shmem: add huge pages support
Here's basic implementation of huge pages support for shmem/tmpfs.
It's all pretty streight-forward:
- shmem_getpage() allcoates huge page if it can and try to inserd into
radix tree with shmem_add_to_page_cache();
- shmem_add_to_page_cache() puts the page onto radix-tree if there's
space for it;
- shmem_undo_range() removes huge pages, if it fully within range.
Partial truncate of huge pages zero out this part of THP.
This have visible effect on fallocate(FALLOC_FL_PUNCH_HOLE)
behaviour. As we don't really create hole in this case,
lseek(SEEK_HOLE) may have inconsistent results depending what
pages happened to be allocated.
- no need to change shmem_fault: core-mm will map an compound page as
huge if VMA is suitable;
Link: http://lkml.kernel.org/r/1466021202-61880-30-git-send-email-kirill.shutemov@linux.intel.com
Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/mm/swap.c b/mm/swap.c
index 90530ff..616df4d 100644
--- a/mm/swap.c
+++ b/mm/swap.c
@@ -292,6 +292,7 @@
void activate_page(struct page *page)
{
+ page = compound_head(page);
if (PageLRU(page) && !PageActive(page) && !PageUnevictable(page)) {
struct pagevec *pvec = &get_cpu_var(activate_page_pvecs);
@@ -316,6 +317,7 @@
{
struct zone *zone = page_zone(page);
+ page = compound_head(page);
spin_lock_irq(&zone->lru_lock);
__activate_page(page, mem_cgroup_page_lruvec(page, zone), NULL);
spin_unlock_irq(&zone->lru_lock);