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rate_limit_us is an unsigned int, while NSEC_PER_USEC is defined as
1000L. On 32-bit systems, the multiplication is therefore performed
using 32-bit unsigned arithmetic before the result is assigned to
freq_update_delay_ns.
For example, writing 4294968 to rate_limit_us wraps the delay from
4294968000 ns to 704 ns. This makes schedutil update far more often
than configured.
Add sugov_update_rate_limit_us() to widen rate_limit_us to s64 before
converting it to nanoseconds. Use the helper when updating the tunable
through sysfs and when starting the governor, so both paths perform the
conversion without overflow.
Fixes: 9bdcb44e391d ("cpufreq: schedutil: New governor based on scheduler utilization data")
Signed-off-by: Hui Su <sh_def@163.com>
Reviewed-by: Zhongqiu Han <zhongqiu.han@oss.qualcomm.com>
Cc: All applicable <stable@vger.kernel.org>
Link: https://patch.msgid.link/20260806142304.1761454-1-sh_def@163.com
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
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sched_class->balance() is gone from sched_ext and what balance_one() does is
run dispatch to produce something pickable. Update the balance-era names to
dispatch terms:
- balance_one() -> dispatch_one()
- SCX_RQ_IN_BALANCE -> SCX_RQ_IN_DISPATCH
No BPF scheduler reads the flag. The enum autogen headers gain the new name
with the old entry retained like other removed enumerators, zero-filling at
load time. No functional changes.
Signed-off-by: Tejun Heo <tj@kernel.org>
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The fixup demoting a keep verdict when @prev is not on ext_sched_class
guarded against the rq-level SCX_RQ_BAL_KEEP flag going stale back when
balancing and picking were separate operations.
The verdict now travels in the return value, created and consumed in one
invocation against the @prev it evaluated, and every keep decision tests
SCX_TASK_QUEUED under the rq lock, which implies ext_sched_class as a class
switch dequeues first. Drop the fixup along with dispatch_core_pick()'s
copy.
Signed-off-by: Tejun Heo <tj@kernel.org>
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kick_sync_wait_bal_cb() assumes it runs on the rq's CPU from the
__schedule() tail: the snapshots it compares against live in that CPU's
percpu area and the busy-wait runs with the rq lock dropped and IRQs
enabled.
However, dispatch can now drop the rq lock while the callback sits queued,
and rq lock takers in that window (the sched class change paths, the scx
task iterator) flush pending balance callbacks on release, running the
callback on a foreign CPU. Such a run compares against unrelated snapshots
and can deadlock when the executing CPU is itself a wait target.
Bail on a foreign CPU and leave the wait state alone. The wait only observes
progress that the resched kicks already guarantee and the rq's next wait
picks up the stale cpus_to_sync bits.
Fixes: 4c95380701f5 ("sched/ext: Fold balance_scx() into pick_task_scx()")
Cc: stable@vger.kernel.org # v6.19+
Signed-off-by: Tejun Heo <tj@kernel.org>
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kernel/sched/ext/arena.c uses the gen_pool allocator, which is built only
when GENERIC_ALLOCATOR is set. SCHED_CLASS_EXT doesn't select it, so on
configs where nothing else does, the build fails to link:
build_policy.o: undefined reference to `gen_pool_create'
build_policy.o: undefined reference to `gen_pool_for_each_chunk'
build_policy.o: undefined reference to `gen_pool_destroy'
Fixes: 9eca087deb0b ("sched_ext: Sub-allocator over kernel-claimed BPF arena pages")
Reported-by: kernel test robot <lkp@intel.com>
Closes: https://lore.kernel.org/oe-kbuild-all/202608151315.tvN3X0Oq-lkp@intel.com/
Closes: https://lore.kernel.org/oe-kbuild-all/202608151632.3p91bTQj-lkp@intel.com/
Signed-off-by: Tejun Heo <tj@kernel.org>
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scx_bpf_dsq_reenq() queues a deferred reenq (dru) that runs from
run_deferred(), not ops.dispatch(). If the DSQ is destroyed before the dru
runs, process_deferred_reenq_users() sees dsq->id == SCX_DSQ_INVALID and
hits the BUG_ON. destroy_dsq() doesn't flush pending drus, so just skip.
tj: Read dsq->id once with READ_ONCE(). Reading it separately in the INVALID
check and the BUG_ON would leave a window where destroy_dsq() can
invalidate the id between the two reads and still trigger the BUG_ON.
