On Mon, Mar 28, 2016 at 06:12:49PM -0700, Mike Kravetz wrote: > When creating a hugetlb mapping, attempt PUD_SIZE alignment if the > following conditions are met: > - Address passed to mmap or shmat is NULL > - The mapping is flaged as shared > - The mapping is at least PUD_SIZE in length > If a PUD_SIZE aligned mapping can not be created, then fall back to a > huge page size mapping.
It would be kinder if the patch description includes why this change. Simply "to facilitate pmd sharing" is helpful for someone who read "git log". > > Signed-off-by: Mike Kravetz <[email protected]> > --- > fs/hugetlbfs/inode.c | 29 +++++++++++++++++++++++++++-- > 1 file changed, 27 insertions(+), 2 deletions(-) > > diff --git a/fs/hugetlbfs/inode.c b/fs/hugetlbfs/inode.c > index 540ddc9..22b2e38 100644 > --- a/fs/hugetlbfs/inode.c > +++ b/fs/hugetlbfs/inode.c > @@ -175,6 +175,17 @@ hugetlb_get_unmapped_area(struct file *file, unsigned > long addr, > struct vm_area_struct *vma; > struct hstate *h = hstate_file(file); > struct vm_unmapped_area_info info; > + bool pud_size_align = false; > + unsigned long ret_addr; > + > + /* > + * If PMD sharing is enabled, align to PUD_SIZE to facilitate > + * sharing. Only attempt alignment if no address was passed in, > + * flags indicate sharing and size is big enough. > + */ > + if (IS_ENABLED(CONFIG_ARCH_WANT_HUGE_PMD_SHARE) && > + !addr && flags & MAP_SHARED && len >= PUD_SIZE) > + pud_size_align = true; This code will have duplicates in the next patch, so how about checking this in a separate check routine? Thanks, Naoya Horiguchi
