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When reducing ring buffer size, pages are removed by scheduling a work
item on each CPU for the corresponding CPU ring buffer. After the pages
are removed from ring buffer linked list, the pages are free()d in a
tight loop. The loop does not give up CPU until all pages are removed.
In a worst case behavior, when lot of pages are to be freed, it can
cause system stall.
After the pages are removed from the list, the free() can happen while
the work is rescheduled. Call cond_resched() in the loop to prevent the
system hangup.
Link: http://lkml.kernel.org/r/20180907223129.71994-1-vnagarnaik@google.com
Cc: stable@vger.kernel.org
Fixes: 83f40318dab00 ("ring-buffer: Make removal of ring buffer pages atomic")
Reported-by: Jason Behmer <jbehmer@google.com>
Signed-off-by: Vaibhav Nagarnaik <vnagarnaik@google.com>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
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git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace
Pull tracing fixes from Steven Rostedt:
"Masami found an off by one bug in the code that keeps "notrace"
functions from being traced by kprobes. During my testing, I found
that there's places that we may want to add kprobes to notrace, thus
we may end up changing this code before 4.19 is released.
The history behind this change is that we found that adding kprobes to
various notrace functions caused the kernel to crashed. We took the
safe route and decided not to allow kprobes to trace any notrace
function.
But because notrace is added to functions that just cause weird side
effects to the function tracer, but are still safe, preventing kprobes
for all notrace functios may be too much of a big hammer.
One such place is __schedule() is marked notrace, to keep function
tracer from doing strange recursive loops when it gets traced with
NEED_RESCHED set. With this change, one can not add kprobes to the
scheduler.
Masami also added code to use gcov on ftrace"
* tag 'trace-v4.19-1' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace:
tracing/kprobes: Fix to check notrace function with correct range
tracing: Allow gcov profiling on only ftrace subsystem
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Fix within_notrace_func() to check notrace function correctly.
Since the ftrace_location_range(start, end) function checks
the range inclusively (start <= ftrace-loc <= end), the end
address must not include the entry address of next function.
However, within_notrace_func() uses kallsyms_lookup_size_offset()
to get the function size and calculate the end address from
adding the size to the entry address. This means the end address
is the entry address of the next function.
In the result, within_notrace_func() fails to find notrace
function if the next function of the target function is
ftraced.
Let's subtract 1 from the end address so that ftrace_location_range()
can check it correctly.
Link: http://lkml.kernel.org/r/153485669706.16611.17726752296213785504.stgit@devbox
Fixes: commit 45408c4f9250 ("tracing: kprobes: Prohibit probing on notrace function")
Reported-by: Michael Rodin <michael@rodin.online>
Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
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Add GCOV_PROFILE_FTRACE to allow gcov profiling on only files in ftrace
subsystem. This config option will be used for checking kselftest/ftrace
coverage.
Link: http://lkml.kernel.org/r/153483647755.32472.4746349899604275441.stgit@devbox
Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
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Pull more block updates from Jens Axboe:
- Set of bcache fixes and changes (Coly)
- The flush warn fix (me)
- Small series of BFQ fixes (Paolo)
- wbt hang fix (Ming)
- blktrace fix (Steven)
- blk-mq hardware queue count update fix (Jianchao)
- Various little fixes
* tag 'for-4.19/post-20180822' of git://git.kernel.dk/linux-block: (31 commits)
block/DAC960.c: make some arrays static const, shrinks object size
blk-mq: sync the update nr_hw_queues with blk_mq_queue_tag_busy_iter
blk-mq: init hctx sched after update ctx and hctx mapping
block: remove duplicate initialization
tracing/blktrace: Fix to allow setting same value
pktcdvd: fix setting of 'ret' error return for a few cases
block: change return type to bool
block, bfq: return nbytes and not zero from struct cftype .write() method
block, bfq: improve code of bfq_bfqq_charge_time
block, bfq: reduce write overcharge
block, bfq: always update the budget of an entity when needed
block, bfq: readd missing reset of parent-entity service
blk-wbt: fix IO hang in wbt_wait()
block: don't warn for flush on read-only device
bcache: add the missing comments for smp_mb()/smp_wmb()
bcache: remove unnecessary space before ioctl function pointer arguments
bcache: add missing SPDX header
bcache: move open brace at end of function definitions to next line
bcache: add static const prefix to char * array declarations
bcache: fix code comments style
...
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Masami Hiramatsu reported:
Current trace-enable attribute in sysfs returns an error
if user writes the same setting value as current one,
e.g.
# cat /sys/block/sda/trace/enable
0
# echo 0 > /sys/block/sda/trace/enable
bash: echo: write error: Invalid argument
# echo 1 > /sys/block/sda/trace/enable
# echo 1 > /sys/block/sda/trace/enable
bash: echo: write error: Device or resource busy
But this is not a preferred behavior, it should ignore
if new setting is same as current one. This fixes the
problem as below.
# cat /sys/block/sda/trace/enable
0
# echo 0 > /sys/block/sda/trace/enable
# echo 1 > /sys/block/sda/trace/enable
# echo 1 > /sys/block/sda/trace/enable
Link: http://lkml.kernel.org/r/20180816103802.08678002@gandalf.local.home
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: linux-block@vger.kernel.org
Cc: stable@vger.kernel.org
Fixes: cd649b8bb830d ("blktrace: remove sysfs_blk_trace_enable_show/store()")
Reported-by: Masami Hiramatsu <mhiramat@kernel.org>
Tested-by: Masami Hiramatsu <mhiramat@kernel.org>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace
Pull tracing updates from Steven Rostedt:
- Restructure of lockdep and latency tracers
This is the biggest change. Joel Fernandes restructured the hooks
from irqs and preemption disabling and enabling. He got rid of a lot
of the preprocessor #ifdef mess that they caused.
