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 <hughd@xxxxxxxxxx>
>
> Acked-by: Paul Gortmaker <paul.gortmaker@xxxxxxxxxxxxx>
>
> 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);
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