Pull tracing fixes from Steven Rostedt:
- Fix to /sys/kernel/tracing/per_cpu/cpu*/stats read and entries.
If a resize shrinks the buffer it clears the read count to notify
readers that they need to reset. But the read count is also used for
accounting and this causes the numbers to be off. Instead, create a
separate variable to use to notify readers to reset.
- Fix the ref counts of the "soft disable" mode. The wrong value was
used for testing if soft disable mode should be enabled or disable,
but instead, just change the logic to do the enable and disable in
place when the SOFT_MODE is set or cleared.
- Several kernel-doc fixes
- Removal of unused external declarations
* tag 'trace-v6.5-rc3' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace:
tracing: Fix warning in trace_buffered_event_disable()
ftrace: Remove unused extern declarations
tracing: Fix kernel-doc warnings in trace_seq.c
tracing: Fix kernel-doc warnings in trace_events_trigger.c
tracing/synthetic: Fix kernel-doc warnings in trace_events_synth.c
ring-buffer: Fix kernel-doc warnings in ring_buffer.c
ring-buffer: Fix wrong stat of cpu_buffer->read
Warning happened in trace_buffered_event_disable() at
WARN_ON_ONCE(!trace_buffered_event_ref)
Call Trace:
? __warn+0xa5/0x1b0
? trace_buffered_event_disable+0x189/0x1b0
__ftrace_event_enable_disable+0x19e/0x3e0
free_probe_data+0x3b/0xa0
unregister_ftrace_function_probe_func+0x6b8/0x800
event_enable_func+0x2f0/0x3d0
ftrace_process_regex.isra.0+0x12d/0x1b0
ftrace_filter_write+0xe6/0x140
vfs_write+0x1c9/0x6f0
[...]
The cause of the warning is in __ftrace_event_enable_disable(),
trace_buffered_event_enable() was called once while
trace_buffered_event_disable() was called twice.
Reproduction script show as below, for analysis, see the comments:
```
#!/bin/bash
cd /sys/kernel/tracing/
# 1. Register a 'disable_event' command, then:
# 1) SOFT_DISABLED_BIT was set;
# 2) trace_buffered_event_enable() was called first time;
echo 'cmdline_proc_show:disable_event:initcall:initcall_finish' > \
set_ftrace_filter
# 2. Enable the event registered, then:
# 1) SOFT_DISABLED_BIT was cleared;
# 2) trace_buffered_event_disable() was called first time;
echo 1 > events/initcall/initcall_finish/enable
# 3. Try to call into cmdline_proc_show(), then SOFT_DISABLED_BIT was
# set again!!!
cat /proc/cmdline
# 4. Unregister the 'disable_event' command, then:
# 1) SOFT_DISABLED_BIT was cleared again;
# 2) trace_buffered_event_disable() was called second time!!!
echo '!cmdline_proc_show:disable_event:initcall:initcall_finish' > \
set_ftrace_filter
```
To fix it, IIUC, we can change to call trace_buffered_event_enable() at
fist time soft-mode enabled, and call trace_buffered_event_disable() at
last time soft-mode disabled.
Link: https://lore.kernel.org/linux-trace-kernel/20230726095804.920457-1-zhengyejian1@huawei.com
Cc: <mhiramat@kernel.org>
Fixes: 0fc1b09ff1 ("tracing: Use temp buffer when filtering events")
Signed-off-by: Zheng Yejian <zhengyejian1@huawei.com>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
Fix kernel-doc warnings:
kernel/trace/ring_buffer.c:954: warning: Function parameter or
member 'cpu' not described in 'ring_buffer_wake_waiters'
kernel/trace/ring_buffer.c:3383: warning: Excess function parameter
'event' description in 'ring_buffer_unlock_commit'
kernel/trace/ring_buffer.c:5359: warning: Excess function parameter
'cpu' description in 'ring_buffer_reset_online_cpus'
Link: https://lkml.kernel.org/r/20230724140827.1023266-2-cuigaosheng1@huawei.com
Cc: <mhiramat@kernel.org>
Signed-off-by: Gaosheng Cui <cuigaosheng1@huawei.com>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
When pages are removed in rb_remove_pages(), 'cpu_buffer->read' is set
to 0 in order to make sure any read iterators reset themselves. However,
this will mess 'entries' stating, see following steps:
# cd /sys/kernel/tracing/
# 1. Enlarge ring buffer prepare for later reducing:
# echo 20 > per_cpu/cpu0/buffer_size_kb
# 2. Write a log into ring buffer of cpu0:
# taskset -c 0 echo "hello1" > trace_marker
# 3. Read the log:
# cat per_cpu/cpu0/trace_pipe
<...>-332 [000] ..... 62.406844: tracing_mark_write: hello1
# 4. Stop reading and see the stats, now 0 entries, and 1 event readed:
# cat per_cpu/cpu0/stats
entries: 0
[...]
