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Callbacks are invoked in RCU kthreads when calbacks are offloaded
(rcu_nocbs boot parameter) or when RCU's softirq handler has been
offloaded to rcuc kthreads (use_softirq==0). The current code allows
for the rcu_nocbs case but not the use_softirq case. This commit adds
support for the use_softirq case.
Reported-by: kernel test robot <lkp@intel.com>
Signed-off-by: Zqiang <qiang1.zhang@intel.com>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
Reviewed-by: Neeraj Upadhyay <quic_neeraju@quicinc.com>
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Systems built with CONFIG_RCU_NOCB_CPU=y but booted without either
the rcu_nocbs= or rcu_nohz_full= kernel-boot parameters will not have
callback offloading on any of the CPUs, nor can any of the CPUs be
switched to enable callback offloading at runtime. Although this is
intentional, it would be nice to have a way to offload all the CPUs
without having to make random bootloaders specify either the rcu_nocbs=
or the rcu_nohz_full= kernel-boot parameters.
This commit therefore provides a new CONFIG_RCU_NOCB_CPU_DEFAULT_ALL
Kconfig option that switches the default so as to offload callback
processing on all of the CPUs. This default can still be overridden
using the rcu_nocbs= and rcu_nohz_full= kernel-boot parameters.
Reviewed-by: Kalesh Singh <kaleshsingh@google.com>
Reviewed-by: Uladzislau Rezki <urezki@gmail.com>
(In v4.1, fixed issues with CONFIG maze reported by kernel test robot).
Reported-by: kernel test robot <lkp@intel.com>
Signed-off-by: Joel Fernandes <joel@joelfernandes.org>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
Reviewed-by: Neeraj Upadhyay <quic_neeraju@quicinc.com>
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direct call
If the rcuog/o[p] kthreads spawn failed, the offloaded rdp needs to
be explicitly deoffloaded, otherwise the target rdp is still considered
offloaded even though nothing actually handles the callbacks.
Signed-off-by: Zqiang <qiang1.zhang@intel.com>
Cc: Neeraj Upadhyay <quic_neeraju@quicinc.com>
Cc: Boqun Feng <boqun.feng@gmail.com>
Cc: Uladzislau Rezki <uladzislau.rezki@sony.com>
Cc: Joel Fernandes <joel@joelfernandes.org>
Signed-off-by: Frederic Weisbecker <frederic@kernel.org>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
Reviewed-by: Neeraj Upadhyay <quic_neeraju@quicinc.com>
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In case of failure to spawn either rcuog or rcuo[p] kthreads for a given
rdp, rcu_nocb_rdp_deoffload() needs to be called with the hotplug
lock and the barrier_mutex held. However cpus write lock is already held
while calling rcutree_prepare_cpu(). It's not possible to call
rcu_nocb_rdp_deoffload() from there with just locking the barrier_mutex
or this would result in a locking inversion against
rcu_nocb_cpu_deoffload() which holds both locks in the reverse order.
Simply solve this with inverting the locking order inside
rcu_nocb_cpu_[de]offload(). This will be a pre-requisite to toggle NOCB
states toward cpusets anyway.
Signed-off-by: Zqiang <qiang1.zhang@intel.com>
Cc: Neeraj Upadhyay <quic_neeraju@quicinc.com>
Cc: Boqun Feng <boqun.feng@gmail.com>
Cc: Uladzislau Rezki <uladzislau.rezki@sony.com>
Cc: Joel Fernandes <joel@joelfernandes.org>
Signed-off-by: Frederic Weisbecker <frederic@kernel.org>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
Reviewed-by: Neeraj Upadhyay <quic_neeraju@quicinc.com>
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NOCB rdp's are part of a group whose list is iterated by the
corresponding rdp leader.
This list is RCU traversed because an rdp can be either added or
deleted concurrently. Upon addition, a new iteration to the list after
a synchronization point (a pair of LOCK/UNLOCK ->nocb_gp_lock) is forced
to make sure:
1) we didn't miss a new element added in the middle of an iteration
2) we didn't ignore a whole subset of the list due to an element being
quickly deleted and then re-added.
3) we prevent from probably other surprises...
Although this layout is expected to be safe, it doesn't help anybody
to sleep well.
Simplify instead the nocb state toggling with moving the list
modification from the nocb (de-)offloading workqueue to the rcuog
kthreads instead.
Whenever the rdp leader is expected to (re-)set the SEGCBLIST_KTHREAD_GP
flag of a target rdp, the latter is queued so that the leader handles
the flag flip along with adding or deleting the target rdp to the list
to iterate. This way the list modification and iteration happen from the
same kthread and those operations can't race altogether.
As a bonus, the flags for each rdp don't need to be checked locklessly
before each iteration, which is one less opportunity to produce
nightmares.
Signed-off-by: Frederic Weisbecker <frederic@kernel.org>
Cc: Neeraj Upadhyay <quic_neeraju@quicinc.com>
Cc: Boqun Feng <boqun.feng@gmail.com>
Cc: Uladzislau Rezki <uladzislau.rezki@sony.com>
Cc: Joel Fernandes <joel@joelfernandes.org>
Cc: Zqiang <qiang1.zhang@intel.com>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
Reviewed-by: Neeraj Upadhyay <quic_neeraju@quicinc.com>
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Add a comment to explain why !rcu_preempt_blocked_readers_cgp() condition
is required on root rnp node, for GP completion check in rcu_gp_fqs_loop().
