From 7124f1ac028439cd8a4a588b6e39d99cad6fe646 Mon Sep 17 00:00:00 2001 From: Yang Shi Date: Fri, 26 Oct 2018 15:07:18 -0700 Subject: [PATCH] mm: unmap VM_PFNMAP mappings with optimized path to #28718400 commit cb4922496ae40a775a1b17025eaa1060e8991253 upstream. 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. Link: http://lkml.kernel.org/r/1537376621-51150-4-git-send-email-yang.shi@linux.alibaba.com Signed-off-by: Yang Shi Reviewed-by: Matthew Wilcox Acked-by: Kirill A. Shutemov Acked-by: Vlastimil Babka Cc: Michal Hocko Cc: Vlastimil Babka Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds Signed-off-by: Xu Yu Reviewed-by: Yang Shi --- mm/mmap.c | 9 --------- 1 file changed, 9 deletions(-) diff --git a/mm/mmap.c b/mm/mmap.c index ad34641cc966..7a88c5f0d3e9 100644 --- a/mm/mmap.c +++ b/mm/mmap.c @@ -2775,15 +2775,6 @@ 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; } } -- GitLab