Fixes: 84b1a0ea0b7c ("sched_ext: Implement scx_bpf_dsq_reenq() for user DSQs")
Cc: stable@vger.kernel.org # v7.1+
Signed-off-by: Tao Cui <cuitao@kylinos.cn>
Signed-off-by: Tejun Heo <tj@kernel.org>
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scx_bpf_events() always reads the root scheduler's event counters, so a
sub-scheduler program querying its own events silently gets the root's
instead and has no BPF-visible way to read its own (the per-scheduler sysfs
"events" file is the only interface). Resolve the scheduler from the calling
program with scx_prog_sched(). Unassociated programs follow the usual
scx_prog_sched() resolution: the root scheduler under a pre-sub-attach
compat root and zeroed counters otherwise.
Also fix up the malformed comment into proper kerneldoc.
Signed-off-by: Tejun Heo <tj@kernel.org>
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scx_root_disable() invalidates each rq's clock before taking the rq lock.
scx_rq_clock_invalidate() is a plain read-modify-write of rq->scx.flags and
every other writer of the word runs under the rq lock, so the unlocked
update can race a concurrent flags update and lose one side's bits.
The invalidation doesn't matter in the first place. The cached clock is read
only by scx_bpf_now() from a loaded scheduler's BPF programs, nothing can
re-validate the clock while sched_ext is disabled as scx_rq_clock_update()
is gated on scx_enabled() too, and the usual rq lock cycles under the next
scheduler refresh or invalidate it before it's practically observable. Drop
the invalidation instead of fixing the locking.
v2: Description and comment updated - the invalidation is unnecessary rather
than subsumed by the rq lock cycle below.
Fixes: 3a9910b5904d ("sched_ext: Implement scx_bpf_now()")
Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Changwoo Min <changwoo@igalia.com>
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Changes:
Make expedited grace periods expedite normal RCU callbacks
Miscellaneous fixes:
* Improve diagnostic output with character task states.
* Mark accesses to inform KCSAN of concurrency design.
* Move from kmalloc() to kmalloc_obj().
* Documentation updates.
* Improve handling of RCU deferred quiescent states.
* Clean up unused function arguments and structure fields.
* Reduce show_rcu_gp_kthreads() stack space.
Tasks RCU updates:
* Clean up after SRCU re-implementation of Tasks Trace RCU.
* Mark accesses to inform KCSAN of concurrency design.
* Add ->lazy_timer status to diagnostic output.
* Remove an unnecessary memory barrier.
* Fix a data race, courtesy of KCSAN.
* Documentation updates.
* Convert cond_resched_tasks_rcu_qs() from macro to static inline
function.
SRCU updates:
* Add Rust helpers for SRCU.
* Avoid losing queued work at cleanup_srcu_struct() time.
Torture-test updates:
* Preparation work for immediate RCU priority deboosting.
* Test RCU readers from real interrupt handlers (as opposed to softirq).
* Simplify code through use of cpumask_next_wrap().
* Improve diagnostic output with character task states.
* Add rcutorture.nwriters parameter to allow lightweight stall testing,
and rcutorture.stall_only to make doing so easier.
* Test an RCU Tasks Trace grace period implying an RCU grace period.
* Make RCU Tasks Trace torturing track reader batches.
* Fix a data race, courtesy of KCSAN.
* Plug a shuffle_tmp_mask memory leak on kthread spawn failure.
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This comment is missing a closing parenthesis:
* The in_atomic_preempt_off() check ensures that we come here holding
* the last preempt_count (which will get dropped once we return to
* __rcu_read_unlock().
This commit therefore adds it at the end of the sentence.