Reviewed-by: Joel Fernandes (Google) <joel@joelfernandes.org>
Signed-off-by: Neeraj Upadhyay <quic_neeraju@quicinc.com>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
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This commit saves a line of code by initializing the rcu_gp_fqs()
function's first_gp_fqs local variable in its declaration.
Reported-by: Frederic Weisbecker <frederic@kernel.org>
Reported-by: Neeraj Upadhyay <quic_neeraju@quicinc.com>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
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monitor_todo is not needed as the work struct already tracks
if work is pending. Just use that to know if work is pending
using schedule_delayed_work() helper.
Signed-off-by: Joel Fernandes (Google) <joel@joelfernandes.org>
Signed-off-by: Uladzislau Rezki (Sony) <urezki@gmail.com>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
Reviewed-by: Neeraj Upadhyay <quic_neeraju@quicinc.com>
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When a CPU is slow to provide a quiescent state for a given grace
period, RCU takes steps to encourage that CPU to get with the
quiescent-state program in a more timely fashion. These steps
include these flags in the rcu_data structure:
1. ->rcu_urgent_qs, which causes the scheduling-clock interrupt to
request an otherwise pointless context switch from the scheduler.
2. ->rcu_need_heavy_qs, which causes both cond_resched() and RCU's
context-switch hook to do an immediate momentary quiscent state.
3. ->rcu_need_heavy_qs, which causes the scheduler-clock tick to
be enabled even on nohz_full CPUs with only one runnable task.
These flags are of course cleared once the corresponding CPU has passed
through a quiescent state. Unless that quiescent state is the CPU
going offline, which means that when the CPU comes back online, it will
needlessly consume additional CPU time and incur additional latency,
which constitutes a minor but very real performance bug.
This commit therefore adds the call to rcu_disable_urgency_upon_qs()
that clears these flags to the CPU-hotplug offlining code path.
Signed-off-by: Zqiang <qiang1.zhang@intel.com>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
Reviewed-by: Neeraj Upadhyay <quic_neeraju@quicinc.com>
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When running KASAN with Tiny RCU (e.g. under ARCH=um, where
a working KASAN patch is now available), we don't get any
information on the original kfree_rcu() (or similar) caller
when a problem is reported, as Tiny RCU doesn't record this.
Add the recording, which required pulling kvfree_call_rcu()
out of line for the KASAN case since the recording function
(kasan_record_aux_stack_noalloc) is neither exported, nor
can we include kasan.h into rcutiny.h.
without KASAN, the patch has no size impact (ARCH=um kernel):
text data bss dec hex filename
6151515 4423154 33148520 43723189 29b29b5 linux
6151515 4423154 33148520 43723189 29b29b5 linux + patch
with KASAN, the impact on my build was minimal:
text data bss dec hex filename
13915539 7388050 33282304 54585893 340ea25 linux
13911266 7392114 33282304 54585684 340e954 linux + patch
-4273 +4064 +-0 -209
Acked-by: Dmitry Vyukov <dvyukov@google.com>
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
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The csdlock_debug kernel-boot parameter is parsed by the
early_param() function csdlock_debug(). If set, csdlock_debug()
invokes static_branch_enable() to enable csd_lock_wait feature, which
triggers a panic on arm64 for kernels built with CONFIG_SPARSEMEM=y and
CONFIG_SPARSEMEM_VMEMMAP=n.
With CONFIG_SPARSEMEM_VMEMMAP=n, __nr_to_section is called in
static_key_enable() and returns NULL, resulting in a NULL dereference
because mem_section is initialized only later in sparse_init().
This is also a problem for powerpc because early_param() functions
are invoked earlier than jump_label_init(), also resulting in
static_key_enable() failures. These failures cause the warning "static
key 'xxx' used before call to jump_label_init()".
Thus, early_param is too early for csd_lock_wait to run
static_branch_enable(), so changes it to __setup to fix these.
Fixes: 8d0968cc6b8f ("locking/csd_lock: Add boot parameter for controlling CSD lock debugging")
Cc: stable@vger.kernel.org
Reported-by: Chen jingwen <chenjingwen6@huawei.com>
Signed-off-by: Chen Zhongjin <chenzhongjin@huawei.com>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
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The purpose of commit 282d8998e997 ("srcu: Prevent expedited GPs
and blocking readers from consuming CPU") was to prevent a long
series of never-blocking expedited SRCU grace periods from blocking
kernel-live-patching (KLP) progress. Although it was successful, it also
resulted in excessive boot times on certain embedded workloads running
under qemu with the "-bios QEMU_EFI.fd" command line. Here "excessive"
means increasing the boot time up into the three-to-four minute range.
This increase in boot time was due to the more than 6000 back-to-back
invocations of synchronize_rcu_expedited() within the KVM host OS, which
in turn resulted from qemu's emulation of a long series of MMIO accesses.
Commit 640a7d37c3f4 ("srcu: Block less aggressively for expedited grace
periods") did not significantly help this particular use case.
