Steven Rostedt (Google) 7aeda81191 tracing: Do not free snapshot if tracer is on cmdline ... [ Upstream commit a541a9559b ] The ftrace_boot_snapshot and alloc_snapshot cmdline options allocate the snapshot buffer at boot up for use later. The ftrace_boot_snapshot in particular requires the snapshot to be allocated because it will take a snapshot at the end of boot up allowing to see the traces that happened during boot so that it's not lost when user space takes over. When a tracer is registered (started) there's a path that checks if it requires the snapshot buffer or not, and if it does not and it was allocated it will do a synchronization and free the snapshot buffer. This is only required if the previous tracer was using it for "max latency" snapshots, as it needs to make sure all max snapshots are complete before freeing. But this is only needed if the previous tracer was using the snapshot buffer for latency (like irqoff tracer and friends). But it does not make sense to free it, if the previous tracer was not using it, and the snapshot was allocated by the cmdline parameters. This basically takes away the point of allocating it in the first place! Note, the allocated snapshot worked fine for just trace events, but fails when a tracer is enabled on the cmdline. Further investigation, this goes back even further and it does not require a tracer on the cmdline to fail. Simply enable snapshots and then enable a tracer, and it will remove the snapshot. Link: https://lkml.kernel.org/r/20221005113757.041df7fe@gandalf.local.home Cc: Masami Hiramatsu <mhiramat@kernel.org> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: stable@vger.kernel.org Fixes: 45ad21ca55 ("tracing: Have trace_array keep track if snapshot buffer is allocated") Reported-by: Ross Zwisler <zwisler@kernel.org> Tested-by: Ross Zwisler <zwisler@kernel.org> Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org> Signed-off-by: Sasha Levin <sashal@kernel.org>		2022-10-29 10:12:58 +02:00
..
bpf	bpf: Ensure correct locking around vulnerable function find_vpid()	2022-10-26 12:34:44 +02:00
cgroup	cgroup/cpuset: Enable update_tasks_cpumask() on top_cpuset	2022-10-26 12:35:25 +02:00
configs
debug	lockdown: also lock down previous kgdb use	2022-05-25 09:57:37 +02:00
dma	swiotlb: max mapping size takes min align mask into account	2022-10-05 10:39:40 +02:00
entry	lockdep: Fix -Wunused-parameter for _THIS_IP_	2022-09-20 12:39:42 +02:00
events	perf/core: Fix data race between perf_event_set_output() and perf_mmap_close()	2022-07-29 17:25:11 +02:00
gcov	gcov: support GCC 12.1 and newer compilers	2022-10-26 12:35:56 +02:00
irq	irqdomain: Report irq number for NOMAP domains	2022-08-17 14:23:14 +02:00
kcsan	LKMM updates:	2021-09-02 13:00:15 -07:00
livepatch	livepatch: fix race between fork and KLP transition	2022-10-26 12:34:30 +02:00
locking	lockdep: Fix -Wunused-parameter for _THIS_IP_	2022-09-20 12:39:42 +02:00
power	PM: hibernate: defer device probing when resuming from hibernation	2022-08-17 14:23:04 +02:00
printk	printk: wake waiters for safe and NMI contexts	2022-06-09 10:22:49 +02:00
rcu	rcu-tasks: Convert RCU_LOCKDEP_WARN() to WARN_ONCE()	2022-10-26 12:35:29 +02:00
