Alexey Kardashevskiy <a...@ozlabs.ru> writes: > 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 <a...@ozlabs.ru> > --- > > 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))
A checked for compound page should be sufficient here, because a Huge/TransHuge page is also marked compound. If we want to indicate that we don't handle hugetlb and THP pages, we can write that as a comment ? > 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