Zhangfei Gao and Shameerali Kolothum Thodi did experiments varying the
value of SRCU_MAX_NODELAY_PHASE with HZ=250 and with various values
of non-sleeping per phase counts on a system with preemption enabled,
and observed the following boot times:
+──────────────────────────+────────────────+
| SRCU_MAX_NODELAY_PHASE | Boot time (s) |
+──────────────────────────+────────────────+
| 100 | 30.053 |
| 150 | 25.151 |
| 200 | 20.704 |
| 250 | 15.748 |
| 500 | 11.401 |
| 1000 | 11.443 |
| 10000 | 11.258 |
| 1000000 | 11.154 |
+──────────────────────────+────────────────+
Analysis on the experiment results show additional improvements with
CPU-bound delays approaching one jiffy in duration. This improvement was
also seen when number of per-phase iterations were scaled to one jiffy.
This commit therefore scales per-grace-period phase number of non-sleeping
polls so that non-sleeping polls extend for about one jiffy. In addition,
the delay-calculation call to srcu_get_delay() in srcu_gp_end() is
replaced with a simple check for an expedited grace period. This change
schedules callback invocation immediately after expedited grace periods
complete, which results in greatly improved boot times. Testing done
by Marc and Zhangfei confirms that this change recovers most of the
performance degradation in boottime; for CONFIG_HZ_250 configuration,
specifically, boot times improve from 3m50s to 41s on Marc's setup;
and from 2m40s to ~9.7s on Zhangfei's setup.
In addition to the changes to default per phase delays, this
change adds 3 new kernel parameters - srcutree.srcu_max_nodelay,
srcutree.srcu_max_nodelay_phase, and srcutree.srcu_retry_check_delay.
This allows users to configure the srcu grace period scanning delays in
order to more quickly react to additional use cases.
Fixes: 640a7d37c3f4 ("srcu: Block less aggressively for expedited grace periods")
Fixes: 282d8998e997 ("srcu: Prevent expedited GPs and blocking readers from consuming CPU")
Reported-by: Zhangfei Gao <zhangfei.gao@linaro.org>
Reported-by: yueluck <yueluck@163.com>
Signed-off-by: Neeraj Upadhyay <quic_neeraju@quicinc.com>
Tested-by: Marc Zyngier <maz@kernel.org>
Tested-by: Zhangfei Gao <zhangfei.gao@linaro.org>
Link: https://lore.kernel.org/all/20615615-0013-5adc-584f-2b1d5c03ebfc@linaro.org/
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
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The RCU_STRICT_GRACE_PERIOD Kconfig option does nothing in kernels
built with CONFIG_TINY_RCU=y, so this commit adjusts the dependencies
to disallow this combination.
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
Reviewed-by: Neeraj Upadhyay <quic_neeraju@quicinc.com>
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Commit 282d8998e997 ("srcu: Prevent expedited GPs and blocking readers
from consuming CPU") fixed a problem where a long-running expedited SRCU
grace period could block kernel live patching. It did so by giving up
on expediting once a given SRCU expedited grace period grew too old.
Unfortunately, this added excessive delays to boots of virtual embedded
systems specifying "-bios QEMU_EFI.fd" to qemu. This commit therefore
makes the transition away from expediting less aggressive, increasing
the per-grace-period phase number of non-sleeping polls of readers from
one to three and increasing the required grace-period age from one jiffy
(actually from zero to one jiffies) to two jiffies (actually from one
to two jiffies).
Fixes: 282d8998e997 ("srcu: Prevent expedited GPs and blocking readers from consuming CPU")
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
Reported-by: Zhangfei Gao <zhangfei.gao@linaro.org>
Reported-by: chenxiang (M)" <chenxiang66@hisilicon.com>
Cc: Shameerali Kolothum Thodi <shameerali.kolothum.thodi@huawei.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Reviewed-by: Neeraj Upadhyay <quic_neeraju@quicinc.com>
Link: https://lore.kernel.org/all/20615615-0013-5adc-584f-2b1d5c03ebfc@linaro.org/
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The intent of the CONFIG_RCU_STRICT_GRACE_PERIOD Konfig option is to
cause normal grace periods to complete quickly in order to better catch
errors resulting from improperly leaking pointers from RCU read-side
critical sections. However, kernels built with this option enabled still
wait for some hundreds of milliseconds before boosting RCU readers that
have been preempted within their current critical section. The value
of this delay is set by the CONFIG_RCU_BOOST_DELAY Kconfig option,
which defaults to 500 milliseconds.
This commit therefore causes kernels build with strict grace periods
to ignore CONFIG_RCU_BOOST_DELAY. This causes rcu_initiate_boost()
to start boosting immediately after all CPUs on a given leaf rcu_node
structure have passed through their quiescent states.
Signed-off-by: Zqiang <qiang1.zhang@intel.com>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
Reviewed-by: Neeraj Upadhyay <quic_neeraju@quicinc.com>
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Currently, the rcu_node structure's ->cbovlmask field is set in call_rcu()
when a given CPU is suffering from callback overload. But if that CPU
goes offline, the outgoing CPU's callbacks is migrated to the running
CPU, which is likely to overload the running CPU. However, that CPU's
bit in its leaf rcu_node structure's ->cbovlmask field remains zero.
Initially, this is OK because the outgoing CPU's bit remains set.
However, that bit will be cleared at the next end of a grace period,
at which time it is quite possible that the running CPU will still
be overloaded. If the running CPU invokes call_rcu(), then overload
will be checked for and the bit will be set. Except that there is no
guarantee that the running CPU will invoke call_rcu(), in which case the
next grace period will fail to take the running CPU's overload condition
into account. Plus, because the bit is not set, the end of the grace
period won't check for overload on this CPU.