He turned both lockdep and the latency tracers to use trace events
inserted in the preempt/irqs disabling paths. But unfortunately,
these started to cause issues in corner cases. Thus, parts of the
code was reverted back to where lockdep and the latency tracers just
get called directly (without using the trace events). But because the
original change cleaned up the code very nicely we kept that, as well
as the trace events for preempt and irqs disabling, but they are
limited to not being called in NMIs.
- Have trace events use SRCU for "rcu idle" calls. This was required
for the preempt/irqs off trace events. But it also had to not allow
them to be called in NMI context. Waiting till Paul makes an NMI safe
SRCU API.
- New notrace SRCU API to allow trace events to use SRCU.
- Addition of mcount-nop option support
- SPDX headers replacing GPL templates.
- Various other fixes and clean ups.
- Some fixes are marked for stable, but were not fully tested before
the merge window opened.
* tag 'trace-v4.19' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace: (44 commits)
tracing: Fix SPDX format headers to use C++ style comments
tracing: Add SPDX License format tags to tracing files
tracing: Add SPDX License format to bpf_trace.c
blktrace: Add SPDX License format header
s390/ftrace: Add -mfentry and -mnop-mcount support
tracing: Add -mcount-nop option support
tracing: Avoid calling cc-option -mrecord-mcount for every Makefile
tracing: Handle CC_FLAGS_FTRACE more accurately
Uprobe: Additional argument arch_uprobe to uprobe_write_opcode()
Uprobes: Simplify uprobe_register() body
tracepoints: Free early tracepoints after RCU is initialized
uprobes: Use synchronize_rcu() not synchronize_sched()
tracing: Fix synchronizing to event changes with tracepoint_synchronize_unregister()
ftrace: Remove unused pointer ftrace_swapper_pid
tracing: More reverting of "tracing: Centralize preemptirq tracepoints and unify their usage"
tracing/irqsoff: Handle preempt_count for different configs
tracing: Partial revert of "tracing: Centralize preemptirq tracepoints and unify their usage"
tracing: irqsoff: Account for additional preempt_disable
trace: Use rcu_dereference_raw for hooks from trace-event subsystem
tracing/kprobes: Fix within_notrace_func() to check only notrace functions
...
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The Linux kernel adopted the SPDX License format headers to ease license
compliance management, and uses the C++ '//' style comments for the SPDX
header tags. Some files in the tracing directory used the C style /* */
comments for them. To be consistent across all files, replace the /* */
C style SPDX tags with the C++ // SPDX tags.
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
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Add the SPDX License header to ease license compliance management.
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
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Add the SPDX License header to ease license compliance management.
Acked-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
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Add the SPDX License header to ease license compliance management.
Acked-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
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-mcount-nop gcc option generates the calls to the profiling functions
as nops which allows to avoid patching mcount jump with NOP instructions
initially.
-mcount-nop gcc option will be activated if platform selects
HAVE_NOP_MCOUNT and gcc actually supports it.
In addition to that CC_USING_NOP_MCOUNT is defined and could be used by
architectures to adapt ftrace patching behavior.
Link: http://lkml.kernel.org/r/patch-3.thread-aa7b8d.git-e02ed2dc082b.your-ad-here.call-01533557518-ext-9465@work.hours
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
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While debugging another bug, I was looking at all the synchronize*()
functions being used in kernel/trace, and noticed that trace_uprobes was
using synchronize_sched(), with a comment to synchronize with
{u,ret}_probe_trace_func(). When looking at those functions, the data is
protected with "rcu_read_lock()" and not with "rcu_read_lock_sched()". This
is using the wrong synchronize_*() function.
Link: http://lkml.kernel.org/r/20180809160553.469e1e32@gandalf.local.home
Cc: stable@vger.kernel.org
Fixes: 70ed91c6ec7f8 ("tracing/uprobes: Support ftrace_event_file base multibuffer")
Acked-by: Oleg Nesterov <oleg@redhat.com>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
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tracepoint_synchronize_unregister()
Now that some trace events can be protected by srcu_read_lock(tracepoint_srcu),
we need to make sure all locations that depend on this are also protected.
There were many places that did a synchronize_sched() thinking that it was
enough to protect againts access to trace events. This use to be the case,
but now that we use SRCU for _rcuidle() trace events, they may not be
protected by synchronize_sched(), as they may be called in paths that RCU is
not watching for preempt disable.
Fixes: e6753f23d961d ("tracepoint: Make rcuidle tracepoint callers use SRCU")
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
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Pointer ftrace_swapper_pid is defined but is never used hence it is
redundant and can be removed. The use of this variable was removed
in commit 345ddcc882d8 ("ftrace: Have set_ftrace_pid use the bitmap
like events do").
Cleans up clang warning:
warning: 'ftrace_swapper_pid' defined but not used [-Wunused-const-variable=]
Link: http://lkml.kernel.org/r/20180809125609.13142-1-colin.king@canonical.com
Signed-off-by: Colin Ian King <colin.king@canonical.com>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
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unify their usage"
Joel Fernandes created a nice patch that cleaned up the duplicate hooks used
by lockdep and irqsoff latency tracer. It made both use tracepoints. But the
latency tracer is triggering warnings when using tracepoints to call into
the latency tracer's routines. Mainly, they can be called from NMI context.
