From: Khalid Aziz <khalid@xxxxxxxxxx>
Add a bit to vm_flags to indicate a vma shares PTEs with others. Add
a function to determine if a vma shares PTEs by checking this flag.
This is to be used to find the shared page table entries on page fault
for vmas sharing PTEs.
Signed-off-by: Khalid Aziz <khalid@xxxxxxxxxx>
Signed-off-by: Matthew Wilcox (Oracle) <willy@xxxxxxxxxxxxx>
Signed-off-by: Anthony Yznaga <anthony.yznaga@xxxxxxxxxx>
---
include/linux/mm.h | 7 +++++++
include/trace/events/mmflags.h | 3 +++
mm/internal.h | 5 +++++
3 files changed, 15 insertions(+)
diff --git a/include/linux/mm.h b/include/linux/mm.h
index 6549d0979b28..3aa0b3322284 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -413,6 +413,13 @@ extern unsigned int kobjsize(const void *objp);
#define VM_DROPPABLE VM_NONE
#endif
+#ifdef CONFIG_64BIT
+#define VM_SHARED_PT_BIT 41
+#define VM_SHARED_PT BIT(VM_SHARED_PT_BIT)
+#else
+#define VM_SHARED_PT VM_NONE
+#endif
+
#ifdef CONFIG_64BIT
/* VM is sealed, in vm_flags */
#define VM_SEALED _BITUL(63)
diff --git a/include/trace/events/mmflags.h b/include/trace/events/mmflags.h
index b63d211bd141..e1ae1e60d086 100644
--- a/include/trace/events/mmflags.h
+++ b/include/trace/events/mmflags.h
@@ -167,8 +167,10 @@ IF_HAVE_PG_ARCH_X(arch_3)
#ifdef CONFIG_64BIT
# define IF_HAVE_VM_DROPPABLE(flag, name) {flag, name},
+# define IF_HAVE_VM_SHARED_PT(flag, name) {flag, name},
#else
# define IF_HAVE_VM_DROPPABLE(flag, name)
+# define IF_HAVE_VM_SHARED_PT(flag, name)
#endif
#define __def_vmaflag_names \
@@ -204,6 +206,7 @@ IF_HAVE_VM_SOFTDIRTY(VM_SOFTDIRTY, "softdirty" ) \
{VM_HUGEPAGE, "hugepage" }, \
{VM_NOHUGEPAGE, "nohugepage" }, \
IF_HAVE_VM_DROPPABLE(VM_DROPPABLE, "droppable" ) \
+IF_HAVE_VM_SHARED_PT(VM_SHARED_PT, "sharedpt" ) \
{VM_MERGEABLE, "mergeable" } \
#define show_vma_flags(flags) \
diff --git a/mm/internal.h b/mm/internal.h
index b4d86436565b..8005d5956b6e 100644
--- a/mm/internal.h
+++ b/mm/internal.h
@@ -1578,4 +1578,9 @@ void unlink_file_vma_batch_init(struct unlink_vma_file_batch *);
void unlink_file_vma_batch_add(struct unlink_vma_file_batch *, struct vm_area_struct *);
void unlink_file_vma_batch_final(struct unlink_vma_file_batch *);
+static inline bool vma_is_shared(const struct vm_area_struct *vma)
+{
+ return VM_SHARED_PT && (vma->vm_flags & VM_SHARED_PT);
+}
+
#endif /* __MM_INTERNAL_H */
--
2.43.5
