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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> Precedence: bulk X-Mailing-List: linux-rt-devel@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: 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> 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