From: akpm@linux-foundation.org
To: aarcange@redhat.com, axelrasmussen@google.com,
mm-commits@vger.kernel.org, nadav.amit@gmail.com,
peterx@redhat.com
Subject: + userfaultfd-selftests-dropping-verify-check-in-locking_thread.patch added to -mm tree
Date: Wed, 10 Mar 2021 15:53:50 -0800 [thread overview]
Message-ID: <20210310235350.LvdsWFkcA%akpm@linux-foundation.org> (raw)
The patch titled
Subject: userfaultfd/selftests: drop 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@redhat.com>
Subject: userfaultfd/selftests: drop 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/20210310004511.51996-4-peterx@redhat.com
Signed-off-by: Peter Xu <peterx@redhat.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Axel Rasmussen <axelrasmussen@google.com>
Cc: Nadav Amit <nadav.amit@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---
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
@@ -603,58 +603,6 @@ 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]) {
@@ -786,8 +734,7 @@ 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@redhat.com are
hugetlb-dedup-the-code-to-add-a-new-file_region.patch
hugetlg-break-earlier-in-add_reservation_in_range-when-we-can.patch
mm-introduce-page_needs_cow_for_dma-for-deciding-whether-cow.patch
mm-use-is_cow_mapping-across-tree-where-proper.patch
hugetlb-do-early-cow-when-page-pinned-on-src-mm.patch
hugetlb-pass-vma-into-huge_pte_alloc-and-huge_pmd_share.patch
hugetlb-pass-vma-into-huge_pte_alloc-and-huge_pmd_share-fix.patch
hugetlb-userfaultfd-forbid-huge-pmd-sharing-when-uffd-enabled.patch
hugetlb-userfaultfd-forbid-huge-pmd-sharing-when-uffd-enabled-fix.patch
mm-hugetlb-move-flush_hugetlb_tlb_range-into-hugetlbh.patch
hugetlb-userfaultfd-unshare-all-pmds-for-hugetlbfs-when-register-wp.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
next reply other threads:[~2021-03-10 23:54 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-03-10 23:53 akpm [this message]
2021-05-09 4:10 + userfaultfd-selftests-dropping-verify-check-in-locking_thread.patch added to -mm tree akpm
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