All failure exits prior to fdget() leave the scope, all matching fdput()
are immediately followed by leaving the scope.
Reviewed-by: Christian Brauner <brauner@kernel.org>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
fdget() is the first thing done in scope, all matching fdput() are
immediately followed by leaving the scope.
Reviewed-by: Christian Brauner <brauner@kernel.org>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Calling conventions for __bpf_map_get() would be more convenient
if it left fpdut() on failure to callers. Makes for simpler logics
in the callers.
Among other things, the proof of memory safety no longer has to
rely upon file->private_data never being ERR_PTR(...) for bpffs files.
Original calling conventions made it impossible for the caller to tell
whether __bpf_map_get() has returned ERR_PTR(-EINVAL) because it has found
the file not be a bpf map one (in which case it would've done fdput())
or because it found that ERR_PTR(-EINVAL) in file->private_data of a
bpf map file (in which case fdput() would _not_ have been done).
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Reviewed-by: Christian Brauner <brauner@kernel.org>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Factor out the logic to extract bpf_map instances from FD embedded in
bpf_insns, adding it to the list of used_maps (unless it's already
there, in which case we just reuse map's index). This simplifies the
logic in resolve_pseudo_ldimm64(), especially around `struct fd`
handling, as all that is now neatly contained in the helper and doesn't
leak into a dozen error handling paths.
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Irregularity here is fdput() not in the same scope as fdget();
just fold ____bpf_prog_get() into its (only) caller and that's
it...
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Acked-by: Andrii Nakryiko <andrii@kernel.org>
Reviewed-by: Christian Brauner <brauner@kernel.org>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
consume_remote_task() and dispatch_to_local_dsq() use
move_task_to_local_dsq() to migrate the task to the target CPU. Currently,
move_task_to_local_dsq() expects the caller to lock both the source and
destination rq's. While this may save a few lock operations while the rq's
are not contended, under contention, the double locking can exacerbate the
situation significantly (refer to the linked message below).
Update the migration path so that double locking is not used.
move_task_to_local_dsq() now expects the caller to be locking the source rq,
drops it and then acquires the destination rq lock. Code is simpler this way
and, on a 2-way NUMA machine w/ Xeon Gold 6138, 'hackbench 100 thread 5000`
shows ~3% improvement with scx_simple.
Signed-off-by: Tejun Heo <tj@kernel.org>
Suggested-by: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/20240806082716.GP37996@noisy.programming.kicks-ass.net
Acked-by: David Vernet <void@manifault.com>
Add an interface for a user-defined workqueue lockdep map, which is
helpful when multiple workqueues are created for the same purpose. This
also helps avoid leaking lockdep maps on each workqueue creation.
v2:
- Add alloc_workqueue_lockdep_map (Tejun)
v3:
- Drop __WQ_USER_OWNED_LOCKDEP (Tejun)
- static inline alloc_ordered_workqueue_lockdep_map (Tejun)
Cc: Tejun Heo <tj@kernel.org>
Cc: Lai Jiangshan <jiangshanlai@gmail.com>
Signed-off-by: Matthew Brost <matthew.brost@intel.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
`__bpf_ops_sched_ext_ops` was missing the initialization of some struct
attributes. With
https://lore.kernel.org/all/20240722183049.2254692-4-martin.lau@linux.dev/
every single attributes need to be initialized programs (like scx_layered)
will fail to load.
