From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by smtp.lore.kernel.org (Postfix) with ESMTP id C4A23C3DA6D for ; Tue, 20 May 2025 13:00:58 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 09DBF6B0088; Tue, 20 May 2025 09:00:58 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 04EF26B0089; Tue, 20 May 2025 09:00:57 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id EA6986B008A; Tue, 20 May 2025 09:00:57 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0010.hostedemail.com [216.40.44.10]) by kanga.kvack.org (Postfix) with ESMTP id C83436B0088 for ; Tue, 20 May 2025 09:00:57 -0400 (EDT) Received: from smtpin06.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay10.hostedemail.com (Postfix) with ESMTP id 345D2C0183 for ; Tue, 20 May 2025 13:00:57 +0000 (UTC) X-FDA: 83463296154.06.B71E4FE Received: from shelob.surriel.com (shelob.surriel.com [96.67.55.147]) by imf09.hostedemail.com (Postfix) with ESMTP id 6BDB014001A for ; Tue, 20 May 2025 13:00:55 +0000 (UTC) Authentication-Results: imf09.hostedemail.com; dkim=none; dmarc=none; spf=pass (imf09.hostedemail.com: domain of riel@shelob.surriel.com designates 96.67.55.147 as permitted sender) smtp.mailfrom=riel@shelob.surriel.com ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1747746055; a=rsa-sha256; cv=none; b=gmbG17ouM4naM/UZVIuLgc8na+T1DOTUJkJ7IS1vJtq5WQEcdju/vbHdIDpzixmb48cLGf +XguqoFn8sH7n1j/n5aGt1F7JnM7mXN1gOZmpuph324pABtVYOfrXKkVqhCEFyyDMCOhfz bsQdhBf1YDFY3X8Tkp1zQFB3Ix+GpAM= ARC-Authentication-Results: i=1; imf09.hostedemail.com; dkim=none; dmarc=none; spf=pass (imf09.hostedemail.com: domain of riel@shelob.surriel.com designates 96.67.55.147 as permitted sender) smtp.mailfrom=riel@shelob.surriel.com ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1747746055; h=from:from:sender:sender:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=s3xlh3uXDOram5h7mRZq0VTmCxawhLVTWZeMbWuMgRU=; b=egUUsAbQiWLRQRcjuKjX3tewySFrpkttCrsB2xfn1XsiDW2pvwgO9EkbNCqR/fzy/Oo+dU hnCr73KZAT55JADqZPx4zVjPh/jGIbxttpTCyLt29k83bk5AkJix6yXTGx21fNsQDln1UY 52Ugm/GiiQfF2n+1g2hSX380CxlAvCA= 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 1uHMa9-00000000119-2u1g; Tue, 20 May 2025 09:00:33 -0400 Message-ID: <6a3290319031cd68a383e416f53aa7549bac9407.camel@surriel.com> Subject: Re: [RFC v2 7/9] x86/mm: Introduce Remote Action Request From: Rik van Riel To: Nadav Amit Cc: Linux Kernel Mailing List , "open list:MEMORY MANAGEMENT" , the arch/x86 maintainers , kernel-team@meta.com, Dave Hansen , luto@kernel.org, peterz@infradead.org, Thomas Gleixner , Ingo Molnar , Borislav Petkov , "H. Peter Anvin" , Yu-cheng Yu Date: Tue, 20 May 2025 09:00:33 -0400 In-Reply-To: <4A879001-E213-4239-9D25-CDA8EC3E2CD9@gmail.com> References: <20250520010350.1740223-1-riel@surriel.com> <20250520010350.1740223-8-riel@surriel.com> <4A879001-E213-4239-9D25-CDA8EC3E2CD9@gmail.com> 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 3.54.3 (3.54.3-1.fc41) MIME-Version: 1.0 X-Stat-Signature: ztfd1d5c9i4bp65cx4ryaub1ghoz9yqy X-Rspam-User: X-Rspamd-Queue-Id: 6BDB014001A X-Rspamd-Server: rspam06 X-HE-Tag: 1747746055-802208 X-HE-Meta: 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 BLoKO9pT xZLAasXY7Z2YgxBhCuMgM6HKoxrYvXuSTPB45djNvHPmwyck1JwmQusL1zjjNNssQJSXjhDub7SM8sXrlI5CjwG+Zwfi2nYzw3P5ON/FlqehJdYahuwoN7mzXKh5MUhGVfuIsXaUZI+5YmZOdfAT1oU00s/MFJjCc4QIVuuOV1JgGlKCiryPyYeKcBoDpMY0GYHY2tgP/FvoXg45Zx0q5zIzekq09cMl0Gyqgmaa0s9urdXNLut2afWriQ7TDlMSE3f+TgTBkLkNsr17H/+IQlQVCwjZhQSWsEaK36ojpSaEGUITNTmmiVkJUgCjyUNnpHPeex40Rev/V+jXmSs01sIrLOQtvPfdN3NQhEiA6nQSS8C6XDE9B1HMXErhJrRtmdHWYkNh5bbDg3wo= 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 Tue, 2025-05-20 at 14:29 +0300, Nadav Amit wrote: > Not a full review, but.. >=20 > > On 20 May 2025, at 4:02, Rik van Riel wrote: > >=20 > > +/* > > + * This is a modified version of smp_call_function_many() of > > kernel/smp.c, >=20 > The updated function names is smp_call_function_many_cond() and it is > not aligned with smp_call_rar_many. I think the new version is > (suprisingly) > better, so it=E2=80=99d be beneficial to bring smp_call_rar_many() to be = like > the > updated one in smp.c. >=20 Agreed, it will be good to conditionally not send=20 the RAR vector to some CPUs, especially ones that are in deeper idle states. That means structuring the code more like smp_call_function_many_cond() > > + /* > > + * Can deadlock when called with interrupts disabled. > > + * We allow cpu's that are not yet online though, as no > > one else can > > + * send smp call function interrupt to this cpu and as > > such deadlocks > > + * can't happen. > > + */ > > + WARN_ON_ONCE(cpu_online(this_cpu) && irqs_disabled() > > + =C2=A0=C2=A0=C2=A0=C2=A0 && !oops_in_progress && > > !early_boot_irqs_disabled); >=20 > I thought you agreed to change it to make it use lockdep instead (so > it will > be compiled out without LOCKDEP), like done in > smp_call_function_many_cond() >=20 I thought I had made that change in my tree. I guess I lost it in a rebase :( > > + > > + /* Try to fastpath.=C2=A0 So, what's a CPU they want?=C2=A0 Ignoring > > this one. */ > > + cpu =3D cpumask_first_and(mask, cpu_online_mask); > > + if (cpu =3D=3D this_cpu) > > + cpu =3D cpumask_next_and(cpu, mask, > > cpu_online_mask); > > + >=20 > Putting aside the rest of the code, I see you don=E2=80=99t call > should_flush_tlb(). > I think it is worth mentioning in commit log or comment the rationale > behind > it (and maybe benchmarks to justify it). >=20 >=20 The long term plan here is to simply have the originating CPU included in the cpumask, and have it send a RAR request to itself. That way all the CPUs can invalidate their entries in parallel, without any extra code. --=20 All Rights Reversed.