read events: 1
# 5. Reduce the ring buffer
# echo 7 > per_cpu/cpu0/buffer_size_kb
# 6. Now entries became unexpected 1 because actually no entries!!!
# cat per_cpu/cpu0/stats
entries: 1
[...]
read events: 0
To fix it, introduce 'page_removed' field to count total removed pages
since last reset, then use it to let read iterators reset themselves
instead of changing the 'read' pointer.
Link: https://lore.kernel.org/linux-trace-kernel/20230724054040.3489499-1-zhengyejian1@huawei.com
Cc: <mhiramat@kernel.org>
Cc: <vnagarnaik@google.com>
Fixes: 83f40318da ("ring-buffer: Make removal of ring buffer pages atomic")
Signed-off-by: Zheng Yejian <zhengyejian1@huawei.com>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
In internal testing of test_maps, we sometimes observed failures like:
test_maps: test_maps.c:173: void test_hashmap_percpu(unsigned int, void *):
Assertion `bpf_map_update_elem(fd, &key, value, BPF_ANY) == 0' failed.
where the errno is ENOMEM. After some troubleshooting and enabling
the warnings, we saw:
[ 91.304708] percpu: allocation failed, size=8 align=8 atomic=1, atomic alloc failed, no space left
[ 91.304716] CPU: 51 PID: 24145 Comm: test_maps Kdump: loaded Tainted: G N 6.1.38-smp-DEV #7
[ 91.304719] Hardware name: Google Astoria/astoria, BIOS 0.20230627.0-0 06/27/2023
[ 91.304721] Call Trace:
[ 91.304724] <TASK>
[ 91.304730] [<ffffffffa7ef83b9>] dump_stack_lvl+0x59/0x88
[ 91.304737] [<ffffffffa7ef83f8>] dump_stack+0x10/0x18
[ 91.304738] [<ffffffffa75caa0c>] pcpu_alloc+0x6fc/0x870
[ 91.304741] [<ffffffffa75ca302>] __alloc_percpu_gfp+0x12/0x20
[ 91.304743] [<ffffffffa756785e>] alloc_bulk+0xde/0x1e0
[ 91.304746] [<ffffffffa7566c02>] bpf_mem_alloc_init+0xd2/0x2f0
[ 91.304747] [<ffffffffa7547c69>] htab_map_alloc+0x479/0x650
[ 91.304750] [<ffffffffa751d6e0>] map_create+0x140/0x2e0
[ 91.304752] [<ffffffffa751d413>] __sys_bpf+0x5a3/0x6c0
[ 91.304753] [<ffffffffa751c3ec>] __x64_sys_bpf+0x1c/0x30
[ 91.304754] [<ffffffffa7ef847a>] do_syscall_64+0x5a/0x80
[ 91.304756] [<ffffffffa800009b>] entry_SYSCALL_64_after_hwframe+0x63/0xcd
This makes sense, because in atomic context, percpu allocation would
not create new chunks; it would only create in non-atomic contexts.
And if during prefill all precpu chunks are full, -ENOMEM would
happen immediately upon next unit_alloc.
Prefill phase does not actually run in atomic context, so we can
use this fact to allocate non-atomically with GFP_KERNEL instead
of GFP_NOWAIT. This avoids the immediate -ENOMEM.
