laptop-kernel/kernel/trace, branch master

Merge tag 'trace-v7.3-rc7' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace

2026-10-17T00:27:22Z

Pull tracing fixes from Steven Rostedt: - Fix NULL dereference when copying histogram field variable If event_hist_trigger_parse() creates an action that uses one of pseudo fields for its keys, the hist_data field element will have a NULL for its field member. When looking to match that key, the lookup uses key_field->field->name which will dereference a NULL pointer. Instead use the helper function that handles such cases: expr_field_str(). - Take the trace_types_lock when dropping the buffer_meta reference The tracing_buffer_meta_open() error return drops the trace_array reference with __trace_array_put() instead of trace_array_put() where the former doesn't take the lock and the latter does. - Fix NULL pointer dereference when reading per_cpu/cpuN/buffer_meta These files are created for every possible CPU. But it only contains data for CPUs that have come online. If one is read for a CPU that hasn't come online yet, it triggers a NULL pointer dereference. Have reading of CPUs that have not come on line yet return -ENODEV. - Fix an out-of-bounds shift in the log2 histogram modifier Histograms can take a log2 modifier to have the buckets defined by log2 increments. If a shift is greater than ULONG_MAX or above 2^63, the key falls into a lower order bucket. Use order_base_2() instead of "ilog2(n - 1) + 1" to have all overflowed keys go into the top bucket. - Fix the persistent ring buffer rb_meta_subbuf_idx() accounting The algorithm for finding the index of a sub-buffer in a persistent ring buffer buffer did not take into account the meta data at the beginning of the buffer causing the wrong index to be returned. As rb_subbufs_from_meta() does the proper accounting to find the first sub-buffer, use that function instead of repeating the logic (incorrectly) and make the calculations based off of that. - Fix the symbol name checks for the remote buffer code The remote ring buffer has a build time check to make sure its not using any code that will not be in the hypervisor. For various architectures, there has been false positive reports from this checker. Fix them. - Fix false warning in ring_buffer_map_get_reader() There is a WARN_ON() after rb_get_reader_page() if no reader is returned. But there are legitimate cases where this can happen. Remove the WARN_ON() and also a check that covers one of the legitimate cases that tries to exit out early. There's no need for the check if it just simply allows the return of NULL from rb_get_reader_page(). - Fix the ignored return value from resize_buffer_duplicate_size() Some clean up of the code in tracing_snapshot_write() removed checking the return value of resize_buffer_duplicate_size() and if that failed it would not be detected. - Fix the histogram timestamps for buffered events The histogram timestamps are taken from the events that are recorded. It currently reads ring_buffer_event_time_stamp() but if the event is buffered it does not read it properly. Use tracing_event_time_stamp() which handles both buffered and normal events. - Do not initialize tracefs if tracing is disabled at boot If tracing fails to allocate or some other error is detected, tracing_disabled is set. Do not initialize tracefs in this case as it may expect data to be initialized but is not. - Free eventfs inode after an RCU grace period Currently eventfs_inodes are freed after a SRCU grace period as the iterations in the code use SRCU. There are locations that the inode may still be accessed from the VFS that uses RCU which does not have the same synchronization as SRCU. Add an RCU wait before free eventfs inodes. - Do not fail persistent and remote buffers under memory pressure As persistent and remote buffers have their own pre-allocated memory, there's no reason to check how much memory is available before created them. By checking the memory pressure, these buffers may fail to be created even though their memory is already present. - Account for subbuffer size when checking how much memory is available Before allocating a ring buffer, the size is checked against the current memory pressure of the system. But it assumes every sub-buffer is of page size. This is no longer the case. Use the actual sub-buffer size when calculating how much memory will be used. - Reject non-stack fields for synthetic stacktrace fields Stack traces are special fields and the checks currently do not do enough to make sure that the fields being processed as stack traces are indeed stack traces. Update the logic to properly detect what is or is not a stack trace. - Fix a crash in print_graph_function_event() When a tracer does not define static or default flags the tr->current_trace_flags is set to NULL. If the ring buffer is not cleared when switching tracers, the previous tracers events could be read. The function_graph entries will dereference the tr->current_trace_flags and cause a crash. Set the tr->current_trace_flags to a empty set of flags to prevent it from being NULL. - Separate tracing filter predicate count from allocation The amount allocated for the predicate program is the number of predicates defined plus two for adding "true" and "false" at the end. The nr_preds is incremented by two to accommodate the booleans but is then used as the limit check for number of predicates. This is incorrect as it is now two higher than what is expected. Use a separate variable for the size of the predicate array. - Fix the filter operator stack check The operator stack increments the pointer and then writes the content onto the stack. The check for overflow compared the current pointer to see if it was greater than the stack size before doing so. This is an off by 2 error as the write will be at the size - 1 and the compare is done before the increment. Adjust the check accordingly. * tag 'trace-v7.3-rc7' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace: tracing: Check operator stack capacity before pushing tracing: Keep the predicate limit separate from program capacity tracing: Fix crash in print_graph_function_event() tracing/histograms: Reject non-stacktrace fields for synthetic stacktrace fields ring-buffer: Use subbuf_order in available memory estimation ring-buffer: Skip si_mem_available() for persistent and remote buffers eventfs: Free the eventfs_inode after an rcu grace period too tracing: Do not initialize tracefs work if tracing is disabled tracing: Fix hist trigger timestamps for buffered events tracing: Fix ignored return value of resize_buffer_duplicate_size() ring-buffer: Fix false warning in ring_buffer_map_get_reader() tracing: Fix simple_ring_buffer undef check on sparc64 tracing: Fix simple_ring_buffer undef check on parisc tracing: Fix empty symbol names in simple_ring_buffer undef check ring-buffer: Fix the sub-buffer array base in rb_meta_subbuf_idx() tracing: Fix the shift out of bounds in the log2 histogram modifier ring-buffer: Do not show buffer_meta for CPUs without a buffer tracing: Take trace_types_lock when dropping the buffer_meta reference tracing: Fix NULL dereference when copying keys for a field variable

