From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751571AbaA0F3l (ORCPT ); Mon, 27 Jan 2014 00:29:41 -0500 Received: from mail1.windriver.com ([147.11.146.13]:36755 "EHLO mail1.windriver.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750766AbaA0F3j (ORCPT ); Mon, 27 Jan 2014 00:29:39 -0500 Date: Mon, 27 Jan 2014 00:29:59 -0500 From: Paul Gortmaker To: Hugh Dickins CC: Linus Torvalds , Andrew Morton , , Subject: Re: [PATCH] mm: bring back /sys/kernel/mm Message-ID: <20140127052959.GA20111@windriver.com> References: <20140127040330.GA17584@windriver.com> MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org [Re: [PATCH] mm: bring back /sys/kernel/mm] On 26/01/2014 (Sun 21:02) Hugh Dickins wrote: > 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. Aha - yeah, I would have never seen that; the subtle rename is too easy to overlook unless one is used to going after some path by habit, and wonders why tab completion isn't working anymore... > > 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 ;) Agreed. Thanks again for the root cause, I don't feel so bad for missing it now. Paul. -- > > 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);