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=-8.1 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_PASS,USER_AGENT_MUTT autolearn=ham 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 938EAC004D3 for ; Mon, 22 Oct 2018 17:02:51 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 0FE2220651 for ; Mon, 22 Oct 2018 17:02:52 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="CQd6s/W9" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 0FE2220651 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=gmail.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728726AbeJWBWH (ORCPT ); Mon, 22 Oct 2018 21:22:07 -0400 Received: from mail-pf1-f196.google.com ([209.85.210.196]:38747 "EHLO mail-pf1-f196.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727218AbeJWBWH (ORCPT ); Mon, 22 Oct 2018 21:22:07 -0400 Received: by mail-pf1-f196.google.com with SMTP id f29-v6so20225179pff.5; Mon, 22 Oct 2018 10:02:48 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=date:from:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to:user-agent; bh=mbfS97ueMh/U3Uc84irH8w2tyfm3vAFNCKyGURRujkI=; b=CQd6s/W978y7rX/gbBfjV5SaJXoTv2FTXbUGfRY/UCI+kU6MI7uDxGgIntkx5V6lx4 EcNjtoO9FtvVoAdzawfzkiJDWyZOaZKg8hXBdgfOtOMlYxKkrEY1mSXCgbHxwPpZEya9 5aAMePIA397cnxeKcLQPv8krZ0I+8kmY/vG6UenYsGrDPvIUQBVgetCSMcUkDCU6z/0c 5v+pnRJkBESI0gTMq7aJ95FChbcWZfuY+qTy7OVLAnCaRVZ1wA9Y7VdlwBi5YJHoRSuN GYLPFAi3iZ157s0s2cFDSVqGULzaTlwuuBFtYrZ/mdGaeX4qYILcO5SkcQEkusgjapqp tIqQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:in-reply-to:user-agent; bh=mbfS97ueMh/U3Uc84irH8w2tyfm3vAFNCKyGURRujkI=; b=DXSpEA5ziMNLfrqMLSvDZF/kE+FogsY5ArgaOvHP0xOZx5uJRwBqggWzlK+3tImXP6 z8yVZ6s6URCgfAx/xDvYgl6goe+KmMKTZv0AhdyLljpokzFxXvmd0H9OY4WyTAZ9b+zf 7LTMCEALBEktgJlb2YFzPSXvOTQA0O8eyk9MkUwhjzPWqqsqAo9Ff8r0tM57IlvFWATm wnLp2BmtLLvRoJ2Fh+jgoKVxoCJ4aJG9v9cnFcC1+HpSfuYqBt3pFzW7Lccpb+mBgSfC vMwJtSRJJhKdjcqDauqeA+e79ld5t4Qo0VuZLFUBUqvtb+EHpJ/ypAlbF/MyybBLYIs3 p5tQ== X-Gm-Message-State: ABuFfohm7oe+St9+43SOQVWRFE1vjX4TrqqejL6raU4rcIjPeoXWRV7D 2kVF6U2MQthSQgoWOY24GqXHN69A7qg= X-Google-Smtp-Source: ACcGV635iwThS+q6mLtvCt57JDEAGzgnlnJLh3XFkBZLfTWE6fKR5atSj9q62/UE17xh3gG+vLhQEg== X-Received: by 2002:a62:1f9d:: with SMTP id l29-v6mr45544391pfj.121.1540227768203; Mon, 22 Oct 2018 10:02:48 -0700 (PDT) Received: from dtor-ws ([2620:15c:202:201:3adc:b08c:7acc:b325]) by smtp.gmail.com with ESMTPSA id n7-v6sm32235549pgv.63.2018.10.22.10.02.46 (version=TLS1_2 cipher=ECDHE-RSA-CHACHA20-POLY1305 bits=256/256); Mon, 22 Oct 2018 10:02:47 -0700 (PDT) Date: Mon, 22 Oct 2018 10:02:44 -0700 From: Dmitry Torokhov To: Sasha Levin Cc: stable@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH AUTOSEL 4.18 08/27] Input: evdev - add a schedule point in evdev_write() Message-ID: <20181022170244.GB27929@dtor-ws> References: <20181022101924.40531-1-sashal@kernel.org> <20181022101924.40531-8-sashal@kernel.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20181022101924.40531-8-sashal@kernel.org> User-Agent: Mutt/1.10.1 (2018-07-13) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi Sasha, On Mon, Oct 22, 2018 at 06:19:05AM -0400, Sasha Levin wrote: > From: Dmitry Torokhov > > [ Upstream commit 36d2582ff235b4e01ad64a734c877a52dc762d9c ] > > Large writes to evdev interface may cause rcu stalls. Let's add > cond_resched() to the loop to avoid this. This is not needed in stable: - the interfaces are not accessible for unprivileged users so there is no DOS concerns - the issue can only happen on non-preemptible kernels - the issue only showed up with synthetic test and not real life use cases - this is not a regression The same goes to similar patches to mousedev, joydev and uinput that you autoselected. Thanks. > > Reviewed-by: Paul E. McKenney > Signed-off-by: Dmitry Torokhov > Signed-off-by: Sasha Levin > --- > drivers/input/evdev.c | 1 + > 1 file changed, 1 insertion(+) > > diff --git a/drivers/input/evdev.c b/drivers/input/evdev.c > index c81c79d01d93..718d5622267d 100644 > --- a/drivers/input/evdev.c > +++ b/drivers/input/evdev.c > @@ -564,6 +564,7 @@ static ssize_t evdev_write(struct file *file, const char __user *buffer, > > input_inject_event(&evdev->handle, > event.type, event.code, event.value); > + cond_resched(); > } > > out: > -- > 2.17.1 > -- Dmitry