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From: "David Hildenbrand (Arm)" <david@kernel.org>
To: Zi Yan <ziy@nvidia.com>,
	"Matthew Wilcox (Oracle)" <willy@infradead.org>,
	Andrew Morton <akpm@linux-foundation.org>,
	Muchun Song <muchun.song@linux.dev>,
	Lorenzo Stoakes <ljs@kernel.org>,
	"Liam R. Howlett" <liam@infradead.org>,
	Vlastimil Babka <vbabka@kernel.org>,
	Mike Rapoport <rppt@kernel.org>,
	Suren Baghdasaryan <surenb@google.com>,
	Michal Hocko <mhocko@suse.com>,
	Baolin Wang <baolin.wang@linux.alibaba.com>,
	Nico Pache <nico.pache@linux.dev>,
	Ryan Roberts <ryan.roberts@arm.com>, Dev Jain <dev.jain@arm.com>,
	Barry Song <baohua@kernel.org>, Lance Yang <lance.yang@linux.dev>,
	Usama Arif <usama.arif@linux.dev>,
	Gregory Price <gourry@gourry.net>,
	Ying Huang <ying.huang@linux.alibaba.com>,
	Alistair Popple <apopple@nvidia.com>,
	Johannes Weiner <hannes@cmpxchg.org>,
	Qi Zheng <qi.zheng@linux.dev>,
	Shakeel Butt <shakeel.butt@linux.dev>,
	Kairui Song <kasong@tencent.com>
Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org,
	Gao Xiang <xiang@kernel.org>, Chao Yu <chao@kernel.org>,
	Yue Hu <zbestahu@gmail.com>,
	Jeffle Xu <jefflexu@linux.alibaba.com>,
	Sandeep Dhavale <dhavale@google.com>,
	Hongbo Li <hongbohbli@tencent.com>,
	Chunhai Guo <guochunhai@vivo.com>,
	linux-erofs@lists.ozlabs.org
Subject: Re: [PATCH v3 08/14] erofs: use folio_attach/detach_private() instead of direct assignment
Date: Tue, 8 Sep 2026 18:13:37 +0200	[thread overview]
Message-ID: <5b02f5de-00b6-4f8e-9e30-6d0acedafaf4@kernel.org> (raw)
In-Reply-To: <20260907-remove-pg_private-v3-8-6ae22f9d9272@nvidia.com>

On 9/8/26 04:56, Zi Yan wrote:
> erofs_onlinefolio_init/split/end() use folio->private without setting
> PG_private or increasing folio refcount and it works. But after PG_private
> is replaced by checking folio->private in a future commit, it can break
> folio_expected_ref_count(), since the folio has private data without
> elevated refcount. Change them to use folio_attach/detach_private().

Freezing the folio will properly work I assume, as we'd always freeze with that
refcount in mind or remove the reference (detach private) early?

I'm thinking of folio_ref_freeze() in __folio_freeze_and_split_unmapped().

Or is the ref only very short-lived either way such that we don't care?



-- 
Cheers,

David

  reply	other threads:[~2026-09-08 16:13 UTC|newest]