If that happens, then the SRCU may not work properly because on some
architectures, SRCU is not safe to be called in both NMI and non-NMI
context.
This is a partial revert of the clean up patch c3bc8fd637a9 ("tracing:
Centralize preemptirq tracepoints and unify their usage") that adds back the
direct calls into the latency tracer. It also only calls the trace events
when not in NMI.
Link: http://lkml.kernel.org/r/20180809210654.622445925@goodmis.org
Reviewed-by: Joel Fernandes (Google) <joel@joelfernandes.org>
Fixes: c3bc8fd637a9 ("tracing: Centralize preemptirq tracepoints and unify their usage")
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
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I was hitting the following warning:
WARNING: CPU: 0 PID: 1 at kernel/trace/trace_irqsoff.c:631 tracer_hardirqs_off+0x15/0x2a
Modules linked in:
CPU: 0 PID: 1 Comm: swapper/0 Not tainted 4.18.0-rc6-test+ #13
Hardware name: MSI MS-7823/CSM-H87M-G43 (MS-7823), BIOS V1.6 02/22/2014
EIP: tracer_hardirqs_off+0x15/0x2a
Code: ff 85 c0 74 0e 8b 45 00 8b 50 04 8b 45 04 e8 35 ff ff ff 5d c3 55 64 a1 cc 37 51 c1 a9 ff ff ff 7f 89 e5 53 89 d3 89 ca 75 02 <0f> 0b e8 90 fc ff ff 85 c0 74 07 89 d8 e8 0c ff ff ff 5b 5d c3 55
EAX: 80000000 EBX: c04337f0 ECX: c04338e3 EDX: c04338e3
ESI: c04337f0 EDI: c04338e3 EBP: f2aa1d68 ESP: f2aa1d64
DS: 007b ES: 007b FS: 00d8 GS: 00e0 SS: 0068 EFLAGS: 00210046
CR0: 80050033 CR2: 00000000 CR3: 01668000 CR4: 001406f0
Call Trace:
trace_irq_disable_rcuidle+0x63/0x6c
trace_hardirqs_off+0x26/0x30
default_send_IPI_mask_allbutself_logical+0x31/0x93
default_send_IPI_allbutself+0x37/0x48
native_send_call_func_ipi+0x4d/0x6a
smp_call_function_many+0x165/0x19d
? add_nops+0x34/0x34
? trace_hardirqs_on_caller+0x2d/0x2d
? add_nops+0x34/0x34
smp_call_function+0x1f/0x23
on_each_cpu+0x15/0x43
? trace_hardirqs_on_caller+0x2d/0x2d
? trace_hardirqs_on_caller+0x2d/0x2d
? trace_irq_disable_rcuidle+0x1/0x6c
text_poke_bp+0xa0/0xc2
? trace_hardirqs_on_caller+0x2d/0x2d
arch_jump_label_transform+0xa7/0xcb
? trace_irq_disable_rcuidle+0x5/0x6c
__jump_label_update+0x3e/0x6d
jump_label_update+0x7d/0x81
static_key_slow_inc_cpuslocked+0x58/0x6d
static_key_slow_inc+0x19/0x20
tracepoint_probe_register_prio+0x19e/0x1d1
? start_critical_timings+0x1c/0x1c
tracepoint_probe_register+0xf/0x11
irqsoff_tracer_init+0x21/0xf2
tracer_init+0x16/0x1a
trace_selftest_startup_irqsoff+0x25/0xc4
run_tracer_selftest+0xca/0x131
register_tracer+0xd5/0x172
? trace_event_define_fields_preemptirq_template+0x45/0x45
init_irqsoff_tracer+0xd/0x11
do_one_initcall+0xab/0x1e8
? rcu_read_lock_sched_held+0x3d/0x44
? trace_initcall_level+0x52/0x86
kernel_init_freeable+0x195/0x21a
? rest_init+0xb4/0xb4
kernel_init+0xd/0xe4
ret_from_fork+0x2e/0x38
It is due to running a CONFIG_PREEMPT_VOLUNTARY kernel, which would trigger
this warning every time:
WARN_ON_ONCE(preempt_count());
Because on CONFIG_PREEMPT_VOLUNTARY, preempt_count() is always zero.
This warning is to make sure preempt_count is set because
tracer_hardirqs_on() does a preempt_enable_notrace() to make the
preempt_trace() work properly, as being called by a trace event, the trace
event code disables preemption, and the tracer wants to know what the
preemption was before it was called.
Instead of enabling preemption like this, just record the preempt_count,
subtract PREEMPT_DISABLE_OFFSET from it (which is zero with !CONFIG_PREEMPT
set), and pass that value to the necessary functions, which should use the
passed in parameter instead of calling preempt_count() directly.
Fixes: da5b3ebb45277 ("tracing: irqsoff: Account for additional preempt_disable")
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
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unify their usage"
Joel Fernandes created a nice patch that cleaned up the duplicate hooks used
by lockdep and irqsoff latency tracer. It made both use tracepoints. But it
caused lockdep to trigger several false positives. We have not figured out
why yet, but removing lockdep from using the trace event hooks and just call
its helper functions directly (like it use to), makes the problem go away.
This is a partial revert of the clean up patch c3bc8fd637a9 ("tracing:
Centralize preemptirq tracepoints and unify their usage") that adds direct
calls for lockdep, but also keeps most of the clean up done to get rid of
the horrible preprocessor if statements.
