* [PATCH bpf-next 0/2] selftests/bpf: Skip libarena when arena spin locks are unsupported
@ 2026-10-09 1:49 Qiliang Yuan
2026-10-09 1:49 ` [PATCH bpf-next 1/2] selftests/bpf: Return the lock error from buddy_init() of libarena Qiliang Yuan
` (2 more replies)
0 siblings, 3 replies; 6+ messages in thread
From: Qiliang Yuan @ 2026-10-09 1:49 UTC (permalink / raw)
To: Alexei Starovoitov, Daniel Borkmann, Andrii Nakryiko,
Eduard Zingerman, Kumar Kartikeya Dwivedi, Martin KaFai Lau,
Song Liu, Yonghong Song, Jiri Olsa, Emil Tsalapatis,
Ihor Solodrai, Shuah Khan
Cc: bpf, linux-kselftest, linux-kernel, Qiliang Yuan
serial_test_libarena runs the test programs of libarena, whose buddy
allocator serializes its operations with an arena spin lock.
arena_spin_lock() fails with -EOPNOTSUPP on kernels built with more
than 1024 possible CPUs, as distributions commonly configure them.
buddy_init() reports that as -EINVAL, and every test then fails at
arena_buddy_reset.
Patch 1 makes buddy_init() return the error of the lock, patch 2 skips
the tests when resetting the allocator fails with -EOPNOTSUPP.
Signed-off-by: Qiliang Yuan <odys.yuan@gmail.com>
---
Qiliang Yuan (2):
selftests/bpf: Return the lock error from buddy_init() of libarena
selftests/bpf: Skip libarena on kernels with too many possible CPUs
tools/testing/selftests/bpf/libarena/src/buddy.bpf.c | 5 +++--
tools/testing/selftests/bpf/prog_tests/libarena.c | 9 +++++++++
2 files changed, 12 insertions(+), 2 deletions(-)
---
base-commit: e1d84a37cba984388988d2f1ddc84561413f0db2
change-id: 20261009-selftests-bpf-libarena-nr-cpus-50fc5dd00fe2
Best regards,
--
Qiliang Yuan <odys.yuan@gmail.com>
^ permalink raw reply [flat|nested] 6+ messages in thread
* [PATCH bpf-next 1/2] selftests/bpf: Return the lock error from buddy_init() of libarena
2026-10-09 1:49 [PATCH bpf-next 0/2] selftests/bpf: Skip libarena when arena spin locks are unsupported Qiliang Yuan
@ 2026-10-09 1:49 ` Qiliang Yuan
2026-10-09 2:37 ` bot+bpf-ci
2026-10-09 1:49 ` [PATCH bpf-next 2/2] selftests/bpf: Skip libarena on kernels with too many possible CPUs Qiliang Yuan
2026-10-14 19:51 ` [PATCH bpf-next 0/2] selftests/bpf: Skip libarena when arena spin locks are unsupported Emil Tsalapatis
2 siblings, 1 reply; 6+ messages in thread
From: Qiliang Yuan @ 2026-10-09 1:49 UTC (permalink / raw)
To: Alexei Starovoitov, Daniel Borkmann, Andrii Nakryiko,
Eduard Zingerman, Kumar Kartikeya Dwivedi, Martin KaFai Lau,
Song Liu, Yonghong Song, Jiri Olsa, Emil Tsalapatis,
Ihor Solodrai, Shuah Khan
Cc: bpf, linux-kselftest, linux-kernel, Qiliang Yuan
buddy_init() takes the buddy lock, an arena spin lock, to put its first
chunk on the list, and returns -EINVAL when it can't.
arena_spin_lock() fails with -EOPNOTSUPP on kernels built with more
than 1024 possible CPUs, where it has no queue node for every CPU, and
with -ETIMEDOUT or -EBUSY otherwise. Returning -EINVAL for all of them
hides which one happened from the caller.
Return the error of the lock.
