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authorSouptick Joarder <jrdr.linux@gmail.com>2019-03-07 16:31:14 -0800
committerLinus Torvalds <torvalds@linux-foundation.org>2019-03-07 18:32:03 -0800
commit3d3539018d2cbd12e5af4a132636ee7fd8d43ef0 (patch)
tree04a93330b5d3fd876babda6bbd494da909bf2d93
parentc2938eeb8888f0af8862ca1369e89edf9bfc47f3 (diff)
download96b-common-3d3539018d2cbd12e5af4a132636ee7fd8d43ef0.tar.gz
mm: create the new vm_fault_t type
Page fault handlers are supposed to return VM_FAULT codes, but some drivers/file systems mistakenly return error numbers. Now that all drivers/file systems have been converted to use the vm_fault_t return type, change the type definition to no longer be compatible with 'int'. By making it an unsigned int, the function prototype becomes incompatible with a function which returns int. Sparse will detect any attempts to return a value which is not a VM_FAULT code. VM_FAULT_SET_HINDEX and VM_FAULT_GET_HINDEX values are changed to avoid conflict with other VM_FAULT codes. [jrdr.linux@gmail.com: fix warnings] Link: http://lkml.kernel.org/r/20190109183742.GA24326@jordon-HP-15-Notebook-PC Link: http://lkml.kernel.org/r/20190108183041.GA12137@jordon-HP-15-Notebook-PC Signed-off-by: Souptick Joarder <jrdr.linux@gmail.com> Reviewed-by: William Kucharski <william.kucharski@oracle.com> Reviewed-by: Mike Rapoport <rppt@linux.ibm.com> Reviewed-by: Matthew Wilcox <willy@infradead.org> Cc: Michal Hocko <mhocko@suse.com> Cc: Dan Williams <dan.j.williams@intel.com> Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Cc: Rik van Riel <riel@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
-rw-r--r--arch/x86/mm/fault.c2
-rw-r--r--include/linux/mm.h46
-rw-r--r--include/linux/mm_types.h73
3 files changed, 73 insertions, 48 deletions
diff --git a/arch/x86/mm/fault.c b/arch/x86/mm/fault.c
index 9d5c75f02295..667f1da36208 100644
--- a/arch/x86/mm/fault.c
+++ b/arch/x86/mm/fault.c
@@ -1031,7 +1031,7 @@ bad_area_access_error(struct pt_regs *regs, unsigned long error_code,
static void
do_sigbus(struct pt_regs *regs, unsigned long error_code, unsigned long address,
- unsigned int fault)
+ vm_fault_t fault)
{
struct task_struct *tsk = current;
diff --git a/include/linux/mm.h b/include/linux/mm.h
index 20ec56f8e2bb..5801ee849f36 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -1323,52 +1323,6 @@ static inline void clear_page_pfmemalloc(struct page *page)
}
/*
- * Different kinds of faults, as returned by handle_mm_fault().
- * Used to decide whether a process gets delivered SIGBUS or
- * just gets major/minor fault counters bumped up.
- */
-
-#define VM_FAULT_OOM 0x0001
-#define VM_FAULT_SIGBUS 0x0002
-#define VM_FAULT_MAJOR 0x0004
-#define VM_FAULT_WRITE 0x0008 /* Special case for get_user_pages */
-#define VM_FAULT_HWPOISON 0x0010 /* Hit poisoned small page */
-#define VM_FAULT_HWPOISON_LARGE 0x0020 /* Hit poisoned large page. Index encoded in upper bits */
-#define VM_FAULT_SIGSEGV 0x0040
-
-#define VM_FAULT_NOPAGE 0x0100 /* ->fault installed the pte, not return page */
-#define VM_FAULT_LOCKED 0x0200 /* ->fault locked the returned page */
-#define VM_FAULT_RETRY 0x0400 /* ->fault blocked, must retry */
-#define VM_FAULT_FALLBACK 0x0800 /* huge page fault failed, fall back to small */
-#define VM_FAULT_DONE_COW 0x1000 /* ->fault has fully handled COW */
-#define VM_FAULT_NEEDDSYNC 0x2000 /* ->fault did not modify page tables
- * and needs fsync() to complete (for
- * synchronous page faults in DAX) */
-
-#define VM_FAULT_ERROR (VM_FAULT_OOM | VM_FAULT_SIGBUS | VM_FAULT_SIGSEGV | \
- VM_FAULT_HWPOISON | VM_FAULT_HWPOISON_LARGE | \
- VM_FAULT_FALLBACK)
-
-#define VM_FAULT_RESULT_TRACE \
- { VM_FAULT_OOM, "OOM" }, \
- { VM_FAULT_SIGBUS, "SIGBUS" }, \
- { VM_FAULT_MAJOR, "MAJOR" }, \
- { VM_FAULT_WRITE, "WRITE" }, \
- { VM_FAULT_HWPOISON, "HWPOISON" }, \
- { VM_FAULT_HWPOISON_LARGE, "HWPOISON_LARGE" }, \
- { VM_FAULT_SIGSEGV, "SIGSEGV" }, \
- { VM_FAULT_NOPAGE, "NOPAGE" }, \
- { VM_FAULT_LOCKED, "LOCKED" }, \
- { VM_FAULT_RETRY, "RETRY" }, \
- { VM_FAULT_FALLBACK, "FALLBACK" }, \
- { VM_FAULT_DONE_COW, "DONE_COW" }, \
- { VM_FAULT_NEEDDSYNC, "NEEDDSYNC" }
-
-/* Encode hstate index for a hwpoisoned large page */
-#define VM_FAULT_SET_HINDEX(x) ((x) << 12)
-#define VM_FAULT_GET_HINDEX(x) (((x) >> 12) & 0xf)
-
-/*
* Can be called by the pagefault handler when it gets a VM_FAULT_OOM.
