From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from shelob.surriel.com (shelob.surriel.com [96.67.55.147]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id EB6DA19D886; Wed, 29 Jan 2025 16:14:48 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=96.67.55.147 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1738167292; cv=none; b=LUXBSW6mIGzKvXF/bIIz7/HgeGSogn7Kf8/DSd1BbpGGvTvbTXOGm061snPl3YzDc7SwnGN4C/WYh+wFsXpcX04xx7HvWqEItlVLUn3wmKnG0FQQf2QBN4ot941Q0cjQNtpPrrklCPGrz5nldu0RbBzpJfTaxbtj11YF3oum8Aw= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1738167292; c=relaxed/simple; bh=eOrkqF/jEbDwlVLCBKzcKz36pjkWmXUSVUkAlWZd/+o=; h=Message-ID:Subject:From:To:Cc:Date:In-Reply-To:References: Content-Type:MIME-Version; b=tCebLJ00mKHz/k3+dApT1meDHffMO2ScOoovQfuNEqui7ViNgjkizE9ryDOvHTuHrhLcgGITtd8grntfelsWDT1fKJ8MszKHztzmz8b6RUB95rrEcMomy3YhbIrCi4dNNM66WDyffgCQbdp/2Mb1XFF+ASwlVe9E23upclw7wuc= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=surriel.com; spf=pass smtp.mailfrom=shelob.surriel.com; arc=none smtp.client-ip=96.67.55.147 Authentication-Results: smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=surriel.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=shelob.surriel.com Received: from fangorn.home.surriel.com ([10.0.13.7]) by shelob.surriel.com with esmtpsa (TLS1.2) tls TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384 (Exim 4.97.1) (envelope-from ) id 1tdAhx-00000000093-2xkA; Wed, 29 Jan 2025 11:14:29 -0500 Message-ID: <488401565cac6b5f9e3232d0ca481055876c919b.camel@surriel.com> Subject: Re: [linus:master] [x86] 4817f70c25: stress-ng.mmapaddr.ops_per_sec 63.0% regression From: Rik van Riel To: Matthew Wilcox Cc: Qi Zheng , Peter Zijlstra , David Hildenbrand , kernel test robot , oe-lkp@lists.linux.dev, lkp@intel.com, linux-kernel@vger.kernel.org, Andrew Morton , Dave Hansen , Andy Lutomirski , Catalin Marinas , David Rientjes , Hugh Dickins , Jann Horn , Lorenzo Stoakes , Mel Gorman , Muchun Song , Peter Xu , Will Deacon , Zach O'Keefe , Dan Carpenter , "Paul E. McKenney" , Frederic Weisbecker , Neeraj Upadhyay Date: Wed, 29 Jan 2025 11:14:29 -0500 In-Reply-To: References: <202501281734.d408a35b-lkp@intel.com> <46ea4509-0f38-4b22-bd91-f05c68db2562@redhat.com> <20250128113100.GB7145@noisy.programming.kicks-ass.net> <2c599f1f-f63b-4504-a026-46bf73954124@redhat.com> <20250128132847.GB505@noisy.programming.kicks-ass.net> <18172465-37e3-48a9-9d67-0d44fdcb93bd@redhat.com> <8b661116-0a85-4928-91ed-3c01ebbf8d39@bytedance.com> <2212111cad3180948cf388a7e5c8689df0fdda08.camel@surriel.com> <14159fb4-0c59-4653-9265-73f415e70063@bytedance.com> <20250129105920.7a4bffa1@fangorn> Autocrypt: addr=riel@surriel.com; prefer-encrypt=mutual; keydata=mQENBFIt3aUBCADCK0LicyCYyMa0E1lodCDUBf6G+6C5UXKG1jEYwQu49cc/gUBTTk33A eo2hjn4JinVaPF3zfZprnKMEGGv4dHvEOCPWiNhlz5RtqH3SKJllq2dpeMS9RqbMvDA36rlJIIo47 Z/nl6IA8MDhSqyqdnTY8z7LnQHqq16jAqwo7Ll9qALXz4yG1ZdSCmo80VPetBZZPw7WMjo+1hByv/ lvdFnLfiQ52tayuuC1r9x2qZ/SYWd2M4p/f5CLmvG9UcnkbYFsKWz8bwOBWKg1PQcaYHLx06sHGdY