tracing: Check operator stack capacity before pushing

2026-10-15T22:07:15Z

predicate_parse() uses the first operator stack entry before processing any opening parentheses. A push then increments top before writing. The existing check still permits that write when top already points to the last allocated entry, which can access beyond the operator stack. Reject the push when top reaches the last allocated entry. Cc: stable@vger.kernel.org Fixes: 39f7c41c908b ("tracing/filters: Enable filtering a cpumask field by another cpumask") Link: https://patch.msgid.link/atELO9L0I9kg5CpC@Taeyangs-MacBook-Pro.local Signed-off-by: Taeyang Lee <0wn@theori.io> Signed-off-by: Steven Rostedt

tracing: Keep the predicate limit separate from program capacity

2026-10-15T22:07:06Z

predicate_parse() adds two to nr_preds to reserve the terminal TRUE and FALSE entries. It also uses that increased value as the limit for parsed predicates. If the initial count is smaller than the number actually parsed, the program can fill the allocation and subsequent accesses can go past its end. Keep nr_preds as the predicate limit and use a separate value for the allocation size. This leaves space for both terminal entries and a zeroed entry when parsing stops at the limit. Cc: stable@vger.kernel.org Fixes: 39f7c41c908b ("tracing/filters: Enable filtering a cpumask field by another cpumask") Link: https://patch.msgid.link/atELCd1XjKVhrkFL@Taeyangs-MacBook-Pro.local Signed-off-by: Taeyang Lee <0wn@theori.io> Signed-off-by: Steven Rostedt

tracing: Fix crash in print_graph_function_event()

2026-10-15T22:03:48Z

tracing_set_tracer() assigns the flags of the newly selected tracer with: tr->current_trace_flags = t->flags ? : t->tracer->flags; If the new tracer defines neither static flags nor default flags, like hwlat, irqsoff or wakeup, add_tracer() has no per instance flags copy for it, and both operands are NULL, so tr->current_trace_flags ends up being NULL as well. The ring buffer is not cleared when switching tracers: it is reset inside tracer_init(), after current_trace_flags was already assigned. If the buffer still holds function_graph entries of the previous tracer, printing one of them dereferences the NULL pointer. This was hit by cat trace during an ftrace stress test: BUG: kernel NULL pointer dereference, address: 0000000000000000 #PF: supervisor read access in kernel mode RIP: 0010:print_graph_function_event+0xe/0x20 Call Trace: s_show+0x4d/0x110 seq_read_iter+0x2d4/0x490 seq_read+0x130/0x170 vfs_read+0xb5/0x370 ksys_read+0x6d/0xe0 do_syscall_64+0xbc/0x450 The snapshot buffer is not reset at all, so this can be reproduced without a race: echo function_graph > /sys/kernel/tracing/current_tracer echo 1 > /sys/kernel/tracing/snapshot echo hwlat > /sys/kernel/tracing/current_tracer cat /sys/kernel/tracing/snapshot Rather than teaching every user of tr->current_trace_flags about this corner case, make sure it is never NULL: when the newly selected tracer has no flags at all, tracing_set_tracer() falls back to a static empty no_tracer_flags. run_tracer_selftest() can hit the same case, so the same fallback is added there too. The existing users already handle opts == NULL, so these tracers keep behaving as before. Cc: stable@vger.kernel.org Link: https://patch.msgid.link/20261015130658.221198-1-hao.ge@linux.dev Fixes: e29aa918a928 ("tracing: Have function graph tracer define options per instance") Suggested-by: Steven Rostedt Signed-off-by: Hao Ge Signed-off-by: Steven Rostedt

