mm/doc: turn fault flags into an enum

The kernel-doc script complains about

  include/linux/mm.h:425: warning: wrong kernel-doc identifier on line:
   * Fault flag definitions.

I don't know how to document a series of #defines, so turn these
definitions into an enum and document that instead.

Link: https://lkml.kernel.org/r/20210322195022.2143603-3-willy@infradead.orgSigned-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Acked-by: Mike Rapoport <rppt@linux.ibm.com>
Cc: John Hubbard <jhubbard@nvidia.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

include/linux/mm.h

@@ -432,8 +432,7 @@ extern unsigned int kobjsize(const void *objp);
 extern pgprot_t protection_map[16];
 
 /**
- * Fault flag definitions.
- *
+ * enum fault_flag - Fault flag definitions.
  * @FAULT_FLAG_WRITE: Fault was a write fault.
  * @FAULT_FLAG_MKWRITE: Fault was mkwrite of existing PTE.
  * @FAULT_FLAG_ALLOW_RETRY: Allow to retry the fault if blocked.
@@ -464,16 +463,18 @@ extern pgprot_t protection_map[16];
  * signals before a retry to make sure the continuous page faults can still be
  * interrupted if necessary.
  */
-#define FAULT_FLAG_WRITE			0x01
-#define FAULT_FLAG_MKWRITE			0x02
-#define FAULT_FLAG_ALLOW_RETRY			0x04
-#define FAULT_FLAG_RETRY_NOWAIT			0x08
-#define FAULT_FLAG_KILLABLE			0x10
-#define FAULT_FLAG_TRIED			0x20
-#define FAULT_FLAG_USER				0x40
-#define FAULT_FLAG_REMOTE			0x80
-#define FAULT_FLAG_INSTRUCTION  		0x100
-#define FAULT_FLAG_INTERRUPTIBLE		0x200
+enum fault_flag {
+	FAULT_FLAG_WRITE =		1 << 0,
+	FAULT_FLAG_MKWRITE =		1 << 1,
+	FAULT_FLAG_ALLOW_RETRY =	1 << 2,
+	FAULT_FLAG_RETRY_NOWAIT = 	1 << 3,
+	FAULT_FLAG_KILLABLE =		1 << 4,
+	FAULT_FLAG_TRIED = 		1 << 5,
+	FAULT_FLAG_USER =		1 << 6,
+	FAULT_FLAG_REMOTE =		1 << 7,
+	FAULT_FLAG_INSTRUCTION =	1 << 8,
+	FAULT_FLAG_INTERRUPTIBLE =	1 << 9,
+};
 
 /*
  * The default fault flags that should be used by most of the
@@ -496,7 +497,7 @@ extern pgprot_t protection_map[16];
  * Return: true if the page fault allows retry and this is the first
  * attempt of the fault handling; false otherwise.
  */
-static inline bool fault_flag_allow_retry_first(unsigned int flags)
+static inline bool fault_flag_allow_retry_first(enum fault_flag flags)
 {
 	return (flags & FAULT_FLAG_ALLOW_RETRY) &&
 	    (!(flags & FAULT_FLAG_TRIED));
@@ -531,7 +532,7 @@ struct vm_fault {
 		pgoff_t pgoff;			/* Logical page offset based on vma */
 		unsigned long address;		/* Faulting virtual address */
 	};
-	unsigned int flags;		/* FAULT_FLAG_xxx flags
+	enum fault_flag flags;		/* FAULT_FLAG_xxx flags
 					 * XXX: should really be 'const' */
 	pmd_t *pmd;			/* Pointer to pmd entry matching
 					 * the 'address' */