[PATCH 2/3] Add mlockall flag for locking pages on fault

[Eric B Munson <emunson@akamai.com>]

Building on the previous patch, extend mlockall() to give a process a
way to specify that pages should be locked when they are faulted in, but
that pre-faulting is not needed.

Signed-off-by: Eric B Munson <emunson@akamai.com>
Cc: linux-alpha@vger.kernel.org
Cc: linux-kernel@vger.kernel.org
Cc: linux-mips@linux-mips.org
Cc: linux-parisc@vger.kernel.org
Cc: linuxppc-dev@lists.ozlabs.org
Cc: sparclinux@vger.kernel.org
Cc: linux-xtensa@linux-xtensa.org
Cc: linux-arch@vger.kernel.org
Cc: linux-api@vger.kernel.org
Cc: linux-mm@kvack.org
---
 arch/alpha/include/uapi/asm/mman.h   |  1 +
 arch/mips/include/uapi/asm/mman.h    |  1 +
 arch/parisc/include/uapi/asm/mman.h  |  1 +
 arch/powerpc/include/uapi/asm/mman.h |  1 +
 arch/sparc/include/uapi/asm/mman.h   |  1 +
 arch/tile/include/uapi/asm/mman.h    |  1 +
 arch/xtensa/include/uapi/asm/mman.h  |  1 +
 include/uapi/asm-generic/mman.h      |  1 +
 mm/mlock.c                           | 13 +++++++++----
 9 files changed, 17 insertions(+), 4 deletions(-)

diff --git a/arch/alpha/include/uapi/asm/mman.h b/arch/alpha/include/uapi/asm/mman.h
index 15e96e1..3120dfb 100644
--- a/arch/alpha/include/uapi/asm/mman.h
+++ b/arch/alpha/include/uapi/asm/mman.h
@@ -38,6 +38,7 @@
 
 #define MCL_CURRENT	 8192		/* lock all currently mapped pages */
 #define MCL_FUTURE	16384		/* lock all additions to address space */
+#define MCL_ON_FAULT	32768		/* lock all pages that are faulted in */
 
 #define MADV_NORMAL	0		/* no further special treatment */
 #define MADV_RANDOM	1		/* expect random page references */
diff --git a/arch/mips/include/uapi/asm/mman.h b/arch/mips/include/uapi/asm/mman.h
index 47846a5..82aec3c 100644
--- a/arch/mips/include/uapi/asm/mman.h
+++ b/arch/mips/include/uapi/asm/mman.h
@@ -62,6 +62,7 @@
  */
 #define MCL_CURRENT	1		/* lock all current mappings */
 #define MCL_FUTURE	2		/* lock all future mappings */
+#define MCL_ON_FAULT	4		/* lock all pages that are faulted in */
 
 #define MADV_NORMAL	0		/* no further special treatment */
 #define MADV_RANDOM	1		/* expect random page references */
diff --git a/arch/parisc/include/uapi/asm/mman.h b/arch/parisc/include/uapi/asm/mman.h
index 1514cd7..f4601f3 100644
--- a/arch/parisc/include/uapi/asm/mman.h
+++ b/arch/parisc/include/uapi/asm/mman.h
@@ -32,6 +32,7 @@
 
 #define MCL_CURRENT	1		/* lock all current mappings */
 #define MCL_FUTURE	2		/* lock all future mappings */
+#define MCL_ON_FAULT	4		/* lock all pages that are faulted in */
 
 #define MADV_NORMAL     0               /* no further special treatment */
 #define MADV_RANDOM     1               /* expect random page references */
diff --git a/arch/powerpc/include/uapi/asm/mman.h b/arch/powerpc/include/uapi/asm/mman.h
index fce74fe..0a28efc 100644
--- a/arch/powerpc/include/uapi/asm/mman.h
+++ b/arch/powerpc/include/uapi/asm/mman.h
@@ -22,6 +22,7 @@
 
 #define MCL_CURRENT     0x2000          /* lock all currently mapped pages */
 #define MCL_FUTURE      0x4000          /* lock all additions to address space */
+#define MCL_ON_FAULT	0x80000		/* lock all pages that are faulted in */
 
 #define MAP_POPULATE	0x8000		/* populate (prefault) pagetables */
 #define MAP_NONBLOCK	0x10000		/* do not block on IO */
diff --git a/arch/sparc/include/uapi/asm/mman.h b/arch/sparc/include/uapi/asm/mman.h
index 12425d8..119be80 100644
--- a/arch/sparc/include/uapi/asm/mman.h
+++ b/arch/sparc/include/uapi/asm/mman.h
@@ -17,6 +17,7 @@
 
