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. > > [1]: https://github.com/axboe/fio/blob/master/engines/mmap.c > Signed-off-by: Toshi Kani <toshi.kani@xxxxxxx> > Cc: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> > Cc: Dan Williams <dan.j.williams@xxxxxxxxx> > Cc: Matthew Wilcox <mawilcox@xxxxxxxxxxxxx> > Cc: Ross Zwisler <ross.zwisler@xxxxxxxxxxxxxxx> > Cc: Kirill A. Shutemov <kirill.shutemov@xxxxxxxxxxxxxxx> > Cc: Dave Chinner <david@xxxxxxxxxxxxx> > Cc: Jan Kara <jack@xxxxxxx> > Cc: Theodore Ts'o <tytso@xxxxxxx> > Cc: Andreas Dilger <adilger.kernel@xxxxxxxxx> > Cc: Mike Kravetz <mike.kravetz@xxxxxxxxxx> > --- Reviewed-by: Dan Williams <dan.j.williams@xxxxxxxxx> ...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. -- 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>