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=-6.0 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_PASS, URIBL_BLOCKED,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 84A4AECDE44 for ; Fri, 26 Oct 2018 10:57:15 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 494A520856 for ; Fri, 26 Oct 2018 10:57:15 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=kernel.org header.i=@kernel.org header.b="cVf6srx/" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 494A520856 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=kernel.org 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 S1727551AbeJZTdu (ORCPT ); Fri, 26 Oct 2018 15:33:50 -0400 Received: from mail.kernel.org ([198.145.29.99]:36410 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726275AbeJZTdu (ORCPT ); Fri, 26 Oct 2018 15:33:50 -0400 Received: from localhost (unknown [167.98.65.38]) (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 607F02085B; Fri, 26 Oct 2018 10:57:12 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1540551432; bh=PiPQm0YofBWdO7bNuXW32BYcKZKaGyRLyYzjcYKiD8U=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=cVf6srx/1StTIDJa8va/O6Yjw8RyRK2/MQOR5aPdnoJuH+YeiLdTNyWmYowuoFfZ8 ZiN588tfkIrU1sXhzgDAAu1g5nQSGiW0GjXycnqsoXnSxugkgtALBy8gMnogKUHLJW 0cVp1dB1SvpfE8StMtuuxqaRMVBM7X+NKv3zU8/Y= Date: Fri, 26 Oct 2018 06:57:10 -0400 From: Sasha Levin To: Jiri Kosina Cc: dsterba@suse.cz, linux-kernel@vger.kernel.org, stable@vger.kernel.org Subject: Re: [PATCH AUTOSEL 4.4 08/65] btrfs: cleaner_kthread() doesn't need explicit freeze Message-ID: <20181026105710.GD2015@sasha-vm> References: <20181025141705.213937-1-sashal@kernel.org> <20181025141705.213937-8-sashal@kernel.org> <20181025150729.GD16290@suse.cz> <20181025200751.GB1693@sasha-vm> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii; format=flowed Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.9.4 (2018-02-28) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Oct 26, 2018 at 08:58:57AM +0200, Jiri Kosina wrote: >On Thu, 25 Oct 2018, Sasha Levin wrote: > >> >> cleaner_kthread() is not marked freezable, and therefore calling >> >> try_to_freeze() in its context is a pointless no-op. >> >> >> >> In addition to that, as has been clearly demonstrated by 80ad623edd2d >> >> ("Revert "btrfs: clear PF_NOFREEZE in cleaner_kthread()"), it's perfectly >> >> valid / legal for cleaner_kthread() to stay scheduled out in an arbitrary >> >> place during suspend (in that particular example that was waiting for >> >> reading of extent pages), so there is no need to leave any traces of >> >> freezer in this kthread. >> >> >> >> Fixes: 80ad623edd2d ("Revert "btrfs: clear PF_NOFREEZE in >> >> Fixes: cleaner_kthread()") >> >> Fixes: 696249132158 ("btrfs: clear PF_NOFREEZE in cleaner_kthread()") >> >> Signed-off-by: Jiri Kosina >> >> Signed-off-by: David Sterba >> >> Signed-off-by: Sasha Levin >> > >> >IIRC it was some preparatory work for livepatching. I did a quick check >> >if this is safe for 4.4 and would say yes, but the patch does not fix >> >anything so IMO this does not need to go to stable. >> >> Doesn't that also affect hibernation and such? > >This patch just removes pointless try_to_freeze(), that's guaranteed not >to do anything and return immediately, as the btrfs kthread is not >freezable. >So I don't think it's needed in stable; the semantics is equivalent before >and after. Gotcha. I'll drop it. Thank you! -- Thanks, Sasha