From b0506e488da5cf2f07f3a4f6d7acaa8f459ad714 Mon Sep 17 00:00:00 2001 From: Mike Rapoport Date: Wed, 22 Feb 2017 15:43:28 -0800 Subject: [PATCH] userfaultfd: shmem: introduce vma_is_shmem Currently userfault relies on vma_is_anonymous and vma_is_hugetlb to ensure compatibility of a VMA with userfault. Introduction of vma_is_shmem allows detection if tmpfs backed VMAs, so that they may be used with userfaultfd. Current implementation presumes usage of vma_is_shmem only by slow path routines in userfaultfd, therefore the vma_is_shmem is not made inline to leave the few remaining free bits in vm_flags. Link: http://lkml.kernel.org/r/20161216144821.5183-30-aarcange@redhat.com Signed-off-by: Mike Rapoport Signed-off-by: Andrea Arcangeli Cc: "Dr. David Alan Gilbert" Cc: Hillf Danton Cc: Michael Rapoport Cc: Mike Kravetz Cc: Pavel Emelyanov Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- include/linux/mm.h | 10 ++++++++++ mm/shmem.c | 5 +++++ 2 files changed, 15 insertions(+) diff --git a/include/linux/mm.h b/include/linux/mm.h index c3e2be2..bb99749 100644 --- a/include/linux/mm.h +++ b/include/linux/mm.h @@ -1383,6 +1383,16 @@ static inline bool vma_is_anonymous(struct vm_area_struct *vma) return !vma->vm_ops; } +#ifdef CONFIG_SHMEM +/* + * The vma_is_shmem is not inline because it is used only by slow + * paths in userfault. + */ +bool vma_is_shmem(struct vm_area_struct *vma); +#else +static inline bool vma_is_shmem(struct vm_area_struct *vma) { return false; } +#endif + static inline int stack_guard_page_start(struct vm_area_struct *vma, unsigned long addr) { diff --git a/mm/shmem.c b/mm/shmem.c index 14de2a9..8412bae 100644 --- a/mm/shmem.c +++ b/mm/shmem.c @@ -191,6 +191,11 @@ static const struct inode_operations shmem_special_inode_operations; static const struct vm_operations_struct shmem_vm_ops; static struct file_system_type shmem_fs_type; +bool vma_is_shmem(struct vm_area_struct *vma) +{ + return vma->vm_ops == &shmem_vm_ops; +} + static LIST_HEAD(shmem_swaplist); static DEFINE_MUTEX(shmem_swaplist_mutex); -- 2.7.4