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
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An mmap-able BPF array map (BPF_F_MMAPABLE) has its backing memory
vmalloc'ed up front at map creation time. array_map_mmap() then wired up
the whole mapping eagerly via remap_vmalloc_range(), which calls
vm_insert_page() for every page of the map. For large maps this makes
every mmap() O(number of pages): an 8MiB map inserts 2048 PTEs per
mmap() and tears them all down again on munmap(), even when user space
only touches a few pages (or none at all).
Populate the mapping lazily instead, the same way the arena map already
does. array_map_mmap() now only performs the bounds check and returns,
leaving the PTEs unpopulated; pages are inserted on demand by a new
array_map_mmap_fault() handler. Because the memory is already resident,
the fault handler simply resolves the vmalloc page and hands it to the
fault path. This makes mmap() O(1), and munmap() proportional to the
number of pages that were actually faulted in rather than to the size of
the map.
The handler is reached through a new optional ->map_mmap_fault callback.
Maps that provide it get a vm_operations_struct with a .fault handler;
maps that populate their mapping eagerly keep the one they had. Both
share the same open/close callbacks, so the existing VMA accounting
(VM_MAYWRITE write-active tracking, freeze handling) stays centralized
rather than each map installing its own vm_operations_struct.
Callers that want the pages populated up front can still request that
explicitly with MAP_POPULATE. Kernel-side access to the map (via the
vmalloc address) is unaffected.
Time for one mmap()+munmap() of an 8MiB mmap-able array map:
before after
no MAP_POPULATE, no access 226us 1.1us
no MAP_POPULATE, access all pages 236us 1341us
MAP_POPULATE, no access 312us 493us
MAP_POPULATE, access all pages 318us 519us
Mapping without touching the data, which is what this change targets,
gets ~160x cheaper. Faulting in the whole mapping one page at a time is
more expensive than the eager remap_vmalloc_range() loop, so users that
do touch every page should ask for MAP_POPULATE. Note that MAP_POPULATE
is not free before this change either: it adds ~85us (226us => 312us)
for no benefit, as the mapping is already fully populated.
Assisted-by: Claude:claude-opus-4-8
Signed-off-by: Song Liu <song@kernel.org>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20260814155623.111565-1-song@kernel.org
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In overwrite mode ringbuf_avail_data_sz() picks the newer of the consumer
and overwrite positions before measuring how much data is available:
return prod_pos - max(cons_pos, over_pos);
max() is an ordering comparison, and consumer_pos, producer_pos and
overwrite_pos are unsigned long, i.e. 32-bit on 32-bit architectures,
where Documentation/bpf/ringbuf.rst allows them to wrap. Once one of the
two positions has wrapped and the other has not, max() returns the older
one: the result is then a modular difference close to 2^32, so the
function reports far more available data than the ring can hold. Pollers
using BPF_RB_AVAIL_DATA get a bogus figure, and epoll consumers can be
woken with nothing to read.
Compare distances rather than positions. prod_pos - X is the amount of
data produced since X for either position, wrap or no wrap, so the newer
position is simply the one with the smaller distance, which is also the
value the function wants to return.
64-bit hosts are unaffected in practice: their counters would need
16 EiB to wrap. Found by review of the same class of bug fixed in
"bpf: Fix pending_pos walk on 32-bit ring position wrap".
Signed-off-by: Israel Téllez García <i.tellez@btesa.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20260814124843.22041-3-i.tellez@btesa.com
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The reservation path caches the position of the oldest not-yet-committed
record in rb->pending_pos and advances it past already committed records
on every reservation:
while (pend_pos < prod_pos) {
consumer_pos, producer_pos and pending_pos are unsigned long, i.e.
32-bit on 32-bit architectures, and Documentation/bpf/ringbuf.rst states
that these counters may wrap around there. Every other comparison in the
file is written as a difference, so modular arithmetic keeps them
correct across the wrap. This one is an ordering comparison, and it is
not wrap-safe.
