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From: Muchun Song In-Reply-To: Date: Fri, 19 Aug 2022 15:15:13 +0800 Cc: Muchun Song , rafael@kernel.org, Mike Kravetz , Andrew Morton , Oscar Salvador , David Hildenbrand , linux-kernel@vger.kernel.org, Linux MM , lee.schermerhorn@hp.com Content-Transfer-Encoding: quoted-printable Message-Id: <8451D3B9-281E-4FEC-B1B3-A231FE65EC3B@linux.dev> References: <20220819052137.7985-1-songmuchun@bytedance.com> To: Greg KH X-Migadu-Flow: FLOW_OUT X-Migadu-Auth-User: linux.dev ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1660893329; a=rsa-sha256; cv=none; b=g2BM2iDIt3OGJSpUj+4dKBvqMYk43DWu7eIqXlJD4Egmbvx8fcKZIb3l7thv9AarCAziA7 grUN+eVlVFHnx4hLy/3VQFoCG3RVC/LvaxbOuwPulxojZYjKvbm34FPDgVWpRKD1yBUiUJ X7RcWEJ6eNGGkLACYRspdyFSUwMpa2o= ARC-Authentication-Results: i=1; imf28.hostedemail.com; dkim=pass header.d=linux.dev header.s=key1 header.b=LIAap0zK; dmarc=pass (policy=none) header.from=linux.dev; spf=pass (imf28.hostedemail.com: domain of muchun.song@linux.dev designates 94.23.1.103 as permitted sender) smtp.mailfrom=muchun.song@linux.dev ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1660893329; h=from:from:sender:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references:dkim-signature; bh=b1qeRk/32x90/7Q9jzvtl8MH8XALoGSR86o+wJItTaA=; b=FF17648Lfoh8O7W0nCLZGCCxIg4/0byPGwSn5sruGphmrF7do5CmSu5hh0WJbP9OWrDZ10 9Si0Wj/nnoF5gH+BaGSVeQ6ZbcUsXlDGTwe2NLZwNcbxrgzrFiaBrR+ZXR0LG1fHTGYKE/ ruSfRyqb0txScxEqUPgpAa6SE6HXONg= X-Stat-Signature: q91d9cyhbwx5qdoknokc5s8naq4mus1z X-Rspamd-Queue-Id: A4C4EC001A X-Rspam-User: Authentication-Results: imf28.hostedemail.com; dkim=pass header.d=linux.dev header.s=key1 header.b=LIAap0zK; dmarc=pass (policy=none) header.from=linux.dev; spf=pass (imf28.hostedemail.com: domain of muchun.song@linux.dev designates 94.23.1.103 as permitted sender) smtp.mailfrom=muchun.song@linux.dev X-Rspamd-Server: rspam11 X-HE-Tag: 1660893329-550802 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: > On Aug 19, 2022, at 15:00, Greg KH wrote: >=20 > On Fri, Aug 19, 2022 at 02:44:13PM +0800, Muchun Song wrote: >>=20 >>=20 >>> On Aug 19, 2022, at 14:32, Greg KH = wrote: >>>=20 >>> On Fri, Aug 19, 2022 at 01:21:37PM +0800, Muchun Song wrote: >>>> The following commit offload per-node sysfs creation and removal to = a kworker and >>>> did not say why it is needed. And it also said "I don't know that = this is >>>> absolutely required". It seems like the author was not sure as = well. Since it >>>> only complicates the code, this patch will revert the changes to = simplify the code. >>>>=20 >>>> 39da08cb074c ("hugetlb: offload per node attribute registrations") >>>=20 >>> Any specific reason why you did not cc: the original author of this >>> commit, or anyone else on the patch? >>=20 >> OK. Cc Lee Schermerhorn. >=20 > He can't see the patch here, so there is no context. Please resend = the Unluckily, his email is out of date, I cannot resend it to him. > whole thing. You also didn't copy the people who signed off on it = (i.e. > Andi), any reason why? I can resend this to Andi. Why I didn=E2=80=99t send to them this time = is because I just follow the output of scripts/get_maintainer.pl. I will resend a = new one. >=20 >>>> We could use memory hotplug notifier to do per-node sysfs creation = and removal >>>> instead of inserting those operations to node registration and = unregistration. >>>> Then, it can reduce the code coupling between node.c and hugetlb.c. = Also, it can >>>> simplify the code. >>>=20 >>> I do not think we had memory hotplug notifier back in 2009 when this >>> commit was first written. >>=20 >> Maybe not. Commit 39da08cb074c is merger in 2009. However, hotplug = notifier mechanism >> is merged in 2006. The document is updated in 2007 (see commit = 10020ca246c5). >>=20 >>>=20 >>> How did you test this? Did you use a HUGETLBFS system and verify = that >>> everything still works properly? You are deleting a lot of code = (always >>> nice), but making sure everything is still operating the same is a = good >>> thing. >>=20 >> I really did the test (through a VM), it works properly. >=20 > How about on real hardware? On a HUGE system with real hardware? On = a > small system? I have test a VM with 128 GB memory, it works properly. I cannot test it = on a real hardware since I didn=E2=80=99t have a real hardware with hotplug = memory. I am not sure if there is some ways to emulate a hotplug memory node. Thanks. >=20 > thanks, >=20 > greg k-h