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=-5.6 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE, SPF_PASS,USER_AGENT_SANE_1 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 57D28ECE58E for ; Fri, 11 Oct 2019 16:52:21 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 30790206CD for ; Fri, 11 Oct 2019 16:52:21 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1570812741; bh=riC6/nqA7kgSGJCCMP5su4G0ZkQMoidyeWYJvvwwhT8=; h=Date:From:To:Cc:Subject:References:In-Reply-To:List-ID:From; b=yZO5MrUBjgpWBPcwnlQqVJ2Ma7Z2M1s45UitiOOnt1bJkY6lMG9niscap09hivf4v vU9ZKGWvOgjNhReavxBk4AaOiCgKce/+xQ0UZDljZvcjoRVGJDAoc40LriwIk3zbZG d5Lo8+3TRODpFNu1pV23lilaBhJgPZQ8i/vxhUB0= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728479AbfJKQwU (ORCPT ); Fri, 11 Oct 2019 12:52:20 -0400 Received: from mail-qt1-f195.google.com ([209.85.160.195]:42720 "EHLO mail-qt1-f195.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728355AbfJKQwS (ORCPT ); Fri, 11 Oct 2019 12:52:18 -0400 Received: by mail-qt1-f195.google.com with SMTP id w14so14767217qto.9 for ; Fri, 11 Oct 2019 09:52:18 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=sender:date:from:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to:user-agent; bh=ik7esxKqQ0mCGJAgwQWKpkG5b7ss9ViVqj809ayACJg=; b=ftuaXNGdkFZBYx2lEqoYHGXjsPV4yrnzEH1Eljs7OEMLXdjJcSZShneEp9z7v6gYXJ FTazdMvRU09ypUwEjIA4dXstaMHCQSawNuSFPJwo0UdsrlsYHIrOY2ixo6NpH0i786wk o08eK8Cx7i141+ldh59j4eOD2sLEZUHcm7B6Oj8zBRXVRm31fnvCxG8JzbIbfyXT8orx pYGR8VeIdH+Nhh7js5RK/Has0rORGjTZ0VhhmKkVlLDEpX9zGvhsHM9Y3/zBQp/7Qw5g 4uxICTkCEQsaz9hesFafMfNL11KLnNB9ASVXnru0BpBuNP04uVOI2Sr5d7sEugHh1m8E /0jA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:sender:date:from:to:cc:subject:message-id :references:mime-version:content-disposition:in-reply-to:user-agent; bh=ik7esxKqQ0mCGJAgwQWKpkG5b7ss9ViVqj809ayACJg=; b=f1pQFNiJBzIbhFgsCf/LaxUE9RP1+Ks/ODQrCzwC5MsNeGOaxdNYTSNX8vkErZHX1m KouM+q1aTiNwpkcL5nKbczMZtv9dhBNc42t1upCFVlAQRiS3nKFnHAcPGoIzGF1y1K5m aZUPzS92TKaBTDMOFzw/Jyhs1aZ8m56ilAWLXzdZaF1xmLAnUBKLqxag+2/lE8rqTre7 4Q0V2+HotCbedGUlbRB4+wzhP/Hp1FXKRit8G1EIVcUkbIyrCmvvNXaD8s6EFXSEeK3w hji2W8RaJE6TnFYuGYF0BaGMMO21Llcdno7RLvA2E1r/RiA1hsAO1POlop/fd9A4/KJj Vvng== X-Gm-Message-State: APjAAAWuxVXmk7b4qwWdyF4JF8e4yN1axAU78nu+zevvYWjEpFNLoF1r bh3fT/tuC9GvxjfqwTZQmFg= X-Google-Smtp-Source: APXvYqzo9PLo8WMPJCqHlTnbsPp09wKKrhzZUeiLA5xY5uh8XxM4xyMQLWtxOEjcb8Ol6Ic9uu4Mdg== X-Received: by 2002:ac8:36f4:: with SMTP id b49mr17831196qtc.31.1570812737374; Fri, 11 Oct 2019 09:52:17 -0700 (PDT) Received: from localhost ([2620:10d:c091:480::3741]) by smtp.gmail.com with ESMTPSA id q6sm3932678qkj.108.2019.10.11.09.52.16 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Fri, 11 Oct 2019 09:52:16 -0700 (PDT) Date: Fri, 11 Oct 2019 09:52:13 -0700 From: Tejun Heo To: Oleg Nesterov Cc: linux-kernel@vger.kernel.org, Roman Gushchin , Richard Purdie , Bruce Ashfield Subject: Re: [PATCH] cgroup: freezer: call cgroup_enter_frozen() with preemption disabled in ptrace_stop() Message-ID: <20191011165213.GB18794@devbig004.ftw2.facebook.com> References: <20191009150230.GB12511@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20191009150230.GB12511@redhat.com> User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Oct 09, 2019 at 05:02:30PM +0200, Oleg Nesterov wrote: > ptrace_stop() does preempt_enable_no_resched() to avoid the preemption, > but after that cgroup_enter_frozen() does spin_lock/unlock and this adds > another preemption point. > > Reported-and-tested-by: Bruce Ashfield > Fixes: 76f969e8948d ("cgroup: cgroup v2 freezer") > Cc: stable@vger.kernel.org # v5.2+ > Signed-off-by: Oleg Nesterov Applied to cgroup/for-5.4-fixes. Thanks. -- tejun