[PATCH 05/12] mm, thp, tmpfs: request huge page in shm_fault when needed

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

 



Add the function to request huge page in shm_fault when needed.
And it will fall back to regular page if huge page can't be
satisfied or allocated.

If small page requested but huge page is found, the huge page will
be splitted.

Signed-off-by: Ning Qu <quning@xxxxxxxxx>
---
 mm/shmem.c | 32 +++++++++++++++++++++++++++++---
 1 file changed, 29 insertions(+), 3 deletions(-)

diff --git a/mm/shmem.c b/mm/shmem.c
index 68a0e1d..2fc450d 100644
--- a/mm/shmem.c
+++ b/mm/shmem.c
@@ -1472,19 +1472,45 @@ unlock:
 static int shmem_fault(struct vm_area_struct *vma, struct vm_fault *vmf)
 {
 	struct inode *inode = file_inode(vma->vm_file);
+	struct page *page = NULL;
 	int error;
 	int ret = VM_FAULT_LOCKED;
 	gfp_t gfp = mapping_gfp_mask(inode->i_mapping);
-
-	error = shmem_getpage(inode, vmf->pgoff, &vmf->page, SGP_CACHE, gfp,
-				0, &ret);
+	bool must_use_thp = vmf->flags & FAULT_FLAG_TRANSHUGE;
+	int flags = 0;
+#ifdef CONFIG_TRANSPARENT_HUGEPAGE_PAGECACHE
+	flags |= AOP_FLAG_TRANSHUGE;
+#endif
+retry_find:
+	error = shmem_getpage(inode, vmf->pgoff, &page, SGP_CACHE, gfp,
+				flags, &ret);
 	if (error)
 		return ((error == -ENOMEM) ? VM_FAULT_OOM : VM_FAULT_SIGBUS);
 
+	/* Split huge page if we don't want huge page to be here */
+	if (!must_use_thp && PageTransCompound(page)) {
+		unlock_page(page);
+		page_cache_release(page);
+		split_huge_page(compound_trans_head(page));
+		page = NULL;
+		goto retry_find;
+	}
+
+	if (must_use_thp && !PageTransHuge(page)) {
+		/*
+		 * Caller asked for huge page, but we have small page
+		 * by this offset. Fallback to small pages.
+		 */
+		unlock_page(page);
+		page_cache_release(page);
+		return VM_FAULT_FALLBACK;
+	}
+
 	if (ret & VM_FAULT_MAJOR) {
 		count_vm_event(PGMAJFAULT);
 		mem_cgroup_count_vm_event(vma->vm_mm, PGMAJFAULT);
 	}
+	vmf->page = page;
 	return ret;
 }
 
-- 
1.8.4


--
To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html




[Index of Archives]     [Linux Ext4 Filesystem]     [Union Filesystem]     [Filesystem Testing]     [Ceph Users]     [Ecryptfs]     [AutoFS]     [Kernel Newbies]     [Share Photos]     [Security]     [Netfilter]     [Bugtraq]     [Yosemite News]     [MIPS Linux]     [ARM Linux]     [Linux Security]     [Linux Cachefs]     [Reiser Filesystem]     [Linux RAID]     [Samba]     [Device Mapper]     [CEPH Development]
  Powered by Linux