[PATCH 7.1.y v2] selftests/bpf: Add tests for sleepable tracepoint programs

[PATCH 7.1.y v2] selftests/bpf: Add tests for sleepable tracepoint programs

[Ricardo B. Marlière (SUSE)]

From: Mykyta Yatsenko <yatsenko@meta.com>

[ Upstream commit 8a20655749c625dcc4debdfdeeaa0cf8bb85c203 ]

Cover all three sleepable tracepoint types (tp_btf.s, raw_tp.s, tp.s)
and sys_exit (via bpf_task_pt_regs) with functional tests using
bpf_copy_from_user() on getcwd. Verify alias and bare SEC variants,
bpf_prog_test_run_raw_tp() with BPF_F_TEST_RUN_ON_CPU rejection,
attach-time rejection on non-faultable tracepoints, and load-time
rejection for sleepable tp_btf on non-faultable tracepoints.

[ rbm: Removed hunks from (new) files:
        tools/testing/selftests/bpf/prog_tests/sleepable_tracepoints.c
        tools/testing/selftests/bpf/progs/test_sleepable_tracepoints.c
        tools/testing/selftests/bpf/progs/test_sleepable_tracepoints_fail.c
       These rely on libbpf's ".s" tracepoint section handlers
       (0cd420a6f40c7) and on kernel-side sleepable tracepoint runtime
       support (439ebd5b5708, 12628ffaf98b, 57918341dd19), none of which
       are backported here; kept only the verifier/sleepable.c hunk, which
       is correct and needed on its own. ]

Signed-off-by: Mykyta Yatsenko <yatsenko@meta.com>
Acked-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
Link: https://lore.kernel.org/bpf/20260422-sleepable_tracepoints-v13-6-99005dff21ef@meta.com
Signed-off-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
---
Changes in v2:
- Dropped hunks which miss dependencies
- Added a small note about it in the commit
- Link to v1: https://patch.msgid.link/20260805-selftests-bpf-sleepable-v1-1-e29fa5af4119@marliere.net
---
 tools/testing/selftests/bpf/verifier/sleepable.c | 17 +++++++++++++++--
 1 file changed, 15 insertions(+), 2 deletions(-)

diff --git a/tools/testing/selftests/bpf/verifier/sleepable.c b/tools/testing/selftests/bpf/verifier/sleepable.c
index c2b7f5ebf168..6dabc5522945 100644
--- a/tools/testing/selftests/bpf/verifier/sleepable.c
+++ b/tools/testing/selftests/bpf/verifier/sleepable.c
@@ -76,7 +76,20 @@
 	.runs = -1,
 },
 {
-	"sleepable raw tracepoint reject",
+	"sleepable raw tracepoint accept",
+	.insns = {
+	BPF_MOV64_IMM(BPF_REG_0, 0),
+	BPF_EXIT_INSN(),
+	},
+	.prog_type = BPF_PROG_TYPE_TRACING,
+	.expected_attach_type = BPF_TRACE_RAW_TP,
+	.kfunc = "sys_enter",
+	.result = ACCEPT,
+	.flags = BPF_F_SLEEPABLE,
+	.runs = -1,
+},
+{
+	"sleepable raw tracepoint reject non-faultable",
 	.insns = {
 	BPF_MOV64_IMM(BPF_REG_0, 0),
 	BPF_EXIT_INSN(),
@@ -85,7 +98,7 @@
 	.expected_attach_type = BPF_TRACE_RAW_TP,
 	.kfunc = "sched_switch",
 	.result = REJECT,
-	.errstr = "Only fentry/fexit/fsession/fmod_ret, lsm, iter, uprobe, and struct_ops programs can be sleepable",
+	.errstr = "Sleepable program cannot attach to non-faultable tracepoint",
 	.flags = BPF_F_SLEEPABLE,
 	.runs = -1,
 },

---
base-commit: 74b69060ba6e44e20c2e4dc1847eca21db6e4a7c
change-id: 20260803-selftests-bpf-sleepable-eebf2d962201

Best regards,
--  
Ricardo B. Marlière (SUSE) <ricardo@marliere.net>

Re: [PATCH 7.1.y v2] selftests/bpf: Add tests for sleepable tracepoint programs

[sashiko-bot]

Thank you for your contribution! Sashiko AI review found 1 potential issue(s) to consider:

Pre-existing issues:
- [Critical] Test codifies a critical kernel crash bug due to incomplete backport of sleepable tracepoint support
--

--- Patch [1]: [PATCH 7.1.y v2] selftests/bpf: Add tests for sleepable tracepoint programs ---
commit d01560ee1bdaeec333977b1890fc06598668aa9f
Author: Mykyta Yatsenko <yatsenko@meta.com>

selftests/bpf: Add tests for sleepable tracepoint programs

Cover all three sleepable tracepoint types (tp_btf.s, raw_tp.s, tp.s)
and sys_exit (via bpf_task_pt_regs) with functional tests using
bpf_copy_from_user() on getcwd.

