From f822566165dd46ff5de9bf895cfa6c51f53bb0c4 Mon Sep 17 00:00:00 2001 From: "Michael S. Tsirkin" Date: Tue, 14 Feb 2006 13:53:08 -0800 Subject: [PATCH] madvise MADV_DONTFORK/MADV_DOFORK Currently, copy-on-write may change the physical address of a page even if the user requested that the page is pinned in memory (either by mlock or by get_user_pages). This happens if the process forks meanwhile, and the parent writes to that page. As a result, the page is orphaned: in case of get_user_pages, the application will never see any data hardware DMA's into this page after the COW. In case of mlock'd memory, the parent is not getting the realtime/security benefits of mlock. In particular, this affects the Infiniband modules which do DMA from and into user pages all the time. This patch adds madvise options to control whether memory range is inherited across fork. Useful e.g. for when hardware is doing DMA from/into these pages. Could also be useful to an application wanting to speed up its forks by cutting large areas out of consideration. Signed-off-by: Michael S. Tsirkin Acked-by: Hugh Dickins Cc: Michael Kerrisk Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- include/asm-parisc/mman.h | 2 ++ 1 file changed, 2 insertions(+) (limited to 'include/asm-parisc/mman.h') diff --git a/include/asm-parisc/mman.h b/include/asm-parisc/mman.h index 736b0abcac0..a381cf5c8f5 100644 --- a/include/asm-parisc/mman.h +++ b/include/asm-parisc/mman.h @@ -49,6 +49,8 @@ #define MADV_4M_PAGES 22 /* Use 4 Megabyte pages */ #define MADV_16M_PAGES 24 /* Use 16 Megabyte pages */ #define MADV_64M_PAGES 26 /* Use 64 Megabyte pages */ +#define MADV_DONTFORK 0x30 /* dont inherit across fork */ +#define MADV_DOFORK 0x31 /* do inherit across fork */ /* compatibility flags */ #define MAP_ANON MAP_ANONYMOUS -- cgit v1.2.3 From 5f6164f3092832e0d9b12eed52e09a76bf39c64a Mon Sep 17 00:00:00 2001 From: "Michael S. Tsirkin" Date: Wed, 15 Feb 2006 15:17:39 -0800 Subject: [PATCH] add asm-generic/mman.h Make new MADV_REMOVE, MADV_DONTFORK, MADV_DOFORK consistent across all arches. The idea is to make it possible to use them portably even before distros include them in libc headers. Move common flags to asm-generic/mman.h Signed-off-by: Michael S. Tsirkin Cc: Roland Dreier Cc: Badari Pulavarty Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- include/asm-parisc/mman.h | 8 +++++--- 1 file changed, 5 insertions(+), 3 deletions(-) (limited to 'include/asm-parisc/mman.h') diff --git a/include/asm-parisc/mman.h b/include/asm-parisc/mman.h index a381cf5c8f5..0ef15ee0f17 100644 --- a/include/asm-parisc/mman.h +++ b/include/asm-parisc/mman.h @@ -38,7 +38,11 @@ #define MADV_SPACEAVAIL 5 /* insure that resources are reserved */ #define MADV_VPS_PURGE 6 /* Purge pages from VM page cache */ #define MADV_VPS_INHERIT 7 /* Inherit parents page size */ -#define MADV_REMOVE 8 /* remove these pages & resources */ + +/* common/generic parameters */ +#define MADV_REMOVE 9 /* remove these pages & resources */ +#define MADV_DONTFORK 10 /* don't inherit across fork */ +#define MADV_DOFORK 11 /* do inherit across fork */ /* The range 12-64 is reserved for page size specification. */ #define MADV_4K_PAGES 12 /* Use 4K pages */ @@ -49,8 +53,6 @@ #define MADV_4M_PAGES 22 /* Use 4 Megabyte pages */ #define MADV_16M_PAGES 24 /* Use 16 Megabyte pages */ #define MADV_64M_PAGES 26 /* Use 64 Megabyte pages */ -#define MADV_DONTFORK 0x30 /* dont inherit across fork */ -#define MADV_DOFORK 0x31 /* do inherit across fork */ /* compatibility flags */ #define MAP_ANON MAP_ANONYMOUS -- cgit v1.2.3