On Wed, Sep 25, 2019 at 10:44:58AM -0700, Mike Kravetz wrote: >On 9/25/19 5:18 AM, Wei Yang wrote: >> The warning here is to make sure address(dst_addr) and length(len - >> copied) are huge page size aligned. >> >> While this is ensured by: >> >> dst_start and len is huge page size aligned >> dst_addr equals to dst_start and increase huge page size each time >> copied increase huge page size each time > >Can we also remove the following for the same reasons? > >diff --git a/mm/userfaultfd.c b/mm/userfaultfd.c >index 640ff2bd9a69..f82d5ec698d8 100644 >--- a/mm/userfaultfd.c >+++ b/mm/userfaultfd.c >@@ -262,7 +262,6 @@ static __always_inline ssize_t __mcopy_atomic_hugetlb(struct mm_struct *dst_mm, > pte_t dst_pteval; > > BUG_ON(dst_addr >= dst_start + len); >- VM_BUG_ON(dst_addr & ~huge_page_mask(h)); > Thanks for your comment. It looks good, while I lack some knowledge between vma_hpagesize and huge_page_mask(). If they are the same, why not use the same interface for all those checks in this function? > /* > * Serialize via hugetlb_fault_mutex > >-- >Mike Kravetz > >> >> This means this warning will never be triggered. >> >> Signed-off-by: Wei Yang <richardw.yang@xxxxxxxxxxxxxxx> >> --- >> mm/userfaultfd.c | 4 ---- >> 1 file changed, 4 deletions(-) >> >> diff --git a/mm/userfaultfd.c b/mm/userfaultfd.c >> index c7ae74ce5ff3..7895c715000e 100644 >> --- a/mm/userfaultfd.c >> +++ b/mm/userfaultfd.c >> @@ -243,10 +243,6 @@ static __always_inline ssize_t __mcopy_atomic_hugetlb(struct mm_struct *dst_mm, >> vm_shared = dst_vma->vm_flags & VM_SHARED; >> } >> >> - if (WARN_ON(dst_addr & (vma_hpagesize - 1) || >> - (len - copied) & (vma_hpagesize - 1))) >> - goto out_unlock; >> - >> /* >> * If not shared, ensure the dst_vma has a anon_vma. >> */ >> -- Wei Yang Help you, Help me
