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There was some desire in large applications using MAP_HUGETLB or SHM_HUGETLB to use 1GB huge pages on some mappings, and stay with 2MB on others. This is useful together with NUMA policy: use 2MB interleaving on some mappings, but 1GB on local mappings. This patch extends the IPC/SHM syscall interfaces slightly to allow specifying the page size. It borrows some upper bits in the existing flag arguments and allows encoding the log of the desired page size in addition to the *_HUGETLB flag. When 0 is specified the default size is used, this makes the change fully compatible. Extending the internal hugetlb code to handle this is straight forward. Instead of a single mount it just keeps an array of them and selects the right mount based on the specified page size. When no page size is specified it uses the mount of the default page size. The change is not visible in /proc/mounts because internal mounts don't appear there. It also has very little overhead: the additional mounts just consume a super block, but not more memory when not used. I also exported the new flags to the user headers (they were previously under __KERNEL__). Right now only symbols for x86 and some other architecture for 1GB and 2MB are defined. The interface should already work for all other architectures though. Only architectures that define multiple hugetlb sizes actually need it (that is currently x86, tile, powerpc). However tile and powerpc have user configurable hugetlb sizes, so it's not easy to add defines. A program on those architectures would need to query sysfs and use the appropiate log2. [akpm@linux-foundation.org: cleanups] [rientjes@google.com: fix build] [akpm@linux-foundation.org: checkpatch fixes] Signed-off-by: Andi Kleen <ak@linux.intel.com> Cc: Michael Kerrisk <mtk.manpages@gmail.com> Acked-by: Rik van Riel <riel@redhat.com> Acked-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Cc: Hillf Danton <dhillf@gmail.com> Signed-off-by: David Rientjes <rientjes@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
22 lines
873 B
C
22 lines
873 B
C
#ifndef __ASM_GENERIC_MMAN_H
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#define __ASM_GENERIC_MMAN_H
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#include <asm-generic/mman-common.h>
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#define MAP_GROWSDOWN 0x0100 /* stack-like segment */
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#define MAP_DENYWRITE 0x0800 /* ETXTBSY */
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#define MAP_EXECUTABLE 0x1000 /* mark it as an executable */
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#define MAP_LOCKED 0x2000 /* pages are locked */
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#define MAP_NORESERVE 0x4000 /* don't check for reservations */
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#define MAP_POPULATE 0x8000 /* populate (prefault) pagetables */
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#define MAP_NONBLOCK 0x10000 /* do not block on IO */
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#define MAP_STACK 0x20000 /* give out an address that is best suited for process/thread stacks */
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#define MAP_HUGETLB 0x40000 /* create a huge page mapping */
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/* Bits [26:31] are reserved, see mman-common.h for MAP_HUGETLB usage */
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#define MCL_CURRENT 1 /* lock all current mappings */
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#define MCL_FUTURE 2 /* lock all future mappings */
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#endif /* __ASM_GENERIC_MMAN_H */
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