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Thu, 27 Aug 2026 11:15:34 -0400 (EDT) Date: Thu, 27 Aug 2026 16:15:33 +0100 From: Kiryl Shutsemau To: kasong@tencent.com Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, Andrew Morton , David Hildenbrand , Lorenzo Stoakes , Zi Yan , Baolin Wang , "Liam R. Howlett" , Nico Pache , Ryan Roberts , Dev Jain , Lance Yang , Usama Arif , Vlastimil Babka , Mike Rapoport , Suren Baghdasaryan , Michal Hocko , Chris Li , Kemeng Shi , Nhat Pham , Baoquan He , Barry Song , Youngjun Park , Shivam Kalra , Kairui Song Subject: Re: [PATCH v3 06/18] mm/huge_memory: consolidate irq and locking for folio split Message-ID: References: <20260821-swap-thp-cleanup-v3-0-9b43f5163238@tencent.com> <20260821-swap-thp-cleanup-v3-6-9b43f5163238@tencent.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20260821-swap-thp-cleanup-v3-6-9b43f5163238@tencent.com> X-Rspam-User: X-Rspamd-Server: rspam10 X-Rspamd-Queue-Id: CDF3980003 X-Stat-Signature: 8t14ufxz55bxzoj3efkhyfb976k557fd X-HE-Tag: 1787843737-678768 X-HE-Meta: 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 swARQwbv 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 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Fri, Aug 21, 2026 at 02:55:19AM +0800, Kairui Song via B4 Relay wrote: > From: Kairui Song > > Let each split helper handle its own locking instead of relying on > the caller, so both helpers manage their own irq and locking state. > This lets __folio_split() drop its local irq handling and fail label, > preparing for further cleanup. > > The file path now uses xas_lock_irq() instead of local_irq_disable() > with xas_lock(). The two are equivalent on non-RT, and > TRANSPARENT_HUGEPAGE cannot be enabled on RT anyway. This conversion > also buys consistency: every other place in mm/ that freezes a folio > while it is still reachable through the page cache already takes the > lock this way. This was actually the last plain xas_lock() on > mapping->i_pages left in mm. If we are going to support RT, spinning > on frozen folio refs could be a problem, but it already exists in > many places and should be fixed generically. > > The anon helper keeps a single local_irq_disable() as before, because > it has to cover several plain spinlocks at once. > > The dropped xas_reset() was a no-op as the xa_state is not walked > before the xas_load() under the lock. > > Reviewed-by: Zi Yan > Signed-off-by: Kairui Song Reviewed-by: Kiryl Shutsemau (Meta) -- Kiryl Shutsemau / Kirill A. Shutemov