On setting set_ftrace_pid, a extra entry generated by ftrace_pid_func()
is shown on stack trace(CONFIG_UNWINDER_FRAME_POINTER=y).
[004] ..... 68.459382: <stack trace>
=> 0xffffffffa00090af
=> ksys_read
=> __x64_sys_read
=> x64_sys_call
=> do_syscall_64
=> entry_SYSCALL_64_after_hwframe
To resolve this issue, increment skip count
in function_stack_trace_call() if pids are set.
Link: https://lore.kernel.org/linux-trace-kernel/20240528032604.6813-3-tatsuya.s2862@gmail.com
Signed-off-by: Tatsuya S <tatsuya.s2862@gmail.com>
[ Rebased to current tree ]
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
While adding comments to the function __ftrace_hash_rec_update() and
trying to describe in detail what the parameter for "filter_hash" does, I
realized that it basically does exactly the same thing (but differently)
if it is set or not!
If it is set, the idea was the ops->filter_hash was being updated, and the
code should focus on the functions that are in the ops->filter_hash and
add them. But it still had to pay attention to the functions in the
ops->notrace_hash, to ignore them.
If it was cleared, it focused on the ops->notrace_hash, and would add
functions that were not in the ops->notrace_hash but would still keep
functions in the "ops->filter_hash". Basically doing the same thing.
In reality, the __ftrace_hash_rec_update() only needs to either remove the
functions associated to the give ops (if "inc" is set) or remove them (if
"inc" is cleared). It has to pay attention to both the filter_hash and
notrace_hash regardless.
Remove the "filter_hash" parameter from __filter_hash_rec_update() and
comment the function for what it really is doing.
Link: https://lore.kernel.org/linux-trace-kernel/20240605180408.691995506@goodmis.org
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Acked-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Reviewed-by: Mark Rutland <mark.rutland@arm.com>
Tested-by: Mark Rutland <mark.rutland@arm.com>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
Cross-merge networking fixes after downstream PR.
No conflicts.
Adjacent changes:
drivers/net/ethernet/pensando/ionic/ionic_txrx.c
d9c0420999 ("ionic: Mark error paths in the data path as unlikely")
491aee894a ("ionic: fix kernel panic in XDP_TX action")
net/ipv6/ip6_fib.c
b4cb4a1391 ("net: use unrcu_pointer() helper")
b01e1c0307 ("ipv6: fix possible race in __fib6_drop_pcpu_from()")
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
When RCU-TASKS-TRACE pre-gp takes a snapshot of the current task running
on all online CPUs, no explicit ordering synchronizes properly with a
context switch. This lack of ordering can permit the new task to miss
pre-grace-period update-side accesses. The following diagram, courtesy
of Paul, shows the possible bad scenario:
CPU 0 CPU 1
----- -----
// Pre-GP update side access
WRITE_ONCE(*X, 1);
smp_mb();
r0 = rq->curr;
RCU_INIT_POINTER(rq->curr, TASK_B)
spin_unlock(rq)
rcu_read_lock_trace()
r1 = X;
/* ignore TASK_B */
Either r0==TASK_B or r1==1 is needed but neither is guaranteed.
One possible solution to solve this is to wait for an RCU grace period
at the beginning of the RCU-tasks-trace grace period before taking the
current tasks snaphot. However this would introduce large additional
latencies to RCU-tasks-trace grace periods.
Another solution is to lock the target runqueue while taking the current
task snapshot. This ensures that the update side sees the latest context
switch and subsequent context switches will see the pre-grace-period
update side accesses.
This commit therefore adds runqueue locking to cpu_curr_snapshot().
Fixes: e386b67257 ("rcu-tasks: Eliminate RCU Tasks Trace IPIs to online CPUs")
Signed-off-by: Frederic Weisbecker <frederic@kernel.org>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
Fix the following 'make W=1' warnings:
WARNING: modpost: missing MODULE_DESCRIPTION() in kernel/rcu/rcutorture.o
WARNING: modpost: missing MODULE_DESCRIPTION() in kernel/rcu/rcuscale.o
WARNING: modpost: missing MODULE_DESCRIPTION() in kernel/rcu/refscale.o
Signed-off-by: Jeff Johnson <quic_jjohnson@quicinc.com>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
On powerpc systems, spinlock acquisition does not order prior stores
against later loads. This means that this statement:
rfcp->rfc_next = NULL;
Can be reordered to follow this statement:
WRITE_ONCE(*rfcpp, rfcp);
Which is then a data race with rcu_torture_fwd_prog_cr(), specifically,
this statement:
rfcpn = READ_ONCE(rfcp->rfc_next)
KCSAN located this data race, which represents a real failure on powerpc.
