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 56501EB64D7 for ; Fri, 23 Jun 2023 10:43:36 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id DDE4C8D0002; Fri, 23 Jun 2023 06:43:35 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id D8D738D0001; Fri, 23 Jun 2023 06:43:35 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id C54F58D0002; Fri, 23 Jun 2023 06:43:35 -0400 (EDT) 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 B3BAB8D0001 for ; Fri, 23 Jun 2023 06:43:35 -0400 (EDT) Received: from smtpin12.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay04.hostedemail.com (Postfix) with ESMTP id 7F1511A043F for ; Fri, 23 Jun 2023 10:43:35 +0000 (UTC) X-FDA: 80933676390.12.1732783 Received: from smtp-out2.suse.de (smtp-out2.suse.de [195.135.220.29]) by imf12.hostedemail.com (Postfix) with ESMTP id 3D8F940010 for ; Fri, 23 Jun 2023 10:43:32 +0000 (UTC) Authentication-Results: imf12.hostedemail.com; dkim=pass header.d=suse.com header.s=susede1 header.b=CWIUg5js; dmarc=pass (policy=quarantine) header.from=suse.com; spf=pass (imf12.hostedemail.com: domain of mhocko@suse.com designates 195.135.220.29 as permitted sender) smtp.mailfrom=mhocko@suse.com ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1687517013; 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=SXD8/RRwKWR+rrAXbXPncakblTDKpcnL76Ko04yn4uA=; b=uQKdfE9anBtPOUivCtZis9hKZrV2FXBIr2AQeEGZQ7/V7O9cYgG2dbqhbXp21SQSmTtDFe YlJGtKGa7vgJ3FHYGN1lznKf26D5CZp4BGH/unn+i2hTcmD5TbYDhoaFn5adM0sjUR/ZHt 62h+HMX8dZN80GZGNAjJ8XLQrDWiNF0= ARC-Authentication-Results: i=1; imf12.hostedemail.com; dkim=pass header.d=suse.com header.s=susede1 header.b=CWIUg5js; dmarc=pass (policy=quarantine) header.from=suse.com; spf=pass (imf12.hostedemail.com: domain of mhocko@suse.com designates 195.135.220.29 as permitted sender) smtp.mailfrom=mhocko@suse.com ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1687517013; a=rsa-sha256; cv=none; b=w1BRdCUzBiAEAx2MJXMplZn9D/4hM78r7b7ht5aQuDJHzQafHzS9BdrDtTuGOLK4Vdm+rR N9wwfc6TKT1GHeESwX0Xvn7Tpba7na45F0Q/TYdTsf0+5D5pbRV0X8E3K5LfvcsdJDuA6h S8FTHosi4rfG1gWQHZ5cIpR1jsn5x+4= Received: from imap2.suse-dmz.suse.de (imap2.suse-dmz.suse.de [192.168.254.74]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (P-521) server-digest SHA512) (No client certificate requested) by smtp-out2.suse.de (Postfix) with ESMTPS id 06E821F390; Fri, 23 Jun 2023 10:43:32 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.com; s=susede1; t=1687517012; h=from:from:reply-to: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=SXD8/RRwKWR+rrAXbXPncakblTDKpcnL76Ko04yn4uA=; b=CWIUg5js2gY5T8yeGK2AcYGy/HUJevvLeMaz0o5DtDWc+iw60LWzk7KVwCARYfUQcuwBqB eTMZvzs1pC238wJ97zDby4yk/Hs41z6xFoKmE879B5OVMFHId0OPUGWn39a0KP+PKWo7i9 qW4SGVUFs4ytHgMuVYxHQBoJQLcp7Xg= Received: from imap2.suse-dmz.suse.de (imap2.suse-dmz.suse.de [192.168.254.74]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (P-521) server-digest SHA512) (No client certificate requested) by imap2.suse-dmz.suse.de (Postfix) with ESMTPS id DAF2B1331F; Fri, 23 Jun 2023 10:43:31 +0000 (UTC) Received: from dovecot-director2.suse.de ([192.168.254.65]) by imap2.suse-dmz.suse.de with ESMTPSA id cu4+M1N3lWQuCAAAMHmgww (envelope-from ); Fri, 23 Jun 2023 10:43:31 +0000 Date: Fri, 23 Jun 2023 12:43:31 +0200 From: Michal Hocko To: Sebastian Andrzej Siewior Cc: Petr Mladek , Tetsuo Handa , linux-mm@kvack.org, "Luis Claudio R. Goncalves" , Andrew Morton , Mel Gorman , Thomas Gleixner , John Ogness Subject: Re: [PATCH] mm/page_alloc: Use write_seqlock_irqsave() instead write_seqlock() + local_irq_save(). Message-ID: References: <20230621104034.HT6QnNkQ@linutronix.de> <0e9fc992-8e05-2e63-b3b1-d8d3ce89fc16@I-love.SAKURA.ne.jp> <20230621130641.-5iueY1I@linutronix.de> <20230621143421.BgHjJklo@linutronix.de> <20230623081250.h20rlLik@linutronix.de> <20230623095804.Zf03Kn7H@linutronix.de> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20230623095804.Zf03Kn7H@linutronix.de> X-Rspamd-Queue-Id: 3D8F940010 X-Rspam-User: X-Rspamd-Server: rspam04 X-Stat-Signature: fepsf8y1sa99n39coh747fwnrfzps8e5 X-HE-Tag: 1687517012-630911 X-HE-Meta: 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 wOOR7MyL KY8ocu3l1qkaswuNh45mnAQ4kuUMYhebuGN+7wwqOXAPQbz198ZvBHeggdAOMWuSStwwR/UTRyPwf68Z6f3Fj4N1bvfDm0Hrs4fZ5VTbI8sGDh7Xb74TU+il+fLLLcd41pm75+b7X6Ib/zVVBHSSEo5ZB222HiwEnF+UzCTEAifAuc+wW1RiR1svT5skiQPT2O6Of 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 Fri 23-06-23 11:58:04, Sebastian Andrzej Siewior wrote: > On 2023-06-23 11:21:01 [+0200], Michal Hocko wrote: > > On Fri 23-06-23 10:12:50, Sebastian Andrzej Siewior wrote: > > [...] > > > It would do _but_ is it really needed? All users but one (the one in > > > __build_all_zonelists()) have interrupts already disabled. This isn't a > > > hot path and is not used very common. Does it justify the ifdef? > > > > This is not my call of course but let me just stress out that if all > > that is just because of __build_all_zonelists then it is likely not > > really worth it. We are talking about memory hoptlug here. I seriously > > doubt that this is something anybody would be using with RT > > expectations. > > My current plan to repost this with a better explanation and with printk > deferred within the locked region. But first I'm going to use > hotplug-mem to see how it works. If it can be enabled on RT then it > should work even if nobody is using it. Agreed! I merely wanted to point out that this needs a based fix much more than trying to overengineer it. -- Michal Hocko SUSE Labs