05:26:48 [INFO] libbpf: struct_ops layered: member cgroup_init not found in kernel, skipping it as it's set to zero
05:26:48 [INFO] libbpf: struct_ops layered: member cgroup_exit not found in kernel, skipping it as it's set to zero
05:26:48 [INFO] libbpf: struct_ops layered: member cgroup_prep_move not found in kernel, skipping it as it's set to zero
05:26:48 [INFO] libbpf: struct_ops layered: member cgroup_move not found in kernel, skipping it as it's set to zero
05:26:48 [INFO] libbpf: struct_ops layered: member cgroup_cancel_move not found in kernel, skipping it as it's set to zero
05:26:48 [INFO] libbpf: struct_ops layered: member cgroup_set_weight not found in kernel, skipping it as it's set to zero
05:26:48 [WARN] libbpf: prog 'layered_dump': BPF program load failed: unknown error (-524)
05:26:48 [WARN] libbpf: prog 'layered_dump': -- BEGIN PROG LOAD LOG --
attach to unsupported member dump of struct sched_ext_ops
processed 0 insns (limit 1000000) max_states_per_insn 0 total_states 0 peak_states 0 mark_read 0
-- END PROG LOAD LOG --
05:26:48 [WARN] libbpf: prog 'layered_dump': failed to load: -524
05:26:48 [WARN] libbpf: failed to load object 'bpf_bpf'
05:26:48 [WARN] libbpf: failed to load BPF skeleton 'bpf_bpf': -524
Error: Failed to load BPF program
Signed-off-by: Manu Bretelle <chantr4@gmail.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
The regressing commit is new in 6.10. It assumed that anytime event->prog
is set bpf_overflow_handler() should be invoked to execute the attached bpf
program. This assumption is false for tracing events, and as a result the
regressing commit broke bpftrace by invoking the bpf handler with garbage
inputs on overflow.
Prior to the regression the overflow handlers formed a chain (of length 0,
1, or 2) and perf_event_set_bpf_handler() (the !tracing case) added
bpf_overflow_handler() to that chain, while perf_event_attach_bpf_prog()
(the tracing case) did not. Both set event->prog. The chain of overflow
handlers was replaced by a single overflow handler slot and a fixed call to
bpf_overflow_handler() when appropriate. This modifies the condition there
to check event->prog->type == BPF_PROG_TYPE_PERF_EVENT, restoring the
previous behavior and fixing bpftrace.
Signed-off-by: Kyle Huey <khuey@kylehuey.com>
Suggested-by: Andrii Nakryiko <andrii.nakryiko@gmail.com>
Reported-by: Joe Damato <jdamato@fastly.com>
Closes: https://lore.kernel.org/lkml/ZpFfocvyF3KHaSzF@LQ3V64L9R2/
Fixes: f11f10bfa1 ("perf/bpf: Call BPF handler directly, not through overflow machinery")
Cc: stable@vger.kernel.org
Tested-by: Joe Damato <jdamato@fastly.com> # bpftrace
Acked-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/r/20240813151727.28797-1-jdamato@fastly.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
commit 779dbc2e78 ("printk: Avoid non-panic CPUs writing
to ringbuffer") disabled non-panic CPUs to further write messages to
ringbuffer after panicked.
Since the commit, non-panicked CPU's are not allowed to write to
ring buffer after panicked and CPU backtrace which is triggered
after panicked to sample non-panicked CPUs' backtrace no longer
serves its function as it has nothing to print.
Fix the issue by allowing non-panicked CPUs to write into ringbuffer
while CPU backtrace is in flight.
Fixes: 779dbc2e78 ("printk: Avoid non-panic CPUs writing to ringbuffer")
Signed-off-by: Ryo Takakura <takakura@valinux.co.jp>
Reviewed-by: Petr Mladek <pmladek@suse.com>
Link: https://lore.kernel.org/r/20240812072703.339690-1-takakura@valinux.co.jp
Signed-off-by: Petr Mladek <pmladek@suse.com>
We want the compiler to see that fdput() on empty instance
is a no-op. The emptiness check is that file reference is NULL,
while fdput() is "fput() if FDPUT_FPUT is present in flags".
The reason why fdput() on empty instance is a no-op is something
compiler can't see - it's that we never generate instances with
NULL file reference combined with non-zero flags.
It's not that hard to deal with - the real primitives behind
fdget() et.al. are returning an unsigned long value, unpacked by (inlined)
__to_fd() into the current struct file * + int. The lower bits are
used to store flags, while the rest encodes the pointer. Linus suggested
that keeping this unsigned long around with the extractions done by inlined
accessors should generate a sane code and that turns out to be the case.
