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bh=RrTBk4l8xgKnE0zLzA8TtC6W0ocP3bb6+3R/hmfaxoM=; b=4fK++R/3BR88LnWzrXmxsmE6tRPOFK4URrpxLet7uTeZxcRBA8zrzWWWfNPgVk+fbnWETh zQ281DRJecqNlHNTFMRJQtBU2Xw+a+IM5mcTCsrUiz1nw7gAqfENyiml6EvBGohafCmiOb 11CpIy1cpF6sJxd3lIxrmgB6w/4LowtLk9EvPRNa4EH8XCv41V/aMT80Pn6DjnD2kaVrn3 qE/0bEogJpTYMbivPgE3og7DXOvg0SiGc9jLe0iZC4YpkjbKwKeotg5lWk6JmIvbjxt33y U+G6Q0hZmc2liG6jm+rmxozaAofzybBYVR4Uknxw8BYXsaZZ3KmPkDrzaVXEBg== DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020e; t=1743408704; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=RrTBk4l8xgKnE0zLzA8TtC6W0ocP3bb6+3R/hmfaxoM=; b=yP8dsOUQucE4FGkVS5oIQDiSZ4KbEWzFXD0givLvid9ZDyd/7Xk2+0IdW6tA3BuegnfJ3q YkJzBx44aAkD+dAg== From: Sebastian Andrzej Siewior To: Alexei Starovoitov Cc: Linus Torvalds , bpf@vger.kernel.org, daniel@iogearbox.net, andrii@kernel.org, martin.lau@kernel.org, akpm@linux-foundation.org, peterz@infradead.org, vbabka@suse.cz, rostedt@goodmis.org, shakeel.butt@linux.dev, mhocko@suse.com, linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH mm] mm/page_alloc: Avoid second trylock of zone->lock Message-ID: <20250331081143.cPXjY7PZ@linutronix.de> References: <20250331002809.94758-1-alexei.starovoitov@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <20250331002809.94758-1-alexei.starovoitov@gmail.com> X-Rspam-User: X-Rspamd-Server: rspam09 X-Rspamd-Queue-Id: 1871C140010 X-Stat-Signature: 4ea6pwyyjqrzqi4cy5q1zabkpd7pmdxm X-HE-Tag: 1743408706-226397 X-HE-Meta: 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 KXMRBH9m kzHzKTZOHXgZuxD5ACcBfMBfvcBddcZnrAWrvjGJq9xUyfdqt/0ql5PFtrmQ0/BhSvQ64g95FQg2nKggjn8Z3JeL26oThmkekmlPIzPCeW3l5Ee81jnZkcN9aNc/r5VfTXQo0sCo8OF2BOo6+r1uUDxZPV49/l2EkxMgIkJ/zkJhBwJXgETRNyozsWiDOGOszO3PAPkih1xzoa2lqPuMWCtmX6l2tXZQB17WyFls/1C6GoAW1N6VotJT/SLHhu/PsUOXWG2eh/Djt/Wq5rNPnfcsUIgi17fq0ARQcCfN+kp2D2r4MJAFhqruB0s4O5w6aYWQe8JT7JwuQjdZWndtCLcEw/Ys79hYnYbqtr2hQf3lqHH4eJKO81ZZ3o7JE5BKIACro6hkTXebzZNpXQgvp7GG99wPStdQ86uyi 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 2025-03-30 17:28:09 [-0700], Alexei Starovoitov wrote: > From: Alexei Starovoitov > > spin_trylock followed by spin_lock will cause extra write cache > access. If the lock is contended it may cause unnecessary cache > line bouncing and will execute redundant irq restore/save pair. > Therefore, check alloc/fpi_flags first and use spin_trylock or > spin_lock. > > Suggested-by: Linus Torvalds > Fixes: 97769a53f117 ("mm, bpf: Introduce try_alloc_pages() for opportunistic page allocation") > Signed-off-by: Alexei Starovoitov Reviewed-by: Sebastian Andrzej Siewior Sebastian