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dmarc=pass (p=none dis=none) header.from=goodmis.org Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=goodmis.org Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key, unprotected) header.d=goodmis.org header.i=@goodmis.org header.a=rsa-sha256 header.s=dkim1 header.b=F/iDtX73 Received: from omf07.hostedemail.com (lb01a-stub [10.200.18.249]) by unirelay08.hostedemail.com (Postfix) with ESMTP id C76D11405BB; Wed, 4 Nov 2026 00:34:30 +0000 (UTC) Received: from [HIDDEN] (Authenticated sender: rostedt@goodmis.org) by omf07.hostedemail.com (Postfix) with ESMTPA id BE06E2002E; Wed, 4 Nov 2026 00:34:27 +0000 (UTC) Date: Tue, 3 Nov 2026 19:34:21 -0500 From: Steven Rostedt To: Li Pengfei Cc: mhiramat@kernel.org, mathieu.desnoyers@efficios.com, mark.rutland@arm.com, corbet@lwn.net, skhan@linuxfoundation.org, lkp@intel.com, linux-trace-kernel@vger.kernel.org, linux-kernel@vger.kernel.org, linux-doc@vger.kernel.org, linux-kselftest@vger.kernel.org, zhangbo56@xiaomi.com, lipengfei28@xiaomi.com Subject: Re: [RFC PATCH v7 02/10] trace: use the stackmap from the ftrace stack recording path Message-ID: <20261103193421.63f4454a@gandalf.local.home> In-Reply-To: <20260912083753.3426176-3-lipengfei28@xiaomi.com> References: <20260912083753.3426176-1-lipengfei28@xiaomi.com> <20260912083753.3426176-3-lipengfei28@xiaomi.com> X-Mailer: Claws Mail 3.20.0git84 (GTK+ 2.24.33; x86_64-pc-linux-gnu) X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit X-Rspamd-Server: rspamout02 X-Rspamd-Queue-Id: BE06E2002E X-Stat-Signature: ubbfsuba5xjjds7u9skiqbryrfmxjc39 X-Session-Marker: 726F737465647440676F6F646D69732E6F7267 X-Session-ID: U2FsdGVkX18HjDEmAZrCiJFNhjxyKfES+9Y4hyGJnMg= DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=goodmis.org; h=date:from:to:cc:subject:message-id:in-reply-to:references:mime-version:content-type:content-transfer-encoding; s=dkim1; bh=S/N+F00fZjYK5bQ5EspDDlJ3W88B+dtGIBUElMlMpkk=; b=F/iDtX73+AV4gHag9EUIZ+cFdQBXNrwXvfO2lTbq1KLtvB2GFAkzUAqDIvDHATVvfkYSQRs5BZDK9m14yiWM+vyiUndv8sFwZZ/cwBLKXrcSaULkpd6MYpxK3dM3sXEpE1f5SFKXmljzT9IBL+4aAFBQ9FULjbOCF/kaZPY89NE= X-HE-Tag: 1793752467-576457 X-HE-Meta: U2FsdGVkX18AfA7zNO2x5s3fK70vx43IefI7lydkcq/8ugq7fmNDYM4YWa7iMXzDsRGOUdqtuU9RsM/fDpAwU5deWhgbqScV3jdUPE7pryer7rOpZjRc0u805JGEKtl3lNV2Tj9ASlXwWD8DpqXPURiuCHm99TTm4Tm4dq8JzimSf2dxTpevqN0GFAKQOiEhdYYGiF/i4tNml0TTWROmfiUC1FqPWQ/puUuDWIpjDLJqmTGU+suAWjGK7a8elJiz7UzIZjiW8mEf98FMUJCZ+lX7m4+yEymfONwU9wBcNP34Cz7j41eKFKlOxpnj95iZqxTMJzsdSAI6o8pHwL1kIlezr3LOyspx/Ictg4RS7n/JVi0yuyyhsQ== On Sat, 12 Sep 2026 16:37:45 +0800 Li Pengfei wrote: Hi Li, FYI, the tracing subsystem requires starting subjects with capital letters: trace: Use the stackmap from the ftrace stack recording path Also, did you use AI for this? Most of the comments are useless, and sound like they come from AI. > From: Pengfei Li > > Wire ftrace_stackmap into __ftrace_trace_stack(). With 'stackmap' and > 'stacktrace' enabled, the recording path tries to place a 4-byte > stack_id in the ring buffer and stack_map resolves the id. > > Reserve the stack-id ring-buffer slot before consulting the map. This > keeps map records and counters untouched when that reservation fails. > If get_id() then fails, discard the reserved slot. Both paths try the > existing full-stack fallback, whose own ring-buffer reservation can > still fail under normal ring-buffer semantics. > > Stacks deeper than FTRACE_STACKMAP_MAX_DEPTH bypass the map so a > recorded stack is never silently truncated or merged with another stack > sharing the same prefix. Other map failures, including capacity, > reset, and an unpublished map, also try the full-stack path. > > Confine the option to the global trace instance