This commit therefore adds a call to check_cb_ovld_locked() in
rcutree_migrate_callbacks() to set the running CPU's ->cbovlmask bit
appropriately.
Signed-off-by: Zqiang <qiang1.zhang@intel.com>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
Reviewed-by: Neeraj Upadhyay <quic_neeraju@quicinc.com>
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Stop-machine recently started calling additional functions while waiting:
----------------------------------------------------------------
Former stop machine wait loop:
do {
cpu_relax(); => macro
...
} while (curstate != STOPMACHINE_EXIT);
-----------------------------------------------------------------
Current stop machine wait loop:
do {
stop_machine_yield(cpumask); => function (notraced)
...
touch_nmi_watchdog(); => function (notraced, inside calls also notraced)
...
rcu_momentary_dyntick_idle(); => function (notraced, inside calls traced)
} while (curstate != MULTI_STOP_EXIT);
------------------------------------------------------------------
These functions (and the functions that they call) must be marked
notrace to prevent them from being updated while they are executing.
The consequences of failing to mark these functions can be severe:
rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
rcu: 1-...!: (0 ticks this GP) idle=14f/1/0x4000000000000000 softirq=3397/3397 fqs=0
rcu: 3-...!: (0 ticks this GP) idle=ee9/1/0x4000000000000000 softirq=5168/5168 fqs=0
(detected by 0, t=8137 jiffies, g=5889, q=2 ncpus=4)
Task dump for CPU 1:
task:migration/1 state:R running task stack: 0 pid: 19 ppid: 2 flags:0x00000000
Stopper: multi_cpu_stop+0x0/0x18c <- stop_machine_cpuslocked+0x128/0x174
Call Trace:
Task dump for CPU 3:
task:migration/3 state:R running task stack: 0 pid: 29 ppid: 2 flags:0x00000000
Stopper: multi_cpu_stop+0x0/0x18c <- stop_machine_cpuslocked+0x128/0x174
Call Trace:
rcu: rcu_preempt kthread timer wakeup didn't happen for 8136 jiffies! g5889 f0x0 RCU_GP_WAIT_FQS(5) ->state=0x402
rcu: Possible timer handling issue on cpu=2 timer-softirq=594
rcu: rcu_preempt kthread starved for 8137 jiffies! g5889 f0x0 RCU_GP_WAIT_FQS(5) ->state=0x402 ->cpu=2
rcu: Unless rcu_preempt kthread gets sufficient CPU time, OOM is now expected behavior.
rcu: RCU grace-period kthread stack dump:
task:rcu_preempt state:I stack: 0 pid: 14 ppid: 2 flags:0x00000000
Call Trace:
schedule+0x56/0xc2
schedule_timeout+0x82/0x184
rcu_gp_fqs_loop+0x19a/0x318
rcu_gp_kthread+0x11a/0x140
kthread+0xee/0x118
ret_from_exception+0x0/0x14
rcu: Stack dump where RCU GP kthread last ran:
Task dump for CPU 2:
task:migration/2 state:R running task stack: 0 pid: 24 ppid: 2 flags:0x00000000
Stopper: multi_cpu_stop+0x0/0x18c <- stop_machine_cpuslocked+0x128/0x174
Call Trace:
This commit therefore marks these functions notrace:
rcu_preempt_deferred_qs()
rcu_preempt_need_deferred_qs()
rcu_preempt_deferred_qs_irqrestore()
[ paulmck: Apply feedback from Neeraj Upadhyay. ]
Signed-off-by: Patrick Wang <patrick.wang.shcn@gmail.com>
Acked-by: Steven Rostedt (Google) <rostedt@goodmis.org>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
Reviewed-by: Neeraj Upadhyay <quic_neeraju@quicinc.com>
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The force-quiesce-state loop function rcu_gp_fqs_loop() checks for
callback overloading and does an immediate initial scan for idle CPUs
if so. However, subsequent rescans will be carried out at as leisurely a
rate as they always are, as specified by the rcutree.jiffies_till_next_fqs
module parameter. It might be tempting to just continue immediately
rescanning, but this turns the RCU grace-period kthread into a CPU hog.
It might also be tempting to reduce the time between rescans to a single
jiffy, but this can be problematic on larger systems.
This commit therefore divides the normal time between rescans by three,
rounding up. Thus a small system running at HZ=1000 that is suffering
from callback overload will wait only one jiffy instead of the normal
three between rescans.
[ paulmck: Apply Neeraj Upadhyay feedback. ]
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
Reviewed-by: Neeraj Upadhyay <quic_neeraju@quicinc.com>
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Syscall-side map_lookup_elem() and map_update_elem() used to use
kmalloc() to allocate temporary buffers of value_size, so
KMALLOC_MAX_SIZE limit on value_size made sense to prevent creation of
array map that won't be accessible through syscall interface.
But this limitation since has been lifted by relying on kvmalloc() in
syscall handling code. So remove KMALLOC_MAX_SIZE, which among other
things means that it's possible to have BPF global variable sections
(.bss, .data, .rodata) bigger than 8MB now. Keep the sanity check to
prevent trivial overflows like round_up(map->value_size, 8) and restrict
value size to <= INT_MAX (2GB).
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/r/20220715053146.1291891-4-andrii@kernel.org
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
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BPF_MAP_TYPE_ARRAY is rounding value_size to closest multiple of 8 and
stores that as array->elem_size for various memory allocations and
accesses.
