folio, unsigned int n
> * Otherwise, a parallel folio_try_get() can grab @folio
> * and its caller can see stale page cache entries.
> */
> - expected_refs = folio_expected_ref_count(folio) + 1;
> + expected_refs = folio_cache_ref_count(folio) + 1;
> folio_ref_unfreeze(folio, expected_refs);
Can we just get rid of the expected_refs variable as well?
Apart from that LGTM, thanks!
Acked-by: David Hildenbrand (Red Hat) <david@kernel.org>
--
Cheers
David
next prev parent reply other threads:[~2025-11-26 9:56 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-11-26 3:50 [PATCH v3 0/4] Improve folio split related functions Zi Yan
2025-11-26 3:50 ` [PATCH v3 1/4] mm/huge_memory: change folio_split_supported() to folio_check_splittable() Zi Yan
2025-11-26 4:14 ` Balbir Singh
2025-11-26 16:55 ` Zi Yan
2025-11-26 9:54 ` David Hildenbrand (Red Hat)
2025-11-26 16:59 ` Zi Yan
2025-11-27 5:23 ` Barry Song
2025-11-26 3:50 ` [PATCH v3 2/4] mm/huge_memory: replace can_split_folio() with direct refcount calculation Zi Yan
2025-11-26 9:56 ` David Hildenbrand (Red Hat) [this message]
2025-11-26 16:59 ` Zi Yan
2025-11-26 3:50 ` [PATCH v3 3/4] mm/huge_memory: make min_order_for_split() always return an order Zi Yan
2025-11-26 3:50 ` [PATCH v3 4/4] mm/huge_memory: fix folio split stats counting Zi Yan
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