If application does mlockall(MCL_FUTURE) it is no longer possible to mmap file bigger than main memory or allocate big area of anonymous memory. Sometimes it is desirable to lock everything related to program execution into memory, but still be able to mmap big file or allocate huge amount of memory and allow OS to swap them on demand. MAP_UNLOCKED allows to do that.
Signed-off-by: Gleb Natapov <[email protected]> diff --git a/include/asm-generic/mman.h b/include/asm-generic/mman.h index 32c8bd6..0ab4c74 100644 --- a/include/asm-generic/mman.h +++ b/include/asm-generic/mman.h @@ -12,6 +12,7 @@ #define MAP_NONBLOCK 0x10000 /* do not block on IO */ #define MAP_STACK 0x20000 /* give out an address that is best suited for process/thread stacks */ #define MAP_HUGETLB 0x40000 /* create a huge page mapping */ +#define MAP_UNLOKED 0x80000 /* pages are unlocked */ #define MCL_CURRENT 1 /* lock all current mappings */ #define MCL_FUTURE 2 /* lock all future mappings */ diff --git a/mm/mmap.c b/mm/mmap.c index 73f5e4b..7c2abdb 100644 --- a/mm/mmap.c +++ b/mm/mmap.c @@ -985,6 +985,9 @@ unsigned long do_mmap_pgoff(struct file *file, unsigned long addr, if (!can_do_mlock()) return -EPERM; + if (flags & MAP_UNLOKED) + vm_flags &= ~VM_LOCKED; + /* mlock MCL_FUTURE? */ if (vm_flags & VM_LOCKED) { unsigned long locked, lock_limit; -- Gleb. -- To unsubscribe from this list: send the line "unsubscribe linux-api" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html
