Hi Naoya,

quoted

Yes, splitting the huge pages and isolating a base page is ideal. And
we do this with dissolve_free_huge_page() when page_mapping() return
NULL. I think there is a reason(but I do not get it) why we don't split
huge pags in hugetlbfs_error_remove_page() or after. So I choose to 
add a new count.

Maybe the resource is the main reason of this incompleteness, I noticed this
for years and continued to say "this is in my todo list", but still don't
make it (really sorry about that...).  Anyway, if you can (I hope) solve
your problem with "/proc/kpageflag" approach, which is a recommended solution.

I do not understand the exact meaning of the "resource". I have tried to call
dissolve_free_huge_page() after hugetlbfs_error_remove_page() and it worked.
In my opinion, the error huge page has been truncated from the hugetlbfs. It
cannot be accessed and allocated again. I think it is safe to split it.

I would appreciate it if you could point out what I overlooked. And I will
try to solve it.

Thanks,
Bin Wang