From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from ozlabs.ru (ozlabs.ru [107.173.13.209]) by lists.ozlabs.org (Postfix) with ESMTP id 3vsfWL2xHgzDqZn for ; Tue, 28 Mar 2017 16:26:04 +1100 (AEDT) From: Alexey Kardashevskiy To: linuxppc-dev@lists.ozlabs.org Cc: Alexey Kardashevskiy , Balbir Singh , Paul Mackerras , "Aneesh Kumar K . V" , Greg Kurz Subject: [PATCH kernel] powerpc/iommu: Do not call PageTransHuge() on tail pages Date: Tue, 28 Mar 2017 16:25:59 +1100 Message-Id: <20170328052559.12912-1-aik@ozlabs.ru> List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , 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 should be called on head pages. Since we also test for PageCompound(), and it contains PageTail(), we can simply move PageCompound() in front of PageTransHuge() and therefore avoid possible VM_BUG_ON_PAGE. Signed-off-by: Alexey Kardashevskiy --- Some of actual POWER8 systems do crash on that BUG_ON. --- arch/powerpc/mm/mmu_context_iommu.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/arch/powerpc/mm/mmu_context_iommu.c b/arch/powerpc/mm/mmu_context_iommu.c index 497130c5c742..ba7fccf993b3 100644 --- a/arch/powerpc/mm/mmu_context_iommu.c +++ b/arch/powerpc/mm/mmu_context_iommu.c @@ -81,7 +81,7 @@ struct page *new_iommu_non_cma_page(struct page *page, unsigned long private, gfp_t gfp_mask = GFP_USER; struct page *new_page; - if (PageHuge(page) || PageTransHuge(page) || PageCompound(page)) + if (PageCompound(page) || PageHuge(page) || PageTransHuge(page)) return NULL; if (PageHighMem(page)) @@ -100,7 +100,7 @@ static int mm_iommu_move_page_from_cma(struct page *page) LIST_HEAD(cma_migrate_pages); /* Ignore huge pages for now */ - if (PageHuge(page) || PageTransHuge(page) || PageCompound(page)) + if (PageCompound(page) || PageHuge(page) || PageTransHuge(page)) return -EBUSY; lru_add_drain(); -- 2.11.0