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]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 5270CCFD2F6 for ; Thu, 27 Nov 2025 12:45:48 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 7D7736B0005; Thu, 27 Nov 2025 07:45:47 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id 788226B0023; Thu, 27 Nov 2025 07:45:47 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 676B96B0029; Thu, 27 Nov 2025 07:45:47 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0017.hostedemail.com [216.40.44.17]) by kanga.kvack.org (Postfix) with ESMTP id 52CE66B0005 for ; Thu, 27 Nov 2025 07:45:47 -0500 (EST) Received: from smtpin26.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay10.hostedemail.com (Postfix) with ESMTP id F2E80C0121 for ; Thu, 27 Nov 2025 12:45:46 +0000 (UTC) X-FDA: 84156358692.26.6AFF28B Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by imf23.hostedemail.com (Postfix) with ESMTP id DF923140014 for ; Thu, 27 Nov 2025 12:45:44 +0000 (UTC) Authentication-Results: imf23.hostedemail.com; dkim=none; dmarc=pass (policy=none) header.from=arm.com; spf=pass (imf23.hostedemail.com: domain of kevin.brodsky@arm.com designates 217.140.110.172 as permitted sender) smtp.mailfrom=kevin.brodsky@arm.com ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1764247545; a=rsa-sha256; cv=none; b=F0vYozwgHanDa2+lPE00BvZOwzZrfjJfczuwvO2ohC4yZ7wtnFztox/sSgWN56WfzJZkoU o77lbCgD5yopg5qwMOnqAFryBgOBAPu+W3P7ePKNamuAcYM4lLrWaCT4VSkZYZB2KSpODf O5rJnBSIEFiM2mC8UN8pTbxplG5S0x8= ARC-Authentication-Results: i=1; imf23.hostedemail.com; dkim=none; dmarc=pass (policy=none) header.from=arm.com; spf=pass (imf23.hostedemail.com: domain of kevin.brodsky@arm.com designates 217.140.110.172 as permitted sender) smtp.mailfrom=kevin.brodsky@arm.com ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1764247545; h=from:from: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=n5j7xH8fTEoSKbVxXFkE4YpsGUIr1lBxjhNUPeg+DYg=; b=aYJtn8iufYm/c79KPjmxO9h15FwEJ2AquxiIclQAQpoRx4ObcwX7lg53hPCeqv+zKfhKbw YQYgGSWbl9ZHd7Tjtj2tDO/0tSSS6aKYr5YDW0KXLfN4sOZ/RU78UwbZL8eTxO8McYrYFc GrL/5aMSv/vQi9QsArTGXN+GOtvXqcs= Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 11C781477; Thu, 27 Nov 2025 04:45:36 -0800 (PST) Received: from [10.57.43.59] (unknown [10.57.43.59]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id EC00D3F73B; Thu, 27 Nov 2025 04:45:35 -0800 (PST) Message-ID: <0cb512ba-de15-4ba6-a85a-8287ab67fb53@arm.com> Date: Thu, 27 Nov 2025 13:45:33 +0100 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v5 08/12] mm: enable lazy_mmu sections to nest To: Alexander Gordeev Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, Andreas Larsson , Andrew Morton , Boris Ostrovsky , Borislav Petkov , Catalin Marinas , Christophe Leroy , Dave Hansen , David Hildenbrand , "David S. Miller" , David Woodhouse , "H. Peter Anvin" , Ingo Molnar , Jann Horn , Juergen Gross , "Liam R. Howlett" , Lorenzo Stoakes , Madhavan Srinivasan , Michael Ellerman , Michal Hocko , Mike Rapoport , Nicholas Piggin , Peter Zijlstra , "Ritesh Harjani (IBM)" , Ryan Roberts , Suren Baghdasaryan , Thomas Gleixner , Venkat Rao Bagalkote , Vlastimil Babka , Will Deacon , Yeoreum Yun , linux-arm-kernel@lists.infradead.org, linuxppc-dev@lists.ozlabs.org, sparclinux@vger.kernel.org, xen-devel@lists.xenproject.org, x86@kernel.org References: <20251124132228.622678-1-kevin.brodsky@arm.com> <20251124132228.622678-9-kevin.brodsky@arm.com> <4d0eab1a-e1dc-49cf-8640-727c9734233d-agordeev@linux.ibm.com> From: Kevin Brodsky Content-Language: en-GB In-Reply-To: <4d0eab1a-e1dc-49cf-8640-727c9734233d-agordeev@linux.ibm.