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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 70676EB64DB for ; Mon, 19 Jun 2023 07:17:01 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229783AbjFSHRA (ORCPT ); Mon, 19 Jun 2023 03:17:00 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:58164 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229657AbjFSHQy (ORCPT ); Mon, 19 Jun 2023 03:16:54 -0400 Received: from dfw.source.kernel.org (dfw.source.kernel.org [IPv6:2604:1380:4641:c500::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id EACDF1A4; Mon, 19 Jun 2023 00:16:51 -0700 (PDT) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (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 dfw.source.kernel.org (Postfix) with ESMTPS id 6E7F261519; Mon, 19 Jun 2023 07:16:51 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 10265C433C0; Mon, 19 Jun 2023 07:16:49 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1687159010; bh=o+Yg6fiH7DKx/W+p5TZzhJozyVoxj8T/PH9KRwjpmVA=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=1F1od9YQM9AQZg698c8+I623lXF1RJXw4ooSbal/RPaDqDIMbG5tVSxWnBxc4HMNc M4BN0Jp0O1gIuxyow+R2zKW6zQMzIGINYtjukEUY98FLzWIMJKkB9FgjjJXo2PUl4p R7caEwn5xCLd+Ujk/IslzPZkDv2dR8Z4xoHdIgjo= Date: Mon, 19 Jun 2023 09:16:47 +0200 From: Greg KH To: Wupeng Ma Cc: akpm@linux-foundation.org, david@redhat.com, linux-mm@kvack.org, linux-kernel@vger.kernel.org, stable@vger.kernel.org, Wei Yang , "Michael S. Tsirkin" , Jason Wang , Pankaj Gupta , Michal Hocko , Oscar Salvador Subject: Re: [PATCH stable 5.10] mm/memory_hotplug: extend offline_and_remove_memory() to handle more than one memory block Message-ID: <2023061926-monoxide-pastor-fa3b@gregkh> References: <20230619065121.1720912-1-mawupeng1@huawei.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20230619065121.1720912-1-mawupeng1@huawei.com> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Jun 19, 2023 at 02:51:21PM +0800, Wupeng Ma wrote: > From: David Hildenbrand > > commit 8dc4bb58a146655eb057247d7c9d19e73928715b upstream. > > virtio-mem soon wants to use offline_and_remove_memory() memory that > exceeds a single Linux memory block (memory_block_size_bytes()). Let's > remove that restriction. > > Let's remember the old state and try to restore that if anything goes > wrong. While re-onlining can, in general, fail, it's highly unlikely to > happen (usually only when a notifier fails to allocate memory, and these > are rather rare). > > This will be used by virtio-mem to offline+remove memory ranges that are > bigger than a single memory block - for example, with a device block > size of 1 GiB (e.g., gigantic pages in the hypervisor) and a Linux memory > block size of 128MB. > > While we could compress the state into 2 bit, using 8 bit is much > easier. > > This handling is similar, but different to acpi_scan_try_to_offline(): > > a) We don't try to offline twice. I am not sure if this CONFIG_MEMCG > optimization is still relevant - it should only apply to ZONE_NORMAL > (where we have no guarantees). If relevant, we can always add it. > > b) acpi_scan_try_to_offline() simply onlines all memory in case > something goes wrong. It doesn't restore previous online type. Let's do > that, so we won't overwrite what e.g., user space configured. > > Reviewed-by: Wei Yang > Cc: "Michael S. Tsirkin" > Cc: Jason Wang > Cc: Pankaj Gupta > Cc: Michal Hocko > Cc: Oscar Salvador > Cc: Wei Yang > Cc: Andrew Morton > Signed-off-by: David Hildenbrand > Link: https://lore.kernel.org/r/20201112133815.13332-28-david@redhat.com > Signed-off-by: Michael S. Tsirkin > Acked-by: Andrew Morton > Signed-off-by: Ma Wupeng > --- > mm/memory_hotplug.c | 105 +++++++++++++++++++++++++++++++++++++------- > 1 file changed, 89 insertions(+), 16 deletions(-) > Why is this needed in 5.10.y? Looks like a new feature to me, what problem does it solve there? thanks, greg k-h