sched	lockdep: Fix -Wunused-parameter for _THIS_IP_	2022-09-20 12:39:42 +02:00
time	timekeeping: contribute wall clock to rng on time change	2022-08-17 14:24:24 +02:00
trace	tracing: Do not free snapshot if tracer is on cmdline	2022-10-29 10:12:58 +02:00
.gitignore
acct.c	kernel/acct.c: use dedicated helper to access rlimit values	2021-09-08 11:50:26 -07:00
async.c	Revert "module, async: async_synchronize_full() on module init iff async is used"	2022-02-23 12:03:07 +01:00
audit.c	audit: improve audit queue handling when "audit=1" on cmdline	2022-02-08 18:34:03 +01:00
audit.h	audit: log AUDIT_TIME_* records only from rules	2022-04-08 14:23:06 +02:00
audit_fsnotify.c	audit: fix potential double free on error path from fsnotify_add_inode_mark	2022-08-31 17:16:33 +02:00
audit_tree.c	audit: move put_tree() to avoid trim_trees refcount underflow and UAF	2021-08-24 18:52:36 -04:00
audit_watch.c
auditfilter.c
auditsc.c	audit: log AUDIT_TIME_* records only from rules	2022-04-08 14:23:06 +02:00
backtracetest.c
bounds.c
capability.c
cfi.c	cfi: Fix __cfi_slowpath_diag RCU usage with cpuidle	2022-06-22 14:22:04 +02:00
compat.c	arch: remove compat_alloc_user_space	2021-09-08 15:32:35 -07:00
configs.c
context_tracking.c
cpu.c	random: clear fast pool, crng, and batches in cpuhp bring up	2022-05-30 09:29:09 +02:00
cpu_pm.c	PM: cpu: Make notifier chain use a raw_spinlock_t	2021-08-16 18:55:32 +02:00
crash_core.c	kernel/crash_core: suppress unknown crashkernel parameter warning	2021-12-29 12:28:49 +01:00
crash_dump.c
cred.c	ucounts: Base set_cred_ucounts changes on the real user	2022-02-23 12:03:20 +01:00
delayacct.c
dma.c
exec_domain.c
exit.c	fix race between exit_itimers() and /proc/pid/timers	2022-07-21 21:24:11 +02:00
extable.c
fail_function.c
fork.c	IB/core: Fix a nested dead lock as part of ODP flow	2022-09-15 11:30:06 +02:00
freezer.c
futex.c	futex: Remove unused variable 'vpid' in futex_proxy_trylock_atomic()	2021-09-03 23:00:22 +02:00
gen_kheaders.sh
groups.c
hung_task.c
iomem.c
irq_work.c
jump_label.c	jump_label: Fix jump_label_text_reserved() vs __init	2021-07-05 10:46:20 +02:00
kallsyms.c	module: add printk formats to add module build ID to stacktraces	2021-07-08 11:48:22 -07:00
kcmp.c
Kconfig.freezer
Kconfig.hz
Kconfig.locks	locking/rwlock: Provide RT variant	2021-08-17 17:50:51 +02:00
Kconfig.preempt
kcov.c
kexec.c	kexec: avoid compat_alloc_user_space	2021-09-08 15:32:34 -07:00
kexec_core.c	Merge branch 'rework/printk_safe-removal' into for-linus	2021-08-30 16:36:10 +02:00
kexec_elf.c
kexec_file.c	ima: force signature verification when CONFIG_KEXEC_SIG is configured	2022-07-21 21:24:29 +02:00
kexec_internal.h
kheaders.c
kmod.c
kprobes.c	kprobes: Prohibit probes in gate area	2022-09-15 11:30:02 +02:00
ksysfs.c
kthread.c
latencytop.c
Makefile	static_call: Don't make __static_call_return0 static	2022-04-13 20:59:28 +02:00
module-internal.h
module.c	module: fix [e_shstrndx].sh_size=0 OOB access	2022-07-12 16:35:09 +02:00
module_signature.c
module_signing.c
notifier.c	notifier: Remove atomic_notifier_call_chain_robust()	2021-08-16 18:55:32 +02:00
nsproxy.c	memcg: enable accounting for new namesapces and struct nsproxy	2021-09-03 09:58:12 -07:00
padata.c	padata: Remove repeated verbose license text	2021-08-27 16:30:18 +08:00