tracing/histograms: Reject non-stacktrace fields for synthetic stacktrace fields

2026-10-15T12:52:44Z

In check_synth_field(), when a synthetic event field is a stacktrace (field->is_stack) and the histogram field is not a "long[" stacktrace array, validation falls through to the generic size and signedness comparison. Because parse_synth_field() sets a stacktrace field's type to "__data_loc unsigned long[]", its size is sizeof(u64) and synth_field_signed() marks it as signed. Consequently, any 8-byte signed scalar histogram field passes the fallback check, and its scalar value is subsequently dereferenced as a kernel stacktrace pointer in get_field_size() and trace_stack(). Furthermore, checking strstr(hist_field->type, "long[") is insufficient because tracepoint fields defined with __bitmask() or __rel_bitmask() also have type "__data_loc unsigned long[]" or "__rel_loc unsigned long[]", whilst create_hist_field() treats them as 4-byte scalar values without HIST_FIELD_FL_STACKTRACE. Propagate HIST_FIELD_FL_STACKTRACE to variable references and field variables (whilst excluding variable aliases from per-element stacktrace capture), and reject any mismatch between HIST_FIELD_FL_STACKTRACE and field->is_stack in check_synth_field(). Cc: stable@vger.kernel.org Fixes: 00cf3d672a9d ("tracing: Allow synthetic events to pass around stacktraces") Link: https://patch.msgid.link/20261013112449.1006088-1-lee@kernel.org Signed-off-by: Lee Jones Acked-by: Masami Hiramatsu (Google) Signed-off-by: Steven Rostedt

ring-buffer: Use subbuf_order in available memory estimation

2026-10-15T12:52:26Z

To avoid failing in the middle of an allocation of a ring-buffer, __rb_allocate_pages() looks at the available memory estimation with si_mem_available(). Use the subbuffer order with this estimation to fail early if necessary for ring-buffers with an order > 0. Link: https://patch.msgid.link/20261013102047.1488347-3-vdonnefort@google.com Fixes: f9b94daa542a ("ring-buffer: Set new size of the ring buffer sub page") Reviewed-by: Masami Hiramatsu (Google) Signed-off-by: Vincent Donnefort Signed-off-by: Steven Rostedt

tracing: probes: error if BTF is required but unavailable

2026-10-15T01:09:36Z

traceprobe_expand_meta_args expands probe arguments based on BTF info. Return an error if we have arguments that need expanding but BTF is not supported. The params variable is now unused, it can be removed. Link: https://lore.kernel.org/all/20261014083838.31020-1-martin@kaiser.cx/ Fixes: d157d7694460 ("tracing/probes: Support BTF field access from $retval") Signed-off-by: Martin Kaiser Reviewed-by: Steven Rostedt Signed-off-by: Masami Hiramatsu (Google)

ring-buffer: Skip si_mem_available() for persistent and remote buffers

2026-10-14T23:03:40Z

Persistent and remote buffer memory is pre-allocated by the time __rb_allocate_pages() is called. Skip si_mem_available() to avoid wrongly failing the allocation under memory pressure. For the same reason, unset user_thread. Link: https://patch.msgid.link/20261013102047.1488347-2-vdonnefort@google.com Fixes: be68d63a139b ("ring-buffer: Add ring_buffer_alloc_range()") Fixes: 2e67fabd8b77 ("ring-buffer: Introduce ring-buffer remotes") Signed-off-by: Vincent Donnefort Signed-off-by: Steven Rostedt

