From: Lance Yang <lance.yang@linux.dev>
To: ljs@kernel.org
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Subject: Re: [PATCH v4 06/12] mm: enable MMU_GATHER_RCU_TABLE_FREE for sparc64
Date: Wed, 23 Sep 2026 16:54:14 +0800 [thread overview]
Message-ID: <20260923085414.17309-1-lance.yang@linux.dev> (raw)
In-Reply-To: <20260922-rcu-pagetable-freeing-v4-6-fe1ad1f1e303@kernel.org>
On Tue, Sep 22, 2026 at 04:35:37PM +0100, Lorenzo Stoakes (ARM) wrote:
>Commit 4a0100f7546f ("sparc64: use RCU page table freeing") enabled
>CONFIG_MMU_GATHER_RCU_TABLE_FREE for SMP sparc64 architectures, expressly
>for GUP-fast page table walkers.
>
>Naturally, UP systems do not have to worry about concurrent GUP fast
>operations.
>
>However, CONFIG_PREEMPT_RCU is also available even on a UP system, so a
>future pure-RCU page table walker requires MMU_GATHER_RCU_TABLE_FREE to be
>enabled on UP, even if concurrent GUP fast is not possible there.
>
>To enable future pure-RCU page table walkers, enable
>MMU_GATHER_RCU_TABLE_FREE unconditionally.
>
>With this change, it is no longer necessary to have !CONFIG_SMP
>pgtable_free_tlb(), so also remove this now dead code.
>
>This forms part of an overall effort to switch every architecture to this
>mode.
>
>Acked-by: Kiryl Shutsemau (Meta) <kas@kernel.org>
>Signed-off-by: Lorenzo Stoakes (ARM) <ljs@kernel.org>
>---
Also ran page-table teardown stress on qemu-system-sparc64 (sun4u, UP).
That ran cleanly too ;) Feel free to add:
Tested-by: Lance Yang <lance.yang@linux.dev>
Acked-by: Lance Yang <lance.yang@linux.dev>
next prev parent reply other threads:[~2026-09-23 8:54 UTC|newest]
Thread overview: 51+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-09-22 15:35 [PATCH v4 00/12] mm: make userland page table freeing RCU-safe Lorenzo Stoakes (ARM)
2026-09-22 15:35 ` [PATCH v4 01/12] mm/khugepaged: deposit a newly allocated page table on collapse Lorenzo Stoakes (ARM)
2026-09-23 2:24 ` Lance Yang
2026-09-23 7:09 ` Lorenzo Stoakes (ARM)
2026-09-23 7:14 ` Lorenzo Stoakes (ARM)
2026-09-23 7:24 ` Lance Yang
2026-09-23 8:54 ` David Hildenbrand (Arm)
2026-09-23 9:00 ` Lorenzo Stoakes (ARM)
2026-09-22 15:35 ` [PATCH v4 02/12] mm: enable MMU_GATHER_RCU_TABLE_FREE for most 2-level architectures Lorenzo Stoakes (ARM)
2026-09-23 4:39 ` Lance Yang
2026-09-22 15:35 ` [PATCH v4 03/12] mm: enable MMU_GATHER_RCU_TABLE_FREE for MMU riscv Lorenzo Stoakes (ARM)
2026-09-23 6:15 ` Lance Yang
2026-09-23 7:05 ` Lorenzo Stoakes (ARM)
2026-09-23 7:17 ` Lance Yang
2026-09-22 15:35 ` [PATCH v4 04/12] mm: enable MMU_GATHER_RCU_TABLE_FREE for MMU arm Lorenzo Stoakes (ARM)
2026-09-23 8:05 ` Lance Yang
2026-09-23 8:15 ` Lorenzo Stoakes (ARM)
2026-09-22 15:35 ` [PATCH v4 05/12] mm: enable MMU_GATHER_RCU_TABLE_FREE for arc, microblaze, xtensa Lorenzo Stoakes (ARM)
2026-09-23 8:43 ` Lance Yang
2026-09-22 15:35 ` [PATCH v4 06/12] mm: enable MMU_GATHER_RCU_TABLE_FREE for sparc64 Lorenzo Stoakes (ARM)
2026-09-23 8:54 ` Lance Yang [this message]
2026-09-22 15:35 ` [PATCH v4 07/12] mm: enable MMU_GATHER_RCU_TABLE_FREE for m68k-coldfire Lorenzo Stoakes (ARM)
2026-09-23 9:13 ` Lance Yang
2026-09-23 11:31 ` Greg Ungerer
2026-09-23 11:36 ` Lorenzo Stoakes (ARM)
2026-09-22 15:35 ` [PATCH v4 08/12] mm: enable MMU_GATHER_RCU_TABLE_FREE for sh-X2 Lorenzo Stoakes (ARM)
2026-09-23 11:54 ` Lance Yang
2026-09-23 11:56 ` Lorenzo Stoakes (ARM)
2026-09-22 15:35 ` [PATCH v4 09/12] mm: enable MMU_GATHER_RCU_TABLE_FREE for m68k-motorola Lorenzo Stoakes (ARM)
2026-09-23 13:16 ` Lance Yang
2026-09-23 13:21 ` Lorenzo Stoakes (ARM)
2026-09-22 15:35 ` [PATCH v4 10/12] mm: enable MMU_GATHER_RCU_TABLE_FREE for sparc32 Lorenzo Stoakes (ARM)
2026-09-22 15:35 ` [PATCH v4 11/12] mm: make userland page table freeing RCU-safe Lorenzo Stoakes (ARM)
2026-09-23 9:04 ` David Hildenbrand (Arm)
2026-09-23 9:06 ` Lorenzo Stoakes (ARM)
2026-09-23 9:13 ` David Hildenbrand (Arm)
2026-09-23 11:48 ` Lorenzo Stoakes (ARM)
2026-09-23 13:38 ` David Hildenbrand (Arm)
2026-09-23 13:43 ` Lorenzo Stoakes (ARM)
2026-09-22 15:35 ` [PATCH v4 12/12] mm: change the contract for free_pgtables(), update docs Lorenzo Stoakes (ARM)
2026-09-23 9:08 ` David Hildenbrand (Arm)
2026-09-23 11:55 ` Lorenzo Stoakes (ARM)
2026-09-22 16:42 ` [PATCH v4 00/12] mm: make userland page table freeing RCU-safe Matthew Wilcox
2026-09-22 17:22 ` Lorenzo Stoakes (ARM)
2026-09-22 23:00 ` Andrew Morton
2026-09-23 7:04 ` Lorenzo Stoakes (ARM)
2026-09-23 8:45 ` David Hildenbrand (Arm)
2026-09-23 9:04 ` Lorenzo Stoakes (ARM)
2026-09-23 9:15 ` David Hildenbrand (Arm)
2026-09-23 9:39 ` Vlastimil Babka (SUSE)
2026-09-23 11:39 ` Lorenzo Stoakes (ARM)
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