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


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