On Mon, Aug 29, 2016 at 1:44 PM, Kani, Toshimitsu <toshi.kani@xxxxxxx> wrote: > On Mon, 2016-08-29 at 12:34 -0700, Dan Williams wrote: >> On Mon, Aug 29, 2016 at 12:11 PM, Toshi Kani <toshi.kani@xxxxxxx> >> wrote: >> > >> > When CONFIG_FS_DAX_PMD is set, DAX supports mmap() using pmd page >> > size. This feature relies on both mmap virtual address and FS >> > block (i.e. physical address) to be aligned by the pmd page size. >> > Users can use mkfs options to specify FS to align block >> > allocations. However, aligning mmap address requires code changes >> > to existing applications for providing a pmd-aligned address to >> > mmap(). >> > >> > For instance, fio with "ioengine=mmap" performs I/Os with mmap() >> > [1]. It calls mmap() with a NULL address, which needs to be changed >> > to provide a pmd-aligned address for testing with DAX pmd mappings. >> > Changing all applications that call mmap() with NULL is >> > undesirable. >> > >> > Add thp_get_unmapped_area(), which can be called by filesystem's >> > get_unmapped_area to align an mmap address by the pmd size for >> > a DAX file. It calls the default handler, mm->get_unmapped_area(), >> > to find a range and then aligns it for a DAX file. >> > >> > The patch is based on Matthew Wilcox's change that allows adding >> > support of the pud page size easily. > : >> >> Reviewed-by: Dan Williams <dan.j.williams@xxxxxxxxx> > > Great! > >> ...with one minor nit: >> >> >> > >> > include/linux/huge_mm.h | 7 +++++++ >> > mm/huge_memory.c | 43 >> > +++++++++++++++++++++++++++++++++++++++++++ >> > 2 files changed, 50 insertions(+) >> > >> > diff --git a/include/linux/huge_mm.h b/include/linux/huge_mm.h >> > index 6f14de4..4fca526 100644 >> > --- a/include/linux/huge_mm.h >> > +++ b/include/linux/huge_mm.h >> > @@ -87,6 +87,10 @@ extern bool is_vma_temporary_stack(struct >> > vm_area_struct *vma); >> > >> > extern unsigned long transparent_hugepage_flags; >> > >> > +extern unsigned long thp_get_unmapped_area(struct file *filp, >> > + unsigned long addr, unsigned long len, unsigned >> > long pgoff, >> > + unsigned long flags); >> > + >> > extern void prep_transhuge_page(struct page *page); >> > extern void free_transhuge_page(struct page *page); >> > >> > @@ -169,6 +173,9 @@ void put_huge_zero_page(void); >> > static inline void prep_transhuge_page(struct page *page) {} >> > >> > #define transparent_hugepage_flags 0UL >> > + >> > +#define thp_get_unmapped_area NULL >> >> Lets make this: >> >> static inline unsigned long thp_get_unmapped_area(struct file *filp, >> unsigned long addr, unsigned long len, unsigned long >> pgoff, >> unsigned long flags) >> { >> return 0; >> } >> >> ...to get some type checking in the CONFIG_TRANSPARENT_HUGEPAGE=n >> case. >> > > Per get_unmapped_area() in mm/mmap.c, I think we need to set it to NULL > when we do not override current->mm->get_unmapped_area. Ah, ok. -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx"> email@xxxxxxxxx </a>