through > TOP_LEVEL_TRACE_FLAGS, ZEROED_TRACE_FLAGS and a set_tracer_flag() > check. This also rejects writes through a secondary instance's > aggregate trace_options file. > > Create stack_map before publishing global_trace.stackmap. Boot-time > options may be set while initialization is pending; the recording path > uses full-stack fallback until publication. A permanent initialization > failure clears and rejects the option. > > Also add TRACE_STACK_ID, its output handler, and validation needed by > ftrace startup selftests. > > Signed-off-by: Pengfei Li > --- > kernel/trace/Kconfig | 9 ++ > kernel/trace/trace.c | 218 ++++++++++++++++++++++++++- > kernel/trace/trace.h | 16 ++ > kernel/trace/trace_entries.h | 15 ++ > kernel/trace/trace_functions_graph.c | 1 + > kernel/trace/trace_output.c | 23 +++ > kernel/trace/trace_selftest.c | 1 + > 7 files changed, 280 insertions(+), 3 deletions(-) > > diff --git a/kernel/trace/Kconfig b/kernel/trace/Kconfig > index 6c40535a46e1..7001453bbfd3 100644 > --- a/kernel/trace/Kconfig > +++ b/kernel/trace/Kconfig > @@ -426,6 +426,15 @@ config FTRACE_STACKMAP > significantly reducing trace buffer usage when the same call stacks > appear repeatedly. > > + Automatic per-event stack capture requires the stacktrace option: > + > + echo 1 > /sys/kernel/debug/tracing/options/stacktrace > + echo 1 > /sys/kernel/debug/tracing/options/stackmap > + > + Explicit stack records requested through tracing APIs are also > + deduplicated when stackmap is enabled for their trace array. Stackmap > + is currently available only for the global trace array. > + > The deduplicated stacks are exported via: > /sys/kernel/debug/tracing/stack_map > > diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c > index 18710c190c92..06ae8ed11475 100644 > --- a/kernel/trace/trace.c > +++ b/kernel/trace/trace.c > @@ -57,6 +57,7 @@ > > #include "trace.h" > #include "trace_output.h" > +#include "trace_stackmap.h" > > #ifdef CONFIG_FTRACE_STARTUP_TEST > /* > @@ -509,12 +510,13 @@ EXPORT_SYMBOL_GPL(unregister_ftrace_export); > /* trace_options that are only supported by global_trace */ > #define TOP_LEVEL_TRACE_FLAGS (TRACE_ITER(PRINTK) | \ > TRACE_ITER(PRINTK_MSGONLY) | TRACE_ITER(RECORD_CMD) | \ > - TRACE_ITER(PROF_TEXT_OFFSET) | FPROFILE_DEFAULT_FLAGS) > + TRACE_ITER(PROF_TEXT_OFFSET) | TRACE_ITER(STACKMAP) | \ > + FPROFILE_DEFAULT_FLAGS) > > /* trace_flags that are default zero for instances */ > #define ZEROED_TRACE_FLAGS \ > (TRACE_ITER(EVENT_FORK) | TRACE_ITER(FUNC_FORK) | TRACE_ITER(TRACE_PRINTK) | \ > - TRACE_ITER(COPY_MARKER)) > + TRACE_ITER(COPY_MARKER) | TRACE_ITER(STACKMAP)) > > /* > * The global_trace is the descriptor that holds the top-level tracing > @@ -2184,6 +2186,76 @@ void __ftrace_trace_stack(struct trace_array *tr, > } > #endif > > +#ifdef CONFIG_FTRACE_STACKMAP > + /* > + * If stackmap dedup is enabled, try to store only the stack_id > + * in the ring buffer instead of the full stack trace. > + * > + * Reserve the TRACE_STACK_ID ring-buffer slot BEFORE calling > + * get_id(). This guarantees get_id(), and therefore any map mutation > + * or counter update it performs, is attempted only after the stack-id > + * reservation succeeds: > + * - reservation fails -> try full-stack fallback, map untouched > + * - get_id() fails -> discard the reserved slot, then try > + * full-stack fallback > + * A failed stack-id reservation therefore never consumes a map slot > + * or updates the map counters. > + */ It's better to turn this into a function, where we have something like this: #ifdef CONFIG_FTRACE_STACKMAP static inline bool record_stackmap(struct trace_array *tr, struct trace_buffer *buffer, struct ftrace_stack *fstack, unsigned int nr_entries, unsigned