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=-4.0 required=3.0 tests=MAILING_LIST_MULTI, SIGNED_OFF_BY,SPF_PASS,URIBL_BLOCKED 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 39D9CC6786E for ; Fri, 26 Oct 2018 07:02:28 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id E7CD520824 for ; Fri, 26 Oct 2018 07:02:27 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org E7CD520824 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 S1726295AbeJZPiM (ORCPT ); Fri, 26 Oct 2018 11:38:12 -0400 Received: from mx2.suse.de ([195.135.220.15]:37292 "EHLO mx1.suse.de" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1725876AbeJZPiM (ORCPT ); Fri, 26 Oct 2018 11:38:12 -0400 X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay1.suse.de (unknown [195.135.220.254]) by mx1.suse.de (Postfix) with ESMTP id 2E9B0AE58; Fri, 26 Oct 2018 07:02:25 +0000 (UTC) Date: Fri, 26 Oct 2018 08:58:57 +0200 (CEST) From: Jiri Kosina To: Sasha Levin 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 In-Reply-To: <20181025200751.GB1693@sasha-vm> Message-ID: References: <20181025141705.213937-1-sashal@kernel.org> <20181025141705.213937-8-sashal@kernel.org> <20181025150729.GD16290@suse.cz> <20181025200751.GB1693@sasha-vm> User-Agent: Alpine 2.21 (LSU 202 2017-01-01) MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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. Thanks, -- Jiri Kosina SUSE Labs