[PATCH v6 01/11] mm: add MAP_HUGETLB support to vm_mmap

Tycho Andersen
2017-09-07T17:39:43Z

vm_mmap is exported, which means kernel modules can use it. In particular,
for testing XPFO support, we want to use it with the MAP_HUGETLB flag, so
let's support it via vm_mmap.

Signed-off-by: Tycho Andersen <tycho@docker.com>
Tested-by: Marco Benatto <marco.antonio.780@gmail.com>
---
include/linux/mm.h | 2 ++
mm/mmap.c | 19 +------------------
mm/util.c | 32 ++++++++++++++++++++++++++++++++
3 files changed, 35 insertions(+), 18 deletions(-)

diff --git a/include/linux/mm.h b/include/linux/mm.h
index c1f6c95f3496..5dfe009adcb9 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -2141,6 +2141,8 @@ struct vm_unmapped_area_info {
extern unsigned long unmapped_area(struct vm_unmapped_area_info *info);
extern unsigned long unmapped_area_topdown(struct vm_unmapped_area_info *info);

+struct file *map_hugetlb_setup(unsigned long *len, unsigned long flags);
+
/*
* Search for an unmapped address range.
*
diff --git a/mm/mmap.c b/mm/mmap.c
index f19efcf75418..f24fc14808e1 100644
--- a/mm/mmap.c
+++ b/mm/mmap.c
@@ -1490,24 +1490,7 @@ SYSCALL_DEFINE6(mmap_pgoff, unsigned long, addr, unsigned long, len,
if (unlikely(flags & MAP_HUGETLB && !is_file_hugepages(file)))
goto out_fput;
} else if (flags & MAP_HUGETLB) {
- struct user_struct *user = NULL;
- struct hstate *hs;
-
- hs = hstate_sizelog((flags >> MAP_HUGE_SHIFT) & MAP_HUGE_MASK);
- if (!hs)
- return -EINVAL;
-
- len = ALIGN(len, huge_page_size(hs));
- /*
- * VM_NORESERVE is used because the reservations will be
- * taken when vm_ops->mmap() is called
- * A dummy user value is used because we are not locking
- * memory so no accounting is necessary
- */
- file = hugetlb_file_setup(HUGETLB_ANON_FILE, len,
- VM_NORESERVE,
- &user, HUGETLB_ANONHUGE_INODE,
- (flags >> MAP_HUGE_SHIFT) & MAP_HUGE_MASK);
+ file = map_hugetlb_setup(&len, flags);
if (IS_ERR(file))
return PTR_ERR(file);
}
diff --git a/mm/util.c b/mm/util.c
index 9ecddf568fe3..93c253512aaa 100644
--- a/mm/util.c
+++ b/mm/util.c
@@ -340,6 +340,29 @@ unsigned long vm_mmap_pgoff(struct file *file, unsigned long addr,
return ret;
}

+struct file *map_hugetlb_setup(unsigned long *len, unsigned long flags)
+{
+ struct user_struct *user = NULL;
+ struct hstate *hs;
+
+ hs = hstate_sizelog((flags >> MAP_HUGE_SHIFT) & MAP_HUGE_MASK);
+ if (!hs)
+ return ERR_PTR(-EINVAL);
+
+ *len = ALIGN(*len, huge_page_size(hs));
+
+ /*
+ * VM_NORESERVE is used because the reservations will be
+ * taken when vm_ops->mmap() is called
+ * A dummy user value is used because we are not locking
+ * memory so no accounting is necessary
+ */
+ return hugetlb_file_setup(HUGETLB_ANON_FILE, *len,
+ VM_NORESERVE,
+ &user, HUGETLB_ANONHUGE_INODE,
+ (flags >> MAP_HUGE_SHIFT) & MAP_HUGE_MASK);
+}
+
unsigned long vm_mmap(struct file *file, unsigned long addr,
unsigned long len, unsigned long prot,
unsigned long flag, unsigned long offset)
@@ -349,6 +372,15 @@ unsigned long vm_mmap(struct file *file, unsigned long addr,
if (unlikely(offset_in_page(offset)))
return -EINVAL;

+ if (flag & MAP_HUGETLB) {
+ if (file)
+ return -EINVAL;
+
+ file = map_hugetlb_setup(&len, flag);
+ if (IS_ERR(file))
+ return PTR_ERR(file);
+ }
+
return vm_mmap_pgoff(file, addr, len, prot, flag, offset >> PAGE_SHIFT);
}
EXPORT_SYMBOL(vm_mmap);
--
2.11.0