panic.c	Merge branch 'rework/printk_safe-removal' into for-linus	2021-08-30 16:36:10 +02:00
params.c	params: lift param_set_uint_minmax to common code	2021-08-16 14:42:22 +02:00
pid.c	kernel/pid.c: implement additional checks upon pidfd_create() parameters	2021-08-10 12:53:07 +02:00
pid_namespace.c	memcg: enable accounting for new namesapces and struct nsproxy	2021-09-03 09:58:12 -07:00
profile.c	profiling: fix shift too large makes kernel panic	2022-08-17 14:24:04 +02:00
ptrace.c	ptrace: Reimplement PTRACE_KILL by always sending SIGKILL	2022-06-09 10:22:29 +02:00
range.c
reboot.c
regset.c
relay.c
resource.c	kernel/resource: fix kfree() of bootmem memory again	2022-04-08 14:23:43 +02:00
resource_kunit.c
rseq.c	rseq: Remove broken uapi field layout on 32-bit little endian	2022-04-08 14:23:10 +02:00
scftorture.c	scftorture: Fix distribution of short handler delays	2022-06-09 10:22:46 +02:00
scs.c	scs: Release kasan vmalloc poison in scs_free process	2021-11-18 19:16:29 +01:00
seccomp.c	seccomp: Invalidate seccomp mode to catch death failures	2022-02-16 12:56:38 +01:00
signal.c	signal handling: don't use BUG_ON() for debugging	2022-07-21 21:24:42 +02:00
smp.c	locking/csd_lock: Change csdlock_debug from early_param to __setup	2022-08-17 14:24:24 +02:00
smpboot.c	smpboot: Replace deprecated CPU-hotplug functions.	2021-08-10 14:57:42 +02:00
smpboot.h
softirq.c	genirq: Change force_irqthreads to a static key	2021-08-10 22:50:07 +02:00
stackleak.c	gcc-plugins/stackleak: Use noinstr in favor of notrace	2022-02-23 12:03:07 +01:00
stacktrace.c	stacktrace: move filter_irq_stacks() to kernel/stacktrace.c	2022-04-13 20:59:28 +02:00
static_call.c	static_call: Don't make __static_call_return0 static	2022-04-13 20:59:28 +02:00
static_call_inline.c	static_call: Don't make __static_call_return0 static	2022-04-13 20:59:28 +02:00
stop_machine.c
sys.c	ucounts: Move RLIMIT_NPROC handling after set_user	2022-02-23 12:03:20 +01:00
sys_ni.c	kernel/sys_ni: add compat entry for fadvise64_64	2022-08-31 17:16:33 +02:00
sysctl-test.c
sysctl.c	sysctl: move some boundary constants from sysctl.c to sysctl_vals	2022-07-29 17:25:11 +02:00
task_work.c
taskstats.c
test_kprobes.c
torture.c	torture: Replace deprecated CPU-hotplug functions.	2021-08-10 10:48:07 -07:00
tracepoint.c	tracepoint: Fix kerneldoc comments	2021-08-16 11:39:51 -04:00
tsacct.c	taskstats: Cleanup the use of task->exit_code	2022-01-27 11:05:35 +01:00
ucount.c	ucounts: Handle wrapping in is_ucounts_overlimit	2022-02-23 12:03:20 +01:00
uid16.c
uid16.h
umh.c
up.c
user-return-notifier.c
user.c	fs/epoll: use a per-cpu counter for user's watches count	2021-09-08 11:50:27 -07:00
user_namespace.c	ucounts: Fix systemd LimitNPROC with private users regression	2022-03-08 19:12:42 +01:00
usermode_driver.c
utsname.c
utsname_sysctl.c
watch_queue.c	watch_queue: Fix missing locking in add_watch_to_object()	2022-08-03 12:03:43 +02:00
watchdog.c	watchdog: export lockup_detector_reconfigure	2022-08-25 11:40:43 +02:00
watchdog_hld.c
workqueue.c	workqueue: don't skip lockdep work dependency in cancel_work_sync()	2022-09-28 11:11:56 +02:00
workqueue_internal.h	workqueue: Assign a color to barrier work items	2021-08-17 07:49:10 -10:00