GFP_NOWAIT has to be used in unit_alloc when bpf program runs
in atomic context. Even if bpf program runs in non-atomic context,
in most cases, rcu read lock is enabled for the program so
GFP_NOWAIT is still needed. This is often also the case for
BPF_MAP_UPDATE_ELEM syscalls.
Signed-off-by: YiFei Zhu <zhuyifei@google.com>
Acked-by: Yonghong Song <yonghong.song@linux.dev>
Acked-by: Hou Tao <houtao1@huawei.com>
Link: https://lore.kernel.org/r/20230728043359.3324347-1-zhuyifei@google.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
The kernel test robot reported compilation warnings when -Wparentheses is
added to KBUILD_CFLAGS with gcc compiler. The following is the error message:
.../bpf-next/kernel/bpf/verifier.c: In function ‘coerce_reg_to_size_sx’:
.../bpf-next/kernel/bpf/verifier.c:5901:14:
error: suggest parentheses around comparison in operand of ‘==’ [-Werror=parentheses]
if (s64_max >= 0 == s64_min >= 0) {
~~~~~~~~^~~~
.../bpf-next/kernel/bpf/verifier.c: In function ‘coerce_subreg_to_size_sx’:
.../bpf-next/kernel/bpf/verifier.c:5965:14:
error: suggest parentheses around comparison in operand of ‘==’ [-Werror=parentheses]
if (s32_min >= 0 == s32_max >= 0) {
~~~~~~~~^~~~
To fix the issue, add proper parentheses for the above '>=' condition
to silence the warning/error.
I tried a few clang compilers like clang16 and clang18 and they do not emit
such warnings with -Wparentheses.
Reported-by: kernel test robot <lkp@intel.com>
Closes: https://lore.kernel.org/oe-kbuild-all/202307281133.wi0c4SqG-lkp@intel.com/
Signed-off-by: Yonghong Song <yonghong.song@linux.dev>
Acked-by: Jiri Olsa <jolsa@kernel.org>
Link: https://lore.kernel.org/r/20230728055740.2284534-1-yonghong.song@linux.dev
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
As the emergency restart does not call kernel_restart_prepare(), the
system_state stays in SYSTEM_RUNNING.
Since bae1d3a05a, this hinders i2c_in_atomic_xfer_mode() from becoming
active, and therefore might lead to avoidable warnings in the restart
handlers, e.g.:
[ 12.667612] WARNING: CPU: 1 PID: 1 at kernel/rcu/tree_plugin.h:318 rcu_note_context_switch+0x33c/0x6b0
[ 12.676926] Voluntary context switch within RCU read-side critical section!
...
[ 12.742376] schedule_timeout from wait_for_completion_timeout+0x90/0x114
[ 12.749179] wait_for_completion_timeout from tegra_i2c_wait_completion+0x40/0x70
...
[ 12.994527] atomic_notifier_call_chain from machine_restart+0x34/0x58
[ 13.001050] machine_restart from panic+0x2a8/0x32c
Avoid these by setting the correct system_state.
Fixes: bae1d3a05a ("i2c: core: remove use of in_atomic()")
Cc: stable@vger.kernel.org # v5.2+
Reviewed-by: Dmitry Osipenko <dmitry.osipenko@collabora.com>
Tested-by: Nishanth Menon <nm@ti.com>
Signed-off-by: Benjamin Bara <benjamin.bara@skidata.com>
Link: https://lore.kernel.org/r/20230327-tegra-pmic-reboot-v7-1-18699d5dcd76@skidata.com
Signed-off-by: Lee Jones <lee@kernel.org>
Add support to the /sys/devices/system/cpu/smt/control interface for
enabling a specified number of SMT threads per core, including partial
SMT states where not all threads are brought online.
The current interface accepts "on" and "off", to enable either 1 or all
SMT threads per core.
This commit allows writing an integer, between 1 and the number of SMT
threads supported by the machine. Writing 1 is a synonym for "off", 2 or
more enables SMT with the specified number of threads.
When reading the file, if all threads are online "on" is returned, to
avoid changing behaviour for existing users. If some other number of
threads is online then the integer value is returned.