Fixes: b1487dc1b181 ("selftests/bpf: Add selftests for libarena buddy allocator")
Signed-off-by: Qiliang Yuan <odys.yuan@gmail.com>
---
tools/testing/selftests/bpf/libarena/src/buddy.bpf.c | 5 +++--
1 file changed, 3 insertions(+), 2 deletions(-)
diff --git a/tools/testing/selftests/bpf/libarena/src/buddy.bpf.c b/tools/testing/selftests/bpf/libarena/src/buddy.bpf.c
index 2490ab1396de0..7bb99a7cb63ed 100644
--- a/tools/testing/selftests/bpf/libarena/src/buddy.bpf.c
+++ b/tools/testing/selftests/bpf/libarena/src/buddy.bpf.c
@@ -576,9 +576,10 @@ __weak int buddy_init(struct buddy __arena *buddy)
chunk = buddy_chunk_get(buddy);
- if (buddy_lock(buddy, flags)) {
+ ret = buddy_lock(buddy, flags);
+ if (ret) {
bpf_arena_free_pages(&arena, chunk, BUDDY_CHUNK_PAGES);
- return -EINVAL;
+ return ret;
}
/* Chunk is already properly unpoisoned if allocated. */
--
2.43.0
^ permalink raw reply [flat|nested] 6+ messages in thread
* [PATCH bpf-next 2/2] selftests/bpf: Skip libarena on kernels with too many possible CPUs
2026-10-09 1:49 [PATCH bpf-next 0/2] selftests/bpf: Skip libarena when arena spin locks are unsupported Qiliang Yuan
2026-10-09 1:49 ` [PATCH bpf-next 1/2] selftests/bpf: Return the lock error from buddy_init() of libarena Qiliang Yuan
@ 2026-10-09 1:49 ` Qiliang Yuan
2026-10-09 2:37 ` bot+bpf-ci
2026-10-14 19:51 ` [PATCH bpf-next 0/2] selftests/bpf: Skip libarena when arena spin locks are unsupported Emil Tsalapatis
2 siblings, 1 reply; 6+ messages in thread
From: Qiliang Yuan @ 2026-10-09 1:49 UTC (permalink / raw)
To: Alexei Starovoitov, Daniel Borkmann, Andrii Nakryiko,
Eduard Zingerman, Kumar Kartikeya Dwivedi, Martin KaFai Lau,
Song Liu, Yonghong Song, Jiri Olsa, Emil Tsalapatis,
Ihor Solodrai, Shuah Khan
Cc: bpf, linux-kselftest, linux-kernel, Qiliang Yuan
serial_test_libarena runs every test program of libarena, most of them
after resetting the buddy allocator with arena_buddy_reset.
The buddy allocator takes an arena spin lock, which fails with
-EOPNOTSUPP on kernels built with more than 1024 possible CPUs, as
distributions commonly configure them. Every test then fails at
arena_buddy_reset, while the arena_spin_lock test already skips in that
case.
Reset the allocator once before running the tests, and skip them when
that returns -EOPNOTSUPP.
Fixes: b1487dc1b181 ("selftests/bpf: Add selftests for libarena buddy allocator")
Signed-off-by: Qiliang Yuan <odys.yuan@gmail.com>
---
tools/testing/selftests/bpf/prog_tests/libarena.c | 9 +++++++++
1 file changed, 9 insertions(+)
diff --git a/tools/testing/selftests/bpf/prog_tests/libarena.c b/tools/testing/selftests/bpf/prog_tests/libarena.c
index daade4150af66..070a08856ee04 100644
--- a/tools/testing/selftests/bpf/prog_tests/libarena.c
+++ b/tools/testing/selftests/bpf/prog_tests/libarena.c
@@ -240,6 +240,15 @@ void serial_test_libarena(void)
if (!ASSERT_OK(ret, "arena_alloc_reserve"))
goto out;
+ /* Skip on kernels with more possible CPUs than arena spin locks support */
+ ret = libarena_run_prog(bpf_program__fd(skel->progs.arena_buddy_reset));
+ if (ret == -EOPNOTSUPP) {
+ test__skip();
+ goto out;
+ }
+ if (!ASSERT_OK(ret, "arena_buddy_reset"))
+ goto out;
+
bpf_object__for_each_program(prog, skel->obj) {
const char *name = bpf_program__name(prog);
--
2.43.0
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [PATCH bpf-next 1/2] selftests/bpf: Return the lock error from buddy_init() of libarena
2026-10-09 1:49 ` [PATCH bpf-next 1/2] selftests/bpf: Return the lock error from buddy_init() of libarena Qiliang Yuan
@ 2026-10-09 2:37 ` bot+bpf-ci
0 siblings, 0 replies; 6+ messages in thread
From: bot+bpf-ci @ 2026-10-09 2:37 UTC (permalink / raw)
To: odys.yuan, ast, daniel, andrii, eddyz87, memxor, martin.lau,
song, yonghong.song, jolsa, emil, ihor.solodrai, shuah
Cc: bpf, linux-kselftest, linux-kernel, odys.yuan, ast, andrii,
daniel, martin.lau, eddyz87, yonghong.song, mason, ihor.solodrai
[-- Attachment #1: Type: text/plain, Size: 2176 bytes --]
> selftests/bpf: Return the lock error from buddy_init() of libarena
TL;DR: Commit message only: the Fixes: tag may point at the wrong commit
(b1487dc1b181, which doesn't touch buddy_init()); 86426a28c52d introduced the
code being changed.