*/
extern void pagefault_out_of_memory(void);
diff --git a/include/linux/mm_types.h b/include/linux/mm_types.h
index ab9b48420200..86e7a7a46353 100644
--- a/include/linux/mm_types.h
+++ b/include/linux/mm_types.h
@@ -22,7 +22,6 @@
#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;
@@ -621,6 +620,78 @@ static inline bool mm_tlb_flush_nested(struct mm_struct *mm)
struct vm_fault;
+/**
+ * typedef vm_fault_t - Return type for page fault handlers.
+ *
+ * Page fault handlers return a bitmask of %VM_FAULT values.
+ */
+typedef __bitwise unsigned int vm_fault_t;
+
+/**
+ * enum vm_fault_reason - Page fault handlers return a bitmask of
+ * these values to tell the core VM what happened when handling the
+ * fault. Used to decide whether a process gets delivered SIGBUS or
+ * just gets major/minor fault counters bumped up.
+ *
+ * @VM_FAULT_OOM: Out Of Memory
+ * @VM_FAULT_SIGBUS: Bad access
+ * @VM_FAULT_MAJOR: Page read from storage
+ * @VM_FAULT_WRITE: Special case for get_user_pages
+ * @VM_FAULT_HWPOISON: Hit poisoned small page
+ * @VM_FAULT_HWPOISON_LARGE: Hit poisoned large page. Index encoded
+ * in upper bits
+ * @VM_FAULT_SIGSEGV: segmentation fault
+ * @VM_FAULT_NOPAGE: ->fault installed the pte, not return page
+ * @VM_FAULT_LOCKED: ->fault locked the returned page
+ * @VM_FAULT_RETRY: ->fault blocked, must retry
+ * @VM_FAULT_FALLBACK: huge page fault failed, fall back to small
+ * @VM_FAULT_DONE_COW: ->fault has fully handled COW
+ * @VM_FAULT_NEEDDSYNC: ->fault did not modify page tables and needs
+ * fsync() to complete (for synchronous page faults
+ * in DAX)
+ * @VM_FAULT_HINDEX_MASK: mask HINDEX value
+ *
+ */
+enum vm_fault_reason {
+ VM_FAULT_OOM = (__force vm_fault_t)0x000001,
+ VM_FAULT_SIGBUS = (__force vm_fault_t)0x000002,
+ VM_FAULT_MAJOR = (__force vm_fault_t)0x000004,
+ VM_FAULT_WRITE = (__force vm_fault_t)0x000008,
+ VM_FAULT_HWPOISON = (__force vm_fault_t)0x000010,
+ VM_FAULT_HWPOISON_LARGE = (__force vm_fault_t)0x000020,
+ VM_FAULT_SIGSEGV = (__force vm_fault_t)0x000040,
+ VM_FAULT_NOPAGE = (__force vm_fault_t)0x000100,
+ VM_FAULT_LOCKED = (__force vm_fault_t)0x000200,
+ VM_FAULT_RETRY = (__force vm_fault_t)0x000400,
+ VM_FAULT_FALLBACK = (__force vm_fault_t)0x000800,
+ VM_FAULT_DONE_COW = (__force vm_fault_t)0x001000,
+ VM_FAULT_NEEDDSYNC = (__force vm_fault_t)0x002000,
+ VM_FAULT_HINDEX_MASK = (__force vm_fault_t)0x0f0000,
+};
+
+/* Encode hstate index for a hwpoisoned large page */
+#define VM_FAULT_SET_HINDEX(x) ((__force vm_fault_t)((x) << 16))
+#define VM_FAULT_GET_HINDEX(x) (((x) >> 16) & 0xf)
+
+#define VM_FAULT_ERROR (VM_FAULT_OOM | VM_FAULT_SIGBUS | \
+ VM_FAULT_SIGSEGV | VM_FAULT_HWPOISON | \
+ VM_FAULT_HWPOISON_LARGE | VM_FAULT_FALLBACK)
+
+#define VM_FAULT_RESULT_TRACE \
+ { VM_FAULT_OOM, "OOM" }, \
+ { VM_FAULT_SIGBUS, "SIGBUS" }, \
+ { VM_FAULT_MAJOR, "MAJOR" }, \
+ { VM_FAULT_WRITE, "WRITE" }, \
+ { VM_FAULT_HWPOISON, "HWPOISON" }, \
+ { VM_FAULT_HWPOISON_LARGE, "HWPOISON_LARGE" }, \
+ { VM_FAULT_SIGSEGV, "SIGSEGV" }, \
+ { VM_FAULT_NOPAGE, "NOPAGE" }, \
+ { VM_FAULT_LOCKED, "LOCKED" }, \
+ { VM_FAULT_RETRY, "RETRY" }, \
+ { VM_FAULT_FALLBACK, "FALLBACK" }, \
+ { VM_FAULT_DONE_COW, "DONE_COW" }, \
+ { VM_FAULT_NEEDDSYNC, "NEEDDSYNC" }
+
struct vm_special_mapping {
const char *name; /* The name, e.g. "[vdso]". */