From: Lance Yang <lance.yang@linux.dev>
To: songmuchun@bytedance.com
Cc: maddy@linux.ibm.com, rppt@kernel.org, akpm@linux-foundation.org,
david@kernel.org, mpe@ellerman.id.au, npiggin@gmail.com,
chleroy@kernel.org, ritesh.list@gmail.com, sshegde@linux.ibm.com,
ljs@kernel.org, liam@infradead.org, vbabka@kernel.org,
surenb@google.com, mhocko@suse.com, qi.zheng@linux.dev,
linuxppc-dev@lists.ozlabs.org, linux-kernel@vger.kernel.org,
linux-mm@kvack.org, muchun.song@linux.dev,
Lance Yang <lance.yang@linux.dev>
Subject: Re: [PATCH v3 2/6] mm/sparse-vmemmap: support device DAX in common vmemmap path
Date: Wed, 30 Sep 2026 18:02:26 +0800 [thread overview]
Message-ID: <20260930100226.23688-1-lance.yang@linux.dev> (raw)
In-Reply-To: <20260929053231.66085-3-songmuchun@bytedance.com>
On Tue, Sep 29, 2026 at 01:32:27PM +0800, Muchun Song wrote:
>The common vmemmap population path cannot yet handle optimized Device DAX
>mappings on its own. It uses pfn_to_zone() to find the shared tail page,
>but Device DAX populates its vmemmap at runtime before the ZONE_DEVICE span
>is initialized.
>
>Teach the common path to use device_zone() for runtime optimized vmemmap
>population while retaining pfn_to_zone() for early boot. This allows the
>same path to support both early boot mappings and Device DAX.
>
>The backing PFN supplied by the Device DAX-specific population path is no
>longer used, allowing the redundant lookup and population code to be
>removed later.
>
>Signed-off-by: Muchun Song <songmuchun@bytedance.com>
>Acked-by: Qi Zheng <qi.zheng@linux.dev>
>---
Nothing jumped out at me, feel free to add:
Reviewed-by: Lance Yang <lance.yang@linux.dev>
next prev parent reply other threads:[~2026-09-30 10:02 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-09-29 5:32 [PATCH v3 0/6] mm: Unify device DAX and HugeTLB vmemmap population paths Muchun Song
2026-09-29 5:32 ` [PATCH v3 1/6] mm/sparse-vmemmap: drop VMEMMAP_POPULATE_DAX Muchun Song
2026-09-30 4:24 ` Lance Yang
2026-09-29 5:32 ` [PATCH v3 2/6] mm/sparse-vmemmap: support device DAX in common vmemmap path Muchun Song
2026-09-30 8:53 ` Lance Yang
2026-09-30 10:09 ` Muchun Song
2026-09-30 11:11 ` Muchun Song
2026-09-30 10:02 ` Lance Yang [this message]
2026-09-29 5:32 ` [PATCH v3 3/6] mm/sparse-vmemmap: drop Device DAX-specific population path Muchun Song
2026-09-29 5:32 ` [PATCH v3 4/6] mm/sparse-vmemmap: remove the unused ptpfn argument Muchun Song
2026-09-29 5:32 ` [PATCH v3 5/6] mm/sparse-vmemmap: open-code vmemmap_populate_address() Muchun Song
2026-09-29 5:32 ` [PATCH v3 6/6] mm/mm_init: add zone mismatch warning during page init Muchun Song
2026-09-29 21:32 ` [PATCH v3 0/6] mm: Unify device DAX and HugeTLB vmemmap population paths Andrew Morton
2026-09-30 1:26 ` Muchun Song
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