> selftests/bpf: Return the lock error from buddy_init() of libarena
>
> buddy_init() takes the buddy lock, an arena spin lock, to put its first
> chunk on the list, and returns -EINVAL when it can't.
> arena_spin_lock() fails with -EOPNOTSUPP on kernels built with more
> than 1024 possible CPUs, where it has no queue node for every CPU, and
> with -ETIMEDOUT or -EBUSY otherwise. Returning -EINVAL for all of them
> hides which one happened from the caller.
> Return the error of the lock.
> Fixes: b1487dc1b181 ("selftests/bpf: Add selftests for libarena buddy allocator")
> Signed-off-by: Qiliang Yuan <odys.yuan@gmail.com>
Is the Fixes: tag pointing at the right commit?
b1487dc1b181 ("selftests/bpf: Add selftests for libarena buddy allocator")
only adds st_buddy.bpf.c, st_asan_buddy.bpf.c, prog_tests/libarena.c and
prog_tests/libarena_asan.c. It does not touch src/buddy.bpf.c or
buddy_init().
The code being changed here:
if (buddy_lock(buddy, flags)) {
bpf_arena_free_pages(&arena, chunk, BUDDY_CHUNK_PAGES);
return -EINVAL;
}
was introduced by 86426a28c52d ("selftests/bpf: Add buddy allocator for
libarena"), which added buddy.bpf.c with buddy_init() already returning
-EINVAL when buddy_lock() failed. The selftests commit only exposes the
discarded error, it did not introduce the code that discards it.
The same tag is also used by the follow-up commit 27aeee1ef85a
("selftests/bpf: Skip libarena on kernels with too many possible CPUs"),
which depends on this patch to see -EOPNOTSUPP from arena_buddy_reset().
Should this be:
Fixes: 86426a28c52d ("selftests/bpf: Add buddy allocator for libarena")
---
AI reviewed your patch. Please fix the bug or email reply why it's not a bug.
See: https://github.com/kernel-patches/vmtest/blob/master/ci/claude/README.md
CI run summary: https://github.com/kernel-patches/bpf/actions/runs/37873620927
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [PATCH bpf-next 2/2] selftests/bpf: Skip libarena on kernels with too many possible CPUs
2026-10-09 1:49 ` [PATCH bpf-next 2/2] selftests/bpf: Skip libarena on kernels with too many possible CPUs Qiliang Yuan
@ 2026-10-09 2:37 ` bot+bpf-ci
0 siblings, 0 replies; 6+ messages in thread
From: bot+bpf-ci @ 2026-10-09 2:37 UTC (permalink / raw)
To: odys.yuan, ast, daniel, andrii, eddyz87, memxor, martin.lau,
song, yonghong.song, jolsa, emil, ihor.solodrai, shuah
Cc: bpf, linux-kselftest, linux-kernel, odys.yuan, ast, andrii,
daniel, martin.lau, eddyz87, yonghong.song, mason, ihor.solodrai
[-- Attachment #1: Type: text/plain, Size: 2022 bytes --]
> selftests/bpf: Skip libarena on kernels with too many possible CPUs
TL;DR: Nit only: the libarena selftest skips silently on too many possible
CPUs; suggests printing a reason first, as arena_spin_lock.c does, though
leaving it may be acceptable.
> diff --git a/tools/testing/selftests/bpf/prog_tests/libarena.c b/tools/testing/selftests/bpf/prog_tests/libarena.c
> index daade4150af6..070a08856ee0 100644
> --- a/tools/testing/selftests/bpf/prog_tests/libarena.c
> +++ b/tools/testing/selftests/bpf/prog_tests/libarena.c
[ ... ]
> @@ -240,6 +240,15 @@ void serial_test_libarena(void)
> if (!ASSERT_OK(ret, "arena_alloc_reserve"))
> goto out;
>
> + /* Skip on kernels with more possible CPUs than arena spin locks support */
> + ret = libarena_run_prog(bpf_program__fd(skel->progs.arena_buddy_reset));
> + if (ret == -EOPNOTSUPP) {
> + test__skip();
> + goto out;
> + }
> + if (!ASSERT_OK(ret, "arena_buddy_reset"))
> + goto out;
> +
This isn't a bug, but a subsystem guideline flags a test that skips for a
missing capability without printing any reason.