But the code tends to re-calculate round_up(map->value_size, 8) in
multiple places instead of using array->elem_size. Cleaning this up and
making sure we always use array->size to avoid duplication of this
(admittedly simple) logic for consistency.
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/r/20220715053146.1291891-3-andrii@kernel.org
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
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If BPF array map is bigger than 4GB, element pointer calculation can
overflow because both index and elem_size are u32. Fix this everywhere
by forcing 64-bit multiplication. Extract this formula into separate
small helper and use it consistently in various places.
Speculative-preventing formula utilizing index_mask trick is left as is,
but explicit u64 casts are added in both places.
Fixes: c85d69135a91 ("bpf: move memory size checks to bpf_map_charge_init()")
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/r/20220715053146.1291891-2-andrii@kernel.org
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
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This particular ones is about having the following:
CONFIG_BPF_LSM=y
# CONFIG_CGROUP_BPF is not set
Also, add __maybe_unused to the args for the !CONFIG_NET cases.
Reported-by: kernel test robot <lkp@intel.com>
Signed-off-by: Stanislav Fomichev <sdf@google.com>
Acked-by: Yonghong Song <yhs@fb.com>
Link: https://lore.kernel.org/r/20220714185404.3647772-1-sdf@google.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
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NOMAP irq domains use the revmap_size field to indicate the maximum
hwirq number the domain accepts. This is a bit confusing as
revmap_size is usually used to indicate the size of the revmap array,
which a NOMAP domain doesn't have.
Instead, use the hwirq_max field which has the correct semantics, and
keep revmap_size to 0 for a NOMAP domain.
Signed-off-by: Xu Qiang <xuqiang36@huawei.com>
[maz: commit message]
Signed-off-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20220719063641.56541-3-xuqiang36@huawei.com
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When using a NOMAP domain, __irq_resolve_mapping() doesn't store
the Linux IRQ number at the address optionally provided by the caller.
While this isn't a huge deal (the returned value is guaranteed
to the hwirq that was passed as a parameter), let's honour the letter
of the API by writing the expected value.
Fixes: d22558dd0a6c (“irqdomain: Introduce irq_resolve_mapping()”)
Signed-off-by: Xu Qiang <xuqiang36@huawei.com>
[maz: commit message]
Signed-off-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20220719063641.56541-2-xuqiang36@huawei.com
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Streaming DMA mapping involving an IOMMU may be much slower for larger
total mapping size. This is because every IOMMU DMA mapping requires an
IOVA to be allocated and freed. IOVA sizes above a certain limit are not
cached, which can have a big impact on DMA mapping performance.
Provide an API for device drivers to know this "optimal" limit, such that
they may try to produce mapping which don't exceed it.
Signed-off-by: John Garry <john.garry@huawei.com>
Reviewed-by: Damien Le Moal <damien.lemoal@opensource.wdc.com>
Acked-by: Martin K. Petersen <martin.petersen@oracle.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
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The rng's random_init() function contributes the real time to the rng at
boot time, so that events can at least start in relation to something
particular in the real world. But this clock might not yet be set that
point in boot, so nothing is contributed. In addition, the relation
between minor clock changes from, say, NTP, and the cycle counter is
potentially useful entropic data.
This commit addresses this by mixing in a time stamp on calls to
settimeofday and adjtimex. No entropy is credited in doing so, so it
doesn't make initialization faster, but it is still useful input to
have.
Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2")
Cc: stable@vger.kernel.org
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Eric Biggers <ebiggers@google.com>
Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
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No need to expose this structure definition in the header.
Signed-off-by: Christoph Hellwig <hch@lst.de>
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Free slots tracking assumes that slots in a segment can be allocated to
fulfill a request. This implies that slots in a segment should belong to
the same area. Although the possibility of a violation is low, it is better
to explicitly enforce segments won't span multiple areas by adjusting the
number of slabs when configuring areas.
Signed-off-by: Chao Gao <chao.gao@intel.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
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default_nslabs are rounded up in two cases with exactly same comments.
Add a simple wrapper to reduce duplicate code/comments. It is preparatory
to adding more logics into the round-up.
No functional change intended.
Signed-off-by: Chao Gao <chao.gao@intel.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
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Commit 20347fca71a3 ("swiotlb: split up the global swiotlb lock") splits
io_tlb_mem into multiple areas. Each area has its own lock and index. The
global ones are not used so remove them.
Signed-off-by: Chao Gao <chao.gao@intel.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
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Don't dereference "mem" after it has been freed. Flip the
two kfree()s around to address this bug.
Fixes: 26ffb91fa5e0 ("swiotlb: split up the global swiotlb lock")
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
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The total memory size we get in kernel is usually slightly less than the
actual memory size because BIOS/firmware will reserve some memory region.
So it won't export all memory as usable.
E.g, on my x86_64 kvm guest with 1G memory, the total_mem value shows:
UEFI boot with ovmf: 0x3faef000 Legacy boot kvm guest: 0x3ff7ec00
When specifying crashkernel=1G-2G:128M, if we have a 1G memory machine, we
get total size 1023M from firmware. Then it will not fall into 1G-2G,
thus no memory reserved. User will never know this, it is hard to let
user know the exact total value in kernel.
One way is to use dmi/smbios to get physical memory size, but it's not
reliable as well. According to Prarit hardware vendors sometimes screw
this up. Thus round up total size to 128M to work around this problem.
