Re: [PATCH] memcgroup: check and initialize page->cgroup inmemmap_init_zone

[KAMEZAWA Hiroyuki]

On Fri, 18 Apr 2008 13:43:34 +0800
Shi Weihua <shiwh@xxxxxxxxxxxxxx> wrote:

> KAMEZAWA Hiroyuki wrote::
> > On Fri, 18 Apr 2008 12:32:56 +0900
> > KAMEZAWA Hiroyuki <kamezawa.hiroyu@xxxxxxxxxxxxxx> wrote:
> > 
> >>> Or perhaps that page was used and then later freed before we got to
> >>> memmap_init_zone() and was freed with a non-zero ->page_cgroup.  Which is
> >>> unlikely given that page.page_cgroup was only just added and is only
> >>> present if CONFIG_CGROUP_MEM_RES_CTLR.
> >>>
> >> Hmm, I'll try his .config and see what happens.
> >>
> > I reproduced the hang with his config and confirmed his fix works well.
> > But I can't find why...I'll dig a bit more.
> 
> If i use CONFIG_SPARSEMEM instead of CONFIG_DISCONTIGMEM, the kernel 
> boots successfully.
> 
AKAICT,
 CONFIG_DISCONTIGMEM      + 64KB page -> hang --------------(*)
 CONFIG_SPRASEMEM_VMEMMAP + 64KB page -> works well
 CONFIG_DISCONTIGMEM      + 16KB page -> works well
 CONFIG_SPARSEMEM_VMEMMAP + 16KB page -> works well

 CONFIG_DISCONTIGMEM + 64KB page + your patch -> works well

Hmm. maybe memmap(and all possible bootmem) isn't cleared well
in case (*). still chasing it.

Thanks,
-Kame

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