Currently applications can explicitly enable or disable THP for a memory
region using MADV_HUGEPAGE or MADV_NOHUGEPAGE. However, once either of
these advises is used, the region will always have
VM_HUGEPAGE/VM_NOHUGEPAGE flag set in vma->vm_flags.
The MADV_RESET_HUGEPAGE resets both these flags and allows managing THP in
the region according to system-wide settings.
Signed-off-by: Mike Rapoport <rppt@xxxxxxxxxxxxxxxxxx>
Acked-by: Kirill A. Shutemov <kirill.shutemov@xxxxxxxxxxxxxxx>
---
v2 changes:
* Use _RESET_ instead of _CLR_ as per Kirill's suggestion
* Fix build on arches that do not include mman-common.h
arch/alpha/include/uapi/asm/mman.h | 3 +++
arch/mips/include/uapi/asm/mman.h | 3 +++
arch/parisc/include/uapi/asm/mman.h | 3 +++
arch/xtensa/include/uapi/asm/mman.h | 3 +++
include/uapi/asm-generic/mman-common.h | 3 +++
mm/khugepaged.c | 7 +++++++
mm/madvise.c | 5 +++++
7 files changed, 27 insertions(+)
diff --git a/arch/alpha/include/uapi/asm/mman.h b/arch/alpha/include/uapi/asm/mman.h
index 02760f6..cb3095f 100644
--- a/arch/alpha/include/uapi/asm/mman.h
+++ b/arch/alpha/include/uapi/asm/mman.h
@@ -64,6 +64,9 @@
overrides the coredump filter bits */
#define MADV_DODUMP 17 /* Clear the MADV_NODUMP flag */
+#define MADV_RESET_HUGEPAGE 18 /* Reset flags controlling backing with
+ hugepages */
+
/* compatibility flags */
#define MAP_FILE 0
diff --git a/arch/mips/include/uapi/asm/mman.h b/arch/mips/include/uapi/asm/mman.h
index 655e2fb..b5a181b 100644
--- a/arch/mips/include/uapi/asm/mman.h
+++ b/arch/mips/include/uapi/asm/mman.h
@@ -91,6 +91,9 @@
overrides the coredump filter bits */
#define MADV_DODUMP 17 /* Clear the MADV_NODUMP flag */
+#define MADV_RESET_HUGEPAGE 18 /* Reset flags controlling backing with
+ hugepages */
+
/* compatibility flags */
#define MAP_FILE 0
diff --git a/arch/parisc/include/uapi/asm/mman.h b/arch/parisc/include/uapi/asm/mman.h
index 5979745..d671906 100644
--- a/arch/parisc/include/uapi/asm/mman.h
+++ b/arch/parisc/include/uapi/asm/mman.h
@@ -60,6 +60,9 @@
overrides the coredump filter bits */
#define MADV_DODUMP 70 /* Clear the MADV_NODUMP flag */
+#define MADV_RESET_HUGEPAGE 71 /* Reset flags controlling backing with
+ hugepages */
+
/* compatibility flags */
#define MAP_FILE 0
#define MAP_VARIABLE 0
diff --git a/arch/xtensa/include/uapi/asm/mman.h b/arch/xtensa/include/uapi/asm/mman.h
index 24365b3..9c038d0 100644
--- a/arch/xtensa/include/uapi/asm/mman.h
+++ b/arch/xtensa/include/uapi/asm/mman.h
@@ -103,6 +103,9 @@
overrides the coredump filter bits */
#define MADV_DODUMP 17 /* Clear the MADV_NODUMP flag */
+#define MADV_RESET_HUGEPAGE 18 /* Reset flags controlling backing with
+ hugepages */
+
/* compatibility flags */
#define MAP_FILE 0
diff --git a/include/uapi/asm-generic/mman-common.h b/include/uapi/asm-generic/mman-common.h
index 8c27db0..fa62825 100644
--- a/include/uapi/asm-generic/mman-common.h
+++ b/include/uapi/asm-generic/mman-common.h
@@ -58,6 +58,9 @@
overrides the coredump filter bits */
#define MADV_DODUMP 17 /* Clear the MADV_DONTDUMP flag */
+#define MADV_RESET_HUGEPAGE 18 /* Reset flags controlling backing with
+ hugepages */
+
/* compatibility flags */
#define MAP_FILE 0
diff --git a/mm/khugepaged.c b/mm/khugepaged.c
index 945fd1c..32c66e7 100644
--- a/mm/khugepaged.c
+++ b/mm/khugepaged.c
@@ -336,6 +336,13 @@ int hugepage_madvise(struct vm_area_struct *vma,
* it got registered before VM_NOHUGEPAGE was set.
*/
break;
+ case MADV_RESET_HUGEPAGE:
+ *vm_flags &= ~(VM_HUGEPAGE | VM_NOHUGEPAGE);
+ /*
+ * The vma will be treated according to the
+ * system-wide settings in transparent_hugepage_flags
+ */
+ break;
}
return 0;
diff --git a/mm/madvise.c b/mm/madvise.c
index 25b78ee..6d6dd09 100644
--- a/mm/madvise.c
+++ b/mm/madvise.c
@@ -105,6 +105,7 @@ static long madvise_behavior(struct vm_area_struct *vma,
break;
case MADV_HUGEPAGE:
case MADV_NOHUGEPAGE:
+ case MADV_RESET_HUGEPAGE:
error = hugepage_madvise(vma, &new_flags, behavior);
if (error) {
/*
@@ -684,6 +685,7 @@ madvise_behavior_valid(int behavior)
#ifdef CONFIG_TRANSPARENT_HUGEPAGE
case MADV_HUGEPAGE:
case MADV_NOHUGEPAGE:
+ case MADV_RESET_HUGEPAGE:
#endif
case MADV_DONTDUMP:
case MADV_DODUMP:
@@ -739,6 +741,9 @@ madvise_behavior_valid(int behavior)
* MADV_NOHUGEPAGE - mark the given range as not worth being backed by
* transparent huge pages so the existing pages will not be
* coalesced into THP and new pages will not be allocated as THP.
+ * MADV_RESET_HUGEPAGE - clear MADV_HUGEPAGE/MADV_NOHUGEPAGE marking;
+ * the range will be treated by khugepaged according to the
+ * system wide settings
* MADV_DONTDUMP - the application wants to prevent pages in the given range
* from being included in its core dump.
* MADV_DODUMP - cancel MADV_DONTDUMP: no longer exclude from core dump.
--
2.7.4
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