On Fri, Nov 19, 2010 at 04:33:56PM -0700, Eric B Munson wrote:
> When the kernel supports MAP_HUGETLB use it for requesting
> a huge page backed area instead of creating a file descriptor.
>
> Signed-off-by: Eric B Munson <emun...@mgebm.net>
> ---
> alloc.c | 41 +++++++++++++++++++++++++++++++++++------
> 1 files changed, 35 insertions(+), 6 deletions(-)
>
> diff --git a/alloc.c b/alloc.c
> index a7d37e5..bdee7b3 100644
> --- a/alloc.c
> +++ b/alloc.c
> @@ -77,7 +77,7 @@ static void *fallback_base_pages(size_t len, ghp_t flags)
> void *get_huge_pages(size_t len, ghp_t flags)
> {
> void *buf;
> - int buf_fd;
> + int buf_fd = -1;
> int saved_error;
> int mmap_reserve = __hugetlb_opts.no_reserve ? MAP_NORESERVE : 0;
>
> @@ -85,6 +85,27 @@ void *get_huge_pages(size_t len, ghp_t flags)
> if (flags & GHR_MASK)
> ERROR("Improper use of GHR_* in get_huge_pages()\n");
>
> +#ifdef MAP_HUGETLB
The ifdef here should be unnecessary because it needs to exist for
map_hugetlb to be 1, right? That would avoid code duplication.
> + if (__hugetlb_opts.map_hugetlb &&
> + gethugepagesize() == kernel_default_hugepage_size()) {
> + /* Because we can use MAP_HUGETLB, we simply mmap the region */
> + buf = mmap(NULL, len, PROT_READ|PROT_WRITE,
> + MAP_PRIVATE|MAP_ANONYMOUS|MAP_HUGETLB|mmap_reserve,
> + 0, 0);
> + } else {
> + /* Create a file descriptor for the new region */
> + buf_fd = hugetlbfs_unlinked_fd();
> + if (buf_fd < 0) {
> + WARNING("Couldn't open hugetlbfs file for %zd-sized
> buffer\n",
> + len);
> + return NULL;
> + }
> +
> + /* Map the requested region */
> + buf = mmap(NULL, len, PROT_READ|PROT_WRITE,
> + MAP_PRIVATE|mmap_reserve, buf_fd, 0);
> + }
> +#else
> /* Create a file descriptor for the new region */
> buf_fd = hugetlbfs_unlinked_fd();
> if (buf_fd < 0) {
> @@ -95,20 +116,28 @@ void *get_huge_pages(size_t len, ghp_t flags)
>
> /* Map the requested region */
> buf = mmap(NULL, len, PROT_READ|PROT_WRITE,
> - MAP_PRIVATE|mmap_reserve, buf_fd, 0);
> + MAP_PRIVATE|mmap_reserve, buf_fd, 0);
> +#endif
> +
> if (buf == MAP_FAILED) {
> - close(buf_fd);
> + if (buf_fd >= 0)
> + close(buf_fd);
>
> WARNING("get_huge_pages: New region mapping failed (flags:
> 0x%lX): %s\n",
> flags, strerror(errno));
> return NULL;
> }
>
> - /* Fault the region to ensure accesses succeed */
> + /*
> + * Fault the region to ensure accesses succeed, buf_fd is passed
> + * regarless of how we mmap'd because if MAP_HUGETLB was used the value
> + * in buf_fd is ignored
> + */
> if (hugetlbfs_prefault(buf_fd, buf, len) != 0) {
> saved_error = errno;
> munmap(buf, len);
> - close(buf_fd);
> + if (buf_fd >= 0)
> + close(buf_fd);
>
> WARNING("get_huge_pages: Prefaulting failed (flags: 0x%lX):
> %s\n",
> flags, strerror(saved_error));
> @@ -116,7 +145,7 @@ void *get_huge_pages(size_t len, ghp_t flags)
> }
>
> /* Close the file so we do not have to track the descriptor */
> - if (close(buf_fd) != 0) {
> + if (buf_fd >= 0 && close(buf_fd) != 0) {
> WARNING("Failed to close new buffer fd: %s\n", strerror(errno));
> munmap(buf, len);
> return NULL;
--
Mel Gorman
Part-time Phd Student Linux Technology Center
University of Limerick IBM Dublin Software Lab
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