From: Lance Yang <lance.yang@linux.dev>
To: songmuchun@bytedance.com
Cc: osalvador@suse.de, akpm@linux-foundation.org, rppt@kernel.org,
qi.zheng@linux.dev, lance.yang@linux.dev, jthoughton@google.com,
david@kernel.org, muchun.song@linux.dev, linux-mm@kvack.org,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH 02/12] mm: hugetlb_vmemmap: unify VMEMMAP_{SPLIT,REMAP}_NO_TLB_FLUSH
Date: Thu, 22 Oct 2026 11:52:19 +0800 [thread overview]
Message-ID: <20261022035219.45930-1-lance.yang@linux.dev> (raw)
In-Reply-To: <20261020115824.823278-1-songmuchun@bytedance.com>
On Tue, Oct 20, 2026 at 07:58:14PM +0800, Muchun Song wrote:
>VMEMMAP_SPLIT_NO_TLB_FLUSH and VMEMMAP_REMAP_NO_TLB_FLUSH do not
>describe fully independent choices. A split-only walk can defer the
>PMD-split flush to a later global flush, and a remap-only walk can
>defer the final remap flush. However, when a PMD split is followed
>by PTE remapping, the split flush must happen before the PTEs are
>changed, because stale large-page translations must not overlap with
>new small-page translations that map different physical pages.
>
>Replace the two flags with a single VMEMMAP_REMAP_NO_TLB_FLUSH flag.
>Keep split-only walks able to defer the flush, but force the split
>flush whenever a remap_pte callback is present. Callers that batch
>HVO work can still defer the final remap flush and issue their own
>global flush.
>
>Current callers keep the same flushing behavior.
>
>Signed-off-by: Muchun Song <songmuchun@bytedance.com>
>---
Nice work, don't really need two flags anymore :)
If we're going to remap, we still flush after the PMD split, so we can
keep batching the final flush :)
Reviewed-by: Lance Yang <lance.yang@linux.dev>
prev parent reply other threads:[~2026-10-22 3:52 UTC|newest]
Thread overview: 29+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-10-20 11:52 [PATCH 00/12] mm: Decouple folio-based vmemmap optimization from HugeTLB Muchun Song
2026-10-20 11:52 ` [PATCH 01/12] mm: hugetlb_vmemmap: remove HugeTLB-specific vmemmap optimization macros Muchun Song
2026-10-22 3:43 ` Lance Yang
2026-10-20 11:58 ` [PATCH 02/12] mm: hugetlb_vmemmap: unify VMEMMAP_{SPLIT,REMAP}_NO_TLB_FLUSH Muchun Song
2026-10-20 11:58 ` [PATCH 03/12] mm: hugetlb_vmemmap: simplify vmemmap head page handling Muchun Song
2026-10-22 6:24 ` Lance Yang
2026-10-22 6:27 ` Muchun Song
2026-10-22 7:23 ` Lance Yang
2026-10-20 11:58 ` [PATCH 04/12] mm: hugetlb_vmemmap: generalize vmemmap page allocation Muchun Song
2026-10-22 13:54 ` Lance Yang
2026-10-20 11:58 ` [PATCH 05/12] mm: hugetlb_vmemmap: unify writable vmemmap page preparation Muchun Song
2026-10-22 14:13 ` Lance Yang
2026-10-20 11:58 ` [PATCH 06/12] mm: hugetlb_vmemmap: rename vmemmap_remap_pte() to vmemmap_optimize_pte() Muchun Song
2026-10-23 0:55 ` Lance Yang
2026-10-20 11:58 ` [PATCH 07/12] mm: hugetlb_vmemmap: simplify shared tail page handling Muchun Song
2026-10-23 2:20 ` Lance Yang
2026-10-23 2:32 ` Muchun Song
2026-10-20 11:58 ` [PATCH 08/12] mm: hugetlb_vmemmap: move alloc_vmemmap_page_list() next to its free helper Muchun Song
2026-10-23 2:47 ` Lance Yang
2026-10-20 11:58 ` [PATCH 09/12] mm: hugetlb_vmemmap: make vmemmap optimization folio-oriented Muchun Song
2026-10-23 3:39 ` Lance Yang
2026-10-20 11:58 ` [PATCH 10/12] mm: hugetlb_vmemmap: make vmemmap restoration folio-oriented Muchun Song
2026-10-23 3:46 ` Lance Yang
2026-10-23 3:58 ` Muchun Song
2026-10-20 11:58 ` [PATCH 11/12] mm: hugetlb_vmemmap: unify vmemmap range restoration Muchun Song
2026-10-23 3:53 ` Lance Yang
2026-10-20 11:58 ` [PATCH 12/12] mm: hugetlb_vmemmap: make vmemmap PTE conversion folio-oriented Muchun Song
2026-10-23 7:33 ` Lance Yang
2026-10-22 3:52 ` Lance Yang [this message]
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