Link: http://lkml.kernel.org/r/20180806155058.5ee875f4@gandalf.local.home
Cc: Peter Zijlstra <peterz@infradead.org>
Reviewed-by: Joel Fernandes (Google) <joel@joelfernandes.org>
Fixes: c3bc8fd637a9 ("tracing: Centralize preemptirq tracepoints and unify their usage")
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
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Recently we tried to make the preemptirqsoff tracer to use irqsoff
tracepoint probes. However this causes issues as reported by Masami:
[2.271078] Testing tracer preemptirqsoff: .. no entries found ..FAILED!
[2.381015] WARNING: CPU: 0 PID: 1 at /home/mhiramat/ksrc/linux/kernel/
trace/trace.c:1512 run_tracer_selftest+0xf3/0x154
This is due to the tracepoint code increasing the preempt nesting count
by calling an additional preempt_disable before calling into the
preemptoff tracer which messes up the preempt_count() check in
tracer_hardirqs_off.
To fix this, make the irqsoff tracer probes balance the additional outer
preempt_disable with a preempt_enable_notrace.
The other way to fix this is to just use SRCU for all tracepoints.
However we can't do that because we can't use NMIs from RCU context.
Link: http://lkml.kernel.org/r/20180806034049.67949-1-joel@joelfernandes.org
Fixes: c3bc8fd637a9 ("tracing: Centralize preemptirq tracepoints and unify their usage")
Fixes: e6753f23d961 ("tracepoint: Make rcuidle tracepoint callers use SRCU")
Reported-by: Masami Hiramatsu <mhiramat@kernel.org>
Tested-by: Masami Hiramatsu <mhiramat@kernel.org>
Signed-off-by: Joel Fernandes (Google) <joel@joelfernandes.org>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
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Since we switched to using SRCU for tracepoints used in the idle path,
we can no longer use rcu_dereference_sched for dereferencing points in
trace-event hooks.
Since tracepoints can now use either SRCU or sched-RCU, just use
rcu_dereference_raw for traceevents just like we're doing when
dereferencing the tracepoint table.
This prevents an RCU warning reported by Masami:
[ 282.060593] WARNING: can't dereference registers at 00000000f3c7f62b
[ 282.063200] =============================
[ 282.064082] WARNING: suspicious RCU usage
[ 282.064963] 4.18.0-rc6+ #15 Tainted: G W
[ 282.066048] -----------------------------
[ 282.066923] /home/mhiramat/ksrc/linux/kernel/trace/trace_events.c:242
suspicious rcu_dereference_check() usage!
[ 282.068974]
[ 282.068974] other info that might help us debug this:
[ 282.068974]
[ 282.070770]
[ 282.070770] RCU used illegally from idle CPU!
[ 282.070770] rcu_scheduler_active = 2, debug_locks = 1
[ 282.072938] RCU used illegally from extended quiescent state!
[ 282.074183] no locks held by swapper/0/0.
[ 282.075071]
[ 282.075071] stack backtrace:
[ 282.076121] CPU: 0 PID: 0 Comm: swapper/0 Tainted: G W
[ 282.077782] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996)
[ 282.079604] Call Trace:
[ 282.080212] <IRQ>
[ 282.080755] dump_stack+0x85/0xcb
[ 282.081523] trace_event_ignore_this_pid+0x66/0x70
[ 282.082541] trace_event_raw_event_preemptirq_template+0xa2/0xb0
[ 282.083774] ? interrupt_entry+0xc4/0xe0
[ 282.084665] ? trace_hardirqs_off_thunk+0x1a/0x1c
[ 282.085669] trace_hardirqs_off_caller+0x90/0xd0
[ 282.086597] trace_hardirqs_off_thunk+0x1a/0x1c
[ 282.087433] ? call_function_interrupt+0xa/0x20
[ 282.088201] interrupt_entry+0xc4/0xe0
[ 282.088848] ? call_function_interrupt+0xa/0x20
[ 282.089579] </IRQ>
[ 282.090029] ? native_safe_halt+0x2/0x10
[ 282.090695] ? default_idle+0x1f/0x160
[ 282.091330] ? default_idle_call+0x24/0x40
[ 282.091997] ? do_idle+0x210/0x250
[ 282.092658] ? cpu_startup_entry+0x6f/0x80
[ 282.093338] ? start_kernel+0x49d/0x4bd
[ 282.093987] ? secondary_startup_64+0xa5/0xb0
Link: http://lkml.kernel.org/r/20180803023407.225852-1-joel@joelfernandes.org
Reported-by: Masami Hiramatsu <mhiramat@kernel.org>
Tested-by: Masami Hiramatsu <mhiramat@kernel.org>
Fixes: e6753f23d961 ("tracepoint: Make rcuidle tracepoint callers use SRCU")
Signed-off-by: Joel Fernandes (Google) <joel@joelfernandes.org>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
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Fix within_notrace_func() to check only notrace functions and to ignore the
kprobe-event which can not solve symbol addresses.
within_notrace_func() returns true if the given kprobe events probe point
seems to be out-of-range. But that is not the correct place to check for it,
it should be done in kprobes afterwards.
kprobe-events allow users to define a probe point on "currently unloaded
module" so that it can trace the event during module load. In this case, the
user will put a probe on a symbol which is not in kallsyms yet and it hits
the within_notrace_func(). As a result, kprobe-events always refuses if
user defines a probe on a "currenly unloaded module".
Fixes: commit 45408c4f9250 ("tracing: kprobes: Prohibit probing on notrace function")
Link: http://lkml.kernel.org/r/153319624799.29007.13604430345640129926.stgit@devbox
Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
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Return statements in functions returning bool should use true or false
instead of an integer value.
This code was detected with the help of Coccinelle.
