From c01d5b300774d130a24d787825b01eb24e6e20cb Mon Sep 17 00:00:00 2001 From: Hugh Dickins Date: Tue, 26 Jul 2016 15:26:15 -0700 Subject: shmem: get_unmapped_area align huge page Provide a shmem_get_unmapped_area method in file_operations, called at mmap time to decide the mapping address. It could be conditional on CONFIG_TRANSPARENT_HUGEPAGE, but save #ifdefs in other places by making it unconditional. shmem_get_unmapped_area() first calls the usual mm->get_unmapped_area (which we treat as a black box, highly dependent on architecture and config and executable layout). Lots of conditions, and in most cases it just goes with the address that chose; but when our huge stars are rightly aligned, yet that did not provide a suitable address, go back to ask for a larger arena, within which to align the mapping suitably. There have to be some direct calls to shmem_get_unmapped_area(), not via the file_operations: because of the way shmem_zero_setup() is called to create a shmem object late in the mmap sequence, when MAP_SHARED is requested with MAP_ANONYMOUS or /dev/zero. Though this only matters when /proc/sys/vm/shmem_huge has been set. Link: http://lkml.kernel.org/r/1466021202-61880-29-git-send-email-kirill.shutemov@linux.intel.com Signed-off-by: Hugh Dickins Signed-off-by: Kirill A. Shutemov Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- ipc/shm.c | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-) (limited to 'ipc') diff --git a/ipc/shm.c b/ipc/shm.c index 13282510bc0d..7fa5cbebbf19 100644 --- a/ipc/shm.c +++ b/ipc/shm.c @@ -476,13 +476,15 @@ static const struct file_operations shm_file_operations = { .mmap = shm_mmap, .fsync = shm_fsync, .release = shm_release, -#ifndef CONFIG_MMU .get_unmapped_area = shm_get_unmapped_area, -#endif .llseek = noop_llseek, .fallocate = shm_fallocate, }; +/* + * shm_file_operations_huge is now identical to shm_file_operations, + * but we keep it distinct for the sake of is_file_shm_hugepages(). + */ static const struct file_operations shm_file_operations_huge = { .mmap = shm_mmap, .fsync = shm_fsync, -- cgit v1.2.3