Architectures like x86 only supporting 1 thread or all threads, should not
define CONFIG_SMT_NUM_THREADS_DYNAMIC. Architecture supporting partial SMT
states, like PowerPC, should define it.
[ ldufour: Slightly reword the commit's description ]
[ ldufour: Remove switch() in __store_smt_control() ]
[ ldufour: Rix build issue in control_show() ]
Reported-by: kernel test robot <lkp@intel.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Signed-off-by: Laurent Dufour <ldufour@linux.ibm.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Tested-by: Zhang Rui <rui.zhang@intel.com>
Link: https://lore.kernel.org/r/20230705145143.40545-8-ldufour@linux.ibm.com
Some architectures allows partial SMT states, i.e. when not all SMT threads
are brought online.
To support that, add an architecture helper which checks whether a given
CPU is allowed to be brought online depending on how many SMT threads are
currently enabled. Since this is only applicable to architecture supporting
partial SMT, only these architectures should select the new configuration
variable CONFIG_SMT_NUM_THREADS_DYNAMIC. For the other architectures, not
supporting the partial SMT states, there is no need to define
topology_cpu_smt_allowed(), the generic code assumed that all the threads
are allowed or only the primary ones.
Call the helper from cpu_smt_enable(), and cpu_smt_allowed() when SMT is
enabled, to check if the particular thread should be onlined. Notably,
also call it from cpu_smt_disable() if CPU_SMT_ENABLED, to allow
offlining some threads to move from a higher to lower number of threads
online.
[ ldufour: Slightly reword the commit's description ]
[ ldufour: Introduce CONFIG_SMT_NUM_THREADS_DYNAMIC ]
Suggested-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Signed-off-by: Laurent Dufour <ldufour@linux.ibm.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Tested-by: Zhang Rui <rui.zhang@intel.com>
Link: https://lore.kernel.org/r/20230705145143.40545-7-ldufour@linux.ibm.com
Some architectures allow partial SMT states at boot time, ie. when not all
SMT threads are brought online.
To support that the SMT code needs to know the maximum number of SMT
threads, and also the currently configured number.
The architecture code knows the max number of threads, so have the
architecture code pass that value to cpu_smt_set_num_threads(). Note that
although topology_max_smt_threads() exists, it is not configured early
enough to be used here. As architecture, like PowerPC, allows the threads
number to be set through the kernel command line, also pass that value.
[ ldufour: Slightly reword the commit message ]
[ ldufour: Rename cpu_smt_check_topology and add a num_threads argument ]
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Signed-off-by: Laurent Dufour <ldufour@linux.ibm.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Tested-by: Zhang Rui <rui.zhang@intel.com>
Link: https://lore.kernel.org/r/20230705145143.40545-5-ldufour@linux.ibm.com
Move the simple exit cases, i.e. those which don't depend on the value
written, earlier in the function. That makes it clearer that regardless of
the input those states cannot be transitioned out of.
That does have a user-visible effect, in that the error returned will
now always be EPERM/ENODEV for those states, regardless of the value
written. Previously writing an invalid value would return EINVAL even
when in those states.
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Tested-by: Zhang Rui <rui.zhang@intel.com>
Link: https://lore.kernel.org/r/20230705145143.40545-4-ldufour@linux.ibm.com
In order to export the cpuhp_smt_control enum as part of the interface
between generic and architecture code, the architecture code needs to
include asm/topology.h.
But that leads to circular header dependencies. So split the enum and
related declarations into a separate header.
[ ldufour: Reworded the commit's description ]
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Signed-off-by: Laurent Dufour <ldufour@linux.ibm.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Tested-by: Zhang Rui <rui.zhang@intel.com>
Link: https://lore.kernel.org/r/20230705145143.40545-3-ldufour@linux.ibm.com
The commit 18415f33e2 ("cpu/hotplug: Allow "parallel" bringup up to
CPUHP_BP_KICK_AP_STATE") introduce a dependancy against a global variable
cpu_primary_thread_mask exported by the X86 code. This variable is only
used when CONFIG_HOTPLUG_PARALLEL is set.
