The patch titled
Subject: userfaultfd: selftest: recycle lock threads first
has been added to the -mm tree. Its filename is
userfaultfd-selftest-recycle-lock-threads-first.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/userfaultfd-selftest-recycle-lock-threads-first.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/userfaultfd-selftest-recycle-lock-threads-first.patch
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The -mm tree is included into linux-next and is updated
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------------------------------------------------------
From: Peter Xu <peterx@xxxxxxxxxx>
Subject: userfaultfd: selftest: recycle lock threads first
Now we recycle the uffd servicing threads earlier than the lock threads.
It might happen that when the lock thread is still blocked at a pthread
mutex lock while the servicing thread has already quitted for the cpu so
the lock thread will be blocked forever and hang the test program. To fix
the possible race, recycle the lock threads first.
This never happens with current missing-only tests, but when I start to
run the write-protection tests (the feature is not yet posted upstream) it
happens every time of the run possibly because in that new test we'll need
to service two page faults for each lock operation.
Link: http://lkml.kernel.org/r/20180930074259.18229-4-peterx@xxxxxxxxxx
Signed-off-by: Peter Xu <peterx@xxxxxxxxxx>
Acked-by: Mike Rapoport <rppt@xxxxxxxxxxxxxxxxxx>
Cc: Shuah Khan <shuah@xxxxxxxxxx>
Cc: Mike Kravetz <mike.kravetz@xxxxxxxxxx>
Cc: Jerome Glisse <jglisse@xxxxxxxxxx>
Cc: Zi Yan <zi.yan@xxxxxxxxxxxxxx>
Cc: "Kirill A . Shutemov" <kirill@xxxxxxxxxxxxx>
Cc: Shaohua Li <shli@xxxxxx>
Cc: Andrea Arcangeli <aarcange@xxxxxxxxxx>
Cc: "Dr . David Alan Gilbert" <dgilbert@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
tools/testing/selftests/vm/userfaultfd.c | 11 ++++++-----
1 file changed, 6 insertions(+), 5 deletions(-)
--- a/tools/testing/selftests/vm/userfaultfd.c~userfaultfd-selftest-recycle-lock-threads-first
+++ a/tools/testing/selftests/vm/userfaultfd.c
@@ -626,6 +626,12 @@ static int stress(unsigned long *userfau
if (uffd_test_ops->release_pages(area_src))
return 1;
+
+ finished = 1;
+ for (cpu = 0; cpu < nr_cpus; cpu++)
+ if (pthread_join(locking_threads[cpu], NULL))
+ return 1;
+
for (cpu = 0; cpu < nr_cpus; cpu++) {
char c;
if (bounces & BOUNCE_POLL) {
@@ -643,11 +649,6 @@ static int stress(unsigned long *userfau
}
}
- finished = 1;
- for (cpu = 0; cpu < nr_cpus; cpu++)
- if (pthread_join(locking_threads[cpu], NULL))
- return 1;
-
return 0;
}
_
Patches currently in -mm which might be from peterx@xxxxxxxxxx are
userfaultfd-selftest-cleanup-help-messages.patch
userfaultfd-selftest-generalize-read-and-poll.patch
userfaultfd-selftest-recycle-lock-threads-first.patch