dIDaeVvkIfMFwAprSo5EFU+aes2VB2ZjugOTbkkW2aPSWTRsBhPHhV6dABEBAAG0HlJpayB2YW4gU mllbCA8cmllbEByZWRoYXQuY29tPokBHwQwAQIACQUCW5LcVgIdIAAKCRDOed6ShMTeg05SB/986o gEgdq4byrtaBQKFg5LWfd8e+h+QzLOg/T8mSS3dJzFXe5JBOfvYg7Bj47xXi9I5sM+I9Lu9+1XVb/ r2rGJrU1DwA09TnmyFtK76bgMF0sBEh1ECILYNQTEIemzNFwOWLZZlEhZFRJsZyX+mtEp/WQIygHV WjwuP69VJw+fPQvLOGn4j8W9QXuvhha7u1QJ7mYx4dLGHrZlHdwDsqpvWsW+3rsIqs1BBe5/Itz9o 6y9gLNtQzwmSDioV8KhF85VmYInslhv5tUtMEppfdTLyX4SUKh8ftNIVmH9mXyRCZclSoa6IMd635 Jq1Pj2/Lp64tOzSvN5Y9zaiCc5FucXtB9SaWsgdmFuIFJpZWwgPHJpZWxAc3VycmllbC5jb20+iQE +BBMBAgAoBQJSLd2lAhsjBQkSzAMABgsJCAcDAgYVCAIJCgsEFgIDAQIeAQIXgAAKCRDOed6ShMTe g4PpB/0ZivKYFt0LaB22ssWUrBoeNWCP1NY/lkq2QbPhR3agLB7ZXI97PF2z/5QD9Fuy/FD/jddPx KRTvFCtHcEzTOcFjBmf52uqgt3U40H9GM++0IM0yHusd9EzlaWsbp09vsAV2DwdqS69x9RPbvE/Ne fO5subhocH76okcF/aQiQ+oj2j6LJZGBJBVigOHg+4zyzdDgKM+jp0bvDI51KQ4XfxV593OhvkS3z 3FPx0CE7l62WhWrieHyBblqvkTYgJ6dq4bsYpqxxGJOkQ47WpEUx6onH+rImWmPJbSYGhwBzTo0Mm G1Nb1qGPG+mTrSmJjDRxrwf1zjmYqQreWVSFEt26tBpSaWsgdmFuIFJpZWwgPHJpZWxAZmIuY29tP okBPgQTAQIAKAUCW5LbiAIbIwUJEswDAAYLCQgHAwIGFQgCCQoLBBYCAwECHgECF4AACgkQznneko TE3oOUEQgAsrGxjTC1bGtZyuvyQPcXclap11Ogib6rQywGYu6/Mnkbd6hbyY3wpdyQii/cas2S44N cQj8HkGv91JLVE24/Wt0gITPCH3rLVJJDGQxprHTVDs1t1RAbsbp0XTksZPCNWDGYIBo2aHDwErhI omYQ0Xluo1WBtH/UmHgirHvclsou1Ks9jyTxiPyUKRfae7GNOFiX99+ZlB27P3t8CjtSO831Ij0Ip QrfooZ21YVlUKw0Wy6Ll8EyefyrEYSh8KTm8dQj4O7xxvdg865TLeLpho5PwDRF+/mR3qi8CdGbkE c4pYZQO8UDXUN4S+pe0aTeTqlYw8rRHWF9TnvtpcNzZw== Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable User-Agent: Evolution 3.54.1 (3.54.1-1.fc41) Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Sender: riel@surriel.com On Wed, 2025-01-29 at 16:12 +0000, Matthew Wilcox wrote: > On Wed, Jan 29, 2025 at 10:59:20AM -0500, Rik van Riel wrote: > > Below is a tentative fix for the issue. It is kind of a big hammer, > > and maybe the RCU people have a better idea on how to solve this > > problem, but it may be worth giving this a try to see if it helps > > with the regression you identified. >=20 > Perhaps better to do: >=20 > +++ b/mm/page_alloc.c > @@ -97,8 +97,8 @@ static DEFINE_MUTEX(pcp_batch_high_lock); > =C2=A0 * On SMP, spin_trylock is sufficient protection. > =C2=A0 * On PREEMPT_RT, spin_trylock is equivalent on both SMP and UP. > =C2=A0 */ > -#define pcp_trylock_prepare(flags)=C2=A0=C2=A0=C2=A0=C2=A0 do { } while = (0) > -#define pcp_trylock_finish(flag)=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 do = { } while (0) > +#define pcp_trylock_prepare(flags)=C2=A0=C2=A0=C2=A0=C2=A0 rcu_read_lock= () > +#define pcp_trylock_finish(flag)=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 rcu= _reada_unlock() > =C2=A0#else >=20 > =C2=A0/* UP spin_trylock always succeeds so disable IRQs to prevent re- > entrancy. */ >=20 > with appropriate comment changes >=20 Agreed. Assuming this change even works :) Paul, does this look like it could do the trick, or do we need something else to make RCU freeing happy again? --=20 All Rights Reversed.