* [PATCH v2] mm: introduce MADV_RESET_HUGEPAGE
@ 2017-05-29 5:32 Mike Rapoport
2017-05-30 4:26 ` David Rientjes
0 siblings, 1 reply; 2+ messages in thread
From: Mike Rapoport @ 2017-05-29 5:32 UTC (permalink / raw)
To: Andrew Morton
Cc: Arnd Bergmann, Kirill A. Shutemov, Andrea Arcangeli,
Michal Hocko, Vlastimil Babka, linux-mm, linux-api, lkml,
Mike Rapoport
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@linux.vnet.ibm.com>
Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
---
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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^ permalink raw reply related [flat|nested] 2+ messages in thread
* Re: [PATCH v2] mm: introduce MADV_RESET_HUGEPAGE
2017-05-29 5:32 [PATCH v2] mm: introduce MADV_RESET_HUGEPAGE Mike Rapoport
@ 2017-05-30 4:26 ` David Rientjes
0 siblings, 0 replies; 2+ messages in thread
From: David Rientjes @ 2017-05-30 4:26 UTC (permalink / raw)
To: Mike Rapoport
Cc: Andrew Morton, Arnd Bergmann, Kirill A. Shutemov,
Andrea Arcangeli, Michal Hocko, Vlastimil Babka, linux-mm,
linux-api, lkml
On Mon, 29 May 2017, Mike Rapoport wrote:
> 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@linux.vnet.ibm.com>
> Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
I feel like we may be losing some information from the v1 thread regarding
the usecase. Would it be possible to add something to the changelog to
describe what will use this?
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