Once producer_pos wraps past 2^32, prod_pos is small while pend_pos
still holds its pre-wrap value, so the loop condition is false and
pending_pos is never advanced again. Reservations keep succeeding for a
while, because bpf_ringbuf_has_space() uses differences, but
new_prod_pos - pend_pos grows as the producer advances, and once it
exceeds rb->mask every subsequent __bpf_ringbuf_reserve() call fails:
the kernel believes a pending record spans the whole buffer. The ring
never recovers, bpf_ringbuf_output() drops every event from then on, and
nothing is logged.
Observed on four armv7 devices (i.MX7 Dual, 6.6.52) running a
tracepoint-based collector with a 512 KiB ring and 160-byte records.
Every one of them stopped delivering after exactly 26846821 records and
4295491360 bytes had passed through the ring, at event rates between 441
and 862 records/s, that is after 8 h to 17 h of uptime: the trigger is
the byte count, not time or load. That figure is 2^32 plus 524064 bytes,
and the excess is one ring's worth of grace period, as expected while
new_prod_pos - pend_pos is still below rb->mask. The last reservation
that fits is the largest record boundary X with X + 160 <= 524287, and
since 2^32 mod 160 = 96 the boundaries after the wrap sit at
X = 64 (mod 160), giving X = 524064. Userspace kept consuming normally
until the producer stopped, then read zero records for good. With this
patch applied, one of the four devices took 10 GiB through the same ring
with no stall, while the three unpatched ones kept wedging at the same
byte count.
64-bit hosts are unaffected in practice: their counters would need
16 EiB to wrap.
Compare the two positions as a difference instead. pending_pos never
runs ahead of producer_pos, so the unsigned difference is the real
distance between them and stays correct across the wrap.
Fixes: cfa1a2329a69 ("bpf: Fix overrunning reservations in ringbuf")
Signed-off-by: Israel Téllez García <i.tellez@btesa.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20260814124843.22041-2-i.tellez@btesa.com
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The rcu_read_delay() and srcu_read_delay() functions are suppose to
avoid (or at least to minimize) read-side delays during call_rcu()-based
forward-progress testing. Although rcu_read_delay() does account for
this by testing rcu_fwd_cb_nodelay, it only does so in some cases, and
srcu_read_delay() does not bother at all. And rcutorture testing does
occasionally turn up the MIN_FWD_CBS_LAUNDERED failure when running
forward-progress tests on Tree SRCU flavors.
This commit therefore makes both rcu_read_delay() and srcu_read_delay()
take an immediate exit if rcu_fwd_cb_nodelay is set.
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
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Currently, rcu_torture_fwd_prog_cr() announces function entry,
but silently exits if rcu_fwd_emergency_stop is set or if there is no
->call() function available. This could cause confusion, leading people
to believe that rcu_torture_fwd_prog_cr() is on the job when it is not.
This commit therefore also announces the early exits from this function.
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
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If torture_shuffle_init() successfully allocates shuffle_tmp_mask but
then fails to create the torture_shuffle kthread, the cpumask is never
freed.
Free the cpumask directly on the kthread-creation error path.
Signed-off-by: Joel Fernandes <joelagnelf@nvidia.com>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
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Currently __this_cpu_inc() is used to increment elements of both
the rcu_torture_count[] and rcu_torture_batch[] arrays. However,
this can fail when the increments can happen in interrupt handlers,
as recently became possible. This commit therefore upgrades the uses
of __this_cpu_inc() to the interrupt-safe this_cpu_inc().
KCSAN located this issue.
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
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This commit adds the ->get_sp_seq and ->gp_diff fields to the
tasks_tracing_ops structure so that RCU Tasks Trace rcutorture runs will
track Reader Batch.
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
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An RCU Tasks Trace grace period is supposed to imply an RCU grace period,
and this implication is relied on by BPF. But this is not currently
tested. This commit therefore makes tasks_tracing_torture_read_lock()
sometimes use rcu_read_lock() instead of rcu_read_lock_trace(), thus
testing the required implication.
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
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This commit adds a stall_only module parameter that shuts off all
rcutorture kthreads other than the RCU CPU stall-warning test kthreads.
The purpose of this is to test production applictions' reactions to
CPU stalls, and with minimal additional overhead. Or you can omit the
stall-warning tests as well and get a heavy no-op, your choice!
