On 02.07.24 14:34, Catalin Marinas wrote:
On Tue, Jun 25, 2024 at 04:37:17PM -0700, Yang Shi wrote:
MTE can be supported on ram based filesystem. It is supported on tmpfs.
There is use case to use MTE on hugetlbfs as well, adding MTE support.
Signed-off-by: Yang Shi <yang@xxxxxxxxxxxxxxxxxxxxxx>
---
fs/hugetlbfs/inode.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/fs/hugetlbfs/inode.c b/fs/hugetlbfs/inode.c
index ecad73a4f713..c34faef62daf 100644
--- a/fs/hugetlbfs/inode.c
+++ b/fs/hugetlbfs/inode.c
@@ -110,7 +110,7 @@ static int hugetlbfs_file_mmap(struct file *file, struct vm_area_struct *vma)
* way when do_mmap unwinds (may be important on powerpc
* and ia64).
*/
- vm_flags_set(vma, VM_HUGETLB | VM_DONTEXPAND);
+ vm_flags_set(vma, VM_HUGETLB | VM_DONTEXPAND | VM_MTE_ALLOWED);
vma->vm_ops = &hugetlb_vm_ops;
Last time I checked, about a year ago, this was not sufficient. One
issue is that there's no arch_clear_hugetlb_flags() implemented by your
patch, leaving PG_arch_{2,3} set on a page. The other issue was that I
initially tried to do this only on the head page but this did not go
well with the folio_copy() -> copy_highpage() which expects the
PG_arch_* flags on each individual page. The alternative was for
arch_clear_hugetlb_flags() to iterate over all the pages in a folio.
This would likely also add a blocker for
ARCH_WANT_OPTIMIZE_HUGETLB_VMEMMAP on arm64 (no idea if there are now
ways to move forward with that now, or if we are still not sure if we
can actually add support), correct?
--
Cheers,
David / dhildenb