Thread overview: 60+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2026-09-08  2:56 [PATCH v3 00/14] Remove PG_private by using page/folio->private checks instead Zi Yan
2026-09-08  2:56 ` [PATCH v3 01/14] mm/zsmalloc: replace PG_private with pointer comparison Zi Yan
2026-09-08  4:11   ` Sergey Senozhatsky
2026-09-08 15:07   ` David Hildenbrand (Arm)
2026-09-08 15:21     ` Zi Yan
2026-09-09 14:07       ` David Hildenbrand (Arm)
2026-09-08  2:56 ` [PATCH v3 02/14] perf/ring_buffer: stop using PG_private as AUX page high-order marker Zi Yan
2026-09-08 15:09   ` David Hildenbrand (Arm)
2026-09-08  2:56 ` [PATCH v3 03/14] xen/grant-table: stop setting PG_private on pages for grant mapping Zi Yan
2026-09-08 15:16   ` David Hildenbrand (Arm)
2026-09-08 15:44     ` Zi Yan
2026-09-08  2:56 ` [PATCH v3 04/14] fscrypt: stop setting PG_private on bounce page Zi Yan
2026-09-08 15:16   ` David Hildenbrand (Arm)
2026-09-08  2:56 ` [PATCH v3 05/14] mm/hugetlb: use direct assignment instead of folio_change_private() Zi Yan
2026-09-08 15:26   ` David Hildenbrand (Arm)
2026-09-08 15:28     ` Zi Yan
2026-09-08  2:56 ` [PATCH v3 06/14] f2fs: stop using PG_private Zi Yan
2026-09-08 15:47   ` David Hildenbrand (Arm)
2026-09-08 18:20     ` Tal Zussman
2026-09-09 12:48       ` David Hildenbrand (Arm)
2026-09-09 17:47         ` Tal Zussman
2026-09-10  7:35           ` David Hildenbrand (Arm)
2026-09-10 12:21             ` Zi Yan
2026-09-10 21:11               ` Zi Yan
2026-09-10  2:41     ` Chao Yu
2026-09-10  7:34       ` David Hildenbrand (Arm)
2026-09-10  8:43         ` Chao Yu
2026-09-10  9:15           ` David Hildenbrand (Arm)
2026-09-10 14:15             ` Chao Yu
2026-09-08  2:56 ` [PATCH v3 07/14] erofs: mm/pagemap: add readahead_folio_last() to avoid folio->private Zi Yan
2026-09-08 16:04   ` David Hildenbrand (Arm)
2026-09-08 17:05     ` Zi Yan
2026-09-09 14:10       ` David Hildenbrand (Arm)
2026-09-08  2:56 ` [PATCH v3 08/14] erofs: use folio_attach/detach_private() instead of direct assignment Zi Yan
2026-09-08 16:13   ` David Hildenbrand (Arm) [this message]
2026-09-08 17:19     ` Zi Yan
2026-09-09 13:27       ` David Hildenbrand (Arm)
2026-09-10  2:06         ` Zi Yan
2026-09-08  2:56 ` [PATCH v3 09/14] mm/page-flags: check page/folio->private instead of PG_private Zi Yan
2026-09-08 16:56   ` David Hildenbrand (Arm)
2026-09-10  2:08     ` Zi Yan
2026-09-08  2:56 ` [PATCH v3 10/14] mm/page-flags: introduce folio_test_fs_private() Zi Yan
2026-09-08 16:59   ` David Hildenbrand (Arm)
2026-09-08 17:22     ` Zi Yan
2026-09-08  2:56 ` [PATCH v3 11/14] treewide: remove folio_set/clear_private() Zi Yan
2026-09-08 17:01   ` David Hildenbrand (Arm)
2026-09-08 17:22     ` Zi Yan
2026-09-08  2:56 ` [PATCH v3 12/14] treewide: replace PagePrivate() with page_private() Zi Yan
2026-09-09 14:18   ` David Hildenbrand (Arm)
2026-09-09 14:23     ` David Hildenbrand (Arm)
2026-09-10  2:09       ` Zi Yan
2026-09-08  2:56 ` [PATCH v3 13/14] treewide: adjust comments on PagePrivate and PG_private Zi Yan
2026-09-09 14:20   ` David Hildenbrand (Arm)
2026-09-09 14:27   ` David Hildenbrand (Arm)
2026-09-10  2:12     ` Zi Yan
2026-09-08  2:56 ` [PATCH v3 14/14] mm/page-flags: remove PG_private Zi Yan
2026-09-09 14:31   ` David Hildenbrand (Arm)
2026-09-09 14:48     ` Zi Yan
2026-09-09 14:50       ` David Hildenbrand (Arm)
2026-09-09 14:51         ` Zi Yan

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