Patch series "selftests/mm: fix deadlock after pthread_create".
On Android arm, pthread_create followed by a fork caused a deadlock in the
case where the fork required work to be completed by the created thread.
Update the synchronization primitive to use pthread_barrier instead of
atomic_bool.
Apply the same fix to the wp-fork-with-event test.
This patch (of 2):
Swap synchronization primitive with pthread_barrier, so that stdatomic.h
does not need to be included.
The synchronization is needed on Android ARM64; we see a deadlock with
pthread_create when the parent thread races forward before the child has a
chance to start doing work.
Link: https://lkml.kernel.org/r/20241003211716.371786-1-edliaw@google.com
Link: https://lkml.kernel.org/r/20241003211716.371786-2-edliaw@google.com
Fixes: cff2945827 ("selftests/mm: extend and rename uffd pagemap test")
Signed-off-by: Edward Liaw <edliaw@google.com>
Cc: Lokesh Gidra <lokeshgidra@google.com>
Cc: Peter Xu <peterx@redhat.com>
Cc: Shuah Khan <shuah@kernel.org>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Following issue was observed while running the uffd-unit-tests selftest
on ARM devices. On x86_64 no issues were detected:
pthread_create followed by fork caused deadlock in certain cases wherein
fork required some work to be completed by the created thread. Used
synchronization to ensure that created thread's start function has started
before invoking fork.
[edliaw@google.com: refactored to use atomic_bool]
Link: https://lkml.kernel.org/r/20240325194100.775052-1-edliaw@google.com
Fixes: 760aee0b71 ("selftests/mm: add tests for RO pinning vs fork()")
Signed-off-by: Lokesh Gidra <lokeshgidra@google.com>
Signed-off-by: Edward Liaw <edliaw@google.com>
Cc: Peter Xu <peterx@redhat.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
With the new uffd unit test covering the /dev/userfaultfd path and syscall
path of uffd initializations, we can safely drop the devnode test in the
old stress test.
One thing is to avoid duplication of running the stress test twice which is
an overkill to only test the /dev/ interface in run_vmtests.sh.
The other benefit is now all uffd tests (that uses userfaultfd_open) can
run automatically as long as any type of interface is enabled (either
syscall or dev), so it's more likely to succeed rather than fail due to
unprivilege.
With this patch lands, we can drop all the "mem_type:XXX" handlings too.
Link: https://lkml.kernel.org/r/20230412164525.329176-1-peterx@redhat.com
Signed-off-by: Peter Xu <peterx@redhat.com>
Cc: Axel Rasmussen <axelrasmussen@google.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: Dmitry Safonov <0x7f454c46@gmail.com>
Cc: Mike Kravetz <mike.kravetz@oracle.com>
Cc: Mike Rapoport (IBM) <rppt@kernel.org>
Cc: Zach O'Keefe <zokeefe@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
This moves the minor test to the new unit test.
Rewrite the content check with char* opeartions to avoid fiddling with
my_bcmp().
Drop global vars test_uffdio_minor and test_collapse, just assume test them
always in common code for now.
OTOH make this single test into five tests:
- minor test on [shmem, hugetlb] with wp=false
- minor test on [shmem, hugetlb] with wp=true
- minor test + collapse on shmem only
One thing to mention that we used to test COLLAPSE+WP but that doesn't
sound right at all. It's possible it's silently broken but unnoticed
because COLLAPSE is not part of the default test suite.
Make the MADV_COLLAPSE test fail-able (by skip it when failing), because
it's not guaranteed to success anyway.
Drop a bunch of useless code after the move, because the unit test always
use aligned num of pages and has nothing to do with n_cpus.
Link: https://lkml.kernel.org/r/20230412164357.328779-1-peterx@redhat.com
Signed-off-by: Peter Xu <peterx@redhat.com>
Cc: Zach O'Keefe <zokeefe@google.com>
Cc: Axel Rasmussen <axelrasmussen@google.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: Dmitry Safonov <0x7f454c46@gmail.com>
Cc: Mike Kravetz <mike.kravetz@oracle.com>
Cc: Mike Rapoport (IBM) <rppt@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Add two helpers to register/unregister to an uffd. Use them to drop
duplicate codes.
This patch also drops assert_expected_ioctls_present() and
get_expected_ioctls(). Reasons:
- It'll need a lot of effort to pass test_type==HUGETLB into it from
the upper, so it's the simplest way to get rid of another global var
- The ioctls returned in UFFDIO_REGISTER is hardly useful at all,
because any app can already detect kernel support on any ioctl via its
corresponding UFFD_FEATURE_*. The check here is for sanity mostly but
it's probably destined no user app will even use it.
- It's not friendly to one future goal of uffd to run on old
kernels, the problem is get_expected_ioctls() compiles against
UFFD_API_RANGE_IOCTLS, which is a value that can change depending on
where the test is compiled, rather than reflecting what the kernel
underneath has. It means it'll report false negatives on old kernels
so it's against our will.
So let's make our lives easier.
[peterx@redhat.com; tools/testing/selftests/mm/hugepage-mremap.c: add headers]
Link: https://lkml.kernel.org/r/ZDxrvZh/cw357D8P@x1n
Link: https://lkml.kernel.org/r/20230412164247.328293-1-peterx@redhat.com
Signed-off-by: Peter Xu <peterx@redhat.com>
Reviewed-by: Axel Rasmussen <axelrasmussen@google.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: Dmitry Safonov <0x7f454c46@gmail.com>
Cc: Mike Kravetz <mike.kravetz@oracle.com>
Cc: Mike Rapoport (IBM) <rppt@kernel.org>
Cc: Zach O'Keefe <zokeefe@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
