| Message ID | 1536957299-43536-4-git-send-email-yang.shi@linux.alibaba.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | mm: zap pages with read mmap_sem in munmap for large mapping | expand |
On Sat, Sep 15, 2018 at 04:34:59AM +0800, 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@kernel.org> > Cc: Vlastimil Babka <vbabka@suse.cz> > Signed-off-by: Yang Shi <yang.shi@linux.alibaba.com> Reviewed-by: Matthew Wilcox <willy@infradead.org>
diff --git a/mm/mmap.c b/mm/mmap.c index 991e066..04c1d3b 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, - * 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; } }
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@kernel.org> Cc: Vlastimil Babka <vbabka@suse.cz> Signed-off-by: Yang Shi <yang.shi@linux.alibaba.com> --- mm/mmap.c | 9 --------- 1 file changed, 9 deletions(-)