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Mon, 02 Mar 2026 09:17:58 -0800 (PST) Received: from localhost ([2603:7000:c00:3a00:365a:60ff:fe62:ff29]) by smtp.gmail.com with ESMTPSA id d75a77b69052e-50744ad8f8bsm113862031cf.27.2026.03.02.09.17.57 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 02 Mar 2026 09:17:57 -0800 (PST) Date: Mon, 2 Mar 2026 12:17:56 -0500 From: Johannes Weiner To: Vlastimil Babka Cc: Andrew Morton , Suren Baghdasaryan , Michal Hocko , Brendan Jackman , Zi Yan , Mel Gorman , Matthew Wilcox , "David Hildenbrand (Arm)" , Sebastian Andrzej Siewior , Clark Williams , Steven Rostedt , linux-mm@kvack.org, linux-kernel@vger.kernel.org, linux-rt-devel@lists.linux.dev Subject: Re: [PATCH 2/3] mm/page_alloc: remove IRQ saving/restoring from pcp locking Message-ID: References: <20260227-b4-pcp-locking-cleanup-v1-0-f7e22e603447@kernel.org> <20260227-b4-pcp-locking-cleanup-v1-2-f7e22e603447@kernel.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20260227-b4-pcp-locking-cleanup-v1-2-f7e22e603447@kernel.org> X-Rspamd-Server: rspam10 X-Rspamd-Queue-Id: 8E1DC1A0015 X-Stat-Signature: iybf6ddh9rswaum6jb7ccu37d79kb371 X-Rspam-User: X-HE-Tag: 1772471879-796703 X-HE-Meta: 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 hp2PdSIE 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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, Feb 27, 2026 at 06:07:59PM +0100, Vlastimil Babka wrote: > Effectively revert commit 038a102535eb ("mm/page_alloc: prevent pcp > corruption with SMP=n"). The original problem is now avoided by > pcp_spin_trylock() always failing on CONFIG_SMP=n, so we do not need to > disable IRQs anymore. > > It's not a complete revert, because keeping the pcp_spin_(un)lock() > wrappers is useful. Rename them from _maybe_irqsave/restore to _nopin. > The difference from pcp_spin_trylock()/pcp_spin_unlock() is that the > _nopin variants don't perform pcpu_task_pin/unpin(). > > Signed-off-by: Vlastimil Babka (SUSE) Acked-by: Johannes Weiner