From: sashiko-bot@kernel.org
To: "Lorenzo Stoakes (ARM)" <ljs@kernel.org>
Cc: "Christian Borntraeger" <borntraeger@linux.ibm.com>,
"Heiko Carstens" <hca@linux.ibm.com>,
"Alexander Gordeev" <agordeev@linux.ibm.com>,
linux-s390@vger.kernel.org, "Vasily Gorbik" <gor@linux.ibm.com>
Subject: Re: [PATCH v5 01/12] mm/khugepaged: deposit a newly allocated page table on collapse
Date: Fri, 25 Sep 2026 20:25:09 +0000 [thread overview]
Message-ID: <20260925202510.1E3901F000FF@smtp.kernel.org> (raw)
In-Reply-To: <20260925-rcu-pagetable-freeing-v5-1-31e91065fea4@kernel.org>
> collapse_huge_page() deposits a PTE page table on PMD collapse in order
> that it can be utilised for subsequent split operations, meaning that those
> operations do not need to perform an allocation (as they are in a context
> where it might be unwise).
>
> However the PTE page table which is deposited is the one which is currently
> mapped by the PMD entry that is in the process of being collapsed.
>
> Once deposited, the PTE page table may be used in a split of any other
> unrelated PMD entry.
>
> This is currently not an issue as this operation is performed with VMA/mmap
> write lock + anon rmap locks held, so ordinary page table walkers will
> never accidentally end up walking the wrong thing, and GUP-fast is
> protected by an IPI via tlb_remove_table_sync_one().
> [ ... ]
>
> Reviewed-by: Baolin Wang <baolin.wang@linux.alibaba.com>
> Acked-by: David Hildenbrand (Arm) <david@kernel.org>
> Reviewed-by: Lance Yang <lance.yang@linux.dev>
> Signed-off-by: Lorenzo Stoakes (ARM) <ljs@kernel.org>
Sashiko has reviewed this patch and found no issues. It looks great!
--
Sashiko AI review · https://sashiko.dev/#/patchset/20260925-rcu-pagetable-freeing-v5-0-31e91065fea4@kernel.org?part=1
next prev parent reply other threads:[~2026-09-25 20:25 UTC|newest]
Thread overview: 27+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-09-25 20:09 [PATCH v5 00/12] mm: make userland page table freeing RCU-safe Lorenzo Stoakes (ARM)
2026-09-25 20:09 ` [PATCH v5 01/12] mm/khugepaged: deposit a newly allocated page table on collapse Lorenzo Stoakes (ARM)
2026-09-25 20:25 ` sashiko-bot [this message]
2026-09-25 20:09 ` [PATCH v5 02/12] mm: enable MMU_GATHER_RCU_TABLE_FREE for most 2-level architectures Lorenzo Stoakes (ARM)
2026-09-25 20:24 ` sashiko-bot
2026-09-25 20:09 ` [PATCH v5 03/12] mm: enable MMU_GATHER_RCU_TABLE_FREE for MMU riscv Lorenzo Stoakes (ARM)
2026-09-25 20:19 ` sashiko-bot
2026-09-25 20:09 ` [PATCH v5 04/12] mm: enable MMU_GATHER_RCU_TABLE_FREE for MMU arm Lorenzo Stoakes (ARM)
2026-09-25 20:23 ` sashiko-bot
2026-09-25 20:09 ` [PATCH v5 05/12] mm: enable MMU_GATHER_RCU_TABLE_FREE for arc, microblaze, xtensa Lorenzo Stoakes (ARM)
2026-09-25 20:24 ` sashiko-bot
2026-09-25 20:09 ` [PATCH v5 06/12] mm: enable MMU_GATHER_RCU_TABLE_FREE for sparc64 Lorenzo Stoakes (ARM)
2026-09-25 20:22 ` sashiko-bot
2026-09-25 20:09 ` [PATCH v5 07/12] mm: enable MMU_GATHER_RCU_TABLE_FREE for m68k-coldfire Lorenzo Stoakes (ARM)
2026-09-25 20:21 ` sashiko-bot
2026-09-25 20:09 ` [PATCH v5 08/12] mm: enable MMU_GATHER_RCU_TABLE_FREE for sh-X2 Lorenzo Stoakes (ARM)
2026-09-25 20:25 ` sashiko-bot
2026-09-25 20:09 ` [PATCH v5 09/12] mm: enable MMU_GATHER_RCU_TABLE_FREE for m68k-motorola Lorenzo Stoakes (ARM)
2026-09-25 20:28 ` sashiko-bot
2026-09-25 20:09 ` [PATCH v5 10/12] mm: enable MMU_GATHER_RCU_TABLE_FREE for sparc32 Lorenzo Stoakes (ARM)
2026-09-25 20:29 ` sashiko-bot
2026-09-25 20:09 ` [PATCH v5 11/12] mm: userland pgtable freeing is RCU-safe now, remove leftover bits Lorenzo Stoakes (ARM)
2026-09-25 20:33 ` sashiko-bot
2026-09-25 20:09 ` [PATCH v5 12/12] mm: change the contract for free_pgtables(), update docs Lorenzo Stoakes (ARM)
2026-09-25 20:28 ` sashiko-bot
2026-09-28 12:06 ` David Hildenbrand (Arm)
2026-09-25 22:28 ` [PATCH v5 00/12] mm: make userland page table freeing RCU-safe Andrew Morton
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