Namely, turning struct fd into a struct-wrapped unsinged long, with
fd_empty(f) => unlikely(f.word == 0)
fd_file(f) => (struct file *)(f.word & ~3)
fdput(f) => if (f.word & 1) fput(fd_file(f))
ends up with compiler doing the right thing. The cost is the patch
footprint, of course - we need to switch f.file to fd_file(f) all over
the tree, and it's not doable with simple search and replace; there are
false positives, etc.
Note that the sole member of that structure is an opaque
unsigned long - all accesses should be done via wrappers and I don't
want to use a name that would invite manual casts to file pointers,
etc. The value of that member is equal either to (unsigned long)p | flags,
p being an address of some struct file instance, or to 0 for an empty fd.
For now the new predicate (fd_empty(f)) has no users; all the
existing checks have form (!fd_file(f)). We will convert to fd_empty()
use later; here we only define it (and tell the compiler that it's
unlikely to return true).
This commit only deals with representation change; there will
be followups.
Reviewed-by: Christian Brauner <brauner@kernel.org>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
For any changes of struct fd representation we need to
turn existing accesses to fields into calls of wrappers.
Accesses to struct fd::flags are very few (3 in linux/file.h,
1 in net/socket.c, 3 in fs/overlayfs/file.c and 3 more in
explicit initializers).
Those can be dealt with in the commit converting to
new layout; accesses to struct fd::file are too many for that.
This commit converts (almost) all of f.file to
fd_file(f). It's not entirely mechanical ('file' is used as
a member name more than just in struct fd) and it does not
even attempt to distinguish the uses in pointer context from
those in boolean context; the latter will be eventually turned
into a separate helper (fd_empty()).
NOTE: mass conversion to fd_empty(), tempting as it
might be, is a bad idea; better do that piecewise in commit
that convert from fdget...() to CLASS(...).
[conflicts in fs/fhandle.c, kernel/bpf/syscall.c, mm/memcontrol.c
caught by git; fs/stat.c one got caught by git grep]
[fs/xattr.c conflict]
Reviewed-by: Christian Brauner <brauner@kernel.org>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Daniel Hodges reported a kernel verifier crash when playing with sched-ext.
Further investigation shows that the crash is due to invalid memory access
in stacksafe(). More specifically, it is the following code:
if (exact != NOT_EXACT &&
old->stack[spi].slot_type[i % BPF_REG_SIZE] !=
cur->stack[spi].slot_type[i % BPF_REG_SIZE])
return false;
The 'i' iterates old->allocated_stack.
If cur->allocated_stack < old->allocated_stack the out-of-bound
access will happen.
To fix the issue add 'i >= cur->allocated_stack' check such that if
the condition is true, stacksafe() should fail. Otherwise,
cur->stack[spi].slot_type[i % BPF_REG_SIZE] memory access is legal.
Fixes: 2793a8b015 ("bpf: exact states comparison for iterator convergence checks")
Cc: Eduard Zingerman <eddyz87@gmail.com>
Reported-by: Daniel Hodges <hodgesd@meta.com>
Acked-by: Eduard Zingerman <eddyz87@gmail.com>
Signed-off-by: Yonghong Song <yonghong.song@linux.dev>
Link: https://lore.kernel.org/r/20240812214847.213612-1-yonghong.song@linux.dev
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
If a core is offline then enabling SMT should not online CPUs of
this core. By enabling SMT, what is intended is either changing the SMT
value from "off" to "on" or setting the SMT level (threads per core) from a
lower to higher value.
On PowerPC the ppc64_cpu utility can be used, among other things, to
perform the following functions:
ppc64_cpu --cores-on # Get the number of online cores
ppc64_cpu --cores-on=X # Put exactly X cores online
ppc64_cpu --offline-cores=X[,Y,...] # Put specified cores offline
ppc64_cpu --smt={on|off|value} # Enable, disable or change SMT level
If the user has decided to offline certain cores, enabling SMT should
not online CPUs in those cores. This patch fixes the issue and changes
the behaviour as described, by introducing an arch specific function
topology_is_core_online(). It is currently implemented only for PowerPC.