int trace_ctx) { [..] } #else static inline bool record_stackmap(struct trace_array *tr, struct trace_buffer *buffer, struct ftrace_stack *fstack, unsigned int nr_entries, unsigned int trace_ctx) { return false; } #endif /* CONFIG_FTRACE_STACKMAP */ Where it returns true if it processed the map and false otherwise, that way you can do: if (record_stackmap(tr, buffer, fstack, nr_entries, trace_ctx)) goto out; > + if (tr->trace_flags & TRACE_ITER(STACKMAP)) { > + struct ftrace_stackmap *smap; > + struct stack_id_entry *sid_entry; > + int sid; > + > + /* > + * Pairs with the smp_store_release() that publishes the > + * fully initialized global stackmap at tracefs init. > + */ > + smap = smp_load_acquire(&tr->stackmap); > + if (!smap) > + goto full_stack; > + > + /* > + * The stackmap stores at most FTRACE_STACKMAP_MAX_DEPTH > + * frames per entry. A deeper trace would be truncated, and > + * two distinct stacks that share the first MAX_DEPTH frames > + * would hash and compare equal, silently merging into one > + * stack_id. Use the conservative full-stack path for deep > + * traces to avoid truncating or misattributing a recorded stack. > + * The ring-buffer reservation can still fail. The above comment really isn't needed here. If the nr_entries is greater than the max stackmap then we just don't use stackmap. No need to go into details about why. It's explained elsewhere. > + */ > + if (nr_entries > FTRACE_STACKMAP_MAX_DEPTH) > + goto full_stack; Why not do this check before getting smap? > + > + event = __trace_buffer_lock_reserve(buffer, TRACE_STACK_ID, > + sizeof(*sid_entry), trace_ctx); > + if (!event) > + goto full_stack; > + > + sid = ftrace_stackmap_get_id(smap, fstack->calls, nr_entries); > + if (sid < 0) { > + /* > + * If get_id() cannot return an ID, discard the reserved > + * stack_id slot, then try the full-stack fallback. Its > + * ring-buffer reservation can still fail. > + */ > + __trace_event_discard_commit(buffer, event); > + goto full_stack; > + } > + > + sid_entry = ring_buffer_event_data(event); > + sid_entry->stack_id = sid; > + /* > + * stack_id is a synthetic side-event attached to a > + * primary trace event that was already subject to > + * filtering. No per-event filter is defined for > + * TRACE_STACK_ID, so commit unconditionally. > + */ You don't need the above comment. The original code does this too without the need to comment it here. > + __buffer_unlock_commit(buffer, event); > + goto out; > + } > +full_stack: > +#endif > + > event = __trace_buffer_lock_reserve(buffer, TRACE_STACK, > struct_size(entry, caller, nr_entries), > trace_ctx); > @@ -3976,6 +4048,50 @@ int trace_keep_overwrite(struct tracer *tracer, u64 mask, int set) > return 0; > } > > +#ifdef CONFIG_FTRACE_STACKMAP > +/* > + * Tracks tracefs-time initialization of the global stackmap so that > + * set_tracer_flag() can distinguish "not initialized yet" from > + * "initialization permanently failed". > + * > + * Boot-time options (trace_options=stackmap,stacktrace) are applied > + * very early, before tracer_init_tracefs() creates and publishes the > + * map. We must allow the STACKMAP flag to be set during that window > + * (the hot path falls back to a full stack while tr->stackmap is NULL, > + * then starts using the map once it is published). We must, however, > + * reject the enable once init has *failed*, so options/stackmap never > + * reports an enabled no-op. > + * > + * Written once from the tracefs init work before any concurrent > + * userspace writer to trace_options can run, then only read; a plain > + * int is therefore sufficient. The above is way too verbose, and honestly, doesn't even make sense. I need to look at the code to determine what it means. If you need