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 X-Spam-Level: X-Spam-Status: No, score=-3.8 required=3.0 tests=BAYES_00,DKIM_INVALID, DKIM_SIGNED,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 48699C433E1 for ; Thu, 13 Aug 2020 14:32:38 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id EB2EE207DA for ; Thu, 13 Aug 2020 14:32:37 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b="X/4/G4vZ" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org EB2EE207DA Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=infradead.org Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id 4C9826B0008; Thu, 13 Aug 2020 10:32:37 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 47A5A6B000C; Thu, 13 Aug 2020 10:32:37 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 390BD6B000D; Thu, 13 Aug 2020 10:32:37 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0164.hostedemail.com [216.40.44.164]) by kanga.kvack.org (Postfix) with ESMTP id 22B326B0008 for ; Thu, 13 Aug 2020 10:32:37 -0400 (EDT) Received: from smtpin18.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay05.hostedemail.com (Postfix) with ESMTP id D9A45181AEF1E for ; Thu, 13 Aug 2020 14:32:36 +0000 (UTC) X-FDA: 77145786312.18.book68_4d05a7d26ff4 Received: from filter.hostedemail.com (10.5.16.251.rfc1918.com [10.5.16.251]) by smtpin18.hostedemail.com (Postfix) with ESMTP id A677D100ED3D0 for ; Thu, 13 Aug 2020 14:32:36 +0000 (UTC) X-HE-Tag: book68_4d05a7d26ff4 X-Filterd-Recvd-Size: 2968 Received: from casper.infradead.org (casper.infradead.org [90.155.50.34]) by imf40.hostedemail.com (Postfix) with ESMTP for ; Thu, 13 Aug 2020 14:32:35 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=casper.20170209; h=In-Reply-To:Content-Type:MIME-Version: References:Message-ID:Subject:Cc:To:From:Date:Sender:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description; bh=AZ4M8tKLPliGwtcQpOjdflP90B5wX1qQuYOyiE0uFF0=; b=X/4/G4vZU1JqV4cr8bq0T7Bilf TrPRzkxZp1umwgwIqquTlLpJhKBkeGG2Uo9NZDvLNXS4b/EJ8JJ1vqqylnqZf1FFzHs31mRtFdc2I mEFvyOYpohnq3rsTgzqnLY3I3jwslB/ECCQi+biR/VXAQ+wdUcxED7vhxkhUkeFeobLt9H5p+PZys NiZk6EMIRTK2auuUv+lkIXC56G1axCflYSP+fdCVvB3XucJUkpaDRCcsLHKA/23QXlEcs8yeM9Xet kFCCBkwD/ZTJbhK0q7jY5vA2NNEfotNo2u7h3tF5+n/Vf1ky7ktAjcy/ZFT7vYX8ecrjg9uJls6zd 8zSlI3lg==; Received: from willy by casper.infradead.org with local (Exim 4.92.3 #3 (Red Hat Linux)) id 1k6EHF-0004HL-5Y; Thu, 13 Aug 2020 14:32:21 +0000 Date: Thu, 13 Aug 2020 15:32:21 +0100 From: Matthew Wilcox To: Thomas Gleixner Cc: Michal Hocko , Uladzislau Rezki , paulmck@kernel.org, LKML , RCU , linux-mm@kvack.org, Andrew Morton , Vlastimil Babka , "Theodore Y . Ts'o" , Joel Fernandes , Sebastian Andrzej Siewior , Oleksiy Avramchenko Subject: Re: [RFC-PATCH 1/2] mm: Add __GFP_NO_LOCKS flag Message-ID: <20200813143221.GI17456@casper.infradead.org> References: <20200811210931.GZ4295@paulmck-ThinkPad-P72> <874kp87mca.fsf@nanos.tec.linutronix.de> <20200813075027.GD9477@dhcp22.suse.cz> <20200813095840.GA25268@pc636> <20200813111505.GG9477@dhcp22.suse.cz> <871rkallqk.fsf@nanos.tec.linutronix.de> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <871rkallqk.fsf@nanos.tec.linutronix.de> X-Rspamd-Queue-Id: A677D100ED3D0 X-Spamd-Result: default: False [0.00 / 100.00] X-Rspamd-Server: rspam02 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 Thu, Aug 13, 2020 at 03:27:15PM +0200, Thomas Gleixner wrote: > And guarding it with RT is not working either because then you are back > to square one with the problem which triggered the discussion in the > first place: > > raw_spin_lock() > alloc() > if (RT && !preemptible()) <- False because RT == false > goto bail; > > spin_lock(&zone->lock) --> LOCKDEP complains > > So either you convince Paul not to do that or you need to do something > like I suggested in my other reply. I'd like to throw in the possibility that we do something like: raw_spin_lock() alloc() if (!spin_trylock(&zone->lock)) if (RT && !preemptible()) goto bail; spin_lock(&zone->lock); would that make us feel more comfortable about converting zone->lock to a raw spinlock?