Fixes: 73c58e7e14 ("powerpc: Add HOTPLUG_SMT support")
Reported-by: Tyrel Datwyler <tyreld@linux.ibm.com>
Closes: https://groups.google.com/g/powerpc-utils-devel/c/wrwVzAAnRlI/m/5KJSoqP4BAAJ
Signed-off-by: Nysal Jan K.A <nysal@linux.ibm.com>
Reviewed-by: Shrikanth Hegde <sshegde@linux.ibm.com>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://msgid.link/20240731030126.956210-2-nysal@linux.ibm.com
SRCU keeps a count of the number of callbacks that the current
srcu_barrier() is waiting on, but there is currently no easy way to
work out which callback is stuck. One way to do this is to mark idle
SRCU-barrier callbacks by making the ->next pointer point to the callback
itself, and this commit does just that.
Later commits will use this for debug output.
Signed-off-by: "Paul E. McKenney" <paulmck@kernel.org>
Signed-off-by: Neeraj Upadhyay <neeraj.upadhyay@kernel.org>
SRCU maintains the ->srcu_n_exp_nodelay and ->reschedule_count values
to guide heuristics governing auto-expediting of normal SRCU grace
periods and grace-period-state-machine delays. This commit adds KCSAN
ASSERT_EXCLUSIVE_WRITER() calls to check for concurrent updates to
these fields.
Signed-off-by: "Paul E. McKenney" <paulmck@kernel.org>
Signed-off-by: Neeraj Upadhyay <neeraj.upadhyay@kernel.org>
Using a higher value for the initial gp sequence counters allows for
wrapping to occur faster. It can help with surfacing any issues that may
be happening as a result of the wrap around.
Signed-off-by: JP Kobryn <inwardvessel@gmail.com>
Tested-by: Paul E. McKenney <paulmck@kernel.org>
Signed-off-by: Neeraj Upadhyay <neeraj.upadhyay@kernel.org>
It was discovered that isolated CPUs could sometimes be disturbed by
kworkers processing kfree_rcu() works causing higher than expected
latency. It is because the RCU core uses "system_wq" which doesn't have
the WQ_UNBOUND flag to handle all its work items. Fix this violation of
latency limits by using "system_unbound_wq" in the RCU core instead.
This will ensure that those work items will not be run on CPUs marked
as isolated.
Beside the WQ_UNBOUND flag, the other major difference between system_wq
and system_unbound_wq is their max_active count. The system_unbound_wq
has a max_active of WQ_MAX_ACTIVE (512) while system_wq's max_active
is WQ_DFL_ACTIVE (256) which is half of WQ_MAX_ACTIVE.
Reported-by: Vratislav Bendel <vbendel@redhat.com>
Closes: https://issues.redhat.com/browse/RHEL-50220
Signed-off-by: Waiman Long <longman@redhat.com>
Reviewed-by: "Uladzislau Rezki (Sony)" <urezki@gmail.com>
Tested-by: Breno Leitao <leitao@debian.org>
Signed-off-by: Neeraj Upadhyay <neeraj.upadhyay@kernel.org>
Pull time keeping fixes from Thomas Gleixner:
- Fix a couple of issues in the NTP code where user supplied values are
neither sanity checked nor clamped to the operating range. This
results in integer overflows and eventualy NTP getting out of sync.
According to the history the sanity checks had been removed in favor
of clamping the values, but the clamping never worked correctly under
all circumstances. The NTP people asked to not bring the sanity
checks back as it might break existing applications.
Make the clamping work correctly and add it where it's missing
- If adjtimex() sets the clock it has to trigger the hrtimer subsystem
so it can adjust and if the clock was set into the future expire
timers if needed. The caller should provide a bitmask to tell
hrtimers which clocks have been adjusted.
adjtimex() uses not the proper constant and uses CLOCK_REALTIME
instead, which is 0. So hrtimers adjusts only the clocks, but does
not check for expired timers, which might make them expire really
late. Use the proper bitmask constant instead.
