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Wed, 25 Feb 2026 08:23:56 -0800 (PST) Received: from localhost ([2a03:2880:30ff:49::]) by smtp.gmail.com with ESMTPSA id 5b1f17b1804b1-483bfcb9b97sm25179045e9.7.2026.02.25.08.23.55 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 25 Feb 2026 08:23:56 -0800 (PST) From: Mykyta Yatsenko Date: Wed, 25 Feb 2026 08:23:50 -0800 Subject: [PATCH bpf-next v2 2/6] bpf: Add sleepable execution path for raw tracepoint programs Precedence: bulk X-Mailing-List: bpf@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit Message-Id: <20260225-sleepable_tracepoints-v2-2-0330dafd650f@meta.com> References: <20260225-sleepable_tracepoints-v2-0-0330dafd650f@meta.com> In-Reply-To: <20260225-sleepable_tracepoints-v2-0-0330dafd650f@meta.com> To: bpf@vger.kernel.org, ast@kernel.org, andrii@kernel.org, daniel@iogearbox.net, kafai@meta.com, kernel-team@meta.com, eddyz87@gmail.com Cc: Mykyta Yatsenko X-Mailer: b4 0.13.0 X-Developer-Signature: v=1; a=ed25519-sha256; t=1772036632; l=2270; i=yatsenko@meta.com; s=20260220; h=from:subject:message-id; bh=zyNDRGE2dKauL47MMhg3aMXQev+TDOSHhJuYl3aYgfU=; b=UlVRgygdCUnvtINsaJoTbroEvRJIO9JvFfstuOB0viT0lMI5fS7TbT0dE3OZRfC0fbEnvdAEo AHQNev6yy5JBDCEDiHlmU4WuawCBJtpBn4ngYi/tU7S2kFuU8bjRB0x X-Developer-Key: i=yatsenko@meta.com; a=ed25519; pk=QUfct6THKRRhwIGGKcldE2w7zXPci1gMPcF7qij1gwA= From: Mykyta Yatsenko Modify __bpf_trace_run() to support both sleepable and non-sleepable BPF programs. When the program is sleepable: - Skip cant_sleep() and instead call might_fault() to annotate the faultable context - Use migrate_disable()/migrate_enable() instead of rcu_read_lock()/rcu_read_unlock() to allow sleeping while still protecting percpu data access - The outer rcu_tasks_trace lock is already held by the faultable tracepoint callback (__DECLARE_TRACE_SYSCALL), providing lifetime protection for the BPF program For non-sleepable programs, behavior is unchanged: cant_sleep() check, rcu_read_lock() protection. This allows multiple BPF programs with different sleepable settings to coexist on the same faultable tracepoint, since __bpf_trace_run() is invoked per-link. Signed-off-by: Mykyta Yatsenko --- kernel/trace/bpf_trace.c | 20 +++++++++++++++++--- 1 file changed, 17 insertions(+), 3 deletions(-) diff --git a/kernel/trace/bpf_trace.c b/kernel/trace/bpf_trace.c index 9bc0dfd235af..2dd345e0fdb0 100644 --- a/kernel/trace/bpf_trace.c +++ b/kernel/trace/bpf_trace.c @@ -2076,7 +2076,7 @@ void __bpf_trace_run(struct bpf_raw_tp_link *link, u64 *args) struct bpf_run_ctx *old_run_ctx; struct bpf_trace_run_ctx run_ctx; - rcu_read_lock_dont_migrate(); + migrate_disable(); if (unlikely(!bpf_prog_get_recursion_context(prog))) { bpf_prog_inc_misses_counter(prog); goto out; @@ -2085,12 +2085,26 @@ void __bpf_trace_run(struct bpf_raw_tp_link *link, u64 *args) run_ctx.bpf_cookie = link->cookie; old_run_ctx = bpf_set_run_ctx(&run_ctx.run_ctx); - (void) bpf_prog_run(prog, args); + if (prog->sleepable) { + might_fault(); + (void)bpf_prog_run(prog, args); + } else { + /* + * Non-sleepable programs may run in the faultable context, + * do cant_sleep() only if program is non-sleepable and context + * is non-faultable. + */ + if (!link->link.sleepable) + cant_sleep(); + rcu_read_lock(); + (void)bpf_prog_run(prog, args); + rcu_read_unlock(); + } bpf_reset_run_ctx(old_run_ctx); out: bpf_prog_put_recursion_context(prog); - rcu_read_unlock_migrate(); + migrate_enable(); } #define UNPACK(...) __VA_ARGS__ -- 2.47.3