f822566165
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 <mst@mellanox.co.il> Acked-by: Hugh Dickins <hugh@veritas.com> Cc: Michael Kerrisk <mtk-manpages@gmx.net> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
54 lines
2.3 KiB
C
54 lines
2.3 KiB
C
#ifndef __ALPHA_MMAN_H__
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#define __ALPHA_MMAN_H__
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#define PROT_READ 0x1 /* page can be read */
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#define PROT_WRITE 0x2 /* page can be written */
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#define PROT_EXEC 0x4 /* page can be executed */
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#define PROT_SEM 0x8 /* page may be used for atomic ops */
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#define PROT_NONE 0x0 /* page can not be accessed */
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#define PROT_GROWSDOWN 0x01000000 /* mprotect flag: extend change to start of growsdown vma */
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#define PROT_GROWSUP 0x02000000 /* mprotect flag: extend change to end of growsup vma */
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#define MAP_SHARED 0x01 /* Share changes */
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#define MAP_PRIVATE 0x02 /* Changes are private */
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#define MAP_TYPE 0x0f /* Mask for type of mapping (OSF/1 is _wrong_) */
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#define MAP_FIXED 0x100 /* Interpret addr exactly */
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#define MAP_ANONYMOUS 0x10 /* don't use a file */
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/* not used by linux, but here to make sure we don't clash with OSF/1 defines */
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#define _MAP_HASSEMAPHORE 0x0200
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#define _MAP_INHERIT 0x0400
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#define _MAP_UNALIGNED 0x0800
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/* These are linux-specific */
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#define MAP_GROWSDOWN 0x01000 /* stack-like segment */
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#define MAP_DENYWRITE 0x02000 /* ETXTBSY */
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#define MAP_EXECUTABLE 0x04000 /* mark it as an executable */
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#define MAP_LOCKED 0x08000 /* lock the mapping */
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#define MAP_NORESERVE 0x10000 /* don't check for reservations */
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#define MAP_POPULATE 0x20000 /* populate (prefault) pagetables */
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#define MAP_NONBLOCK 0x40000 /* do not block on IO */
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#define MS_ASYNC 1 /* sync memory asynchronously */
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#define MS_SYNC 2 /* synchronous memory sync */
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#define MS_INVALIDATE 4 /* invalidate the caches */
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#define MCL_CURRENT 8192 /* lock all currently mapped pages */
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#define MCL_FUTURE 16384 /* lock all additions to address space */
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#define MADV_NORMAL 0 /* no further special treatment */
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#define MADV_RANDOM 1 /* expect random page references */
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#define MADV_SEQUENTIAL 2 /* expect sequential page references */
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#define MADV_WILLNEED 3 /* will need these pages */
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#define MADV_SPACEAVAIL 5 /* ensure resources are available */
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#define MADV_DONTNEED 6 /* don't need these pages */
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#define MADV_REMOVE 7 /* remove these pages & resources */
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#define MADV_DONTFORK 0x30 /* dont inherit across fork */
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#define MADV_DOFORK 0x31 /* do inherit across fork */
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/* compatibility flags */
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#define MAP_ANON MAP_ANONYMOUS
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#define MAP_FILE 0
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#endif /* __ALPHA_MMAN_H__ */
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