This patch is a resend of [1] and rebased onto v5.19-rc2, and the
original credit goes to Dave Young.
[1]: http://lists.infradead.org/pipermail/kexec/2018-April/020568.html
Link: https://lkml.kernel.org/r/20220627074440.187222-1-ltao@redhat.com
Signed-off-by: Tao Liu <ltao@redhat.com>
Acked-by: Baoquan He <bhe@redhat.com>
Cc: Dave Young <dyoung@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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The internal kallsyms tables contain information which could be quite
useful to a debugging tool in the absence of other debuginfo. If kallsyms
is enabled, then a debugging tool could parse it and use it as a fallback
symbol table. Combined with BTF data, live & post-mortem debuggers can
support basic operations without needing a large DWARF debuginfo file
available. As many as five symbols are necessary to properly parse
kallsyms names and addresses. Add these to the vmcoreinfo note.
CONFIG_KALLSYMS_ABSOLUTE_PERCPU does impact the computation of symbol
addresses. However, a debugger can infer this configuration value by
comparing the address of _stext in the vmcoreinfo with the address
computed via kallsyms. So there's no need to include information about
this config value in the vmcoreinfo note.
To verify that we're still well below the maximum of 4096 bytes, I created
a script[1] to compute a rough upper bound on the possible size of
vmcoreinfo. On v5.18-rc7, the script reports 3106 bytes, and with this
patch, the maximum become 3370 bytes.
[1]: https://github.com/brenns10/kernel_stuff/blob/master/vmcoreinfosize/
Link: https://lkml.kernel.org/r/20220517000508.777145-3-stephen.s.brennan@oracle.com
Signed-off-by: Stephen Brennan <stephen.s.brennan@oracle.com>
Acked-by: Baoquan He <bhe@redhat.com>
Cc: Bixuan Cui <cuibixuan@huawei.com>
Cc: Dave Young <dyoung@redhat.com>
Cc: David Vernet <void@manifault.com>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Kees Cook <keescook@chromium.org>
Cc: Nick Desaulniers <ndesaulniers@google.com>
Cc: Sami Tolvanen <samitolvanen@google.com>
Cc: Stephen Boyd <swboyd@chromium.org>
Cc: Vivek Goyal <vgoyal@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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Patch series "Expose kallsyms data in vmcoreinfo note".
The kernel can be configured to contain a lot of introspection or
debugging information built-in, such as ORC for unwinding stack traces,
BTF for type information, and of course kallsyms. Debuggers could use
this information to navigate a core dump or live system, but they need to
be able to find it.
This patch series adds the necessary symbols into vmcoreinfo, which would
allow a debugger to find and interpret the kallsyms table. Using the
kallsyms data, the debugger can then lookup any symbol, allowing it to
find ORC, BTF, or any other useful data.
This would allow a live kernel, or core dump, to be debugged without any
DWARF debuginfo. This is useful for many cases: the debuginfo may not
have been generated, or you may not want to deploy the large files
everywhere you need them.
I've demonstrated a proof of concept for this at LSF/MM+BPF during a
lighting talk. Using a work-in-progress branch of the drgn debugger, and
an extended set of BTF generated by a patched version of dwarves, I've
been able to open a core dump without any DWARF info and do basic tasks
such as enumerating slab caches, block devices, tasks, and doing
backtraces. I hope this series can be a first step toward a new
possibility of "DWARFless debugging".
Related discussion around the BTF side of this:
https://lore.kernel.org/bpf/586a6288-704a-f7a7-b256-e18a675927df@oracle.com/T/#u
Some work-in-progress branches using this feature:
https://github.com/brenns10/dwarves/tree/remove_percpu_restriction_1
https://github.com/brenns10/drgn/tree/kallsyms_plus_btf
This patch (of 2):
To include kallsyms data in the vmcoreinfo note, we must make the symbol
declarations visible outside of kallsyms.c. Move these to a new internal
header file.
Link: https://lkml.kernel.org/r/20220517000508.777145-1-stephen.s.brennan@oracle.com
Link: https://lkml.kernel.org/r/20220517000508.777145-2-stephen.s.brennan@oracle.com
Signed-off-by: Stephen Brennan <stephen.s.brennan@oracle.com>
Acked-by: Baoquan He <bhe@redhat.com>
Cc: Nick Desaulniers <ndesaulniers@google.com>
Cc: Dave Young <dyoung@redhat.com>
Cc: Kees Cook <keescook@chromium.org>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Stephen Boyd <swboyd@chromium.org>
Cc: Bixuan Cui <cuibixuan@huawei.com>
Cc: David Vernet <void@manifault.com>
Cc: Vivek Goyal <vgoyal@redhat.com>
Cc: Sami Tolvanen <samitolvanen@google.com>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull perf fix from Borislav Petkov:
- A single data race fix on the perf event cleanup path to avoid
endless loops due to insufficient locking
* tag 'perf_urgent_for_v5.19_rc7' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
perf/core: Fix data race between perf_event_set_output() and perf_mmap_close()
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git://git.kernel.org/pub/scm/linux/kernel/git/printk/linux
Pull printk fix from Petr Mladek:
- Make pr_flush() fast when consoles are suspended.
* tag 'printk-for-5.19-rc7' of git://git.kernel.org/pub/scm/linux/kernel/git/printk/linux:
printk: do not wait for consoles when suspended
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Now that all callers of ->llseek are going through vfs_llseek(), we
don't gain anything by keeping no_llseek around. Nothing actually calls
it and setting ->llseek to no_lseek is completely equivalent to
leaving it NULL.
