Re: [PATCH] mm: fix false-positive WARN_ON() in truncate/invalidate for hugetlb

[Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>]

On Wed, Nov 23, 2016 at 12:30:53PM +0300, Kirill A. Shutemov wrote:
> Sorry, forgot to commit local changes.
> 
> ----8<----
> 
> From 321379738fa2359385a38dfac838a83c261a382d Mon Sep 17 00:00:00 2001
> From: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
> Date: Wed, 23 Nov 2016 12:05:30 +0300
> Subject: [PATCH] mm: fix false-positive WARN_ON() in truncate/invalidate for
>  hugetlb
> 
> Hugetlb pages have ->index in size of the huge pages (PMD_SIZE or
> PUD_SIZE), not in PAGE_SIZE as other types of pages. This means we
> cannot user page_to_pgoff() to check whether we've got the right page
> for the radix-tree index.
> 
> Let's introduce page_to_index() which would return radix-tree index for
> given page.
> 
> We will be able to get rid of this once hugetlb will be switched to
> multi-order entries.
> 
> Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
> Reported-and-tested-by: Doug Nelson <doug.nelson@intel.com>
> Fixes: fc127da085c2 ("truncate: handle file thp")
> Cc: <stable@vger.kernel.org> [4.8+]

Reviewed-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
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