Link: http://lkml.kernel.org/r/20180802010056.GA31012@embeddedor.com
Signed-off-by: Gustavo A. R. Silva <gustavo@embeddedor.com>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
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The value of ring_buffer_record_is_set_on() is either true or false, so have
its return value be bool.
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
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The value of ring_buffer_record_is_on() is either true or false, so have its
return value be bool.
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
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There's code that expects tracer_tracing_is_on() to be either true or false,
not some random number. Currently, it should only return one or zero, but
just in case, change its return value to bool, to enforce it.
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
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The start function of the hwlat tracer should never be called when the hwlat
thread already exists. If it is called, do a WARN_ON().
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
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The hwlat tracer uses a kernel thread to measure latencies. The function
that creates this kernel thread, start_kthread(), can be called when the
tracer is initialized and when the tracer is explicitly enabled.
start_kthread() does not check if there is an existing hwlat kernel
thread and will create a new one each time it is called.
This causes the reference to the previous thread to be lost. Without the
thread reference, the old kernel thread becomes unstoppable and
continues to use CPU time even after the hwlat tracer has been disabled.
This problem can be observed when a system is booted with tracing
enabled and the hwlat tracer is configured like this:
echo hwlat > current_tracer; echo 1 > tracing_on
Add the missing check for an existing kernel thread in start_kthread()
to prevent this problem. This function and the rest of the hwlat kernel
thread setup and teardown are already serialized because they are called
through the tracer core code with trace_type_lock held.
[
Note, this only fixes the symptom. The real fix was not to call
this function when tracing_on was already one. But this still makes
the code more robust, so we'll add it.
]
Link: http://lkml.kernel.org/r/1533120354-22923-1-git-send-email-erica.bugden@linutronix.de
Signed-off-by: Erica Bugden <erica.bugden@linutronix.de>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
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Currently, when one echo's in 1 into tracing_on, the current tracer's
"start()" function is executed, even if tracing_on was already one. This can
lead to strange side effects. One being that if the hwlat tracer is enabled,
and someone does "echo 1 > tracing_on" into tracing_on, the hwlat tracer's
start() function is called again which will recreate another kernel thread,
and make it unable to remove the old one.
Link: http://lkml.kernel.org/r/1533120354-22923-1-git-send-email-erica.bugden@linutronix.de
Cc: stable@vger.kernel.org
Fixes: 2df8f8a6a897e ("tracing: Fix regression with irqsoff tracer and tracing_on file")
Reported-by: Erica Bugden <erica.bugden@linutronix.de>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
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This patch detaches the preemptirq tracepoints from the tracers and
keeps it separate.
Advantages:
* Lockdep and irqsoff event can now run in parallel since they no longer
have their own calls.
* This unifies the usecase of adding hooks to an irqsoff and irqson
event, and a preemptoff and preempton event.
3 users of the events exist:
- Lockdep
- irqsoff and preemptoff tracers
- irqs and preempt trace events
The unification cleans up several ifdefs and makes the code in preempt
tracer and irqsoff tracers simpler. It gets rid of all the horrific
ifdeferry around PROVE_LOCKING and makes configuration of the different
users of the tracepoints more easy and understandable. It also gets rid
of the time_* function calls from the lockdep hooks used to call into
the preemptirq tracer which is not needed anymore. The negative delta in
lines of code in this patch is quite large too.
In the patch we introduce a new CONFIG option PREEMPTIRQ_TRACEPOINTS
as a single point for registering probes onto the tracepoints. With
this,
the web of config options for preempt/irq toggle tracepoints and its
users becomes:
PREEMPT_TRACER PREEMPTIRQ_EVENTS IRQSOFF_TRACER PROVE_LOCKING
| | \ | |
\ (selects) / \ \ (selects) /
TRACE_PREEMPT_TOGGLE ----> TRACE_IRQFLAGS
\ /
\ (depends on) /
PREEMPTIRQ_TRACEPOINTS
Other than the performance tests mentioned in the previous patch, I also
ran the locking API test suite. I verified that all tests cases are
passing.
I also injected issues by not registering lockdep probes onto the
tracepoints and I see failures to confirm that the probes are indeed
working.
This series + lockdep probes not registered (just to inject errors):
[ 0.000000] hard-irqs-on + irq-safe-A/21: ok | ok | ok |
[ 0.000000] soft-irqs-on + irq-safe-A/21: ok | ok | ok |
[ 0.000000] sirq-safe-A => hirqs-on/12:FAILED|FAILED| ok |
[ 0.000000] sirq-safe-A => hirqs-on/21:FAILED|FAILED| ok |
[ 0.000000] hard-safe-A + irqs-on/12:FAILED|FAILED| ok |
[ 0.000000] soft-safe-A + irqs-on/12:FAILED|FAILED| ok |
[ 0.000000] hard-safe-A + irqs-on/21:FAILED|FAILED| ok |
[ 0.000000] soft-safe-A + irqs-on/21:FAILED|FAILED| ok |
[ 0.000000] hard-safe-A + unsafe-B #1/123: ok | ok | ok |
[ 0.000000] soft-safe-A + unsafe-B #1/123: ok | ok | ok |
With this series + lockdep probes registered, all locking tests pass:
[ 0.000000] hard-irqs-on + irq-safe-A/21: ok | ok | ok |
[ 0.000000] soft-irqs-on + irq-safe-A/21: ok | ok | ok |
[ 0.000000] sirq-safe-A => hirqs-on/12: ok | ok | ok |
[ 0.000000] sirq-safe-A => hirqs-on/21: ok | ok | ok |
[ 0.000000] hard-safe-A + irqs-on/12: ok | ok | ok |
[ 0.000000] soft-safe-A + irqs-on/12: ok | ok | ok |
[ 0.000000] hard-safe-A + irqs-on/21: ok | ok | ok |
[ 0.000000] soft-safe-A + irqs-on/21: ok | ok | ok |
[ 0.000000] hard-safe-A + unsafe-B #1/123: ok | ok | ok |
[ 0.000000] soft-safe-A + unsafe-B #1/123: ok | ok | ok |
Link: http://lkml.kernel.org/r/20180730222423.196630-4-joel@joelfernandes.org
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Namhyung Kim <namhyung@kernel.org>
Signed-off-by: Joel Fernandes (Google) <joel@joelfernandes.org>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
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Move selftest function to its own compile unit so it can be compiled
with the ftrace cflags (CC_FLAGS_FTRACE) allowing it to be probed
during the ftrace startup tests.
