From: "David Hildenbrand (Arm)" <david@kernel.org>
To: Muchun Song <songmuchun@bytedance.com>,
Andrew Morton <akpm@linux-foundation.org>,
Oscar Salvador <osalvador@suse.de>,
Madhavan Srinivasan <maddy@linux.ibm.com>,
Michael Ellerman <mpe@ellerman.id.au>,
Jonathan Corbet <corbet@lwn.net>
Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org,
linuxppc-dev@lists.ozlabs.org, linux-doc@vger.kernel.org,
Muchun Song <muchun.song@linux.dev>,
Lorenzo Stoakes <ljs@kernel.org>, Mike Rapoport <rppt@kernel.org>,
Qi Zheng <qi.zheng@linux.dev>,
Nicholas Piggin <npiggin@gmail.com>,
Christophe Leroy <chleroy@kernel.org>,
Randy Dunlap <rdunlap@infradead.org>,
Lance Yang <lance.yang@linux.dev>
Subject: Re: [PATCH v5 10/12] mm/sparse-vmemmap: drop the extra tail page from device DAX reservation
Date: Tue, 29 Sep 2026 09:45:04 +0200 [thread overview]
Message-ID: <29717e90-4b4c-4ee4-8a17-20a7b1792000@kernel.org> (raw)
In-Reply-To: <20260927025441.741633-11-songmuchun@bytedance.com>
On 9/27/26 04:54, Muchun Song wrote:
> The device DAX vmemmap population still reserves one extra tail vmemmap
> page after the head page.
>
> Drop that extra reservation and let the shared tail page cover all tail
> vmemmap pages after the head page, so DAX follows the same reservation
> model as HugeTLB.
>
> This reduces the reserved vmemmap pages for optimized DAX mappings to
> one and removes the now-unneeded first-tail population from the generic
> and powerpc paths to simplify the code as well.
>
> Signed-off-by: Muchun Song <songmuchun@bytedance.com>
> Acked-by: Qi Zheng <qi.zheng@linux.dev>
> ---
Acked-by: David Hildenbrand (Arm) <david@kernel.org>
--
Cheers,
David
next prev parent reply other threads:[~2026-09-29 7:45 UTC|newest]
Thread overview: 39+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-09-27 2:54 [PATCH v5 00/12] mm: Switch device DAX to section-based vmemmap optimization Muchun Song
2026-09-27 2:54 ` [PATCH v5 01/12] mm/sparse-vmemmap: factor out shared vmemmap tail page allocation Muchun Song
2026-09-29 7:16 ` David Hildenbrand (Arm)
2026-09-29 7:55 ` Muchun Song
2026-09-27 2:54 ` [PATCH v5 02/12] mm/sparse-vmemmap: allocate shared tail page array dynamically Muchun Song
2026-09-29 7:21 ` David Hildenbrand (Arm)
2026-09-29 8:00 ` Muchun Song
2026-09-27 2:54 ` [PATCH v5 03/12] mm/sparse-vmemmap: introduce CONFIG_VMEMMAP_OPTIMIZATION Muchun Song
2026-09-29 7:11 ` David Hildenbrand (Arm)
2026-09-29 7:53 ` Muchun Song
2026-09-29 8:43 ` David Hildenbrand (Arm)
2026-09-27 2:54 ` [PATCH v5 04/12] mm/sparse-vmemmap: open-code init_compound_tail() Muchun Song
2026-09-27 2:54 ` [PATCH v5 05/12] mm/sparse-vmemmap: prepare DAX vmemmap population for compound page orders Muchun Song
2026-09-29 7:24 ` David Hildenbrand (Arm)
2026-09-29 8:04 ` Muchun Song
2026-09-27 2:54 ` [PATCH v5 06/12] mm/sparse-vmemmap: set compound page order for device DAX Muchun Song
2026-09-29 7:30 ` David Hildenbrand (Arm)
2026-09-29 8:22 ` Muchun Song
2026-09-29 8:43 ` David Hildenbrand (Arm)
2026-09-27 2:54 ` [PATCH v5 07/12] mm/sparse-vmemmap: switch device DAX to shared tail vmemmap pages Muchun Song
2026-09-28 4:41 ` [PATCH] fixup! " Muchun Song
2026-09-29 7:36 ` [PATCH v5 07/12] " David Hildenbrand (Arm)
2026-09-29 8:36 ` Muchun Song
2026-09-27 2:54 ` [PATCH v5 08/12] mm/sparse-vmemmap: move vmemmap optimization helpers to a public header Muchun Song
2026-09-29 7:39 ` David Hildenbrand (Arm)
2026-09-29 8:44 ` Muchun Song
2026-09-29 10:03 ` Muchun Song
2026-09-27 2:54 ` [PATCH v5 09/12] powerpc/mm: switch device DAX to shared tail vmemmap pages Muchun Song
2026-09-29 8:44 ` David Hildenbrand (Arm)
2026-09-27 2:54 ` [PATCH v5 10/12] mm/sparse-vmemmap: drop the extra tail page from device DAX reservation Muchun Song
2026-09-29 7:45 ` David Hildenbrand (Arm) [this message]
2026-09-27 2:54 ` [PATCH v5 11/12] mm/sparse-vmemmap: drop unused section_nr_vmemmap_pages() arguments Muchun Song
2026-09-29 7:41 ` David Hildenbrand (Arm)
2026-09-27 2:54 ` [PATCH v5 12/12] Documentation/mm: update DAX vmemmap deduplication docs Muchun Song
2026-09-29 7:43 ` David Hildenbrand (Arm)
2026-09-27 5:51 ` [PATCH v5 00/12] mm: Switch device DAX to section-based vmemmap optimization Andrew Morton
2026-09-27 10:51 ` Muchun Song
2026-09-27 19:54 ` Andrew Morton
2026-09-28 4:25 ` Muchun Song
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