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[2607:7c80:54:e::133]) by mx.google.com with ESMTPS id j20si5485962pgh.224.2019.01.29.04.38.58 for (version=TLS1_2 cipher=ECDHE-RSA-CHACHA20-POLY1305 bits=256/256); Tue, 29 Jan 2019 04:38:58 -0800 (PST) Received-SPF: pass (google.com: best guess record for domain of peterz@infradead.org designates 2607:7c80:54:e::133 as permitted sender) client-ip=2607:7c80:54:e::133; Authentication-Results: mx.google.com; dkim=pass header.i=@infradead.org header.s=bombadil.20170209 header.b=PBeiAFj8; spf=pass (google.com: best guess record for domain of peterz@infradead.org designates 2607:7c80:54:e::133 as permitted sender) smtp.mailfrom=peterz@infradead.org DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=bombadil.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:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Id: List-Help:List-Unsubscribe:List-Subscribe:List-Post:List-Owner:List-Archive; bh=hcUmsWqOlUZoA0tGVtVxZVeGi9/WntceTQMLGURqW8U=; b=PBeiAFj84XF4ohPPYvNWj4Frx zy33xge/EQv0zpd59PDLm9VtSeIzpXE/lJEW4322H3P7tFLk4zvJP6dZ4NEifr60zfHbqnunPMmh7 BNEYVN7SeJ/JCiD5JBo3xBvAF9RI/9ho2qVbgzxCcw6ZhcIBUooP2sen9hW8s1fkr46WXVF8hVJlj a5nWrftCspTUGFGV3K0hjkbch5lEitgg+JzHUbTusZps2AsgxgAaYnQ5ToQnDYoMaaPIXiscx/v+o t6qBu0lTsYS/Iq+N4raF0oQZ+VLiBr7q1ajxAP7N6NplyLoU7Zvns33ALWYK968MQoCR7KZslxNfw CmIApdPvA==; Received: from j217100.upc-j.chello.nl ([24.132.217.100] helo=hirez.programming.kicks-ass.net) by bombadil.infradead.org with esmtpsa (Exim 4.90_1 #2 (Red Hat Linux)) id 1goSf8-0003BI-LX; Tue, 29 Jan 2019 12:38:46 +0000 Received: by hirez.programming.kicks-ass.net (Postfix, from userid 1000) id 0A4FD2042CFA9; Tue, 29 Jan 2019 13:38:44 +0100 (CET) Date: Tue, 29 Jan 2019 13:38:44 +0100 From: Peter Zijlstra To: Suren Baghdasaryan Cc: gregkh@linuxfoundation.org, tj@kernel.org, lizefan@huawei.com, hannes@cmpxchg.org, axboe@kernel.dk, dennis@kernel.org, dennisszhou@gmail.com, mingo@redhat.com, akpm@linux-foundation.org, corbet@lwn.net, cgroups@vger.kernel.org, linux-mm@kvack.org, linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, kernel-team@android.com Subject: Re: [PATCH v3 5/5] psi: introduce psi monitor Message-ID: <20190129123843.GK28467@hirez.programming.kicks-ass.net> References: <20190124211518.244221-1-surenb@google.com> <20190124211518.244221-6-surenb@google.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20190124211518.244221-6-surenb@google.com> User-Agent: Mutt/1.10.1 (2018-07-13) X-Bogosity: Ham, tests=bogofilter, spamicity=0.000001, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Thu, Jan 24, 2019 at 01:15:18PM -0800, Suren Baghdasaryan wrote: > + atomic_set(&group->polling, polling); > + /* > + * Memory barrier is needed to order group->polling > + * write before times[] read in collect_percpu_times() > + */ > + smp_mb__after_atomic(); That's broken, smp_mb__{before,after}_atomic() can only be used on atomic RmW operations, something atomic_set() is _not_.