Link: http://lkml.kernel.org/r/153294604271.32740.16490677128630177030.stgit@devbox
Signed-off-by: Francis Deslauriers <francis.deslauriers@efficios.com>
Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
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Prohibit kprobe-events probing on notrace functions. Since probing on a
notrace function can cause a recursive event call. In most cases those are just
skipped, but in some cases it falls into an infinite recursive call.
This protection can be disabled by the kconfig
CONFIG_KPROBE_EVENTS_ON_NOTRACE=y, but it is highly recommended to keep it
"n" for normal kernel builds. Note that this is only available if "kprobes on
ftrace" has been implemented on the target arch and CONFIG_KPROBES_ON_FTRACE=y.
Link: http://lkml.kernel.org/r/153294601436.32740.10557881188933661239.stgit@devbox
Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org>
Tested-by: Francis Deslauriers <francis.deslauriers@efficios.com>
[ Slight grammar and spelling fixes ]
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
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Automatically found by kbuild test robot.
Fixes: ffdc73a3b2ad ("lib: Add module for testing preemptoff/irqsoff latency tracers")
Signed-off-by: kbuild test robot <fengguang.wu@intel.com>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
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The function enable_trace_kprobe() performs slightly differently if the file
parameter is passed in as NULL on non-NULL. Instead of checking file twice,
move the code between the two tests into a static inline helper function to
make the code easier to follow.
Link: http://lkml.kernel.org/r/20180725224728.7b1d5db2@vmware.local.home
Link: http://lkml.kernel.org/r/20180726121152.4dd54330@gandalf.local.home
Reviewed-by: Josh Poimboeuf <jpoimboe@redhat.com>
Acked-by: Masami Hiramatsu <mhiramat@kernel.org>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
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Remove ftrace_nr_registered_ops() because it is no longer used.
ftrace_nr_registered_ops() has been introduced by commit ea701f11da44
("ftrace: Add selftest to test function trace recursion protection"), but
its caller has been removed by commit 05cbbf643b8e ("tracing: Fix selftest
function recursion accounting"). So it is not called anymore.
Link: http://lkml.kernel.org/r/153260907227.12474.5234899025934963683.stgit@devbox
Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
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Remove using_ftrace_ops_list_func() since it is no longer used.
Using ftrace_ops_list_func() has been introduced by commit 7eea4fce0246
("tracing/stack_trace: Skip 4 instead of 3 when using ftrace_ops_list_func")
as a helper function, but its caller has been removed by commit 72ac426a5bb0
("tracing: Clean up stack tracing and fix fentry updates"). So it is not
called anymore.
Link: http://lkml.kernel.org/r/153260904427.12474.9952096317439329851.stgit@devbox
Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
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Nothing uses unregister_trigger() outside of trace_events_trigger.c file,
thus it should be static. Not sure why this was ever converted, because
its counter part, register_trigger(), was always static.
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
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Here we introduce a test module for introducing a long preempt or irq
disable delay in the kernel which the preemptoff or irqsoff tracers can
detect. This module is to be used only for test purposes and is default
disabled.
Following is the expected output (only briefly shown) that can be parsed
to verify that the tracers are working correctly. We will use this from
the kselftests in future patches.
For the preemptoff tracer:
echo preemptoff > /d/tracing/current_tracer
sleep 1
insmod ./preemptirq_delay_test.ko test_mode=preempt delay=500000
sleep 1
bash-4.3# cat /d/tracing/trace
preempt -1066 2...2 0us@: preemptirq_delay_run <-preemptirq_delay_run
preempt -1066 2...2 500002us : preemptirq_delay_run <-preemptirq_delay_run
preempt -1066 2...2 500004us : tracer_preempt_on <-preemptirq_delay_run
preempt -1066 2...2 500012us : <stack trace>
=> kthread
=> ret_from_fork
For the irqsoff tracer:
echo irqsoff > /d/tracing/current_tracer
sleep 1
insmod ./preemptirq_delay_test.ko test_mode=irq delay=500000
sleep 1
bash-4.3# cat /d/tracing/trace
irq dis -1069 1d..1 0us@: preemptirq_delay_run
irq dis -1069 1d..1 500001us : preemptirq_delay_run
irq dis -1069 1d..1 500002us : tracer_hardirqs_on <-preemptirq_delay_run
irq dis -1069 1d..1 500005us : <stack trace>
=> ret_from_fork
Link: http://lkml.kernel.org/r/20180712213611.GA8743@joelaf.mtv.corp.google.com
Cc: Boqun Feng <boqun.feng@gmail.com>
Cc: Byungchul Park <byungchul.park@lge.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Julia Cartwright <julia@ni.com>
Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Paul McKenney <paulmck@linux.vnet.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Shuah Khan <shuah@kernel.org>
Cc: Thomas Glexiner <tglx@linutronix.de>
Cc: Todd Kjos <tkjos@google.com>
Cc: Tom Zanussi <tom.zanussi@linux.intel.com>
Cc: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
[ Erick is a co-developer of this commit ]
Signed-off-by: Erick Reyes <erickreyes@google.com>
Signed-off-by: Joel Fernandes (Google) <joel@joelfernandes.org>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
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Split reset functions into seperate functions in preparation
of future patches that need to do tracer specific reset.