to look at the code to understand the comments, it means the comments are useless. > + */ > +enum { Name the emum. > + STACKMAP_INIT_PENDING, /* tracer_init_tracefs() not run yet */ > + STACKMAP_INIT_DONE, /* map published, stack_map file created */ > + STACKMAP_INIT_FAILED, /* permanent failure, never available */ The above comments are good though. > +}; > + > +static int stackmap_init_state = STACKMAP_INIT_PENDING; This variable should be of that enum type. > + > +/* > + * Mark the global stackmap init as permanently failed. > + * > + * Clears any boot-time STACKMAP flag (trace_options=stackmap applied before > + * the map was created) so options/stackmap does not report an enabled no-op > + * and later userspace enables return -EINVAL. The flag is cleared under > + * trace_types_lock because set_tracer_flag() updates trace_flags under that > + * lock; the tracefs init runs in an unlocked workqueue context that can race > + * with a concurrent trace_options write. > + */ > +static void __init stackmap_mark_init_failed(void) > +{ > + guard(mutex)(&trace_types_lock); > + WRITE_ONCE(stackmap_init_state, STACKMAP_INIT_FAILED); > + global_trace.trace_flags &= ~TRACE_ITER(STACKMAP); > +} > +#endif > + > int set_tracer_flag(struct trace_array *tr, u64 mask, int enabled) > { > switch (mask) { > @@ -3990,6 +4106,33 @@ int set_tracer_flag(struct trace_array *tr, u64 mask, int enabled) > if (!!(tr->trace_flags & mask) == !!enabled) > return 0; > > +#ifdef CONFIG_FTRACE_STACKMAP > + /* > + * STACKMAP is intentionally global-instance-only: the dedup map, > + * its tracefs files and the lifetime/reset semantics are tied > + * to the global trace > + * array. options/stackmap is hidden on secondary instances via > + * TOP_LEVEL_TRACE_FLAGS, but writes still reach set_tracer_flag() > + * through the aggregate trace_options file. Reject the enable on > + * a secondary instance so it cannot be silently accepted and then > + * become a no-op in the hot path (where tr->stackmap is NULL and > + * the code falls back to a full stack trace). > + * > + * On the global instance, allow the enable while init is still > + * pending (boot-time trace_options=stackmap is applied before the > + * tracefs init work creates the map; the hot path falls back > + * until the map is published). Only reject once init has > + * permanently failed, so options/stackmap never reports an > + * enabled no-op. READ_ONCE() suffices: this only inspects the > + * init state, it does not dereference the map (the hot path uses > + * smp_load_acquire(&tr->stackmap) for that). The entire comment above can be replaced with just: /* The stack map is only for the top_level trace array. */ The rest is way too verbose. The failed description is obvious and doesn't need explaining. > + */ > + if (mask == TRACE_ITER(STACKMAP) && enabled && > + (tr != &global_trace || > + READ_ONCE(stackmap_init_state) == STACKMAP_INIT_FAILED)) > + return -EINVAL; > +#endif > + > /* Give the tracer a chance to approve the change */ > if (tr->current_trace->flag_changed) > if (tr->current_trace->flag_changed(tr, mask, !!enabled)) > @@ -9222,6 +9365,70 @@ static __init void tracer_init_tracefs_work_func(struct work_struct *work) > NULL, &tracing_dyn_info_fops); > #endif > > +#ifdef CONFIG_FTRACE_STACKMAP > + { Do not add anonymous blocks. This should be another helper function that is defined in the above #if block that defined the other one I suggested. > + struct ftrace_stackmap *smap; > + struct dentry *map_file; > + > + smap = ftrace_stackmap_create(&global_trace); > + if (!IS_ERR(smap)) { If this was a helper function than you can make this into: if (IS_ERR(smap)) { pr_warn("ftrace stackmap init failed, dedup disabled\n"); stackmap_mark_init_failed(); return