Re: [mmotm] BUG: Bad page state in process khugepaged ?

From: KAMEZAWA Hiroyuki
Date: Wed Feb 09 2011 - 01:59:03 EST


On Wed, 9 Feb 2011 15:50:01 +0900
Daisuke Nishimura <nishimura@xxxxxxxxxxxxxxxxx> wrote:

> >
> > In hex, pc->flags was 7A00000000004 and this means PCG_USED bit is set.
> > This implies page_remove_rmap() may not be called but ->mapping is NULL. Hmm?
> > (7A is encoding of section number.)
> >
> Sigh.. it seems another freed-but-not-uncharged problem..
>

Ah, ok, this is maybe caused by this. I'm sorry that I missed this.
==
static inline int free_pages_check(struct page *page)
{
if (unlikely(page_mapcount(page) |
(page->mapping != NULL) |
(atomic_read(&page->_count) != 0) |
(page->flags & PAGE_FLAGS_CHECK_AT_FREE) |
(mem_cgroup_bad_page_check(page)))) { <==========(*)
bad_page(page);
return 1;
==

Then, ok, this is a memcgroup and hugepage issue.

I'll look into.

Thanks,
-Kame

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