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
Acked-by: Marco Elver <elver@google.com>
Cc: Andrey Konovalov <andreyknvl@gmail.com>
Cc: <kasan-dev@googlegroups.com>
Fix the warning reported by 'make C=1 W=1':
WARNING: modpost: missing MODULE_DESCRIPTION() in kernel/kcsan/kcsan_test.o
Signed-off-by: Jeff Johnson <quic_jjohnson@quicinc.com>
Reviewed-by: Marco Elver <elver@google.com>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
Pull networking fixes from Jakub Kicinski:
"Including fixes from BPF and big collection of fixes for WiFi core and
drivers.
Current release - regressions:
- vxlan: fix regression when dropping packets due to invalid src
addresses
- bpf: fix a potential use-after-free in bpf_link_free()
- xdp: revert support for redirect to any xsk socket bound to the
same UMEM as it can result in a corruption
- virtio_net:
- add missing lock protection when reading return code from
control_buf
- fix false-positive lockdep splat in DIM
- Revert "wifi: wilc1000: convert list management to RCU"
- wifi: ath11k: fix error path in ath11k_pcic_ext_irq_config
Previous releases - regressions:
- rtnetlink: make the "split" NLM_DONE handling generic, restore the
old behavior for two cases where we started coalescing those
messages with normal messages, breaking sloppily-coded userspace
- wifi:
- cfg80211: validate HE operation element parsing
- cfg80211: fix 6 GHz scan request building
- mt76: mt7615: add missing chanctx ops
- ath11k: move power type check to ASSOC stage, fix connecting to
6 GHz AP
- ath11k: fix WCN6750 firmware crash caused by 17 num_vdevs
- rtlwifi: ignore IEEE80211_CONF_CHANGE_RETRY_LIMITS
- iwlwifi: mvm: fix a crash on 7265
Previous releases - always broken:
- ncsi: prevent multi-threaded channel probing, a spec violation
- vmxnet3: disable rx data ring on dma allocation failure
- ethtool: init tsinfo stats if requested, prevent unintentionally
reporting all-zero stats on devices which don't implement any
- dst_cache: fix possible races in less common IPv6 features
- tcp: auth: don't consider TCP_CLOSE to be in TCP_AO_ESTABLISHED
- ax25: fix two refcounting bugs
- eth: ionic: fix kernel panic in XDP_TX action
Misc:
- tcp: count CLOSE-WAIT sockets for TCP_MIB_CURRESTAB"
* tag 'net-6.10-rc3' of git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net: (107 commits)
selftests: net: lib: set 'i' as local
selftests: net: lib: avoid error removing empty netns name
selftests: net: lib: support errexit with busywait
net: ethtool: fix the error condition in ethtool_get_phy_stats_ethtool()
ipv6: fix possible race in __fib6_drop_pcpu_from()
af_unix: Annotate data-race of sk->sk_shutdown in sk_diag_fill().
af_unix: Use skb_queue_len_lockless() in sk_diag_show_rqlen().
af_unix: Use skb_queue_empty_lockless() in unix_release_sock().
af_unix: Use unix_recvq_full_lockless() in unix_stream_connect().
af_unix: Annotate data-race of net->unx.sysctl_max_dgram_qlen.
af_unix: Annotate data-races around sk->sk_sndbuf.
af_unix: Annotate data-races around sk->sk_state in UNIX_DIAG.
af_unix: Annotate data-race of sk->sk_state in unix_stream_read_skb().
af_unix: Annotate data-races around sk->sk_state in sendmsg() and recvmsg().
af_unix: Annotate data-race of sk->sk_state in unix_accept().
af_unix: Annotate data-race of sk->sk_state in unix_stream_connect().
af_unix: Annotate data-races around sk->sk_state in unix_write_space() and poll().
af_unix: Annotate data-race of sk->sk_state in unix_inq_len().
af_unix: Annodate data-races around sk->sk_state for writers.
af_unix: Set sk->sk_state under unix_state_lock() for truly disconencted peer.
...
We observed that the overhead on trigger_load_balance(), now renamed
sched_balance_trigger(), has risen with a system's core counts.
For an OLTP workload running 6.8 kernel on a 2 socket x86 systems
having 96 cores/socket, we saw that 0.7% cpu cycles are spent in
trigger_load_balance(). On older systems with fewer cores/socket, this
function's overhead was less than 0.1%.
