The plan for these patches is to introduce the typedef, initially
just as documentation ("These functions should return a VM_FAULT_ status").
We'll trickle the patches to individual drivers/filesystems in through
the maintainers, as far as possible. Then we'll change the typedef
to an unsigned int and break the compilation of any unconverted
drivers/filesystems.
vmf_insert_page(), vmf_insert_mixed() and vmf_insert_pfn() are three
newly added functions. The various drivers/filesystems where return value
of fault(), huge_fault(), page_mkwrite() and pfn_mkwrite() get converted,
will need them. These functions will return correct VM_FAULT_ code based
on err value.
We've had bugs before where drivers returned -EFOO. And we have this
silly inefficiency where vm_insert_xxx() return an errno which (afaict)
every driver then converts into a VM_FAULT code. In many cases drivers
failed to return correct VM_FAULT code value despite of vm_insert_xxx()
fails. We have indentified and clean up all those existing bugs and silly
inefficiencies in driver/filesystems by adding these three new inline
wrappers. As mentioned above, we will trickle those patches to individual
drivers/filesystems in through maintainers after these three wrapper
functions are merged.
Eventually we can convert vm_insert_xxx() into vmf_insert_xxx() and
remove these inline wrappers, but these are a good intermediate step.
Signed-off-by: Souptick Joarder <jrdr.linux@xxxxxxxxx>
---
include/linux/mm.h | 47 +++++++++++++++++++++++++++++++++++++++++++----
include/linux/mm_types.h | 2 ++
2 files changed, 45 insertions(+), 4 deletions(-)
diff --git a/include/linux/mm.h b/include/linux/mm.h
index ad06d42..a4d8853 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -379,17 +379,18 @@ struct vm_operations_struct {
void (*close)(struct vm_area_struct * area);
int (*split)(struct vm_area_struct * area, unsigned long addr);
int (*mremap)(struct vm_area_struct * area);
- int (*fault)(struct vm_fault *vmf);
- int (*huge_fault)(struct vm_fault *vmf, enum page_entry_size pe_size);
+ vm_fault_t (*fault)(struct vm_fault *vmf);
+ vm_fault_t (*huge_fault)(struct vm_fault *vmf,
+ enum page_entry_size pe_size);
void (*map_pages)(struct vm_fault *vmf,
pgoff_t start_pgoff, pgoff_t end_pgoff);
/* notification that a previously read-only page is about to become
* writable, if an error is returned it will cause a SIGBUS */
- int (*page_mkwrite)(struct vm_fault *vmf);
+ vm_fault_t (*page_mkwrite)(struct vm_fault *vmf);
/* same as page_mkwrite when using VM_PFNMAP|VM_MIXEDMAP */
- int (*pfn_mkwrite)(struct vm_fault *vmf);
+ vm_fault_t (*pfn_mkwrite)(struct vm_fault *vmf);
/* called by access_process_vm when get_user_pages() fails, typically
* for use by special VMAs that can switch between memory and hardware
@@ -2413,6 +2414,44 @@ int vm_insert_mixed_mkwrite(struct vm_area_struct *vma, unsigned long addr,
pfn_t pfn);
int vm_iomap_memory(struct vm_area_struct *vma, phys_addr_t start, unsigned long len);
+static inline vm_fault_t vmf_insert_page(struct vm_area_struct *vma,
+ unsigned long addr, struct page *page)
+{
+ int err = vm_insert_page(vma, addr, page);
+
+ if (err == -ENOMEM)
+ return VM_FAULT_OOM;
+ if (err < 0 && err != -EBUSY)
+ return VM_FAULT_SIGBUS;
+
+ return VM_FAULT_NOPAGE;
+}
+
+static inline vm_fault_t vmf_insert_mixed(struct vm_area_struct *vma,
+ unsigned long addr, pfn_t pfn)
+{
+ int err = vm_insert_mixed(vma, addr, pfn);
+
+ if (err == -ENOMEM)
+ return VM_FAULT_OOM;
+ if (err < 0 && err != -EBUSY)
+ return VM_FAULT_SIGBUS;
+
+ return VM_FAULT_NOPAGE;
+}
+
+static inline vm_fault_t vmf_insert_pfn(struct vm_area_struct *vma,
+ unsigned long addr, unsigned long pfn)
+{
+ int err = vm_insert_pfn(vma, addr, pfn);
+
+ if (err == -ENOMEM)
+ return VM_FAULT_OOM;
+ if (err < 0 && err != -EBUSY)
+ return VM_FAULT_SIGBUS;
+
+ return VM_FAULT_NOPAGE;
+}
struct page *follow_page_mask(struct vm_area_struct *vma,
unsigned long address, unsigned int foll_flags,
diff --git a/include/linux/mm_types.h b/include/linux/mm_types.h
index fd1af6b..2161234 100644
--- a/include/linux/mm_types.h
+++ b/include/linux/mm_types.h
@@ -22,6 +22,8 @@
#endif
#define AT_VECTOR_SIZE (2*(AT_VECTOR_SIZE_ARCH + AT_VECTOR_SIZE_BASE + 1))
+typedef int vm_fault_t;
+
struct address_space;
struct mem_cgroup;
struct hmm;
--
1.9.1
