Re: [PATCH 1/3] HWPOISON, hugetlbfs: fix warning on freeinghwpoisoned hugepage

[Andrew Morton]

On Fri,  7 Dec 2012 10:49:57 -0500
Naoya Horiguchi <n-horiguchi@xxxxxxxxxxxxx> wrote:

> This patch fixes the warning from __list_del_entry() which is triggered
> when a process tries to do free_huge_page() for a hwpoisoned hugepage.

This changelog is very short.  In fact it is too short, resulting in
others having to ask questions about the patch.  When this happens,
please treat it as a sign that the changelog needs additional
information - so that other readers will not feel a need to ask the
same questions!

I added this paragraph:

: free_huge_page() can be called for hwpoisoned hugepage from
: unpoison_memory().  This function gets refcount once and clears
: PageHWPoison, and then puts refcount twice to return the hugepage back to
: free pool.  The second put_page() finally reaches free_huge_page().



Also, is the description accurate?  Is the __list_del_entry() warning
the only problem?

Or is it the case that this bug will cause memory corruption?  If so
then the patch is pretty important and is probably needed in -stable as
well?  I haven't checked how far back in time the bug exists.

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