PTR_ERR(smap); } And remove the indentation for the rest. > + /* > + * Failure-atomic init: stack_map is the single > + * required tracefs file (it doubles as the reset > + * interface and the human-readable resolver). If > + * we cannot create it, the hot path must not be > + * able to emit events that no one can > + * resolve or clear, so refuse to publish the map > + * and tear it down. > + * > + * Create stack_map BEFORE smp_store_release() so an > + * observed non-NULL global_trace.stackmap implies > + * its resolver/reset file exists. > + */ You know that if this is only for top level trace array, this is done before user space starts. The above comment is really useless. Nuke it. > + map_file = trace_create_file("stack_map", > + TRACE_MODE_WRITE, NULL, > + smap, > + &ftrace_stackmap_fops); > + if (!map_file) { > + pr_warn("ftrace stackmap init: stack_map create failed, dedup disabled\n"); > + ftrace_stackmap_destroy(smap); > + /* > + * Permanent failure. Record it and clear a > + * boot-time STACKMAP flag (under > + * trace_types_lock) so options/stackmap does > + * not report an enabled no-op and later > + * userspace enables return -EINVAL. > + */ Nuke this comment. > + stackmap_mark_init_failed(); > + } else { > + /* > + * smp_store_release pairs with the > + * smp_load_acquire() in > + * __ftrace_trace_stack(). Publishing only > + * after the required file exists keeps > + * "smap visible" => "resolver/reset > + * available". > + */ > + smp_store_release(&global_trace.stackmap, smap); > + WRITE_ONCE(stackmap_init_state, STACKMAP_INIT_DONE); > + } > + } else { > + pr_warn("ftrace stackmap init failed, dedup disabled\n"); > + /* > + * global_trace is statically defined; its stackmap > + * field is zero-initialized via BSS, so leaving it > + * NULL ensures the smp_load_acquire() in > + * __ftrace_trace_stack() falls back to full stack. > + * Mark init failed and clear any boot-time STACKMAP > + * flag so userspace enables are rejected rather than > + * becoming silent no-ops. Use the helper so the flag > + * clear happens under trace_types_lock, matching the > + * stack_map-create failure path above. > + */ Again. Useless comment. These comments make it harder to understand what is happening :-( > + stackmap_mark_init_failed(); > + } > + } > +#endif > create_trace_instances(NULL); > > update_tracer_options(); > @@ -9234,8 +9441,13 @@ static __init int tracer_init_tracefs(void) > trace_access_lock_init(); > > ret = tracing_init_dentry(); > - if (ret) > + if (ret) { > +#ifdef CONFIG_FTRACE_STACKMAP > + /* No later path can create or publish the global stackmap. */ Obvious comment. Not needed. > + stackmap_mark_init_failed(); Get rid of the #ifdef here. When not defined, the above function should be defined as: static inline void stackmap_mark_init_failed(void) { } -- Steve > +#endif > return 0; > + } > > if (trace_init_wq) { > INIT_WORK(&tracerfs_init_work, tracer_init_tracefs_work_func); > diff --git a/kernel/trace/trace.h b/kernel/trace/trace.h > index 80fe152af1dd..7e7d5e5a35ff 100644 > --- a/kernel/trace/trace.h > +++ b/kernel/trace/trace.h > @@ -57,6 +57,7 @@ enum trace_type { > TRACE_TIMERLAT, > TRACE_RAW_DATA, > TRACE_FUNC_REPEATS, > + TRACE_STACK_ID, > > __TRACE_LAST_TYPE, > }; > @@ -453,6 +454,9 @@ struct trace_array { > struct cond_snapshot *cond_snapshot; > #endif > struct trace_func_repeats __percpu *last_func_repeats; > +#ifdef CONFIG_FTRACE_STACKMAP > + struct ftrace_stackmap *stackmap; > +#endif > /* > * On boot up, the ring buffer is set to the minimum size, so that > * we do not waste memory on systems that are not using tracing. > @@ -579,6 +583,8 @@ extern void __ftrace_bad_type(void); > TRACE_GRAPH_RET); \ > IF_ASSIGN(var, ent, struct