 #define MCL_CURRENT     0x2000          /* lock all currently mapped pages */
 #define MCL_FUTURE      0x4000          /* lock all additions to address space */
+#define MCL_ON_FAULT	0x80000		/* lock all pages that are faulted in */
 
 #define MAP_POPULATE	0x8000		/* populate (prefault) pagetables */
 #define MAP_NONBLOCK	0x10000		/* do not block on IO */
diff --git a/arch/tile/include/uapi/asm/mman.h b/arch/tile/include/uapi/asm/mman.h
index ec04eaf..66ea935 100644
--- a/arch/tile/include/uapi/asm/mman.h
+++ b/arch/tile/include/uapi/asm/mman.h
@@ -37,6 +37,7 @@
  */
 #define MCL_CURRENT	1		/* lock all current mappings */
 #define MCL_FUTURE	2		/* lock all future mappings */
+#define MCL_ON_FAULT	4		/* lock all pages that are faulted in */
 
 
 #endif /* _ASM_TILE_MMAN_H */
diff --git a/arch/xtensa/include/uapi/asm/mman.h b/arch/xtensa/include/uapi/asm/mman.h
index 42d43cc..9abcc29 100644
--- a/arch/xtensa/include/uapi/asm/mman.h
+++ b/arch/xtensa/include/uapi/asm/mman.h
@@ -75,6 +75,7 @@
  */
 #define MCL_CURRENT	1		/* lock all current mappings */
 #define MCL_FUTURE	2		/* lock all future mappings */
+#define MCL_ON_FAULT	4		/* lock all pages that are faulted in */
 
 #define MADV_NORMAL	0		/* no further special treatment */
 #define MADV_RANDOM	1		/* expect random page references */
diff --git a/include/uapi/asm-generic/mman.h b/include/uapi/asm-generic/mman.h
index fc4e586..6ac7a7b 100644
--- a/include/uapi/asm-generic/mman.h
+++ b/include/uapi/asm-generic/mman.h
@@ -18,5 +18,6 @@
 
 #define MCL_CURRENT	1		/* lock all current mappings */
 #define MCL_FUTURE	2		/* lock all future mappings */
+#define MCL_ON_FAULT	4		/* lock all pages that are faulted in */
 
 #endif /* __ASM_GENERIC_MMAN_H */
diff --git a/mm/mlock.c b/mm/mlock.c
index 6fd2cf1..1406835 100644
--- a/mm/mlock.c
+++ b/mm/mlock.c
@@ -579,7 +579,7 @@ static int do_mlock(unsigned long start, size_t len, int on)
 
 		/* Here we know that  vma->vm_start <= nstart < vma->vm_end. */
 
-		newflags = vma->vm_flags & ~VM_LOCKED;
+		newflags = vma->vm_flags & ~(VM_LOCKED | VM_LOCKONFAULT);
 		if (on)
 			newflags |= VM_LOCKED;
 
@@ -662,13 +662,17 @@ static int do_mlockall(int flags)
 		current->mm->def_flags |= VM_LOCKED;
 	else
 		current->mm->def_flags &= ~VM_LOCKED;
-	if (flags == MCL_FUTURE)
+	if (flags & MCL_ON_FAULT)
+		current->mm->def_flags |= VM_LOCKONFAULT;
+	else
+		current->mm->def_flags &= ~VM_LOCKONFAULT;
+	if (flags == MCL_FUTURE || flags == MCL_ON_FAULT)
 		goto out;
 
 	for (vma = current->mm->mmap; vma ; vma = prev->vm_next) {
 		vm_flags_t newflags;
 
-		newflags = vma->vm_flags & ~VM_LOCKED;
+		newflags = vma->vm_flags & ~(VM_LOCKED | VM_LOCKONFAULT);
 		if (flags & MCL_CURRENT)
 			newflags |= VM_LOCKED;
 
@@ -685,7 +689,8 @@ SYSCALL_DEFINE1(mlockall, int, flags)
 	unsigned long lock_limit;
 	int ret = -EINVAL;
 
-	if (!flags || (flags & ~(MCL_CURRENT | MCL_FUTURE)))
+	if (!flags || (flags & ~(MCL_CURRENT | MCL_FUTURE | MCL_ON_FAULT)) ||
+	    ((flags & MCL_FUTURE) && (flags & MCL_ON_FAULT)))
 		goto out;
 
 	ret = -EPERM;
-- 
1.9.1