Link: http://lkml.kernel.org/r/20180628182149.226164-4-joel@joelfernandes.org
Reviewed-by: Namhyung Kim <namhyung@kernel.org>
Signed-off-by: Joel Fernandes (Google) <joel@joelfernandes.org>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
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git://git.kernel.org/pub/scm/linux/kernel/git/pmladek/printk
Pull printk updates from Petr Mladek:
- Different vendors have a different expectation about a console
quietness. Make it configurable to reduce bike-shedding about the
upstream default
- Decide about the message visibility when the message is stored. It
avoids races caused by a delayed console handling
- Always store printk() messages into the per-CPU buffers again in NMI.
The only exception is when flushing trace log in panic(). There the
risk of loosing messages is worth an eventual reordering
- Handle invalid %pO printf modifiers correctly
- Better handle %p printf modifier tests before crng is initialized
- Some clean up
* tag 'printk-for-4.19' of git://git.kernel.org/pub/scm/linux/kernel/git/pmladek/printk:
lib/vsprintf: Do not handle %pO[^F] as %px
printk: Fix warning about unused suppress_message_printing
printk/nmi: Prevent deadlock when accessing the main log buffer in NMI
printk: Create helper function to queue deferred console handling
printk: Split the code for storing a message into the log buffer
printk: Clean up syslog_print_all()
printk: Remove unnecessary kmalloc() from syslog during clear
printk: Make CONSOLE_LOGLEVEL_QUIET configurable
printk: make sure to print log on console.
lib/test_printf.c: accept "ptrval" as valid result for plain 'p' tests
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The commit 719f6a7040f1bdaf96 ("printk: Use the main logbuf in NMI
when logbuf_lock is available") brought back the possible deadlocks
in printk() and NMI.
The check of logbuf_lock is done only in printk_nmi_enter() to prevent
mixed output. But another CPU might take the lock later, enter NMI, and:
+ Both NMIs might be serialized by yet another lock, for example,
the one in nmi_cpu_backtrace().
+ The other CPU might get stopped in NMI, see smp_send_stop()
in panic().
The only safe solution is to use trylock when storing the message
into the main log-buffer. It might cause reordering when some lines
go to the main lock buffer directly and others are delayed via
the per-CPU buffer. It means that it is not useful in general.
This patch replaces the problematic NMI deferred context with NMI
direct context. It can be used to mark a code that might produce
many messages in NMI and the risk of losing them is more critical
than problems with eventual reordering.
The context is then used when dumping trace buffers on oops. It was
the primary motivation for the original fix. Also the reordering is
even smaller issue there because some traces have their own time stamps.
Finally, nmi_cpu_backtrace() need not longer be serialized because
it will always us the per-CPU buffers again.
Fixes: 719f6a7040f1bdaf96 ("printk: Use the main logbuf in NMI when logbuf_lock is available")
Cc: stable@vger.kernel.org
Link: http://lkml.kernel.org/r/20180627142028.11259-1-pmladek@suse.com
To: Steven Rostedt <rostedt@goodmis.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Cc: Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com>
Cc: linux-kernel@vger.kernel.org
Cc: stable@vger.kernel.org
Acked-by: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
Signed-off-by: Petr Mladek <pmladek@suse.com>
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Pull documentation update from Jonathan Corbet:
"This was a moderately busy cycle for docs, with the usual collection
of small fixes and updates.
We also have new ktime_get_*() docs from Arnd, some kernel-doc fixes,
a new set of Italian translations (non so se vale la pena, ma non fa
male - speriamo bene), and some extensive early memory-management
documentation improvements from Mike Rapoport"
* tag 'docs-4.19' of git://git.lwn.net/linux: (52 commits)
Documentation: corrections to console/console.txt
Documentation: add ioctl number entry for v4l2-subdev.h
Remove gendered language from management style documentation
scripts/kernel-doc: Escape all literal braces in regexes
docs/mm: add description of boot time memory management
docs/mm: memblock: add overview documentation
docs/mm: memblock: add kernel-doc description for memblock types
docs/mm: memblock: add kernel-doc comments for memblock_add[_node]
docs/mm: memblock: update kernel-doc comments
mm/memblock: add a name for memblock flags enumeration
docs/mm: bootmem: add overview documentation
docs/mm: bootmem: add kernel-doc description of 'struct bootmem_data'
docs/mm: bootmem: fix kernel-doc warnings
docs/mm: nobootmem: fixup kernel-doc comments
mm/bootmem: drop duplicated kernel-doc comments
Documentation: vm.txt: Adding 'nr_hugepages_mempolicy' parameter description.
doc:it_IT: translation for kernel-hacking
docs: Fix the reference labels in Locking.rst
doc: tracing: Fix a typo of trace_stat
mm: Introduce new type vm_fault_t
...
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The name of the directory for per-cpu function statistics
is trace_stat, not trace_stats.
Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org>
Acked-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
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Despite being mentioned at Documentation/trace/ftrace.rst as a
rst file, this file was still a text one, with several issues.