* tag 'timers-urgent-2024-08-11' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
timekeeping: Fix bogus clock_was_set() invocation in do_adjtimex()
ntp: Safeguard against time_constant overflow
ntp: Clamp maxerror and esterror to operating range
Pull irq fixes from Thomas Gleixner:
"Three small fixes for interrupt core and drivers:
- The interrupt core fails to honor caller supplied affinity hints
for non-managed interrupts and uses the system default affinity on
startup instead. Set the missing flag in the descriptor to tell the
core to use the provided affinity.
- Fix a shift out of bounds error in the Xilinx driver
- Handle switching to level trigger correctly in the RISCV APLIC
driver. It failed to retrigger the interrupt which causes it to
become stale"
* tag 'irq-urgent-2024-08-11' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
irqchip/riscv-aplic: Retrigger MSI interrupt on source configuration
irqchip/xilinx: Fix shift out of bounds
genirq/irqdesc: Honor caller provided affinity in alloc_desc()
Add the __counted_by compiler attribute to the flexible array member
records to improve access bounds-checking via CONFIG_UBSAN_BOUNDS and
CONFIG_FORTIFY_SOURCE.
Increment nr_records before adding a new pointer to the records array.
Signed-off-by: Thorsten Blum <thorsten.blum@toblux.com>
Reviewed-by: "Gustavo A. R. Silva" <gustavoars@kernel.org>
Reviewed-by: "Uladzislau Rezki (Sony)" <urezki@gmail.com>
Reviewed-by: Paul E. McKenney <paulmck@kernel.org>
Signed-off-by: Neeraj Upadhyay <neeraj.upadhyay@kernel.org>
The context_tracking.state RCU_DYNTICKS subvariable has been renamed to
RCU_WATCHING, and the 'dynticks' prefix can be dropped without losing any
meaning.
Signed-off-by: Valentin Schneider <vschneid@redhat.com>
Reviewed-by: Frederic Weisbecker <frederic@kernel.org>
Signed-off-by: Neeraj Upadhyay <neeraj.upadhyay@kernel.org>
The context_tracking.state RCU_DYNTICKS subvariable has been renamed to
RCU_WATCHING, and the 'dynticks' prefix can be dropped without losing any
meaning.
Suggested-by: Frederic Weisbecker <frederic@kernel.org>
Signed-off-by: Valentin Schneider <vschneid@redhat.com>
Reviewed-by: Frederic Weisbecker <frederic@kernel.org>
Signed-off-by: Neeraj Upadhyay <neeraj.upadhyay@kernel.org>
The context_tracking.state RCU_DYNTICKS subvariable has been renamed to
RCU_WATCHING, and the 'dynticks' prefix can be dropped without losing any
meaning.
Suggested-by: Frederic Weisbecker <frederic@kernel.org>
Signed-off-by: Valentin Schneider <vschneid@redhat.com>
Reviewed-by: Frederic Weisbecker <frederic@kernel.org>
Signed-off-by: Neeraj Upadhyay <neeraj.upadhyay@kernel.org>
The context_tracking.state RCU_DYNTICKS subvariable has been renamed to
RCU_WATCHING, and the 'dynticks' prefix can be dropped without losing any
meaning.
[ neeraj.upadhyay: Fix htmldocs build error reported by Stephen Rothwell ]
Suggested-by: Frederic Weisbecker <frederic@kernel.org>
Signed-off-by: Valentin Schneider <vschneid@redhat.com>
Reviewed-by: Frederic Weisbecker <frederic@kernel.org>
Signed-off-by: Neeraj Upadhyay <neeraj.upadhyay@kernel.org>
The context_tracking.state RCU_DYNTICKS subvariable has been renamed to
RCU_WATCHING, and the 'dynticks' prefix can be dropped without losing any
meaning.
Suggested-by: Frederic Weisbecker <frederic@kernel.org>
Signed-off-by: Valentin Schneider <vschneid@redhat.com>
Reviewed-by: Frederic Weisbecker <frederic@kernel.org>
Signed-off-by: Neeraj Upadhyay <neeraj.upadhyay@kernel.org>
The context_tracking.state RCU_DYNTICKS subvariable has been renamed to
RCU_WATCHING, reflect that change in the related helpers.
