From mboxrd@z Thu Jan 1 00:00:00 1970 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="Zhk5A9ZU" Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.133.124]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id E8A521725 for ; Wed, 29 Nov 2023 11:02:31 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1701284551; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=DsMUlyrWWahUnMy1mIdG5bl9+m+2G0jF1XT7kXxNQuE=; b=Zhk5A9ZUIZQoCHe1mWqIzYyPxZE+KGybwD7be9W12vVUXvfy3Z7fw1vjzAJI8O0U3Em0cg UuAIKOEtEx9/VwJRgVnHyFlu5KKOjPKnjPJOIi8CL+RGua8vUVWzH0ZIGjLaHZ9V7FR6DG eWSydhufGLqryj6L2vspK3bCnlGdJPg= Received: from mimecast-mx02.redhat.com (mimecast-mx02.redhat.com [66.187.233.88]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-172-alrj6Q-xP6e-OIpl-KE93g-1; Wed, 29 Nov 2023 14:02:24 -0500 X-MC-Unique: alrj6Q-xP6e-OIpl-KE93g-1 Received: from smtp.corp.redhat.com (int-mx05.intmail.prod.int.rdu2.redhat.com [10.11.54.5]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by mimecast-mx02.redhat.com (Postfix) with ESMTPS id 86F2F101A594; Wed, 29 Nov 2023 19:02:23 +0000 (UTC) Received: from file1-rdu.file-001.prod.rdu2.dc.redhat.com (unknown [10.11.5.21]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 7E788502A; Wed, 29 Nov 2023 19:02:23 +0000 (UTC) Received: by file1-rdu.file-001.prod.rdu2.dc.redhat.com (Postfix, from userid 12668) id 6339330C1A8C; Wed, 29 Nov 2023 19:02:23 +0000 (UTC) Received: from localhost (localhost [127.0.0.1]) by file1-rdu.file-001.prod.rdu2.dc.redhat.com (Postfix) with ESMTP id 5FF193FB76; Wed, 29 Nov 2023 20:02:23 +0100 (CET) Date: Wed, 29 Nov 2023 20:02:23 +0100 (CET) From: Mikulas Patocka To: Sasha Levin cc: Christian Loehle , stable-commits@vger.kernel.org, stable@vger.kernel.org, Alasdair Kergon , Mike Snitzer , dm-devel@lists.linux.dev Subject: Re: Patch "dm delay: for short delays, use kthread instead of timers and wq" has been added to the 6.6-stable tree In-Reply-To: Message-ID: References: <20231129025441.892320-1-sashal@kernel.org> <30e67bef-4aaf-31d6-483f-2ca6523099c3@redhat.com> Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII X-Scanned-By: MIMEDefang 3.4.1 on 10.11.54.5 On Wed, 29 Nov 2023, Sasha Levin wrote: > On Wed, Nov 29, 2023 at 07:16:52PM +0100, Mikulas Patocka wrote: > > > > > >On Wed, 29 Nov 2023, Sasha Levin wrote: > > > >> On Wed, Nov 29, 2023 at 06:28:16PM +0100, Mikulas Patocka wrote: > >> > > >> > > >> >On Wed, 29 Nov 2023, Christian Loehle wrote: > >> > > >> >> Hi Mikulas, > >> >> Agreed and thanks for fixing. > >> >> Has this been selected for stable because of: > >> >> 6fc45b6ed921 ("dm-delay: fix a race between delay_presuspend and > >> >> delay_bio") > >> >> If so, I would volunteer do the backports for that for you at least. > >> > > >> >I wouldn't backport this patch - it is an enhancement, not a bugfix, so it > >> >doesn't qualify for the stable kernel backports. > >> > >> Right - this watch was selected as a dependency for 6fc45b6ed921 > >> ("dm-delay: fix a race between delay_presuspend and delay_bio"). > >> > >> In general, unless it's impractical, we'd rather take a dependency chain > >> rather than deal with a non-trivial backport as those tend to have > >> issues longer term. > >> > >> -- > >> Thanks, > >> Sasha > > > >The patch 70bbeb29fab0 ("dm delay: for short delays, use kthread instead > >of timers and wq") changes behavior of dm-delay from using timers to > >polling, so it may cause problems to people running legacy kernels - the > >polling consumes more CPU time than the timers - so I think it shouldn't > >go to the stable kernels where users expect that there will be no > >functional change. > > > >Here I'm submitting the patch 6fc45b6ed921 backported for 6.6.3. > > Is this okay for 6.1 too? Yes, it is. It applies to kernels as old as 4.19. Mikulas