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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 <rppt@linux.vnet.ibm.com>
Signed-off-by: Andrea Arcangeli <aarcange@redhat.com>
Cc: "Dr. David Alan Gilbert" <dgilbert@redhat.com>
Cc: Hillf Danton <hillf.zj@alibaba-inc.com>
Cc: Michael Rapoport <RAPOPORT@il.ibm.com>
Cc: Mike Kravetz <mike.kravetz@oracle.com>
Cc: Pavel Emelyanov <xemul@parallels.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
hifive-unleashed-5.1
Mike Rapoport 2017-02-22 15:43:28 -08:00 committed by Linus Torvalds
parent 4c27fe4c4c
commit b0506e488d
2 changed files with 15 additions and 0 deletions
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10
include/linux/mm.h
View File

@ -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)
{

5
mm/shmem.c
View File

@ -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);