When arena_buddy_reset returns -EOPNOTSUPP, this path calls a bare
test__skip(), so the test log shows SKIP with nothing indicating why. The
explanation only exists in the source comment above the call.
The sibling prog_tests/arena_spin_lock.c prints a reason before skipping
for the same condition:
printf("%s:SKIP: CONFIG_NR_CPUS exceed the maximum supported by arena spinlock\n",
__func__);
test__skip();
Would it make sense to print a similar message here before test__skip()?
On the other hand, test__skip() takes no message argument, and the existing
skip in run_libarena_parallel_test() for a disabled parallel test is also
bare, so leaving it as is may be acceptable.
[ ... ]
---
AI reviewed your patch. Please fix the bug or email reply why it's not a bug.
See: https://github.com/kernel-patches/vmtest/blob/master/ci/claude/README.md
CI run summary: https://github.com/kernel-patches/bpf/actions/runs/37873620927
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [PATCH bpf-next 0/2] selftests/bpf: Skip libarena when arena spin locks are unsupported
2026-10-09 1:49 [PATCH bpf-next 0/2] selftests/bpf: Skip libarena when arena spin locks are unsupported Qiliang Yuan
2026-10-09 1:49 ` [PATCH bpf-next 1/2] selftests/bpf: Return the lock error from buddy_init() of libarena Qiliang Yuan
2026-10-09 1:49 ` [PATCH bpf-next 2/2] selftests/bpf: Skip libarena on kernels with too many possible CPUs Qiliang Yuan
@ 2026-10-14 19:51 ` Emil Tsalapatis
2 siblings, 0 replies; 6+ messages in thread
From: Emil Tsalapatis @ 2026-10-14 19:51 UTC (permalink / raw)
To: Qiliang Yuan, Alexei Starovoitov, Daniel Borkmann,
Andrii Nakryiko, Eduard Zingerman, Kumar Kartikeya Dwivedi,
Martin KaFai Lau, Song Liu, Yonghong Song, Jiri Olsa,
Emil Tsalapatis, Ihor Solodrai, Shuah Khan
Cc: bpf, linux-kselftest, linux-kernel
On Fri Oct 9, 2026 at 1:49 AM UTC, Qiliang Yuan wrote:
> serial_test_libarena runs the test programs of libarena, whose buddy
> allocator serializes its operations with an arena spin lock.
>
> arena_spin_lock() fails with -EOPNOTSUPP on kernels built with more
> than 1024 possible CPUs, as distributions commonly configure them.
> buddy_init() reports that as -EINVAL, and every test then fails at
> arena_buddy_reset.
>
> Patch 1 makes buddy_init() return the error of the lock, patch 2 skips
> the tests when resetting the allocator fails with -EOPNOTSUPP.
>
If new kernels expect more than 1024 CPUs, we should update libarena and
arena_spin_lock() to support them instead of returning EOPNOTSUPP.
pw-bot: cr
> Signed-off-by: Qiliang Yuan <odys.yuan@gmail.com>
> ---
> Qiliang Yuan (2):
> selftests/bpf: Return the lock error from buddy_init() of libarena
> selftests/bpf: Skip libarena on kernels with too many possible CPUs
>
> tools/testing/selftests/bpf/libarena/src/buddy.bpf.c | 5 +++--
> tools/testing/selftests/bpf/prog_tests/libarena.c | 9 +++++++++
> 2 files changed, 12 insertions(+), 2 deletions(-)
> ---
> base-commit: e1d84a37cba984388988d2f1ddc84561413f0db2
> change-id: 20261009-selftests-bpf-libarena-nr-cpus-50fc5dd00fe2
>
> Best regards,
^ permalink raw reply [flat|nested] 6+ messages in thread
end of thread, other threads:[~2026-10-14 19:51 UTC | newest]
Thread overview: 6+ messages (download: mbox.gz / follow: Atom feed)
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2026-10-09 1:49 [PATCH bpf-next 0/2] selftests/bpf: Skip libarena when arena spin locks are unsupported Qiliang Yuan
2026-10-09 1:49 ` [PATCH bpf-next 1/2] selftests/bpf: Return the lock error from buddy_init() of libarena Qiliang Yuan
2026-10-09 2:37 ` bot+bpf-ci
2026-10-09 1:49 ` [PATCH bpf-next 2/2] selftests/bpf: Skip libarena on kernels with too many possible CPUs Qiliang Yuan
2026-10-09 2:37 ` bot+bpf-ci
2026-10-14 19:51 ` [PATCH bpf-next 0/2] selftests/bpf: Skip libarena when arena spin locks are unsupported Emil Tsalapatis
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