The cause of this overhead was that there are multiple cpus calling
kick_ilb(flags), updating the balancing work needed to a common idle
load balancer cpu. The ilb_cpu's flags field got updated unconditionally
with atomic_fetch_or(). The atomic read and writes to ilb_cpu's flags
causes much cache bouncing and cpu cycles overhead. This is seen in the
annotated profile below.
kick_ilb():
if (ilb_cpu < 0)
test %r14d,%r14d
↑ js 6c
flags = atomic_fetch_or(flags, nohz_flags(ilb_cpu));
mov $0x2d600,%rdi
movslq %r14d,%r8
mov %rdi,%rdx
add -0x7dd0c3e0(,%r8,8),%rdx
arch_atomic_read():
0.01 mov 0x64(%rdx),%esi
35.58 add $0x64,%rdx
arch_atomic_fetch_or():
static __always_inline int arch_atomic_fetch_or(int i, atomic_t *v)
{
int val = arch_atomic_read(v);
do { } while (!arch_atomic_try_cmpxchg(v, &val, val | i));
0.03 157: mov %r12d,%ecx
arch_atomic_try_cmpxchg():
return arch_try_cmpxchg(&v->counter, old, new);
0.00 mov %esi,%eax
arch_atomic_fetch_or():
do { } while (!arch_atomic_try_cmpxchg(v, &val, val | i));
or %esi,%ecx
arch_atomic_try_cmpxchg():
return arch_try_cmpxchg(&v->counter, old, new);
0.01 lock cmpxchg %ecx,(%rdx)
42.96 ↓ jne 2d2
kick_ilb():
With instrumentation, we found that 81% of the updates do not result in
any change in the ilb_cpu's flags. That is, multiple cpus are asking
the ilb_cpu to do the same things over and over again, before the ilb_cpu
has a chance to run NOHZ load balance.
Skip updates to ilb_cpu's flags if no new work needs to be done.
Such updates do not change ilb_cpu's NOHZ flags. This requires an extra
atomic read but it is less expensive than frequent unnecessary atomic
updates that generate cache bounces.
We saw that on the OLTP workload, cpu cycles from trigger_load_balance()
(or sched_balance_trigger()) got reduced from 0.7% to 0.2%.
Signed-off-by: Tim Chen <tim.c.chen@linux.intel.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Chen Yu <yu.c.chen@intel.com>
Reviewed-by: Vincent Guittot <vincent.guittot@linaro.org>
Link: https://lore.kernel.org/r/20240531205452.65781-1-tim.c.chen@linux.intel.com
In our production environment, we found many hung tasks which are
blocked for more than 18 hours. Their call traces are like this:
[346278.191038] __schedule+0x2d8/0x890
[346278.191046] schedule+0x4e/0xb0
[346278.191049] perf_event_free_task+0x220/0x270
[346278.191056] ? init_wait_var_entry+0x50/0x50
[346278.191060] copy_process+0x663/0x18d0
[346278.191068] kernel_clone+0x9d/0x3d0
[346278.191072] __do_sys_clone+0x5d/0x80
[346278.191076] __x64_sys_clone+0x25/0x30
[346278.191079] do_syscall_64+0x5c/0xc0
[346278.191083] ? syscall_exit_to_user_mode+0x27/0x50
[346278.191086] ? do_syscall_64+0x69/0xc0
[346278.191088] ? irqentry_exit_to_user_mode+0x9/0x20
[346278.191092] ? irqentry_exit+0x19/0x30
[346278.191095] ? exc_page_fault+0x89/0x160
[346278.191097] ? asm_exc_page_fault+0x8/0x30
[346278.191102] entry_SYSCALL_64_after_hwframe+0x44/0xae
The task was waiting for the refcount become to 1, but from the vmcore,
we found the refcount has already been 1. It seems that the task didn't
get woken up by perf_event_release_kernel() and got stuck forever. The
below scenario may cause the problem.
Thread A Thread B
... ...
perf_event_free_task perf_event_release_kernel
...
acquire event->child_mutex
...
get_ctx
... release event->child_mutex
acquire ctx->mutex
...
perf_free_event (acquire/release event->child_mutex)
...
release ctx->mutex
wait_var_event
acquire ctx->mutex
acquire event->child_mutex
# move existing events to free_list
release event->child_mutex
release ctx->mutex
put_ctx
... ...
In this case, all events of the ctx have been freed, so we couldn't
find the ctx in free_list and Thread A will miss the wakeup. It's thus
necessary to add a wakeup after dropping the reference.
