From: Lance Yang <lance.yang@linux.dev>
To: Zi Yan <ziy@nvidia.com>
Cc: linux-mm@kvack.org, Muchun Song <muchun.song@linux.dev>,
Andrew Morton <akpm@linux-foundation.org>,
Vlastimil Babka <vbabka@kernel.org>,
Mike Rapoport <rppt@kernel.org>,
"Liam R. Howlett" <liam@infradead.org>,
David Hildenbrand <david@kernel.org>,
Qi Zheng <qi.zheng@linux.dev>, Nico Pache <nico.pache@linux.dev>,
Usama Arif <usama.arif@linux.dev>,
Baolin Wang <baolin.wang@linux.alibaba.com>,
"Matthew Wilcox (Oracle)" <willy@infradead.org>,
Lorenzo Stoakes <ljs@kernel.org>,
Suren Baghdasaryan <surenb@google.com>,
Johannes Weiner <hannes@cmpxchg.org>, Dev Jain <dev.jain@arm.com>,
Barry Song <baohua@kernel.org>,
Ryan Roberts <ryan.roberts@arm.com>,
Alistair Popple <apopple@nvidia.com>,
Shakeel Butt <shakeel.butt@linux.dev>,
Kairui Song <kasong@tencent.com>,
linux-kernel@vger.kernel.org, Minchan Kim <minchan@kernel.org>,
Sergey Senozhatsky <senozhatsky@chromium.org>,
Gregory Price <gourry@gourry.net>,
Ying Huang <ying.huang@linux.alibaba.com>,
Michal Hocko <mhocko@suse.com>
Subject: Re: [PATCH v5 01/17] mm/zsmalloc: replace PG_private with pointer comparison
Date: Mon, 21 Sep 2026 14:02:27 +0800 [thread overview]
Message-ID: <58fee197-7baa-4507-948e-13b58bc3c6fa@linux.dev> (raw)
In-Reply-To: <20260920-remove-pg_private-v5-1-bb68b6a21869@nvidia.com>
On 2026/9/21 10:27, Zi Yan wrote:
> zsmalloc uses PG_private to indicate first zpdesc in a zspage chain. It is
> equivalent to check zpdesc == zspage->first_zpdesc. Replace
> is_first_zpdesc() with zpdesc == zspage->first_zpdesc in obj_allocated().
>
> For get_first_zpdesc(), first_zpdesc is from zspage->first_zpdesc, so
> replace is_first_zpdesc() with first_zpdesc->zspage == zspage, the second
> requirement of a zspage chain, where all zpdescs point to the same zspage.
>
> is_first_zpdesc(), is only used in VM_BUG_ON_PAGE(), so performance impact
> should be negligible. While at it, change VM_BUG_ON() to
> VM_WARN_ON_ONCE_PAGE().
>
> It prepares for a future commit that remove PG_private.
>
> No functional change intended.
>
> Assisted-by: LLM
> To: Minchan Kim <minchan@kernel.org>
> To: Sergey Senozhatsky <senozhatsky@chromium.org>
> To: Andrew Morton <akpm@linux-foundation.org>
> Cc: linux-mm@kvack.org
> Cc: linux-kernel@vger.kernel.org
> Acked-by: Johannes Weiner <hannes@cmpxchg.org>
> Reviewed-by: Sergey Senozhatsky <senozhatsky@chromium.org>
> Acked-by: David Hildenbrand (Arm) <david@kernel.org>
> Signed-off-by: Zi Yan <ziy@nvidia.com>
> ---
Nice work! Feel free to add:
Reviewed-by: Lance Yang <lance.yang@linux.dev>
next prev parent reply other threads:[~2026-09-21 6:02 UTC|newest]
Thread overview: 32+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-09-21 2:27 [PATCH v5 00/17] Remove PG_private by using page/folio->private checks instead Zi Yan
2026-09-21 2:27 ` [PATCH v5 01/17] mm/zsmalloc: replace PG_private with pointer comparison Zi Yan
2026-09-21 6:02 ` Lance Yang [this message]
2026-09-21 2:27 ` [PATCH v5 02/17] perf/ring_buffer: stop using PG_private as AUX page high-order marker Zi Yan
2026-09-21 6:19 ` Lance Yang
2026-09-21 2:27 ` [PATCH v5 03/17] xen/grant-table: stop setting PG_private on pages for grant mapping Zi Yan
2026-09-21 7:00 ` Lance Yang
2026-09-21 2:28 ` [PATCH v5 04/17] fscrypt: stop setting PG_private on bounce page Zi Yan
2026-09-21 7:03 ` Lance Yang
2026-09-21 2:28 ` [PATCH v5 05/17] mm/hugetlb: use direct assignment instead of folio_change_private() Zi Yan
2026-09-21 7:11 ` Lance Yang
2026-09-21 2:28 ` [PATCH v5 06/17] f2fs: stop using PG_private Zi Yan
2026-09-21 7:24 ` Lance Yang
2026-09-21 2:28 ` [PATCH v5 07/17] f2fs: convert the ->private flag helpers to folio-only Zi Yan
2026-09-21 7:39 ` Lance Yang
2026-09-21 2:28 ` [PATCH v5 08/17] erofs: mm/pagemap: add readahead_folio_last() to avoid folio->private Zi Yan
2026-09-21 8:20 ` Lance Yang
2026-09-21 2:28 ` [PATCH v5 09/17] erofs: use folio_attach/detach_private() instead of direct assignment Zi Yan
2026-09-21 8:45 ` Lance Yang
2026-09-21 2:28 ` [PATCH v5 10/17] mm/page-flags: check page/folio->private instead of PG_private Zi Yan
2026-09-21 9:22 ` David Hildenbrand (Arm)
2026-09-21 2:28 ` [PATCH v5 11/17] treewide: remove folio_set/clear_private() usage Zi Yan
2026-09-21 2:28 ` [PATCH v5 12/17] ceph: replace PagePrivate() with page_private() Zi Yan
2026-09-21 2:28 ` [PATCH v5 13/17] md: Use folio_alloc_buffers() Zi Yan
2026-09-21 9:23 ` David Hildenbrand (Arm)
2026-09-21 2:28 ` [PATCH v5 14/17] md: Use folio APIs in free_page() Zi Yan
2026-09-21 2:28 ` [PATCH v5 15/17] md: Remove the last use of page_buffers() Zi Yan
2026-09-21 2:28 ` [PATCH v5 16/17] treewide: remove PagePrivate() and PG_private from comments and docs Zi Yan
2026-09-21 2:28 ` [PATCH v5 17/17] mm/page-flags: remove PG_private Zi Yan
2026-09-21 2:55 ` sashiko-bot
2026-09-21 15:36 ` Zi Yan
2026-09-21 4:08 ` [PATCH v5 00/17] Remove PG_private by using page/folio->private checks instead Andrew Morton
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