From 9ad9718bfa41f6ae62fb2a7244357e99ac00d25a Mon Sep 17 00:00:00 2001 From: Wei Yang Date: Thu, 6 Aug 2020 23:23:44 -0700 Subject: mm/mremap: calculate extent in one place Page tables is moved on the base of PMD. This requires both source and destination range should meet the requirement. Current code works well since move_huge_pmd() and move_normal_pmd() would check old_addr and new_addr again. And then return to move_ptes() if the either of them is not aligned. Instead of calculating the extent separately, it is better to calculate in one place, so we know it is not necessary to try move pmd. By doing so, the logic seems a little clear. Signed-off-by: Wei Yang Signed-off-by: Andrew Morton Tested-by: Dmitry Osipenko Acked-by: Kirill A. Shutemov Cc: Aneesh Kumar K.V Cc: Anshuman Khandual Cc: Matthew Wilcox Cc: Peter Xu Cc: Sean Christopherson Cc: Thomas Hellstrom Cc: Thomas Hellstrom (VMware) Cc: Vlastimil Babka Cc: Yang Shi Link: http://lkml.kernel.org/r/20200708095028.41706-3-richard.weiyang@linux.alibaba.com Signed-off-by: Linus Torvalds --- mm/mremap.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) (limited to 'mm') diff --git a/mm/mremap.c b/mm/mremap.c index 4f434062d154..c3622bfcf6d9 100644 --- a/mm/mremap.c +++ b/mm/mremap.c @@ -277,6 +277,9 @@ unsigned long move_page_tables(struct vm_area_struct *vma, extent = next - old_addr; if (extent > old_end - old_addr) extent = old_end - old_addr; + next = (new_addr + PMD_SIZE) & PMD_MASK; + if (extent > next - new_addr) + extent = next - new_addr; old_pmd = get_old_pmd(vma->vm_mm, old_addr); if (!old_pmd) continue; @@ -320,9 +323,6 @@ unsigned long move_page_tables(struct vm_area_struct *vma, if (pte_alloc(new_vma->vm_mm, new_pmd)) break; - next = (new_addr + PMD_SIZE) & PMD_MASK; - if (extent > next - new_addr) - extent = next - new_addr; move_ptes(vma, old_pmd, old_addr, old_addr + extent, new_vma, new_pmd, new_addr, need_rmap_locks); } -- cgit v1.2.3