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 F1AB3EB64D7 for ; Wed, 21 Jun 2023 13:25:19 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 975938D0005; Wed, 21 Jun 2023 09:25:19 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 8FEBF8D0003; Wed, 21 Jun 2023 09:25:19 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 7C6778D0005; Wed, 21 Jun 2023 09:25:19 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0016.hostedemail.com [216.40.44.16]) by kanga.kvack.org (Postfix) with ESMTP id 6FFD78D0003 for ; Wed, 21 Jun 2023 09:25:19 -0400 (EDT) Received: from smtpin10.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay02.hostedemail.com (Postfix) with ESMTP id 24A3D1206EA for ; Wed, 21 Jun 2023 13:25:19 +0000 (UTC) X-FDA: 80926826358.10.61FEB5D Received: from galois.linutronix.de (Galois.linutronix.de [193.142.43.55]) by imf23.hostedemail.com (Postfix) with ESMTP id E8C86140016 for ; Wed, 21 Jun 2023 13:25:16 +0000 (UTC) Authentication-Results: imf23.hostedemail.com; dkim=pass header.d=linutronix.de header.s=2020 header.b=mjqZgQP+; dkim=pass header.d=linutronix.de header.s=2020e header.b=opqe9FZQ; spf=pass (imf23.hostedemail.com: domain of bigeasy@linutronix.de designates 193.142.43.55 as permitted sender) smtp.mailfrom=bigeasy@linutronix.de; dmarc=pass (policy=none) header.from=linutronix.de ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1687353917; 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: in-reply-to:in-reply-to:references:references:dkim-signature; bh=xl3NzBSnB9xEaRcjKm1Yzlc2aNcJfRcDD35Z/CiymYg=; b=lMhPaiU3lyA5NxUbg47LeL2nqiQUbsQZiqlxPSD50yWdVBNUmDoShbMAXEBiiaC9M+bAuP zHlHsfhH/k/fVzXpH9QOHhponZR5upcR5DRbo6R2n4HcBFoToTCi+V+/IosHSRr6b/g+nf gFLdJpntzmqPIF1BI2H8R1nl72RDbiA= ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1687353917; a=rsa-sha256; cv=none; b=hbTdPqfKlacuGqSZZ/Zn6hLJvEdwr1oTOZloY2yItr9gRzETadz9cy+28+dT3vmpXxCG+C kq1F5UFzxwc0agBl3+bPZs3X4ymcvDIKjxSV0aoWDodO9tUKF6j/nUrKY4tV7QWhL4Pe2q MLIs1bfSeFWQ7niajz6OqQ0wZ68k/YU= ARC-Authentication-Results: i=1; imf23.hostedemail.com; dkim=pass header.d=linutronix.de header.s=2020 header.b=mjqZgQP+; dkim=pass header.d=linutronix.de header.s=2020e header.b=opqe9FZQ; spf=pass (imf23.hostedemail.com: domain of bigeasy@linutronix.de designates 193.142.43.55 as permitted sender) smtp.mailfrom=bigeasy@linutronix.de; dmarc=pass (policy=none) header.from=linutronix.de Date: Wed, 21 Jun 2023 15:25:13 +0200 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020; t=1687353915; 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=xl3NzBSnB9xEaRcjKm1Yzlc2aNcJfRcDD35Z/CiymYg=; b=mjqZgQP+RjTyOULEPKyAY71MVGgDeAR8CtRAHBLP9cUzCflbr4Ls/Ki8gDOjAgIrORXkWO VwjnqP8KhrBTYRKvft4t0b9ufx78CZF492zZZLm4zteYOCIrZ27bkTsObykiYCteFfgryF WSA1nDFJSB7cMq0NTp+KxlJPmWQqu8Y5HTDtZFxMUHunUVTW8ViN1pPJkquKjRfGl32SNq uZU9lk/XLbaMblOHEIKNToHuwHA6bvgB1myfUFF+LBa0HMiuuLAq6qIb33uXkuEFDyrt1g xDSFW0ybYhFUr1sYHYtcLHr/qnhGewIrXuRrNlaTGbSuE1A+LE9o58JFFKbeNg== DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020e; t=1687353915; 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=xl3NzBSnB9xEaRcjKm1Yzlc2aNcJfRcDD35Z/CiymYg=; b=opqe9FZQPXLh2NAh5tffE8XYVBuzG9+TnJPpmZOWzMiksimDVyqigP44vctaPBk5YnFGCC tnH1u7dtX1nKclAg== From: Sebastian Andrzej Siewior To: Michal Hocko Cc: linux-mm@kvack.org, "Luis Claudio R. Goncalves" , Andrew Morton , Mel Gorman , Tetsuo Handa , Thomas Gleixner Subject: Re: [PATCH] mm/page_alloc: Use write_seqlock_irqsave() instead write_seqlock() + local_irq_save(). Message-ID: <20230621132513.ywlT5wMt@linutronix.de> References: <20230621104034.HT6QnNkQ@linutronix.de> <20230621111636.92RxISzY@linutronix.de> <20230621131125.XC2Pgojw@linutronix.de> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: X-Rspamd-Queue-Id: E8C86140016 X-Rspam-User: X-Rspamd-Server: rspam11 X-Stat-Signature: uin8ceytmyngszcciaa67y64t3nanii9 X-HE-Tag: 1687353916-84889 X-HE-Meta: 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 N6KiKSiV 7vo5McNr/5MaMavabXKJLDYntpPmPrM2sqno74t4fnMhoxlcs/LwZkKaWkruSFEJK493uthlnW0SIevJKKH2LVpzSMS1PTXsD6Kmbwxq+ekp5g2hZO/6i7e7X54VuSzQzzJMna070cwa1huA= 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: On 2023-06-21 15:22:29 [+0200], Michal Hocko wrote: > > The problem is the "local_irq_save()" which I believe I stated. The lock > > + unlock story was just a side story and is already covered. I really > > need just the local_irq_save() invocation to be part of the seqlock API > > so it can be substituted away. > > I really do not want to nitpick but your changelog states: > "This is troublesome and leads to problems on PREEMPT_RT because the > inner spinlock_t is now acquired with disabled interrupts." > > I believe it would be benefitial to state why htis is troublesome > because not everybody has insight into PREEMPT_RT and all the > consequences. Now after re-reading it I do understand what you mean. > Thanks! Sebastian