Convert it to ReST and add it to the trace index:
- Mark the document title as such;
- Identify and indent the literal blocks;
- Use the proper markups for table.
Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>
Acked-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
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Pull block updates from Jens Axboe:
"First pull request for this merge window, there will also be a
followup request with some stragglers.
This pull request contains:
- Fix for a thundering heard issue in the wbt block code (Anchal
Agarwal)
- A few NVMe pull requests:
* Improved tracepoints (Keith)
* Larger inline data support for RDMA (Steve Wise)
* RDMA setup/teardown fixes (Sagi)
* Effects log suppor for NVMe target (Chaitanya Kulkarni)
* Buffered IO suppor for NVMe target (Chaitanya Kulkarni)
* TP4004 (ANA) support (Christoph)
* Various NVMe fixes
- Block io-latency controller support. Much needed support for
properly containing block devices. (Josef)
- Series improving how we handle sense information on the stack
(Kees)
- Lightnvm fixes and updates/improvements (Mathias/Javier et al)
- Zoned device support for null_blk (Matias)
- AIX partition fixes (Mauricio Faria de Oliveira)
- DIF checksum code made generic (Max Gurtovoy)
- Add support for discard in iostats (Michael Callahan / Tejun)
- Set of updates for BFQ (Paolo)
- Removal of async write support for bsg (Christoph)
- Bio page dirtying and clone fixups (Christoph)
- Set of bcache fix/changes (via Coly)
- Series improving blk-mq queue setup/teardown speed (Ming)
- Series improving merging performance on blk-mq (Ming)
- Lots of other fixes and cleanups from a slew of folks"
* tag 'for-4.19/block-20180812' of git://git.kernel.dk/linux-block: (190 commits)
blkcg: Make blkg_root_lookup() work for queues in bypass mode
bcache: fix error setting writeback_rate through sysfs interface
null_blk: add lock drop/acquire annotation
Blk-throttle: reduce tail io latency when iops limit is enforced
block: paride: pd: mark expected switch fall-throughs
block: Ensure that a request queue is dissociated from the cgroup controller
block: Introduce blk_exit_queue()
blkcg: Introduce blkg_root_lookup()
block: Remove two superfluous #include directives
blk-mq: count the hctx as active before allocating tag
block: bvec_nr_vecs() returns value for wrong slab
bcache: trivial - remove tailing backslash in macro BTREE_FLAG
bcache: make the pr_err statement used for ENOENT only in sysfs_attatch section
bcache: set max writeback rate when I/O request is idle
bcache: add code comments for bset.c
bcache: fix mistaken comments in request.c
bcache: fix mistaken code comments in bcache.h
bcache: add a comment in super.c
bcache: avoid unncessary cache prefetch bch_btree_node_get()
bcache: display rate debug parameters to 0 when writeback is not running
...
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Pull in 4.18-rc6 to get the NVMe core AEN change to avoid a
merge conflict down the line.
Signed-of-by: Jens Axboe <axboe@kernel.dk>
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Since @blk_debugfs_root couldn't be configured dynamically, we can
save a few memory allocation if it's not there.
Signed-off-by: Liu Bo <bo.liu@linux.alibaba.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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Signed-off-by: Ingo Molnar <mingo@kernel.org>
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Commit 57ea2a34adf4 ("tracing/kprobes: Fix trace_probe flags on
enable_trace_kprobe() failure") added an if statement that depends on another
if statement that gcc doesn't see will initialize the "link" variable and
gives the warning:
"warning: 'link' may be used uninitialized in this function"
It is really a false positive, but to quiet the warning, and also to make
sure that it never actually is used uninitialized, initialize the "link"
variable to NULL and add an if (!WARN_ON_ONCE(!link)) where the compiler
thinks it could be used uninitialized.
Cc: stable@vger.kernel.org
Fixes: 57ea2a34adf4 ("tracing/kprobes: Fix trace_probe flags on enable_trace_kprobe() failure")
Reported-by: kbuild test robot <lkp@intel.com>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
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There was a case that triggered a double free in event_trigger_callback()
due to the called reg() function freeing the trigger_data and then it
getting freed again by the error return by the caller. The solution there
was to up the trigger_data ref count.
Code inspection found that event_enable_trigger_func() has the same issue,
but is not as easy to trigger (requires harder to trigger failures). It
needs to be solved slightly different as it needs more to clean up when the
reg() function fails.
Link: http://lkml.kernel.org/r/20180725124008.7008e586@gandalf.local.home
Cc: stable@vger.kernel.org
Fixes: 7862ad1846e99 ("tracing: Add 'enable_event' and 'disable_event' event trigger commands")
Reivewed-by: Masami Hiramatsu <mhiramat@kernel.org>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
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If enable_trace_kprobe fails to enable the probe in enable_k(ret)probe
it returns an error, but does not unset the tp flags it set previously.
This results in a probe being considered enabled and failures like being
unable to remove the probe through kprobe_events file since probes_open()
expects every probe to be disabled.
Link: http://lkml.kernel.org/r/20180725102826.8300-1-asavkov@redhat.com
Link: http://lkml.kernel.org/r/20180725142038.4765-1-asavkov@redhat.com
Cc: Ingo Molnar <mingo@redhat.com>
Cc: stable@vger.kernel.org
Fixes: 41a7dd420c57 ("tracing/kprobes: Support ftrace_event_file base multibuffer")
Acked-by: Masami Hiramatsu <mhiramat@kernel.org>
Reviewed-by: Josh Poimboeuf <jpoimboe@redhat.com>
Signed-off-by: Artem Savkov <asavkov@redhat.com>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
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