From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751135AbaA0FDZ (ORCPT ); Mon, 27 Jan 2014 00:03:25 -0500 Received: from mail-pa0-f52.google.com ([209.85.220.52]:34683 "EHLO mail-pa0-f52.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750766AbaA0FDY (ORCPT ); Mon, 27 Jan 2014 00:03:24 -0500 Date: Sun, 26 Jan 2014 21:02:44 -0800 (PST) From: Hugh Dickins X-X-Sender: hugh@eggly.anvils To: Paul Gortmaker cc: Linus Torvalds , Andrew Morton , linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH] mm: bring back /sys/kernel/mm In-Reply-To: <20140127040330.GA17584@windriver.com> Message-ID: References: <20140127040330.GA17584@windriver.com> User-Agent: Alpine 2.11 (LSU 23 2013-08-11) MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Sun, 26 Jan 2014, Paul Gortmaker wrote: > [[PATCH] mm: bring back /sys/kernel/mm] On 26/01/2014 (Sun 18:52) Hugh Dickins wrote: > > > Commit da29bd36224b ("mm/mm_init.c: make creation of the mm_kobj happen > > earlier than device_initcall") changed to pure_initcall(mm_sysfs_init). > > > > That's too early: mm_sysfs_init() depends on core_initcall(ksysfs_init) > > to have made the kernel_kobj directory "kernel" in which to create "mm". > > > > Make it postcore_initcall(mm_sysfs_init). We could use core_initcall(), > > and depend upon Makefile link order kernel/ mm/ fs/ ipc/ security/ ... > > as core_initcall(debugfs_init) and core_initcall(securityfs_init) do; > > but better not. > > Agreed, N+1 is better than link order. I guess it silently fails then, > with /sys/kernel/mm missing as the symptom? I'd booted i386 and ppc > and didn't spot this, unfortunately... wondering now if there was a > hint in dmesg that I simply failed to notice. No, nothing in dmesg at all: both mm_sysfs_init() and ksm_init() (it was /sys/kernel/mm/ksm/run that I was looking for) thought they had succeeded. Ah, I get it: it's normal to pass NULL parent to kobject_create_and_add(), that just means create at the root. And when I look at an unfixed box, yes, there's /sys/mm with all the right contents. Given /sys/block and /sys/fs and /sys/kernel, I think /sys/mm is a better location; but we're a few years too late to be making that change now ;) Hugh > > > > > Signed-off-by: Hugh Dickins > > Acked-by: Paul Gortmaker > > Thanks, > Paul. > > > --- > > > > mm/mm_init.c | 2 +- > > 1 file changed, 1 insertion(+), 1 deletion(-) > > > > --- 3.13.0+/mm/mm_init.c 2014-01-23 21:51:26.004001378 -0800 > > +++ linux/mm/mm_init.c 2014-01-26 18:06:40.488488209 -0800 > > @@ -202,4 +202,4 @@ static int __init mm_sysfs_init(void) > > > > return 0; > > } > > -pure_initcall(mm_sysfs_init); > > +postcore_initcall(mm_sysfs_init);