Fixes: 1cf8dfe8a6 ("perf/core: Fix race between close() and fork()")
Signed-off-by: Haifeng Xu <haifeng.xu@shopee.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Frederic Weisbecker <frederic@kernel.org>
Acked-by: Mark Rutland <mark.rutland@arm.com>
Cc: stable@vger.kernel.org
Link: https://lkml.kernel.org/r/20240513103948.33570-1-haifeng.xu@shopee.com
There's a random number of structure pre-declaration lines in
kernel/sched/sched.h, some of which are unnecessary duplicates.
Move them to the head & order them a bit for readability.
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: linux-kernel@vger.kernel.org
There are cases where a single system will use a single function callback
to handle multiple users. For example, to allow function_graph tracer to
have multiple users where each can trace their own set of functions, it is
useful to only have one ftrace_ops registered to ftrace that will call a
function by the function_graph tracer to handle the multiplexing with the
different registered function_graph tracers.
Add a "subop_list" to the ftrace_ops that will hold a list of other
ftrace_ops that the top ftrace_ops will manage.
The function ftrace_startup_subops() that takes the manager ftrace_ops and
a subop ftrace_ops it will manage. If there are no subops with the
ftrace_ops yet, it will copy the ftrace_ops subop filters to the manager
ftrace_ops and register that with ftrace_startup(), and adds the subop to
its subop_list. If the manager ops already has something registered, it
will then merge the new subop filters with what it has and enable the new
functions that covers all the subops it has.
To remove a subop, ftrace_shutdown_subops() is called which will use the
subop_list of the manager ops to rebuild all the functions it needs to
trace, and update the ftrace records to only call the functions it now has
registered. If there are no more functions registered, it will then call
ftrace_shutdown() to disable itself completely.
Note, it is up to the manager ops callback to always make sure that the
subops callbacks are called if its filter matches, as there are times in
the update where the callback could be calling more functions than those
that are currently registered.
This could be updated to handle other systems other than function_graph,
for example, fprobes could use this (but will need an interface to call
ftrace_startup_subops()).
Link: https://lore.kernel.org/linux-trace-kernel/20240603190822.508431129@goodmis.org
Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Alexei Starovoitov <alexei.starovoitov@gmail.com>
Cc: Florent Revest <revest@chromium.org>
Cc: Martin KaFai Lau <martin.lau@linux.dev>
Cc: bpf <bpf@vger.kernel.org>
Cc: Sven Schnelle <svens@linux.ibm.com>
Cc: Alexei Starovoitov <ast@kernel.org>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Arnaldo Carvalho de Melo <acme@kernel.org>
Cc: Daniel Borkmann <daniel@iogearbox.net>
Cc: Alan Maguire <alan.maguire@oracle.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Guo Ren <guoren@kernel.org>
Reviewed-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
Allow for multiple users to attach to function graph tracer at the same
time. Only 16 simultaneous users can attach to the tracer. This is because
there's an array that stores the pointers to the attached fgraph_ops. When
a function being traced is entered, each of the ftrace_ops entryfunc is
called and if it returns non zero, its index into the array will be added
to the shadow stack.
On exit of the function being traced, the shadow stack will contain the
indexes of the ftrace_ops on the array that want their retfunc to be
called.
Because a function may sleep for a long time (if a task sleeps itself),
the return of the function may be literally days later. If the ftrace_ops
is removed, its place on the array is replaced with a ftrace_ops that
contains the stub functions and that will be called when the function
finally returns.
If another ftrace_ops is added that happens to get the same index into the
array, its return function may be called. But that's actually the way
things current work with the old function graph tracer. If one tracer is
removed and another is added, the new one will get the return calls of the
function traced by the previous one, thus this is not a regression. This
can be fixed by adding a counter to each time the array item is updated and
save that on the shadow stack as well, such that it won't be called if the
index saved does not match the index on the array.
Note, being able to filter functions when both are called is not completely
handled yet, but that shouldn't be too hard to manage.
Co-developed with Masami Hiramatsu:
Link: https://lore.kernel.org/linux-trace-kernel/171509096221.162236.8806372072523195752.stgit@devnote2
Link: https://lore.kernel.org/linux-trace-kernel/20240603190821.555493396@goodmis.org
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Alexei Starovoitov <alexei.starovoitov@gmail.com>
Cc: Florent Revest <revest@chromium.org>
Cc: Martin KaFai Lau <martin.lau@linux.dev>
Cc: bpf <bpf@vger.kernel.org>
Cc: Sven Schnelle <svens@linux.ibm.com>
Cc: Alexei Starovoitov <ast@kernel.org>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Arnaldo Carvalho de Melo <acme@kernel.org>
Cc: Daniel Borkmann <daniel@iogearbox.net>
Cc: Alan Maguire <alan.maguire@oracle.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Guo Ren <guoren@kernel.org>
Reviewed-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Signed-off-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