func_repeats_entry, \ > TRACE_FUNC_REPEATS); \ > + IF_ASSIGN(var, ent, struct stack_id_entry, \ > + TRACE_STACK_ID); \ > __ftrace_bad_type(); \ > } while (0) > > @@ -1449,7 +1455,16 @@ extern int trace_get_user(struct trace_parser *parser, const char __user *ubuf, > # define STACK_FLAGS > #endif > > +#ifdef CONFIG_FTRACE_STACKMAP > +# define STACKMAP_FLAGS \ > + C(STACKMAP, "stackmap"), > +#else > +# define STACKMAP_FLAGS > +# define TRACE_ITER_STACKMAP_BIT -1 > +#endif > + > #ifdef CONFIG_FUNCTION_PROFILER > + > # define PROFILER_FLAGS \ > C(PROF_TEXT_OFFSET, "prof-text-offset"), > # ifdef CONFIG_FUNCTION_GRAPH_TRACER > @@ -1506,6 +1521,7 @@ extern int trace_get_user(struct trace_parser *parser, const char __user *ubuf, > FUNCTION_FLAGS \ > FGRAPH_FLAGS \ > STACK_FLAGS \ > + STACKMAP_FLAGS \ > BRANCH_FLAGS \ > PROFILER_FLAGS \ > FPROFILE_FLAGS > diff --git a/kernel/trace/trace_entries.h b/kernel/trace/trace_entries.h > index 54417468fdeb..89ed14b7e5fd 100644 > --- a/kernel/trace/trace_entries.h > +++ b/kernel/trace/trace_entries.h > @@ -250,6 +250,21 @@ FTRACE_ENTRY(user_stack, userstack_entry, > (void *)__entry->caller[6], (void *)__entry->caller[7]) > ); > > +/* > + * Stack ID entry - stores only a stack_id referencing the stackmap. > + * Used when CONFIG_FTRACE_STACKMAP is enabled to deduplicate stacks. > + */ > +FTRACE_ENTRY(stack_id, stack_id_entry, > + > + TRACE_STACK_ID, > + > + F_STRUCT( > + __field( int, stack_id ) > + ), > + > + F_printk("", __entry->stack_id) > +); > + > /* > * trace_printk entry: > */ > diff --git a/kernel/trace/trace_functions_graph.c b/kernel/trace/trace_functions_graph.c > index 0d2d3a2ea7dd..0e1a390a6130 100644 > --- a/kernel/trace/trace_functions_graph.c > +++ b/kernel/trace/trace_functions_graph.c > @@ -1492,6 +1492,7 @@ print_graph_function_flags(struct trace_iterator *iter, u32 flags) > return print_graph_return(field, s, entry, iter, flags); > } > case TRACE_STACK: > + case TRACE_STACK_ID: > case TRACE_FN: > /* dont trace stack and functions as comments */ > return TRACE_TYPE_UNHANDLED; > diff --git a/kernel/trace/trace_output.c b/kernel/trace/trace_output.c > index a5ad76175d10..68678ea88159 100644 > --- a/kernel/trace/trace_output.c > +++ b/kernel/trace/trace_output.c > @@ -1517,6 +1517,28 @@ static struct trace_event trace_user_stack_event = { > .funcs = &trace_user_stack_funcs, > }; > > +/* TRACE_STACK_ID */ > +static enum print_line_t trace_stack_id_print(struct trace_iterator *iter, > + int flags, struct trace_event *event) > +{ > + struct stack_id_entry *field; > + struct trace_seq *s = &iter->seq; > + > + trace_assign_type(field, iter->ent); > + trace_seq_printf(s, "\n", field->stack_id); > + > + return trace_handle_return(s); > +} > + > +static struct trace_event_functions trace_stack_id_funcs = { > + .trace = trace_stack_id_print, > +}; > + > +static struct trace_event trace_stack_id_event = { > + .type = TRACE_STACK_ID, > + .funcs = &trace_stack_id_funcs, > +}; > + > /* TRACE_HWLAT */ > static enum print_line_t > trace_hwlat_print(struct trace_iterator *iter, int flags, > @@ -1908,6 +1930,7 @@ static struct trace_event *events[] __initdata = { > &trace_wake_event, > &trace_stack_event, > &trace_user_stack_event, > + &trace_stack_id_event, > &trace_bputs_event, > &trace_bprint_event, > &trace_print_event, > diff --git a/kernel/trace/trace_selftest.c b/kernel/trace/trace_selftest.c > index 929c84075315..0c97065b0d68 100644 > --- a/kernel/trace/trace_selftest.c > +++ b/kernel/trace/trace_selftest.c > @@ -14,6 +14,7 @@ static inline int trace_valid_entry(struct trace_entry *entry) > case TRACE_CTX: > case TRACE_WAKE: > case TRACE_STACK: > + case TRACE_STACK_ID: > case TRACE_PRINT: > case TRACE_BRANCH: > case TRACE_GRAPH_ENT: