6.17-stable review patch. If anyone has any objections, please let me know.
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From: Waiman Long longman@redhat.com
[ Upstream commit d8e2f919997b14665e4509ef9a5278f291598d6e ]
The "Memory out of range" subtest of futex_numa_mpol assumes that memory access outside of the mmap'ed area is invalid. That may not be the case depending on the actual memory layout of the test application. When that subtest was run on an x86-64 system with latest upstream kernel, the test passed as an error was returned from futex_wake(). On another PowerPC system, the same subtest failed because futex_wake() returned 0.
Bail out! futex2_wake(64, 0x86) should fail, but didn't
Looking further into the passed subtest on x86-64, it was found that an -EINVAL was returned instead of -EFAULT. The -EINVAL error was returned because the node value test with FLAGS_NUMA set failed with a node value of 0x7f7f. IOW, the futex memory was accessible and futex_wake() failed because the supposed node number wasn't valid. If that memory location happens to have a very small value (e.g. 0), the test will pass and no error will be returned.
Since this subtest is non-deterministic, drop it unless a guard page beyond the mmap region is explicitly set.
The other problematic test is the "Memory too small" test. The futex_wake() function returns the -EINVAL error code because the given futex address isn't 8-byte aligned, not because only 4 of the 8 bytes are valid and the other 4 bytes are not. So change the name of this subtest to "Mis-aligned futex" to reflect the reality.
[ bp: Massage commit message. ]
Fixes: 3163369407ba ("selftests/futex: Add futex_numa_mpol") Signed-off-by: Waiman Long longman@redhat.com Signed-off-by: Sebastian Andrzej Siewior bigeasy@linutronix.de Signed-off-by: Borislav Petkov (AMD) bp@alien8.de Reviewed-by: Sebastian Andrzej Siewior bigeasy@linutronix.de Link: https://lore.kernel.org/20250827130011.677600-3-bigeasy@linutronix.de Signed-off-by: Sasha Levin sashal@kernel.org --- tools/testing/selftests/futex/functional/futex_numa_mpol.c | 6 ++---- 1 file changed, 2 insertions(+), 4 deletions(-)
diff --git a/tools/testing/selftests/futex/functional/futex_numa_mpol.c b/tools/testing/selftests/futex/functional/futex_numa_mpol.c index a9ecfb2d3932a..802c15c821906 100644 --- a/tools/testing/selftests/futex/functional/futex_numa_mpol.c +++ b/tools/testing/selftests/futex/functional/futex_numa_mpol.c @@ -182,12 +182,10 @@ int main(int argc, char *argv[]) if (futex_numa->numa == FUTEX_NO_NODE) ksft_exit_fail_msg("NUMA node is left uninitialized\n");
- ksft_print_msg("Memory too small\n"); + /* FUTEX2_NUMA futex must be 8-byte aligned */ + ksft_print_msg("Mis-aligned futex\n"); test_futex(futex_ptr + mem_size - 4, 1);
- ksft_print_msg("Memory out of range\n"); - test_futex(futex_ptr + mem_size, 1); - futex_numa->numa = FUTEX_NO_NODE; mprotect(futex_ptr, mem_size, PROT_READ); ksft_print_msg("Memory, RO\n");