The patch titled
Subject: dax: Split pmd map when fallback on COW
has been added to the -mm tree. Its filename is
dax-split-pmd-map-when-fallback-on-cow.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/dax-split-pmd-map-when-fallback-on-cow.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/dax-split-pmd-map-when-fallback-on-cow.patch
Before you just go and hit "reply", please:
a) Consider who else should be cc'ed
b) Prefer to cc a suitable mailing list as well
c) Ideally: find the original patch on the mailing list and do a
reply-to-all to that, adding suitable additional cc's
*** Remember to use Documentation/SubmitChecklist when testing your code ***
The -mm tree is included into linux-next and is updated
there every 3-4 working days
------------------------------------------------------
From: Toshi Kani <toshi.kani@xxxxxxx>
Subject: dax: Split pmd map when fallback on COW
An infinite loop of PMD faults was observed when attempted to mlock() a
private read-only PMD mmap'd range of a DAX file.
__dax_pmd_fault() simply returns with VM_FAULT_FALLBACK when falling back
to PTE on COW. However, __handle_mm_fault() returns without falling back
to handle_pte_fault() because a PMD map is present in this case.
Change __dax_pmd_fault() to split the PMD map, if present, before
returning with VM_FAULT_FALLBACK.
Signed-off-by: Toshi Kani <toshi.kani@xxxxxxx>
Signed-off-by: Dan Williams <dan.j.williams@xxxxxxxxx>
Cc: Kirill A. Shutemov <kirill.shutemov@xxxxxxxxxxxxxxx>
Cc: Matthew Wilcox <willy@xxxxxxxxxxxxxxx>
Cc: Ross Zwisler <ross.zwisler@xxxxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
fs/dax.c | 4 +++-
1 file changed, 3 insertions(+), 1 deletion(-)
diff -puN fs/dax.c~dax-split-pmd-map-when-fallback-on-cow fs/dax.c
--- a/fs/dax.c~dax-split-pmd-map-when-fallback-on-cow
+++ a/fs/dax.c
@@ -578,8 +578,10 @@ int __dax_pmd_fault(struct vm_area_struc
return VM_FAULT_FALLBACK;
/* Fall back to PTEs if we're going to COW */
- if (write && !(vma->vm_flags & VM_SHARED))
+ if (write && !(vma->vm_flags & VM_SHARED)) {
+ split_huge_pmd(vma, pmd, address);
return VM_FAULT_FALLBACK;
+ }
/* If the PMD would extend outside the VMA */
if (pmd_addr < vma->vm_start)
return VM_FAULT_FALLBACK;
_
Patches currently in -mm which might be from toshi.kani@xxxxxxx are
dax-split-pmd-map-when-fallback-on-cow.patch
--
To unsubscribe from this list: send the line "unsubscribe mm-commits" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