Longer term (== by the end of merge window) we want to remove all such
intializations. To simplify the merge window this commit does *not*
touch initializers - it only defines no_llseek as NULL (and simplifies
the tests on file opening).
At -rc1 we'll need do a mechanical removal of no_llseek -
git grep -l -w no_llseek | grep -v porting.rst | while read i; do
sed -i '/\<no_llseek\>/d' $i
done
would do it.
Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
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Reflect recent changes in the blk_fill_rwbs() kernel-doc header.
Reported-by: Stephen Rothwell <sfr@canb.auug.org.au>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Li Zefan <lizf@cn.fujitsu.com>
Cc: Chaitanya Kulkarni <kch@nvidia.com>
Cc: Stephen Rothwell <sfr@canb.auug.org.au>
Fixes: 919dbca8670d ("blktrace: Use the new blk_opf_t type")
Signed-off-by: Bart Van Assche <bvanassche@acm.org>
Link: https://lore.kernel.org/r/20220715184735.2326034-3-bvanassche@acm.org
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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kernel/bpf/preload/iterators use bpftool for vmlinux.h, skeleton, and
static linking only. So we can use lightweight bootstrap version of
bpftool to handle these, and it will be faster.
Suggested-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Pu Lehui <pulehui@huawei.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20220714024612.944071-4-pulehui@huawei.com
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Give the LSM framework the ability to filter setgroups() syscalls. There
are already analagous hooks for the set*uid() and set*gid() syscalls.
The SafeSetID LSM will use this new hook to ensure setgroups() calls are
allowed by the installed security policy. Tested by putting print
statement in security_task_fix_setgroups() hook and confirming that it
gets hit when userspace does a setgroups() syscall.
Acked-by: Casey Schaufler <casey@schaufler-ca.com>
Reviewed-by: Serge Hallyn <serge@hallyn.com>
Signed-off-by: Micah Morton <mortonm@chromium.org>
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The milli-Watts precision causes rounding errors while calculating
efficiency cost for each OPP. This is especially visible in the 'simple'
Energy Model (EM), where the power for each OPP is provided from OPP
framework. This can cause some OPPs to be marked inefficient, while
using micro-Watts precision that might not happen.
Update all EM users which access 'power' field and assume the value is
in milli-Watts.
Solve also an issue with potential overflow in calculation of energy
estimation on 32bit machine. It's needed now since the power value
(thus the 'cost' as well) are higher.
Example calculation which shows the rounding error and impact:
power = 'dyn-power-coeff' * volt_mV * volt_mV * freq_MHz
power_a_uW = (100 * 600mW * 600mW * 500MHz) / 10^6 = 18000
power_a_mW = (100 * 600mW * 600mW * 500MHz) / 10^9 = 18
power_b_uW = (100 * 605mW * 605mW * 600MHz) / 10^6 = 21961
power_b_mW = (100 * 605mW * 605mW * 600MHz) / 10^9 = 21
max_freq = 2000MHz
cost_a_mW = 18 * 2000MHz/500MHz = 72
cost_a_uW = 18000 * 2000MHz/500MHz = 72000
cost_b_mW = 21 * 2000MHz/600MHz = 70 // <- artificially better
cost_b_uW = 21961 * 2000MHz/600MHz = 73203
The 'cost_b_mW' (which is based on old milli-Watts) is misleadingly
better that the 'cost_b_uW' (this patch uses micro-Watts) and such
would have impact on the 'inefficient OPPs' information in the Cpufreq
framework. This patch set removes the rounding issue.
Signed-off-by: Lukasz Luba <lukasz.luba@arm.com>
Acked-by: Daniel Lezcano <daniel.lezcano@linaro.org>
Acked-by: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
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When checking with sparse, btf_show_type_value() is causing a
warning about checking integer vs NULL when the macro is passed
a pointer, due to the 'value != 0' check. Stop sparse complaining
about any type-casting by adding a cast to the typeof(value).
This fixes the following sparse warnings:
kernel/bpf/btf.c:2579:17: warning: Using plain integer as NULL pointer
kernel/bpf/btf.c:2581:17: warning: Using plain integer as NULL pointer
kernel/bpf/btf.c:3407:17: warning: Using plain integer as NULL pointer
kernel/bpf/btf.c:3758:9: warning: Using plain integer as NULL pointer
Signed-off-by: Ben Dooks <ben.dooks@sifive.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Acked-by: Yonghong Song <yhs@fb.com>
Link: https://lore.kernel.org/bpf/20220714100322.260467-1-ben.dooks@sifive.com
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git://git.kernel.org/pub/scm/linux/kernel/git/mcgrof/linux
Pyll sysctl fix from Luis Chamberlain:
"Only one fix for sysctl"
* tag 'sysctl-fixes-5.19-rc7' of git://git.kernel.org/pub/scm/linux/kernel/git/mcgrof/linux:
mm: sysctl: fix missing numa_stat when !CONFIG_HUGETLB_PAGE
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commit 278311e417be ("kexec, KEYS: Make use of platform keyring for
signature verify") adds platform keyring support on x86 kexec but not
arm64.
The code in bzImage64_verify_sig uses the keys on the
.builtin_trusted_keys, .machine, if configured and enabled,
.secondary_trusted_keys, also if configured, and .platform keyrings
to verify the signed kernel image as PE file.
