The patch titled
Subject: userfaultfd/selftests: dropping VERIFY check in locking_thread
has been added to the -mm tree. Its filename is
userfaultfd-selftests-dropping-verify-check-in-locking_thread.patch
This patch should soon appear at
https://ozlabs.org/~akpm/mmots/broken-out/userfaultfd-selftests-dropping-verify-check-in-locking_thread.patch
and later at
https://ozlabs.org/~akpm/mmotm/broken-out/userfaultfd-selftests-dropping-verify-check-in-locking_thread.patch
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------------------------------------------------------
From: Peter Xu <peterx@xxxxxxxxxx>
Subject: userfaultfd/selftests: dropping VERIFY check in locking_thread
It tries to check against all zeros and looped for quite a few times.
However after that we'll verify the same page with count_verify, while
count_verify can never be zero. So it means if it's a zero page we'll
detect it anyways with below code.
There's yet another place we conditionally check the fault flag - just do
it unconditionally.
Link: https://lkml.kernel.org/r/20210412232753.1012412-4-peterx@xxxxxxxxxx
Signed-off-by: Peter Xu <peterx@xxxxxxxxxx>
Reviewed-by: Axel Rasmussen <axelrasmussen@xxxxxxxxxx>
Cc: Alexander Viro <viro@xxxxxxxxxxxxxxxxxx>
Cc: Andrea Arcangeli <aarcange@xxxxxxxxxx>
Cc: Brian Geffon <bgeffon@xxxxxxxxxx>
Cc: "Dr . David Alan Gilbert" <dgilbert@xxxxxxxxxx>
Cc: Hugh Dickins <hughd@xxxxxxxxxx>
Cc: Jerome Glisse <jglisse@xxxxxxxxxx>
Cc: Joe Perches <joe@xxxxxxxxxxx>
Cc: Kirill A. Shutemov <kirill@xxxxxxxxxxxxx>
Cc: Lokesh Gidra <lokeshgidra@xxxxxxxxxx>
Cc: Mike Kravetz <mike.kravetz@xxxxxxxxxx>
Cc: Mike Rapoport <rppt@xxxxxxxxxxxxxxxxxx>
Cc: Mina Almasry <almasrymina@xxxxxxxxxx>
Cc: Oliver Upton <oupton@xxxxxxxxxx>
Cc: Shaohua Li <shli@xxxxxx>
Cc: Shuah Khan <shuah@xxxxxxxxxx>
Cc: Stephen Rothwell <sfr@xxxxxxxxxxxxxxxx>
Cc: Wang Qing <wangqing@xxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
tools/testing/selftests/vm/userfaultfd.c | 55 ---------------------
1 file changed, 1 insertion(+), 54 deletions(-)
--- a/tools/testing/selftests/vm/userfaultfd.c~userfaultfd-selftests-dropping-verify-check-in-locking_thread
+++ a/tools/testing/selftests/vm/userfaultfd.c
@@ -430,58 +430,6 @@ static void *locking_thread(void *arg)
} else
page_nr += 1;
page_nr %= nr_pages;
-
- if (bounces & BOUNCE_VERIFY) {
- count = *area_count(area_dst, page_nr);
- if (!count) {
- fprintf(stderr,
- "page_nr %lu wrong count %Lu %Lu\n",
- page_nr, count,
- count_verify[page_nr]);
- exit(1);
- }
-
-
- /*
- * We can't use bcmp (or memcmp) because that
- * returns 0 erroneously if the memory is
- * changing under it (even if the end of the
- * page is never changing and always
- * different).
- */
-#if 1
- if (!my_bcmp(area_dst + page_nr * page_size, zeropage,
- page_size)) {
- fprintf(stderr,
- "my_bcmp page_nr %lu wrong count %Lu %Lu\n",
- page_nr, count, count_verify[page_nr]);
- exit(1);
- }
-#else
- unsigned long loops;
-
- loops = 0;
- /* uncomment the below line to test with mutex */
- /* pthread_mutex_lock(area_mutex(area_dst, page_nr)); */
- while (!bcmp(area_dst + page_nr * page_size, zeropage,
- page_size)) {
- loops += 1;
- if (loops > 10)
- break;
- }
- /* uncomment below line to test with mutex */
- /* pthread_mutex_unlock(area_mutex(area_dst, page_nr)); */
- if (loops) {
- fprintf(stderr,
- "page_nr %lu all zero thread %lu %p %lu\n",
- page_nr, cpu, area_dst + page_nr * page_size,
- loops);
- if (loops > 10)
- exit(1);
- }
-#endif
- }
-
pthread_mutex_lock(area_mutex(area_dst, page_nr));
count = *area_count(area_dst, page_nr);
if (count != count_verify[page_nr]) {
@@ -613,8 +561,7 @@ static void uffd_handle_page_fault(struc
stats->minor_faults++;
} else {
/* Missing page faults */
- if (bounces & BOUNCE_VERIFY &&
- msg->arg.pagefault.flags & UFFD_PAGEFAULT_FLAG_WRITE) {
+ if (msg->arg.pagefault.flags & UFFD_PAGEFAULT_FLAG_WRITE) {
fprintf(stderr, "unexpected write fault\n");
exit(1);
}
_
Patches currently in -mm which might be from peterx@xxxxxxxxxx are
mm-hugetlb-fix-f_seal_future_write.patch
mm-hugetlb-fix-cow-where-page-writtable-in-child.patch
mm-gup_benchmark-support-threading.patch
userfaultfd-selftests-use-user-mode-only.patch
userfaultfd-selftests-remove-the-time-check-on-delayed-uffd.patch
userfaultfd-selftests-dropping-verify-check-in-locking_thread.patch
userfaultfd-selftests-only-dump-counts-if-mode-enabled.patch
userfaultfd-selftests-unify-error-handling.patch
mm-thp-simplify-copying-of-huge-zero-page-pmd-when-fork.patch
mm-userfaultfd-fix-uffd-wp-special-cases-for-fork.patch
mm-userfaultfd-fix-a-few-thp-pmd-missing-uffd-wp-bit.patch
mm-userfaultfd-fail-uffd-wp-registeration-if-not-supported.patch
mm-pagemap-export-uffd-wp-protection-information.patch
userfaultfd-selftests-add-pagemap-uffd-wp-test.patch
