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From: Shakeel Butt To: Harry Yoo Cc: Qi Zheng , hannes@cmpxchg.org, hughd@google.com, mhocko@suse.com, roman.gushchin@linux.dev, muchun.song@linux.dev, david@redhat.com, lorenzo.stoakes@oracle.com, ziy@nvidia.com, imran.f.khan@oracle.com, kamalesh.babulal@oracle.com, axelrasmussen@google.com, yuanchu@google.com, weixugc@google.com, akpm@linux-foundation.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org, cgroups@vger.kernel.org, Muchun Song , Qi Zheng , Sebastian Andrzej Siewior , Clark Williams , Steven Rostedt , linux-rt-devel@lists.linux.dev Subject: Re: [PATCH v1 04/26] mm: vmscan: refactor move_folios_to_lru() Message-ID: References: <97ea4728568459f501ddcab6c378c29064630bb9.1761658310.git.zhengqi.arch@bytedance.com> <366385a3-ed0e-440b-a08b-9cf14165ee8f@linux.dev> <2a68bddf-e6e6-4960-b5bc-1a39d747ea9b@linux.dev> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-Migadu-Flow: FLOW_OUT X-Rspamd-Server: rspam04 X-Rspamd-Queue-Id: BDB0B180005 X-Stat-Signature: ip7nmn416h13457i6saa5nto9do8qny3 X-Rspam-User: X-HE-Tag: 1762793287-30346 X-HE-Meta: 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 oJfdwuCf 0kZdJ1ONJK0PPpPNNw+ZXa2OHYoqwSM/Fm7Ugl0cUaZeHxjT92EDeNl4AA55sr1TXuvIMR4jrAmYjwTsBiE7gg21yc48ek5ADbclkfsl8ySbeyWMT+17EYmDoM/y8/4Wya9/elTIGs4ckkSTsTUvlOPoYo1fk2s8uBN7VWpurkhSzYTvIOtydiUOmcEPtCQZugWmFameffTw/xzXuwmC8rQmoGczpqNuSLH8tnf+hgaSIGFI5dbo/e/++POWun0sRfUat X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Mon, Nov 10, 2025 at 02:43:21PM +0900, Harry Yoo wrote: > On Mon, Nov 10, 2025 at 12:30:06PM +0800, Qi Zheng wrote: > > > Maybe we could make it safe against re-entrant IRQ handlers by using > > > read-modify-write operations? > > > > Isn't it because of the RMW operation that we need to use IRQ to > > guarantee atomicity? Or have I misunderstood something? > > I meant using atomic operations instead of disabling IRQs, like, by > using this_cpu_add() or cmpxchg() instead. We already have mod_node_page_state() which is safe from IRQs and is optimized to not disable IRQs for archs with HAVE_CMPXCHG_LOCAL which includes x86 and arm64. Let me send the patch to cleanup the memcg code which uses __mod_node_page_state.