Cc: kexec@lists.infradead.org
Cc: keyrings@vger.kernel.org
Cc: linux-security-module@vger.kernel.org
Reviewed-by: Michal Suchanek <msuchanek@suse.de>
Signed-off-by: Coiby Xu <coxu@redhat.com>
Signed-off-by: Mimi Zohar <zohar@linux.ibm.com>
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Before commit 105e10e2cf1c ("kexec_file: drop weak attribute from
functions"), there was already no arch-specific implementation
of arch_kexec_kernel_verify_sig. With weak attribute dropped by that
commit, arch_kexec_kernel_verify_sig is completely useless. So clean it
up.
Note later patches are dependent on this patch so it should be backported
to the stable tree as well.
Cc: stable@vger.kernel.org
Suggested-by: Eric W. Biederman <ebiederm@xmission.com>
Reviewed-by: Michal Suchanek <msuchanek@suse.de>
Acked-by: Baoquan He <bhe@redhat.com>
Signed-off-by: Coiby Xu <coxu@redhat.com>
[zohar@linux.ibm.com: reworded patch description "Note"]
Link: https://lore.kernel.org/linux-integrity/20220714134027.394370-1-coxu@redhat.com/
Signed-off-by: Mimi Zohar <zohar@linux.ibm.com>
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Drop __weak attribute from functions in kexec_core.c:
- machine_kexec_post_load()
- arch_kexec_protect_crashkres()
- arch_kexec_unprotect_crashkres()
- crash_free_reserved_phys_range()
Link: https://lkml.kernel.org/r/c0f6219e03cb399d166d518ab505095218a902dd.1656659357.git.naveen.n.rao@linux.vnet.ibm.com
Signed-off-by: Naveen N. Rao <naveen.n.rao@linux.vnet.ibm.com>
Suggested-by: Eric Biederman <ebiederm@xmission.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Mimi Zohar <zohar@linux.ibm.com>
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As requested
(http://lkml.kernel.org/r/87ee0q7b92.fsf@email.froward.int.ebiederm.org),
this series converts weak functions in kexec to use the #ifdef approach.
Quoting the 3e35142ef99fe ("kexec_file: drop weak attribute from
arch_kexec_apply_relocations[_add]") changelog:
: Since commit d1bcae833b32f1 ("ELF: Don't generate unused section symbols")
: [1], binutils (v2.36+) started dropping section symbols that it thought
: were unused. This isn't an issue in general, but with kexec_file.c, gcc
: is placing kexec_arch_apply_relocations[_add] into a separate
: .text.unlikely section and the section symbol ".text.unlikely" is being
: dropped. Due to this, recordmcount is unable to find a non-weak symbol in
: .text.unlikely to generate a relocation record against.
This patch (of 2);
Drop __weak attribute from functions in kexec_file.c:
- arch_kexec_kernel_image_probe()
- arch_kimage_file_post_load_cleanup()
- arch_kexec_kernel_image_load()
- arch_kexec_locate_mem_hole()
- arch_kexec_kernel_verify_sig()
arch_kexec_kernel_image_load() calls into kexec_image_load_default(), so
drop the static attribute for the latter.
arch_kexec_kernel_verify_sig() is not overridden by any architecture, so
drop the __weak attribute.
Link: https://lkml.kernel.org/r/cover.1656659357.git.naveen.n.rao@linux.vnet.ibm.com
Link: https://lkml.kernel.org/r/2cd7ca1fe4d6bb6ca38e3283c717878388ed6788.1656659357.git.naveen.n.rao@linux.vnet.ibm.com
Signed-off-by: Naveen N. Rao <naveen.n.rao@linux.vnet.ibm.com>
Suggested-by: Eric Biederman <ebiederm@xmission.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Mimi Zohar <zohar@linux.ibm.com>
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The console_stop() and console_start() functions call pr_flush().
When suspending, these functions are called by the serial subsystem
while the serial port is suspended. In this scenario, if there are
any pending messages, a call to pr_flush() will always result in a
timeout because the serial port cannot make forward progress. This
causes longer suspend and resume times.
Add a check in pr_flush() so that it will immediately timeout if
the consoles are suspended.
Fixes: 3b604ca81202 ("printk: add pr_flush()")
Reported-by: Todd Brandt <todd.e.brandt@linux.intel.com>
Signed-off-by: John Ogness <john.ogness@linutronix.de>
Tested-by: Todd Brandt <todd.e.brandt@linux.intel.com>
Signed-off-by: Petr Mladek <pmladek@suse.com>
Link: https://lore.kernel.org/r/20220715061042.373640-2-john.ogness@linutronix.de
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The commit 7337224fc150 ("bpf: Improve the info.func_info and info.func_info_rec_size behavior")
accidently made bpf_prog_ksym_set_name() conservative for bpf subprograms.
Fixed it so instead of "bpf_prog_tag_F" the stack traces print "bpf_prog_tag_full_subprog_name".
Fixes: 7337224fc150 ("bpf: Improve the info.func_info and info.func_info_rec_size behavior")
Reported-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Acked-by: Martin KaFai Lau <kafai@fb.com>
Acked-by: Yonghong Song <yhs@fb.com>
Link: https://lore.kernel.org/bpf/20220714211637.17150-1-alexei.starovoitov@gmail.com
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