On 9/19/18 7:03 PM, Yang Shi wrote: > When unmapping VM_PFNMAP mappings, vm flags need to be updated. Since > the vmas have been detached, so it sounds safe to update vm flags with > read mmap_sem. > > Cc: Michal Hocko <mhocko@xxxxxxxxxx> > Cc: Vlastimil Babka <vbabka@xxxxxxx> > Reviewed-by: Matthew Wilcox <willy@xxxxxxxxxxxxx> > Signed-off-by: Yang Shi <yang.shi@xxxxxxxxxxxxxxxxx> > --- > mm/mmap.c | 9 --------- > 1 file changed, 9 deletions(-) > > diff --git a/mm/mmap.c b/mm/mmap.c > index 490340e..847a17d 100644 > --- a/mm/mmap.c > +++ b/mm/mmap.c > @@ -2771,15 +2771,6 @@ static int __do_munmap(struct mm_struct *mm, unsigned long start, size_t len, > munlock_vma_pages_all(tmp); > } > > - /* > - * Unmapping vmas, which have VM_HUGETLB or VM_PFNMAP, Ah, the comment should have been already updated with the previous patch. But nevermind as that all goes away. Acked-by: Vlastimil Babka <vbabka@xxxxxxx> > - * need get done with write mmap_sem held since they may > - * update vm_flags. > - */ > - if (downgrade && > - (tmp->vm_flags & VM_PFNMAP)) > - downgrade = false; > - > tmp = tmp->vm_next; > } > } >