Since cpuhp_get_primary_thread_mask() and cpuhp_smt_aware() are only used
when CONFIG_HOTPLUG_PARALLEL is set, don't define them when it is not set.
No functional change.
Signed-off-by: Laurent Dufour <ldufour@linux.ibm.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Tested-by: Zhang Rui <rui.zhang@intel.com>
Link: https://lore.kernel.org/r/20230705145143.40545-2-ldufour@linux.ibm.com
Add asm support for new instructions so kernel verifier and bpftool
xlated insn dumps can have proper asm syntax for new instructions.
Acked-by: Eduard Zingerman <eddyz87@gmail.com>
Acked-by: Quentin Monnet <quentin@isovalent.com>
Signed-off-by: Yonghong Song <yonghong.song@linux.dev>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Currently, if user accesses a ctx member with signed types,
the compiler will generate an unsigned load followed by
necessary left and right shifts.
With the introduction of sign-extension load, compiler may
just emit a ldsx insn instead. Let us do a final movsx sign
extension to the final unsigned ctx load result to
satisfy original sign extension requirement.
Acked-by: Eduard Zingerman <eddyz87@gmail.com>
Signed-off-by: Yonghong Song <yonghong.song@linux.dev>
Link: https://lore.kernel.org/r/20230728011207.3712528-1-yonghong.song@linux.dev
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Add interpreter/jit support for new sign-extension mov insns.
The original 'MOV' insn is extended to support reg-to-reg
signed version for both ALU and ALU64 operations. For ALU mode,
the insn->off value of 8 or 16 indicates sign-extension
from 8- or 16-bit value to 32-bit value. For ALU64 mode,
the insn->off value of 8/16/32 indicates sign-extension
from 8-, 16- or 32-bit value to 64-bit value.
Acked-by: Eduard Zingerman <eddyz87@gmail.com>
Signed-off-by: Yonghong Song <yonghong.song@linux.dev>
Link: https://lore.kernel.org/r/20230728011202.3712300-1-yonghong.song@linux.dev
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Add interpreter/jit support for new sign-extension load insns
which adds a new mode (BPF_MEMSX).
Also add verifier support to recognize these insns and to
do proper verification with new insns. In verifier, besides
to deduce proper bounds for the dst_reg, probed memory access
is also properly handled.
Acked-by: Eduard Zingerman <eddyz87@gmail.com>
Signed-off-by: Yonghong Song <yonghong.song@linux.dev>
Link: https://lore.kernel.org/r/20230728011156.3711870-1-yonghong.song@linux.dev
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Mark the time KUnit test, time64_to_tm_test_date_range, as slow using test
attributes.
This test ran relatively much slower than most other KUnit tests.
By marking this test as slow, the test can now be filtered using the KUnit
test attribute filtering feature. Example: --filter "speed>slow". This will
run only the tests that have speeds faster than slow. The slow attribute
will also be outputted in KTAP.
Reviewed-by: David Gow <davidgow@google.com>
Signed-off-by: Rae Moar <rmoar@google.com>
Signed-off-by: Shuah Khan <skhan@linuxfoundation.org>
Commit eda0047296 ("mm: make the page fault mmap locking killable")
intentionally made it much easier to trigger the "page fault fails
because a fatal signal is pending" situation, by having the mmap locking
fail early in that case.
We have long aborted page faults in other fatal cases when the actual IO
for a page is interrupted by SIGKILL - which is particularly useful for
the traditional case of NFS hanging due to network issues, but local
filesystems could cause it too if you happened to get the SIGKILL while
waiting for a page to be faulted in (eg lock_folio_maybe_drop_mmap()).
So aborting the page fault wasn't a new condition - but it now triggers
earlier, before we even get to 'handle_mm_fault()'. And as a result the
error doesn't go through our 'fault_signal_pending()' logic, and doesn't
get filtered away there.
Normally you'd never even notice, because if a fatal signal is pending,
the new SIGSEGV we send ends up being ignored anyway.
But it turns out that there is one very noticeable exception: if you
enable 'show_unhandled_signals', the aborted page fault will be logged
in the kernel messages, and you'll get a scary line looking something
like this in your logs:
pverados[2183248]: segfault at 55e5a00f9ae0 ip 000055e5a00f9ae0 sp 00007ffc0720bea8 error 14 in perl[55e5a00d4000+195000] likely on CPU 10 (core 4, socket 0)
which is rather misleading. It's not really a segfault at all, it's
just "the thread was killed before the page fault completed, so we
aborted the page fault".
Fix this by just making it clear that a pending fatal signal means that
any new signal coming in after that is implicitly handled. This will
avoid the misleading logging, since now the signal isn't 'unhandled' any
more.
Reported-and-tested-by: Fiona Ebner <f.ebner@proxmox.com>
Tested-by: Thomas Lamprecht <t.lamprecht@proxmox.com>
Link: https://lore.kernel.org/lkml/8d063a26-43f5-0bb7-3203-c6a04dc159f8@proxmox.com/
Acked-by: Oleg Nesterov <oleg@redhat.com>
Fixes: eda0047296 ("mm: make the page fault mmap locking killable")
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
The flags of the child of a given scheduling domain are used to initialize
the flags of its scheduling groups. When the child of a scheduling domain
is degenerated, the flags of its local scheduling group need to be updated
to align with the flags of its new child domain.
The flag SD_SHARE_CPUCAPACITY was aligned in
Commit bf2dc42d6b ("sched/topology: Propagate SMT flags when removing degenerate domain").
Further generalize this alignment so other flags can be used later, such as
in cluster-based task wakeup. [1]
Reported-by: Yicong Yang <yangyicong@huawei.com>
Suggested-by: Ricardo Neri <ricardo.neri@intel.com>
Signed-off-by: Chen Yu <yu.c.chen@intel.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Tim Chen <tim.c.chen@linux.intel.com>
Reviewed-by: Yicong Yang <yangyicong@hisilicon.com>
Link: https://lore.kernel.org/r/20230713013133.2314153-1-yu.c.chen@intel.com
There is no need to use runnable_avg when estimating util_est and that
even generates wrong behavior because one includes blocked tasks whereas
the other one doesn't. This can lead to accounting twice the waking task p,
once with the blocked runnable_avg and another one when adding its
util_est.
cpu's runnable_avg is already used when computing util_avg which is then
compared with util_est.
In some situation, feec will not select prev_cpu but another one on the
same performance domain because of higher max_util
Fixes: 7d0583cf9e ("sched/fair, cpufreq: Introduce 'runnable boosting'")
Signed-off-by: Vincent Guittot <vincent.guittot@linaro.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Dietmar Eggemann <dietmar.eggemann@arm.com>
Tested-by: Dietmar Eggemann <dietmar.eggemann@arm.com>
Link: https://lore.kernel.org/r/20230706135144.324311-1-vincent.guittot@linaro.org
Splitting these out into separate helper functions means that we
actually pass an uninitialized variable into another function call
if dec_active() happens to not be inlined, and CONFIG_PREEMPT_RT
is disabled:
kernel/bpf/memalloc.c: In function 'add_obj_to_free_list':
kernel/bpf/memalloc.c:200:9: error: 'flags' is used uninitialized [-Werror=uninitialized]
200 | dec_active(c, flags);
Avoid this by passing the flags by reference, so they either get
initialized and dereferenced through a pointer, or the pointer never
gets accessed at all.
Fixes: 18e027b1c7 ("bpf: Factor out inc/dec of active flag into helpers.")
Suggested-by: Alexei Starovoitov <alexei.starovoitov@gmail.com>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Link: https://lore.kernel.org/r/20230725202653.2905259-1-arnd@kernel.org
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
We received report [1] of kernel crash, which is caused by
using nesting protection without disabled preemption.
The bpf_event_output can be called by programs executed by
bpf_prog_run_array_cg function that disabled migration but
keeps preemption enabled.
This can cause task to be preempted by another one inside the
nesting protection and lead eventually to two tasks using same
perf_sample_data buffer and cause crashes like:
BUG: kernel NULL pointer dereference, address: 0000000000000001
#PF: supervisor instruction fetch in kernel mode
#PF: error_code(0x0010) - not-present page
...
? perf_output_sample+0x12a/0x9a0
? finish_task_switch.isra.0+0x81/0x280
? perf_event_output+0x66/0xa0
? bpf_event_output+0x13a/0x190
? bpf_event_output_data+0x22/0x40
? bpf_prog_dfc84bbde731b257_cil_sock4_connect+0x40a/0xacb
? xa_load+0x87/0xe0
? __cgroup_bpf_run_filter_sock_addr+0xc1/0x1a0
? release_sock+0x3e/0x90
? sk_setsockopt+0x1a1/0x12f0
? udp_pre_connect+0x36/0x50
? inet_dgram_connect+0x93/0xa0
? __sys_connect+0xb4/0xe0
? udp_setsockopt+0x27/0x40
? __pfx_udp_push_pending_frames+0x10/0x10
? __sys_setsockopt+0xdf/0x1a0
? __x64_sys_connect+0xf/0x20
? do_syscall_64+0x3a/0x90
? entry_SYSCALL_64_after_hwframe+0x72/0xdc
Fixing this by disabling preemption in bpf_event_output.
[1] https://github.com/cilium/cilium/issues/26756
Cc: stable@vger.kernel.org
Reported-by: Oleg "livelace" Popov <o.popov@livelace.ru>
Closes: https://github.com/cilium/cilium/issues/26756
Fixes: 2a916f2f54 ("bpf: Use migrate_disable/enable in array macros and cgroup/lirc code.")
Acked-by: Hou Tao <houtao1@huawei.com>
Signed-off-by: Jiri Olsa <jolsa@kernel.org>
Link: https://lore.kernel.org/r/20230725084206.580930-3-jolsa@kernel.org
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
The nesting protection in bpf_perf_event_output relies on disabled
preemption, which is guaranteed for kprobes and tracepoints.
However bpf_perf_event_output can be also called from uprobes context
through bpf_prog_run_array_sleepable function which disables migration,
but keeps preemption enabled.
This can cause task to be preempted by another one inside the nesting
protection and lead eventually to two tasks using same perf_sample_data
buffer and cause crashes like:
kernel tried to execute NX-protected page - exploit attempt? (uid: 0)
BUG: unable to handle page fault for address: ffffffff82be3eea
...
Call Trace:
? __die+0x1f/0x70
? page_fault_oops+0x176/0x4d0
? exc_page_fault+0x132/0x230
? asm_exc_page_fault+0x22/0x30
? perf_output_sample+0x12b/0x910
? perf_event_output+0xd0/0x1d0
? bpf_perf_event_output+0x162/0x1d0
? bpf_prog_c6271286d9a4c938_krava1+0x76/0x87
? __uprobe_perf_func+0x12b/0x540
? uprobe_dispatcher+0x2c4/0x430
? uprobe_notify_resume+0x2da/0xce0
? atomic_notifier_call_chain+0x7b/0x110
? exit_to_user_mode_prepare+0x13e/0x290
? irqentry_exit_to_user_mode+0x5/0x30
? asm_exc_int3+0x35/0x40
Fixing this by disabling preemption in bpf_perf_event_output.
Cc: stable@vger.kernel.org
Fixes: 8c7dcb84e3 ("bpf: implement sleepable uprobes by chaining gps")
Acked-by: Hou Tao <houtao1@huawei.com>
Signed-off-by: Jiri Olsa <jolsa@kernel.org>
Link: https://lore.kernel.org/r/20230725084206.580930-2-jolsa@kernel.org
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
wq_cpu_intensive_thresh_us is used to detect CPU-hogging per-cpu work items.
Once detected, they're excluded from concurrency management to prevent them
from blocking other per-cpu work items. If CONFIG_WQ_CPU_INTENSIVE_REPORT is
enabled, repeat offenders are also reported so that the code can be updated.