Link: https://lore.kernel.org/bpf/20260422-sleepable_tracepoints-v13-6-99005dff21ef@meta.com

> diff --git a/tools/testing/selftests/bpf/verifier/sleepable.c b/tools/testing/selftests/bpf/verifier/sleepable.c
> index c2b7f5ebf168c..6dabc55229455 100644
> --- a/tools/testing/selftests/bpf/verifier/sleepable.c
> +++ b/tools/testing/selftests/bpf/verifier/sleepable.c
> @@ -76,7 +76,20 @@
>  	.runs = -1,
>  },
>  {
> -	"sleepable raw tracepoint reject",
> +	"sleepable raw tracepoint accept",
> +	.insns = {
> +	BPF_MOV64_IMM(BPF_REG_0, 0),
> +	BPF_EXIT_INSN(),
> +	},
> +	.prog_type = BPF_PROG_TYPE_TRACING,
> +	.expected_attach_type = BPF_TRACE_RAW_TP,
> +	.kfunc = "sys_enter",
> +	.result = ACCEPT,
> +	.flags = BPF_F_SLEEPABLE,
> +	.runs = -1,
> +},

[Severity: Critical]
This is a pre-existing issue, but does this test codify a kernel crash bug
in the baseline tree?

The commit message notes that kernel-side sleepable tracepoint runtime support
was not backported here. Because of an earlier backport, the verifier
currently accepts sleepable raw tracepoints if tracepoint_is_faultable() is
true (like sys_enter), which makes this verifier test pass.

However, without the runtime support, the execution happens unconditionally
under atomic contexts. For example, in __bpf_trace_run():

kernel/trace/bpf_trace.c:__bpf_trace_run() {
    ...
    rcu_read_lock_dont_migrate();
    ...
}

Or via the tracepoint wrapper:

include/trace/bpf_probe.h:__BPF_DECLARE_TRACE_SYSCALL() {
    ...
    preempt_disable_notrace();
    ...
}

If a sleepable program is attached to this tracepoint and actually sleeps, it
will trigger a scheduling while atomic panic.

Should this test be removed or adjusted until the runtime support is fully
backported to prevent asserting this unsafe verifier state?

-- 
Sashiko AI review · https://sashiko.dev/#/patchset/20260807-selftests-bpf-sleepable-v2-1-f7e6566f36a1@marliere.net?part=1

Re: [PATCH 7.1.y v2] selftests/bpf: Add tests for sleepable tracepoint programs

[Greg KH]

On Fri, Aug 07, 2026 at 09:32:43AM -0300, Ricardo B. Marlière (SUSE) wrote:
> From: Mykyta Yatsenko <yatsenko@meta.com>
> 
> [ Upstream commit 8a20655749c625dcc4debdfdeeaa0cf8bb85c203 ]
> 
> Cover all three sleepable tracepoint types (tp_btf.s, raw_tp.s, tp.s)
> and sys_exit (via bpf_task_pt_regs) with functional tests using
> bpf_copy_from_user() on getcwd. Verify alias and bare SEC variants,
> bpf_prog_test_run_raw_tp() with BPF_F_TEST_RUN_ON_CPU rejection,
> attach-time rejection on non-faultable tracepoints, and load-time
> rejection for sleepable tp_btf on non-faultable tracepoints.
> 
> [ rbm: Removed hunks from (new) files:
>         tools/testing/selftests/bpf/prog_tests/sleepable_tracepoints.c
>         tools/testing/selftests/bpf/progs/test_sleepable_tracepoints.c
>         tools/testing/selftests/bpf/progs/test_sleepable_tracepoints_fail.c
>        These rely on libbpf's ".s" tracepoint section handlers
>        (0cd420a6f40c7) and on kernel-side sleepable tracepoint runtime
>        support (439ebd5b5708, 12628ffaf98b, 57918341dd19), none of which
>        are backported here; kept only the verifier/sleepable.c hunk, which
>        is correct and needed on its own. ]
> 
> Signed-off-by: Mykyta Yatsenko <yatsenko@meta.com>
> Acked-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
> Link: https://lore.kernel.org/bpf/20260422-sleepable_tracepoints-v13-6-99005dff21ef@meta.com
> Signed-off-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>

You did not sign off on this :(