diff options
| -rw-r--r-- | mm/hugetlb.c | 50 |
1 files changed, 15 insertions, 35 deletions
diff --git a/mm/hugetlb.c b/mm/hugetlb.c index 01f3e36caa6c..0ad53ad98e74 100644 --- a/mm/hugetlb.c +++ b/mm/hugetlb.c @@ -6687,10 +6687,11 @@ static unsigned long page_table_shareable(struct vm_area_struct *svma, return saddr; } -static bool __vma_aligned_range_pmd_shareable(struct vm_area_struct *vma, - unsigned long start, unsigned long end, - bool check_vma_lock) +bool want_pmd_share(struct vm_area_struct *vma, unsigned long addr) { + unsigned long start = addr & PUD_MASK; + unsigned long end = start + PUD_SIZE; + #ifdef CONFIG_USERFAULTFD if (uffd_disable_huge_pmd_share(vma)) return false; @@ -6700,38 +6701,13 @@ static bool __vma_aligned_range_pmd_shareable(struct vm_area_struct *vma, */ if (!(vma->vm_flags & VM_MAYSHARE)) return false; - if (check_vma_lock && !vma->vm_private_data) + if (!vma->vm_private_data) /* vma lock required for sharing */ return false; if (!range_in_vma(vma, start, end)) return false; return true; } -static bool vma_pmd_shareable(struct vm_area_struct *vma) -{ - unsigned long start = ALIGN(vma->vm_start, PUD_SIZE), - end = ALIGN_DOWN(vma->vm_end, PUD_SIZE); - - if (start >= end) - return false; - - return __vma_aligned_range_pmd_shareable(vma, start, end, false); -} - -static bool vma_addr_pmd_shareable(struct vm_area_struct *vma, - unsigned long addr) -{ - unsigned long start = addr & PUD_MASK; - unsigned long end = start + PUD_SIZE; - - return __vma_aligned_range_pmd_shareable(vma, start, end, true); -} - -bool want_pmd_share(struct vm_area_struct *vma, unsigned long addr) -{ - return vma_addr_pmd_shareable(vma, addr); -} - /* * Determine if start,end range within vma could be mapped by shared pmd. * If yes, adjust start and end to cover range associated with possible @@ -6880,17 +6856,21 @@ static void hugetlb_vma_lock_alloc(struct vm_area_struct *vma) if (vma->vm_private_data) return; - /* Check size/alignment for pmd sharing possible */ - if (!vma_pmd_shareable(vma)) - return; - vma_lock = kmalloc(sizeof(*vma_lock), GFP_KERNEL); - if (!vma_lock) + if (!vma_lock) { /* * If we can not allocate structure, then vma can not - * participate in pmd sharing. + * participate in pmd sharing. This is only a possible + * performance enhancement and memory saving issue. + * However, the lock is also used to synchronize page + * faults with truncation. If the lock is not present, + * unlikely races could leave pages in a file past i_size + * until the file is removed. Warn in the unlikely case of + * allocation failure. */ + pr_warn_once("HugeTLB: unable to allocate vma specific lock\n"); return; + } kref_init(&vma_lock->refs); init_rwsem(&vma_lock->rw_sema); |