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 0FC2EEB64D7 for ; Wed, 21 Jun 2023 12:40:58 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 567DF8D0002; Wed, 21 Jun 2023 08:40:58 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 4F09A8D0001; Wed, 21 Jun 2023 08:40:58 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 3B8108D0002; Wed, 21 Jun 2023 08:40:58 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0014.hostedemail.com [216.40.44.14]) by kanga.kvack.org (Postfix) with ESMTP id 280898D0001 for ; Wed, 21 Jun 2023 08:40:58 -0400 (EDT) Received: from smtpin01.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay07.hostedemail.com (Postfix) with ESMTP id F17131606F0 for ; Wed, 21 Jun 2023 12:40:57 +0000 (UTC) X-FDA: 80926714554.01.7FA1D7C Received: from smtp-out2.suse.de (smtp-out2.suse.de [195.135.220.29]) by imf13.hostedemail.com (Postfix) with ESMTP id 1A98D2001E for ; Wed, 21 Jun 2023 12:40:55 +0000 (UTC) Authentication-Results: imf13.hostedemail.com; dkim=pass header.d=suse.com header.s=susede1 header.b=Hd4JTYs6; spf=pass (imf13.hostedemail.com: domain of pmladek@suse.com designates 195.135.220.29 as permitted sender) smtp.mailfrom=pmladek@suse.com; dmarc=pass (policy=quarantine) header.from=suse.com ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1687351256; a=rsa-sha256; cv=none; b=YxRyiFg7XmJUShmZXUhqZ6tLoNGGFdSk777XmY9ZBoOZ+l/Bdeo0q8cxznlIu9WAVqiGyS FjcPMmJmLeRIjBSU7/0MSvz0yZsn3ig3WYZACueoAeoJiNI9JGf0fUIjSNJN7Bnv5a9RmT +NLGN9Qbh2oedn/LEoKSCuhfpbaZrr4= ARC-Authentication-Results: i=1; imf13.hostedemail.com; dkim=pass header.d=suse.com header.s=susede1 header.b=Hd4JTYs6; spf=pass (imf13.hostedemail.com: domain of pmladek@suse.com designates 195.135.220.29 as permitted sender) smtp.mailfrom=pmladek@suse.com; dmarc=pass (policy=quarantine) header.from=suse.com ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1687351256; 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=eIbMmHAXyvNOYMfRP0+aHpwhsQTS6cTMg55iLsBh5QM=; b=bBQdiDKzIyhjOTKIparGNIz86LdSGrIismeClzEyDsg8P5kz5mTkRR6zVI7ikACc24hSjS Gg0A7Rsc5tIO/99Rg8gxNNXCMK0dKym3fgtLL0LQ5OhZUPRZxKPa9dGX4OFa+0iZsXW2b+ Rpktllwvl2cZhPx1ucqLBiLqWLjzATc= Received: from relay2.suse.de (relay2.suse.de [149.44.160.134]) by smtp-out2.suse.de (Postfix) with ESMTP id 7CA6F1FE33; Wed, 21 Jun 2023 12:40:54 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.com; s=susede1; t=1687351254; 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=eIbMmHAXyvNOYMfRP0+aHpwhsQTS6cTMg55iLsBh5QM=; b=Hd4JTYs6alTL8WATQJYk2WRhSi461boX5IJLzk6G3dWRhjpIhB/fdS853A27Xk1z+5oVZB uatKZ3EOer1rTuAC3yOyftkZ51iB7iyfKO75eho7YQuk6/8xFsuBXEXgrmu5hQWmu4wRqe 3pAscZqLZDQzBp1harvSfpbeLWCjY/A= Received: from suse.cz (unknown [10.100.201.202]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by relay2.suse.de (Postfix) with ESMTPS id 1F1412C141; Wed, 21 Jun 2023 12:40:53 +0000 (UTC) Date: Wed, 21 Jun 2023 14:40:50 +0200 From: Petr Mladek To: Tetsuo Handa Cc: Sebastian Andrzej Siewior , linux-mm@kvack.org, "Luis Claudio R. Goncalves" , Andrew Morton , Mel Gorman , Michal Hocko , Thomas Gleixner 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> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <0e9fc992-8e05-2e63-b3b1-d8d3ce89fc16@I-love.SAKURA.ne.jp> X-Rspamd-Server: rspam08 X-Rspamd-Queue-Id: 1A98D2001E X-Stat-Signature: sct5akk4uidmeek7rjets14ad8nxq49j X-Rspam-User: X-HE-Tag: 1687351255-815251 X-HE-Meta: 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 QD2QB5vi r+ohMoJirNqJcFXqdZ57Suyi9+LJoItY3PBmAkDbsgn1/d4/0ncx5eGyQKJYIsjDCCtvOg+HfczVSKZluHFrd3PrXGXPrgrhsr/DhJ4ohhVhfQbPBXQr4UDmo7RohjsopdlxxnIrData53NBKqHpJCAzvz3NDERLukYmizRmRKNIvIT41105zYX6rVojNxckadDHucg6FbRiq7GUvscsvF4OmcjlrYGIVMJQmL6i9i9mPSh//taqhgmPna2KbUjeqmd32Q9bkFYnnGAZ2brfJKEjF9axml3LG2Cc7vuKWawJSMIUOPK/OganSMg== 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 Wed 2023-06-21 20:33:35, Tetsuo Handa wrote: > On 2023/06/21 19:40, Sebastian Andrzej Siewior wrote: > > printk_deferred_enter() has to be invoked in non-migrate-able context to > > ensure that deferred printing is enabled and disabled on the same CPU. > > I can't catch. local_irq_save(flags); makes non-migrate-able context > because sleeping is not allowed while IRQ is disabled, doesn't it? > > > This is the case after zonelist_update_seq has been acquired. > > > > Acquire zonelist_update_seq with write_seqlock_irqsave() and then defer > > printk output. > > What guarantees that write_seqlock_irqsave() never calls printk() > (e.g. lockdep warning) before printk_deferred_enter() takes effect? I think that we should explicitly disable preemption in printk_deferred_enter(). The disabled interrupts are not strictly necessary. I am going to resurrect the patch https://lore.kernel.org/r/20230419074210.17646-1-pmladek@suse.com and add the preempt_disable()/enable() at the same time. Is this going to work for you? Best Regards, Petr