Suggested-by: Frederic Weisbecker <frederic@kernel.org>
Signed-off-by: Valentin Schneider <vschneid@redhat.com>
Reviewed-by: Frederic Weisbecker <frederic@kernel.org>
Signed-off-by: Neeraj Upadhyay <neeraj.upadhyay@kernel.org>
The context_tracking.state RCU_DYNTICKS subvariable has been renamed to
RCU_WATCHING, reflect that change in the related helpers.
[ neeraj.upadhyay: Fix htmldocs build error reported by Stephen Rothwell ]
Suggested-by: Frederic Weisbecker <frederic@kernel.org>
Signed-off-by: Valentin Schneider <vschneid@redhat.com>
Reviewed-by: Frederic Weisbecker <frederic@kernel.org>
Signed-off-by: Neeraj Upadhyay <neeraj.upadhyay@kernel.org>
Pull dma-mapping fix from Christoph Hellwig:
- avoid a deadlock with dma-debug and netconsole (Rik van Riel)
* tag 'dma-mapping-6.11-2024-08-10' of git://git.infradead.org/users/hch/dma-mapping:
dma-debug: avoid deadlock between dma debug vs printk and netconsole
Devices can provide multiple interrupt lines. One reason for this is that
a device has multiple subfunctions, each providing its own interrupt line.
Another reason is that a device can be designed to be used (also) on a
system where some of the interrupts can be routed to another processor.
A line often further acts as a demultiplex for specific interrupts
and has it's respective set of interrupt (status, mask, ack, ...)
registers.
Regmap supports the handling of these registers and demultiplexing
interrupts, but the interrupt domain code ends up assigning the same name
for the per interrupt line domains. This causes a naming collision in the
debugFS code and leads to confusion, as /proc/interrupts shows two separate
interrupts with the same domain name and hardware interrupt number.
Instead of adding a workaround in regmap or driver code, allow giving a
name suffix for the domain name when the domain is created.
Add a name_suffix field in the irq_domain_info structure and make
irq_domain_instantiate() use this suffix if it is given when a domain is
created.
[ tglx: Adopt it to the cleanup patch and fixup the invalid NULL return ]
Signed-off-by: Matti Vaittinen <mazziesaccount@gmail.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lore.kernel.org/all/871q2yvk5x.ffs@tglx
irq_domain_create_simple() and irq_domain_create_legacy() use
__irq_domain_instantiate(), but have extra handling of allocating interrupt
descriptors and associating interrupts in them. Some of that is duplicated.
There are also call sites which have conditonals to invoke different
interrupt domain creator functions, where one of them is usually
irq_domain_create_legacy(). Alternatively they associate the interrupts for
the legacy case after creating the domain.
Moving the extra logic of irq_domain_create_simple()/legacy() into
__irq_domain_instantiate() allows to consolidate that.
Introduce hwirq_base and virq_base members in the irq_domain_info
structure, which allows to transport the required information and add the
conditional interrupt descriptor allocation and interrupt association into
__irq_domain_instantiate().
This reduces irq_domain_create_legacy() and irq_domain_create_simple() to
trivial wrappers which fill in the info structure and allows call sites
which must support the legacy case along with more modern mechanism to
select the domain type via the parameters of the info struct.
[ tglx: Massaged change log ]
Suggested-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Matti Vaittinen <mazziesaccount@gmail.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lore.kernel.org/all/32d07bd79eb2b5416e24da9e9e8fe5955423dcf9.1723120028.git.mazziesaccount@gmail.com
When running the following:
# cd /sys/kernel/tracing/
# echo 1 > events/sched/sched_waking/enable
# echo 1 > events/sched/sched_switch/enable
# echo 0 > tracing_on
# dd if=per_cpu/cpu0/trace_pipe_raw of=/tmp/raw0.dat
The dd task would get stuck in an infinite loop in the kernel. What would
happen is the following:
When ring_buffer_read_page() returns -1 (no data) then a check is made to
see if the buffer is empty (as happens when the page is not full), it will
call wait_on_pipe() to wait until the ring buffer has data. When it is it
will try again to read data (unless O_NONBLOCK is set).
The issue happens when there's a reader and the file descriptor is closed.
