On 2026-04-26 06:58, Mike Rapoport wrote:
On Fri, Apr 24, 2026 at 01:11:45PM -0400, Luiz Capitulino wrote:
On 2026-04-18 06:55, Mike Rapoport wrote:
From: "Mike Rapoport (Microsoft)" <[email protected]>
migration skips HugeTLB tests if there are no free huge pages
prepared by a wrapper script.
Add setup of HugeTLB pages to the test and make sure that the original
settings are restored on the test exit.
Since kselftest_harness runs fixture setup and the tests in child
processes, use HUGETLB_SETUP_DEFAULT_PAGES() that defines a constructor
that runs in the main process and add verification that there are enough
free huge pages to the tests that use them.
Signed-off-by: Mike Rapoport (Microsoft) <[email protected]>
---
tools/testing/selftests/mm/migration.c | 8 ++++++++
1 file changed, 8 insertions(+)
diff --git a/tools/testing/selftests/mm/migration.c
b/tools/testing/selftests/mm/migration.c
index ccf42002ce86..61fb00953f83 100644
--- a/tools/testing/selftests/mm/migration.c
+++ b/tools/testing/selftests/mm/migration.c
@@ -23,6 +23,8 @@
#define MAX_RETRIES 100
#define ALIGN(x, a) (((x) + (a - 1)) & (~((a) - 1)))
+HUGETLB_SETUP_DEFAULT_PAGES(1)
Hey Mike,
I've been reviewing and testing this series and got a reproducible issue
with this test when running it on a x86 KVM guest with 88 vCPUs.
The issue is that, when executing the full MM suite with
sudo ./run_vmtests.sh -d -a, all 6 migration test pass but it doesn't exit.
Instead, it gets stuck after this output:
"""
# # PASSED: 6 / 6 tests passed.
# # Totals: pass:6 fail:0 xfail:0 xpass:0 skip:0 error:0
"""
Getting a backtrace from gdb I see:
"""
#0 0x00007efd2f2c247b in __lll_lock_wait_private () from /lib64/libc.so.6
#1 0x00007efd2f26fa88 in __run_exit_handlers () from /lib64/libc.so.6
#2 0x00007efd2f26fabe in exit () from /lib64/libc.so.6
#3 0x0000000000404f2e in hugepage_restore_settings_sighandler ()
#4 <signal handler called>
#5 0x00007efd2f32f416 in __unregister_atfork () from /lib64/libc.so.6
#6 0x00007efd2f26f338 in __cxa_finalize () from /lib64/libc.so.6
#7 0x00007efd2f4548c7 in __do_global_dtors_aux () from /lib64/libm.so.6
#8 0x00007ffd66ae0320 in ?? ()
#9 0x00007efd2f55b2d2 in _dl_call_fini (closure_map=0x7efd2f5500c0) at
dl-call_fini.c:43
"""
Could we be messing with libc internal state somehow? I also get systemd
services hung when I try to reboot.
I don't think we are messing with libc internal state, but we surely leave
zombies around.
All the tests that fork() terminate the children with kill() but they never
call wait*() to collect the exit status.
Right!
Some of the migration tests fork() and then kill() their children
processes. Won't those all restore the hugetlb state concurrently
from hugepage_restore_settings_atexit()?
Yeah, I missed the kill()s :/
Also, for shared_anon_htlb, don't we need to reserve a HugeTLB page per
children?
We only mmap() a single huge page in the parent, the children don't create
new mappings.
You're right, I missed the fact that the children only read from the
page.
And there's another issue: when running the migration test individually,
private_anon_htlb gets skipped. I guess it's because the previous test
is restoring the HugeTLB state:
It could be.
I pushed the updated version that has the fixes for both zombie and
signal issues:
https://git.kernel.org/pub/scm/linux/kernel/git/rppt/linux.git/log/?h=mm-selftest/v3
Would be great if you can test it in your setup.
This works! Both issues are fixed: the migration test completes w/o
hanging and when I run it individually all tests run.
One last question: should we munmap() the mappings in this test? Though
I understand this goes beyond your series goal.
