Patch "powerpc/iommu: Do not call PageTransHuge() on tail pages" has been added to the 4.9-stable tree

This is a note to let you know that I've just added the patch titled

powerpc/iommu: Do not call PageTransHuge() on tail pages

to the 4.9-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
powerpc-iommu-do-not-call-pagetranshuge-on-tail-pages.patch
and it can be found in the queue-4.9 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree, please let <[email protected]> know about it.

From: Alexey Kardashevskiy <[email protected]>
Date: Tue, 11 Apr 2017 17:54:57 +1000
Subject: powerpc/iommu: Do not call PageTransHuge() on tail pages

From: Alexey Kardashevskiy <[email protected]>

commit e889e96e98e8da97bd39e46b7253615eabe14397 upstream.

The CMA pages migration code does not support compound pages at the moment so it performs few tests before proceeding to actual page migration.

One of the tests - PageTransHuge() - has VM_BUG_ON_PAGE(PageTail()) as it is designed to be called on head pages only. Since we also test for PageCompound(), and it contains PageTail() and PageHead(), we can simplify the check by leaving just PageCompound() and therefore avoid possible VM_BUG_ON_PAGE.

---
 arch/powerpc/mm/mmu_context_iommu.c |    4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

@@ -81,7 +81,7 @@ struct page *new_iommu_non_cma_page(stru
 	gfp_t gfp_mask = GFP_USER;
 	struct page *new_page;
 
-	if (PageHuge(page) || PageTransHuge(page) || PageCompound(page))
+	if (PageCompound(page))
 		return NULL;
 
 	if (PageHighMem(page))

@@ -100,7 +100,7 @@ static int mm_iommu_move_page_from_cma(s
 	LIST_HEAD(cma_migrate_pages);
 
 	/* Ignore huge pages for now */
-	if (PageHuge(page) || PageTransHuge(page) || PageCompound(page))
+	if (PageCompound(page))
 		return -EBUSY;
 
 	lru_add_drain();

Patches currently in stable-queue which might be from [email protected] are

queue-4.9/powerpc-iommu-do-not-call-pagetranshuge-on-tail-pages.patch queue-4.9/powerpc-eeh-avoid-use-after-free-in-eeh_handle_special_event.patch