The wait_on_pipe() will return when that is the case. But this loop will
continue to try again and wait_on_pipe() will again return immediately and
the loop will continue and never stop.
Simply check if the file was closed before looping and exit out if it is.
Cc: stable@vger.kernel.org
Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Link: https://lore.kernel.org/20240808235730.78bf63e5@rorschach.local.home
Fixes: 2aa043a55b ("tracing/ring-buffer: Fix wait_on_pipe() race")
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
Pull kprobe fixes from Masami Hiramatsu:
- Fix misusing str_has_prefix() parameter order to check symbol prefix
correctly
- bpf: remove unused declaring of bpf_kprobe_override
* tag 'probes-fixes-v6.11-rc2' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace:
kprobes: Fix to check symbol prefixes correctly
bpf: kprobe: remove unused declaring of bpf_kprobe_override
It turns out that the WARN_ON_ONCE() call in css_release_work_fn
introduced by commit ab03125268 ("cgroup: Show # of subsystem CSSes
in cgroup.stat") is incorrect. Although css->nr_descendants must be
0 when a css is released and ready to be freed, the corresponding
cgrp->nr_dying_subsys[ss->id] may not be 0 if a subsystem is activated
and deactivated multiple times with one or more of its previous
activation leaving behind dying csses.
Fix the incorrect warning by removing the cgrp->nr_dying_subsys check.
Fixes: ab03125268 ("cgroup: Show # of subsystem CSSes in cgroup.stat")
Closes: https://lore.kernel.org/cgroups/6f301773-2fce-4602-a391-8af7ef00b2fb@redhat.com/T/#t
Signed-off-by: Waiman Long <longman@redhat.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
The recursive aes-arm-bs module load situation reported by Russell King
is getting fixed in the crypto layer, but this in the meantime fixes the
"recursive load hangs forever" by just making the waiting for the first
module load be interruptible.
This should now match the old behavior before commit 9b9879fc03
("modules: catch concurrent module loads, treat them as idempotent"),
which used the different "wait for module to be ready" code in
module_patient_check_exists().
End result: a recursive module load will still block, but now a signal
will interrupt it and fail the second module load, at which point the
first module will successfully complete loading.
Fixes: 9b9879fc03 ("modules: catch concurrent module loads, treat them as idempotent")
Cc: Russell King <linux@armlinux.org.uk>
Cc: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
sched_ext currently doesn't generate messages when the BPF scheduler is
enabled and disabled unless there are errors. It is useful to have paper
trail. Improve logging around enable/disable:
- Generate info messages on enable and non-error disable.
- Update error exit message formatting so that it's consistent with
non-error message. Also, prefix ei->msg with the BPF scheduler's name to
make it clear where the message is coming from.
- Shorten scx_exit_reason() strings for SCX_EXIT_UNREG* for brevity and
consistency.
v2: Use pr_*() instead of KERN_* consistently. (David)
Signed-off-by: Tejun Heo <tj@kernel.org>
Suggested-by: Phil Auld <pauld@redhat.com>
Reviewed-by: Phil Auld <pauld@redhat.com>
Acked-by: David Vernet <void@manifault.com>
scx_rq_online() currently only tests SCX_RQ_ONLINE. This isn't fully correct
- e.g. consume_dispatch_q() uses task_run_on_remote_rq() which tests
scx_rq_online() to see whether the current rq can run the task, and, if so,
calls consume_remote_task() to migrate the task to @rq. While the test
itself was done while locking @rq, @rq can be temporarily unlocked by
consume_remote_task() and nothing prevents SCX_RQ_ONLINE from going offline
before the migration takes place.
To address the issue, add cpu_active() test to scx_rq_online(). There is a
synchronize_rcu() between cpu_active() being cleared and the rq going
offline, so if an on-going scheduling operation sees cpu_active(), the
associated rq is guaranteed to not go offline until the scheduling operation
is complete.
Signed-off-by: Tejun Heo <tj@kernel.org>
Fixes: 60c27fb59f ("sched_ext: Implement sched_ext_ops.cpu_online/offline()")
Acked-by: David Vernet <void@manifault.com>