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-Rspamd-Server: rspam10 X-Rspamd-Queue-Id: DF923140014 X-Stat-Signature: c8hyr3pc47xzjajozak5sy411c9zoicy X-Rspam-User: X-HE-Tag: 1764247544-136895 X-HE-Meta: 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 8MRibasc 2KKeR46WSnoUdP0yQUYDJofhOM0YksAw+RSsZqI4dn2cz6tNz9kE9gNYt02VindEszS2Inci3C6h3qZnXBv+YlITmbuXptfWdizgjDtdnQDPcZBu3uiDw4LgG5HGXJzRhhDSZHqOZpsHaLIhCNdhNregASzKSvmJ85wtu6PCc0ou+jom2R5WL/V4WtJWGZAVj2i5ZA2m4yP03UfQrueKTSKbJbRIbWuRgSYDGplpSSgpUaAsPH3djFwOLZEmgp2iYSHzM+tY4B163G9/J99RNm6PpS0Ai4Gb4gdB1G6jDtzeMIfTfXCiSGunVPB+1UEOg7onZKZKC9vSyjWKgoaS2h7cxEk6vBr5nnnaofLZggrKElw5DJGYyfYb1S4A6I474L557R1cFy3UVQmU= 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 27/11/2025 13:33, Alexander Gordeev wrote: > On Mon, Nov 24, 2025 at 01:22:24PM +0000, Kevin Brodsky wrote: > > Hi Kevin, > > ... >> +/** >> + * lazy_mmu_mode_pause() - Pause the lazy MMU mode. >> + * >> + * Pauses the lazy MMU mode; if it is currently active, disables it and calls >> + * arch_leave_lazy_mmu_mode(). >> + * >> + * Must be paired with a call to lazy_mmu_mode_resume(). Calls to the >> + * lazy_mmu_mode_* API have no effect until the matching resume() call. > Sorry if it was discussed already - if yes, I somehow missed it. If I read > the whole thing correctly enter()/pause() interleaving is not forbidden? Correct, any call inside pause()/resume() is now allowed (but effectively ignored). See discussion with Ryan in v4 [1]. [1] https://lore.kernel.org/all/824bf705-e9d6-4eeb-9532-9059fa56427f@arm.com/ > lazy_mmu_mode_enable() > lazy_mmu_mode_pause() > lazy_mmu_mode_enable() > ... > lazy_mmu_mode_disable() > lazy_mmu_mode_resume() > lazy_mmu_mode_disable() > >> + * >> + * Has no effect if called: >> + * - While paused (inside another pause()/resume() pair) >> + * - In interrupt context >> + */ >> static inline void lazy_mmu_mode_pause(void) >> { >> + struct lazy_mmu_state *state = ¤t->lazy_mmu_state; >> + >> if (in_interrupt()) >> return; >> >> - arch_leave_lazy_mmu_mode(); >> + VM_WARN_ON_ONCE(state->pause_count == U8_MAX); >> + >> + if (state->pause_count++ == 0 && state->enable_count > 0) >> + arch_leave_lazy_mmu_mode(); >> } >> >> +/** >> + * lazy_mmu_mode_pause() - Resume the lazy MMU mode. > resume() ? Good catch! One copy-paste too many... - Kevin >> + * >> + * Resumes the lazy MMU mode; if it was active at the point where the matching >> + * call to lazy_mmu_mode_pause() was made, re-enables it and calls >> + * arch_enter_lazy_mmu_mode(). >> + * >> + * Must match a call to lazy_mmu_mode_pause(). >> + * >> + * Has no effect if called: >> + * - While paused (inside another pause()/resume() pair) >> + * - In interrupt context >> + */ >> static inline void lazy_mmu_mode_resume(void) >> { >> + struct lazy_mmu_state *state = ¤t->lazy_mmu_state; >> + >> if (in_interrupt()) >> return; >> >> - arch_enter_lazy_mmu_mode(); >> + VM_WARN_ON_ONCE(state->pause_count == 0); >> + >> + if (--state->pause_count == 0 && state->enable_count > 0) >> + arch_enter_lazy_mmu_mode(); >> } > ... > Thanks!