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[198.145.29.99]) by mx.google.com with ESMTPS id i198si6736428pfe.228.2019.07.04.12.32.19 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Thu, 04 Jul 2019 12:32:19 -0700 (PDT) Received-SPF: pass (google.com: domain of akpm@linux-foundation.org designates 198.145.29.99 as permitted sender) client-ip=198.145.29.99; Authentication-Results: mx.google.com; dkim=pass header.i=@kernel.org header.s=default header.b=xLYlLoVc; spf=pass (google.com: domain of akpm@linux-foundation.org designates 198.145.29.99 as permitted sender) smtp.mailfrom=akpm@linux-foundation.org Received: from localhost.localdomain (c-73-223-200-170.hsd1.ca.comcast.net [73.223.200.170]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id D707D2189E; Thu, 4 Jul 2019 19:32:18 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1562268739; bh=sDn9pqNnZNQls6TlQC0E4i4OA5fVIAHZsv1mK7QjuUU=; h=Date:From:To:Cc:Subject:In-Reply-To:References:From; b=xLYlLoVcNxDZe4xjXUvwx/phI6Gk2I2s1MqHsJnhvK2dhiM5vmmOgxqD3KpPOq1GI YZNDgDS+RHGtv/QAuLWVM4LeZoRGCgQfTba6bUvfTmu8bvT07N8/18ASofU5gvPZM6 qTzELQghgD4BvffARvPi77TQK27tSY7dRePWiBGY= Date: Thu, 4 Jul 2019 12:32:18 -0700 From: Andrew Morton To: Oleg Nesterov Cc: Qian Cai , axboe@kernel.dk, hch@lst.de, peterz@infradead.org, gkohli@codeaurora.org, mingo@redhat.com, linux-mm@kvack.org, linux-kernel@vger.kernel.org, Hugh Dickins Subject: Re: [PATCH] swap_readpage: avoid blk_wake_io_task() if !synchronous Message-Id: <20190704123218.87a763f771efad158e1b0a89@linux-foundation.org> In-Reply-To: <20190704160301.GA5956@redhat.com> References: <1559161526-618-1-git-send-email-cai@lca.pw> <20190704160301.GA5956@redhat.com> X-Mailer: Sylpheed 3.5.1 (GTK+ 2.24.31; x86_64-pc-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit 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, 4 Jul 2019 18:03:01 +0200 Oleg Nesterov wrote: > swap_readpage() sets waiter = bio->bi_private even if synchronous = F, > this means that the caller can get the spurious wakeup after return. This > can be fatal if blk_wake_io_task() does set_current_state(TASK_RUNNING) > after the caller does set_special_state(), in the worst case the kernel > can crash in do_task_dead(). I think we need a Fixes: and a cc:stable here? IIRC, we're fixing 0619317ff8baa2 ("block: add polled wakeup task helper").