From b8aa9d9d95b3b4b60d42ac95f65d33a92527aef3 Mon Sep 17 00:00:00 2001 From: Wei Yang Date: Thu, 6 Aug 2020 23:23:40 -0700 Subject: [PATCH] mm/mremap: it is sure to have enough space when extent meets requirement Patch series "mm/mremap: cleanup move_page_tables() a little", v5. move_page_tables() tries to move page table by PMD or PTE. The root reason is if it tries to move PMD, both old and new range should be PMD aligned. But current code calculate old range and new range separately. This leads to some redundant check and calculation. This cleanup tries to consolidate the range check in one place to reduce some extra range handling. This patch (of 3): old_end is passed to these two functions to check whether there is enough space to do the move, while this check is done before invoking these functions. These two functions only would be invoked when extent meets the requirement and there is one check before invoking these functions: if (extent > old_end - old_addr) extent = old_end - old_addr; This implies (old_end - old_addr) won't fail the check in these two functions. Signed-off-by: Wei Yang Signed-off-by: Andrew Morton Tested-by: Dmitry Osipenko Acked-by: Kirill A. Shutemov Cc: Vlastimil Babka Cc: Yang Shi Cc: Thomas Hellstrom (VMware) Cc: Anshuman Khandual Cc: Sean Christopherson Cc: Wei Yang Cc: Peter Xu Cc: Aneesh Kumar K.V Cc: Matthew Wilcox Cc: Thomas Hellstrom Link: http://lkml.kernel.org/r/20200710092835.56368-1-richard.weiyang@linux.alibaba.com Link: http://lkml.kernel.org/r/20200710092835.56368-2-richard.weiyang@linux.alibaba.com Link: http://lkml.kernel.org/r/20200708095028.41706-1-richard.weiyang@linux.alibaba.com Link: http://lkml.kernel.org/r/20200708095028.41706-2-richard.weiyang@linux.alibaba.com Signed-off-by: Linus Torvalds --- include/linux/huge_mm.h | 2 +- mm/huge_memory.c | 7 ++----- mm/mremap.c | 10 ++++------ 3 files changed, 7 insertions(+), 12 deletions(-) diff --git a/include/linux/huge_mm.h b/include/linux/huge_mm.h index 71f20776b06c..17c4c4975145 100644 --- a/include/linux/huge_mm.h +++ b/include/linux/huge_mm.h @@ -42,7 +42,7 @@ extern int mincore_huge_pmd(struct vm_area_struct *vma, pmd_t *pmd, unsigned long addr, unsigned long end, unsigned char *vec); extern bool move_huge_pmd(struct vm_area_struct *vma, unsigned long old_addr, - unsigned long new_addr, unsigned long old_end, + unsigned long new_addr, pmd_t *old_pmd, pmd_t *new_pmd); extern int change_huge_pmd(struct vm_area_struct *vma, pmd_t *pmd, unsigned long addr, pgprot_t newprot, diff --git a/mm/huge_memory.c b/mm/huge_memory.c index 78c84bee7e29..1e580fdad4d0 100644 --- a/mm/huge_memory.c +++ b/mm/huge_memory.c @@ -1722,17 +1722,14 @@ static pmd_t move_soft_dirty_pmd(pmd_t pmd) } bool move_huge_pmd(struct vm_area_struct *vma, unsigned long old_addr, - unsigned long new_addr, unsigned long old_end, - pmd_t *old_pmd, pmd_t *new_pmd) + unsigned long new_addr, pmd_t *old_pmd, pmd_t *new_pmd) { spinlock_t *old_ptl, *new_ptl; pmd_t pmd; struct mm_struct *mm = vma->vm_mm; bool force_flush = false; - if ((old_addr & ~HPAGE_PMD_MASK) || - (new_addr & ~HPAGE_PMD_MASK) || - old_end - old_addr < HPAGE_PMD_SIZE) + if ((old_addr & ~HPAGE_PMD_MASK) || (new_addr & ~HPAGE_PMD_MASK)) return false; /* diff --git a/mm/mremap.c b/mm/mremap.c index 6b153dc05fe4..4f434062d154 100644 --- a/mm/mremap.c +++ b/mm/mremap.c @@ -193,15 +193,13 @@ static void move_ptes(struct vm_area_struct *vma, pmd_t *old_pmd, #ifdef CONFIG_HAVE_MOVE_PMD static bool move_normal_pmd(struct vm_area_struct *vma, unsigned long old_addr, - unsigned long new_addr, unsigned long old_end, - pmd_t *old_pmd, pmd_t *new_pmd) + unsigned long new_addr, pmd_t *old_pmd, pmd_t *new_pmd) { spinlock_t *old_ptl, *new_ptl; struct mm_struct *mm = vma->vm_mm; pmd_t pmd; - if ((old_addr & ~PMD_MASK) || (new_addr & ~PMD_MASK) - || old_end - old_addr < PMD_SIZE) + if ((old_addr & ~PMD_MASK) || (new_addr & ~PMD_MASK)) return false; /* @@ -292,7 +290,7 @@ unsigned long move_page_tables(struct vm_area_struct *vma, if (need_rmap_locks) take_rmap_locks(vma); moved = move_huge_pmd(vma, old_addr, new_addr, - old_end, old_pmd, new_pmd); + old_pmd, new_pmd); if (need_rmap_locks) drop_rmap_locks(vma); if (moved) @@ -312,7 +310,7 @@ unsigned long move_page_tables(struct vm_area_struct *vma, if (need_rmap_locks) take_rmap_locks(vma); moved = move_normal_pmd(vma, old_addr, new_addr, - old_end, old_pmd, new_pmd); + old_pmd, new_pmd); if (need_rmap_locks) drop_rmap_locks(vma); if (moved)