The patch titled
Subject: userfaultfd: hugetlbfs: fix __mcopy_atomic_hugetlb retry/error processing
has been added to the -mm tree. Its filename is
userfaultfd-hugetlbfs-fix-__mcopy_atomic_hugetlb-retry-error-processing.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/userfaultfd-hugetlbfs-fix-__mcopy_atomic_hugetlb-retry-error-processing.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/userfaultfd-hugetlbfs-fix-__mcopy_atomic_hugetlb-retry-error-processing.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: Mike Kravetz <mike.kravetz@xxxxxxxxxx>
Subject: userfaultfd: hugetlbfs: fix __mcopy_atomic_hugetlb retry/error processing
The new routine copy_huge_page_from_user() uses kmap_atomic() to map
PAGE_SIZE pages. However, this prevents page faults in the subsequent
call to copy_from_user(). This is OK in the case where the routine is
copied with mmap_sema held. However, in another case we want to allow
page faults. So, add a new argument allow_pagefault to indicate if the
routine should allow page faults.
Link: http://lkml.kernel.org/r/20161216144821.5183-20-aarcange@xxxxxxxxxx
Signed-off-by: Mike Kravetz <mike.kravetz@xxxxxxxxxx>
Signed-off-by: Andrea Arcangeli <aarcange@xxxxxxxxxx>
Cc: "Dr. David Alan Gilbert" <dgilbert@xxxxxxxxxx>
Cc: Hillf Danton <hillf.zj@xxxxxxxxxxxxxxx>
Cc: Michael Rapoport <RAPOPORT@xxxxxxxxxx>
Cc: Mike Rapoport <rppt@xxxxxxxxxxxxxxxxxx>
Cc: Pavel Emelyanov <xemul@xxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
include/linux/mm.h | 3 ++-
mm/hugetlb.c | 2 +-
mm/memory.c | 13 ++++++++++---
mm/userfaultfd.c | 2 +-
4 files changed, 14 insertions(+), 6 deletions(-)
diff -puN include/linux/mm.h~userfaultfd-hugetlbfs-fix-__mcopy_atomic_hugetlb-retry-error-processing include/linux/mm.h
--- a/include/linux/mm.h~userfaultfd-hugetlbfs-fix-__mcopy_atomic_hugetlb-retry-error-processing
+++ a/include/linux/mm.h
@@ -2398,7 +2398,8 @@ extern void copy_user_huge_page(struct p
unsigned int pages_per_huge_page);
extern long copy_huge_page_from_user(struct page *dst_page,
const void __user *usr_src,
- unsigned int pages_per_huge_page);
+ unsigned int pages_per_huge_page,
+ bool allow_pagefault);
#endif /* CONFIG_TRANSPARENT_HUGEPAGE || CONFIG_HUGETLBFS */
extern struct page_ext_operations debug_guardpage_ops;
diff -puN mm/hugetlb.c~userfaultfd-hugetlbfs-fix-__mcopy_atomic_hugetlb-retry-error-processing mm/hugetlb.c
--- a/mm/hugetlb.c~userfaultfd-hugetlbfs-fix-__mcopy_atomic_hugetlb-retry-error-processing
+++ a/mm/hugetlb.c
@@ -3954,7 +3954,7 @@ int hugetlb_mcopy_atomic_pte(struct mm_s
ret = copy_huge_page_from_user(page,
(const void __user *) src_addr,
- pages_per_huge_page(h));
+ pages_per_huge_page(h), false);
/* fallback to copy_from_user outside mmap_sem */
if (unlikely(ret)) {
diff -puN mm/memory.c~userfaultfd-hugetlbfs-fix-__mcopy_atomic_hugetlb-retry-error-processing mm/memory.c
--- a/mm/memory.c~userfaultfd-hugetlbfs-fix-__mcopy_atomic_hugetlb-retry-error-processing
+++ a/mm/memory.c
@@ -4158,7 +4158,8 @@ void copy_user_huge_page(struct page *ds
long copy_huge_page_from_user(struct page *dst_page,
const void __user *usr_src,
- unsigned int pages_per_huge_page)
+ unsigned int pages_per_huge_page,
+ bool allow_pagefault)
{
void *src = (void *)usr_src;
void *page_kaddr;
@@ -4166,11 +4167,17 @@ long copy_huge_page_from_user(struct pag
unsigned long ret_val = pages_per_huge_page * PAGE_SIZE;
for (i = 0; i < pages_per_huge_page; i++) {
- page_kaddr = kmap_atomic(dst_page + i);
+ if (allow_pagefault)
+ page_kaddr = kmap(dst_page + i);
+ else
+ page_kaddr = kmap_atomic(dst_page + i);
rc = copy_from_user(page_kaddr,
(const void __user *)(src + i * PAGE_SIZE),
PAGE_SIZE);
- kunmap_atomic(page_kaddr);
+ if (allow_pagefault)
+ kunmap(page_kaddr);
+ else
+ kunmap_atomic(page_kaddr);
ret_val -= (PAGE_SIZE - rc);
if (rc)
diff -puN mm/userfaultfd.c~userfaultfd-hugetlbfs-fix-__mcopy_atomic_hugetlb-retry-error-processing mm/userfaultfd.c
--- a/mm/userfaultfd.c~userfaultfd-hugetlbfs-fix-__mcopy_atomic_hugetlb-retry-error-processing
+++ a/mm/userfaultfd.c
@@ -274,7 +274,7 @@ retry:
err = copy_huge_page_from_user(page,
(const void __user *)src_addr,
- pages_per_huge_page(h));
+ pages_per_huge_page(h), true);
if (unlikely(err)) {
err = -EFAULT;
goto out;
_
Patches currently in -mm which might be from mike.kravetz@xxxxxxxxxx are
userfaultfd-hugetlbfs-add-copy_huge_page_from_user-for-hugetlb-userfaultfd-support.patch
userfaultfd-hugetlbfs-add-hugetlb_mcopy_atomic_pte-for-userfaultfd-support.patch
userfaultfd-hugetlbfs-add-__mcopy_atomic_hugetlb-for-huge-page-uffdio_copy.patch
userfaultfd-hugetlbfs-fix-__mcopy_atomic_hugetlb-retry-error-processing.patch
userfaultfd-hugetlbfs-add-userfaultfd-hugetlb-hook.patch
userfaultfd-hugetlbfs-allow-registration-of-ranges-containing-huge-pages.patch
userfaultfd-hugetlbfs-add-userfaultfd_hugetlb-test.patch
userfaultfd-hugetlbfs-userfaultfd_huge_must_wait-for-hugepmd-ranges.patch
userfaultfd-hugetlbfs-reserve-count-on-error-in-__mcopy_atomic_hugetlb.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