The default threshold is 10ms which is long enough to do fair bit of work on
modern CPUs while short enough to be usually not noticeable. This
unfortunately leads to a lot of, arguable spurious, detections on very slow
CPUs. Using the same threshold across CPUs whose performance levels may be
apart by multiple levels of magnitude doesn't make whole lot of sense.
This patch scales up wq_cpu_intensive_thresh_us upto 1 second when BogoMIPS
is below 4000. This is obviously very inaccurate but it doesn't have to be
accurate to be useful. The mechanism is still useful when the threshold is
fully scaled up and the benefits of reports are usually shared with everyone
regardless of who's reporting, so as long as there are sufficient number of
fast machines reporting, we don't lose much.
Some (or is it all?) ARM CPUs systemtically report significantly lower
BogoMIPS. While this doesn't break anything, given how widespread ARM CPUs
are, it's at least a missed opportunity and it probably would be a good idea
to teach workqueue about it.
Signed-off-by: Tejun Heo <tj@kernel.org>
Reported-and-Tested-by: Geert Uytterhoeven <geert@linux-m68k.org>
On ChromeOS we've observed a considerable number of in-use pages filled with
zeros. Today with hibernate it's entirely possible that saveable pages are just
zero filled. Since we're already copying pages word-by-word in do_copy_page it
becomes almost free to determine if a page was completely filled with zeros.
This change introduces a new bitmap which will track these zero pages. If a page
is zero it will not be included in the saved image, instead to track these zero
pages in the image file we will introduce a new flag which we will set on the
packed PFN list. When reading back in the image file we will detect these zero
page PFNs and rebuild the zero page bitmap.
When the image is being loaded through calls to write_next_page if we encounter
a zero page we will silently memset it to 0 and then continue on to the next
page. Given the implementation in snapshot_read_next/snapshot_write_next this
change will be transparent to non-compressed/compressed and swsusp modes of
operation.
To provide some concrete numbers from simple ad-hoc testing, on a device which
was lightly in use we saw that:
PM: hibernation: Image created (964408 pages copied, 548304 zero pages)
Of the approximately 6.2GB of saveable pages 2.2GB (36%) were just zero filled
and could be tracked entirely within the packed PFN list. The savings would
obviously be much lower for lzo compressed images, but even in the case of
compression not copying pages across to the compression threads will still
speed things up. It's also possible that we would see better overall compression
ratios as larger regions of "real data" would improve the compressibility.
Finally, such an approach could dramatically improve swsusp performance
as each one of those zero pages requires a write syscall to reload, by
handling it as part of the packed PFN list we're able to fully avoid
that.
Signed-off-by: Brian Geffon <bgeffon@google.com>
[ rjw: Whitespace adjustments, removal of redundant parentheses ]
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Pull tracing fixes from Steven Rostedt:
- Swapping the ring buffer for snapshotting (for things like irqsoff)
can crash if the ring buffer is being resized. Disable swapping when
this happens. The missed swap will be reported to the tracer
- Report error if the histogram fails to be created due to an error in
adding a histogram variable, in event_hist_trigger_parse()
- Remove unused declaration of tracing_map_set_field_descr()
* tag 'trace-v6.5-rc2' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace:
tracing/histograms: Return an error if we fail to add histogram to hist_vars list
ring-buffer: Do not swap cpu_buffer during resize process
tracing: Remove unused extern declaration tracing_map_set_field_descr()
Since commit 743210386c ("cgroup: use cgrp->kn->id as the cgroup ID"),
cgrp is associated with its kernfs_node. Update corresponding comment.
Signed-off-by: Miaohe Lin <linmiaohe@huawei.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
Change 'new_usage' type to u64 so it can be compared with unsigned 'max'
and 'capacity' properly even if the value crosses the signed boundary.
Signed-off-by: Haitao Huang <haitao.huang@linux.intel.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
After changes in commit 0590b9335a ("fixing audit rule ordering mess,
part 1"), audit_filter_inodes() returns void, so if CONFIG_AUDITSYSCALL
not defined, it should be do {} while(0).
Signed-off-by: Xiu Jianfeng <xiujianfeng@huawei.com>
Signed-off-by: Paul Moore <paul@paul-moore.com>