tracing: Do not initialize tracefs work if tracing is disabled

2026-10-14T23:03:40Z

If trace buffer allocation fails during early boot (e.g. in early_trace_init() -> allocate_trace_buffers()), tracing_disabled is left set to 1 and the global trace array events list remains uninitialized. Later during boot, tracer_init_tracefs() (invoked via fs_initcall) queues tracerfs_init_work asynchronously without checking if tracing was disabled. When tracer_init_tracefs_work_func() runs, it calls event_trace_init() and init_tracer_tracefs(&global_trace, NULL) unconditionally. This leads to __find_event_file() dereferencing an uninitialized tr->events list, causing an early boot NULL pointer dereference Oops: BUG: Kernel NULL pointer dereference on read at 0x00000010 Faulting instruction address: 0xc000000000485be0 Oops: Kernel access of bad area, sig: 7 [#1] ... NIP [c000000000485be0] __find_event_file+0x70/0x3c0 LR [c000000000448874] init_tracer_tracefs+0x274/0xc80 Call Trace: init_tracer_tracefs+0x274/0xc80 tracer_init_tracefs_work_func+0x50/0x320 process_one_work+0x1e8/0x5c0 worker_thread+0x1dc/0x3d0 kthread+0x194/0x1b0 start_kernel_thread+0x14/0x18 Check tracing_disabled at the beginning of tracer_init_tracefs_work_func() and return immediately if tracing is disabled or failed to initialize, preventing the crash. Cc: stable@vger.kernel.org Fixes: 6621a7004684 ("tracing: make tracer_init_tracefs initcall asynchronous") Link: https://patch.msgid.link/20261009163557.88467-2-amachhiw@linux.ibm.com Reported-by: Michal Suchánek Closes: https://lore.kernel.org/all/arYskzbiaNzBR9MD@kunlun.suse.cz/ Signed-off-by: Amit Machhiwal Tested-by: Michal Suchánek Acked-by: Masami Hiramatsu (Google) Signed-off-by: Steven Rostedt

tracing: Fix hist trigger timestamps for buffered events

2026-10-14T23:03:40Z

Syzkaller triggered a WARN_ON_ONCE(!nest) warning: WARNING: kernel/trace/ring_buffer.c:821 at ring_buffer_event_time_stamp Call trace: ring_buffer_event_time_stamp hist_field_timestamp hist_fn_call event_hist_trigger event_triggers_call __event_trigger_test_discard trace_event_buffer_commit do_trace_event_raw_event_sched_switch trace_event_raw_event_sched_switch The warning is probabilistically reproducible and is related to syzkaller executing the following commands: echo 'prev_pid == 999999' > events/sched/sched_switch/filter echo 'hist:keys=common_timestamp' > events/sched/sched_switch/trigger The specific triggering process is as follows: CPU 0 CPU 1 (context switching) (echo 'hist:keys=common_timestamp' > \ events/sched/sched_switch/trigger) do_trace_event_raw_event_##call trace_event_buffer_lock_reserve if (!tr->no_filter_buffering_ref && trace_file->flags & EVENT_FILE_FL_FILTERED) return entry; // return directly event_hist_trigger_parse hist_register_trigger tracing_set_filter_buffering(file->tr, true); tr->no_filter_buffering_ref++; __trace_buffer_lock_reserve rb_start_commit local_inc(&cpu_buffer->committing); // skipped and not executed trace_event_buffer_commit __event_trigger_test_discard event_triggers_call event_hist_trigger hist_fn_call hist_field_timestamp ring_buffer_event_time_stamp nest = local_read(&cpu_buffer->committing); WARN_ON_ONCE(!nest) // trigger warning The root cause is that when an event file has a filter attached and the hist trigger has not yet been attached, trace_event_buffer_lock_reserve() writes the event into the per-CPU trace_buffered_event temp buffer instead of reserving it in the ring buffer, so cpu_buffer->committing is not incremented. When the event is later processed at commit time by a hist trigger, hist_field_timestamp() -> ring_buffer_event_time_stamp() sees a zero committing count, triggering WARN_ON_ONCE(!nest). tracing_event_time_stamp() was added by commit d8279bfc5e959 ("tracing: Add tracing_event_time_stamp() API") for exactly this case: if the event is the per-CPU trace_buffered_event, it returns the current ring buffer timestamp. But it never gained a caller. Use it in hist_field_timestamp(), so that a hist trigger that races onto a buffered event records the current time, which is only marginally later than when the event was recorded, instead of warning and recording a bogus timestamp. Cc: stable@vger.kernel.org Link: https://patch.msgid.link/20260929104015.1689921-1-wutengda@huaweicloud.com Fixes: b94bc80df648 ("tracing: Use a no_filter_buffering_ref to stop using the filter buffer") Signed-off-by: Tengda Wu Signed-off-by: Steven Rostedt