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
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Believe it or not, there are people who would like to run rcutorture
without actually torturing RCU. For example, some people would like to
induce various types of stall warnings without placing any unnecessary
additional overhead on their systems running in production. And
rcutorture provides the stall_cpu, stall_cpu_holdoff, stall_no_softlockup,
stall_cpu_irqsoff, stall_cpu_block, and stall_cpu_repeat module parameters
in order to allow the user to force numerous types of stalls. In addition,
rcutorture provides a great number of other module parameters to allow the
user to reduce other overhead.
But unfortunately, there is no way to turn of the rcu_torture_writer()
portion of this torture test, which on my x86 laptop consumes somewhere
between 40% and 45% of a CPU. Although this is quite lightweight for a
torture test, it is not welcome on systems running production workloads.
This commit therefore adds an nwriters module parameter that defaults
to 1 but can be set to 0 in order to disable the rcu_torture_writer()
portion of the torture test, but that cannot be set to any other value
(that is what the fakewriters module parameter is for!). This reduces
the overhead to well under 1% of a CPU, which is much more likely to be
compatible with production workloads.
Reported-by: Breno Leitao <leitao@debian.org>
Reported-by: Puranjay Mohan <puranjay@kernel.org>
Reported-by: Usama Arif <usama.arif@linux.dev>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
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Use the kernel's standard symbolic task-state representation instead of
printing raw hexadecimal task-state values.
Suggested-by: Zqiang <qiang.zhang@linux.dev>
Co-developed-by: Wang Lian <lianux.mm@gmail.com>
Signed-off-by: Wang Lian <lianux.mm@gmail.com>
Signed-off-by: Kunwu Chan <kunwu.chan@gmail.com>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
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The rcu_torture_preempt() function uses cpumask_next(), and if that
returns an out-of-bounds result, re-invokes cpumask_next() on -1.
Which is exactly what cpumask_next_wrap() does. This commit therefore
saves a couple of lines by instead using cpumask_next_wrap().
This was reported by metacode when asked to look for opportunities
to use cpumask_next_wrap() in kernel/rcu.
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
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Although rcutorture has long had the irqreader module parameter, this
parameter results only in RCU readers in softirq handlers, specifically,
timers. This commit therefore uses smp_call_function_single() to test
RCU readers in real hardware interrupt handlers, thus providing the full
effect from the irqreader module parameter.
However, consistency/debug checks must account for the possibility that
the smp_call_function_single() handler function is directly invoked
from the idle loop, in which case, for example, in_hardirq() will
return false. This commit uses a per-CPU variable to record being in
the rcu_torture_irq() smp_call_function_single() handler function.
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
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This commit adds a check for failure to have fully deboosted a
multi-segmented RCU reader at the end of the full read-side critical
section. This check only happens for fully task-level readers, because
a a handler might have interrupted an already-boosted task-level RCU
reader, and a reader in that handler could then cause false positives.
The first failed check (due to an RCU reader that was not immediately
deboosted) causes a splat, but only when the disabled-by-default
deboost_timeliness_check module parameter is enabled. Regardless of the
value of this parameter, it produces a list of the segments making up that
RCU reader following a "Slow-deboost rcutorture reader segments" heading.
Subsequent failures fail silently, all in the name of keeping console
output down to a dull roar.
Although most uses of RCU priority boosting serve as debugging aids,
this might change, and in fact might already have changed. And allowing
(for example) RCU priority boosting to persist until the next scheduler
tick could cause an aggressively real-time system to miss sub-millisecond
deadlines. So we do need to find this sort of problem during testing,
and preferably not in the field.
The name and type of the newly added rcu_torture_ops function pointer
(named "->is_task_rcu_boosted()") may need to change should other
end-of-reader checks be needed. But let's start simple.
Oh, and Claude figured out that rcu_is_task_rcu_boosted() could be
lockless. Perhaps there is hope for AI yet! ;-)
[ paulmck: Apply Akira Yokosawa feedback. ]
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
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scx_fork() initializes tasks when scx_init_task_enabled is set, but
scx_cancel_fork() only exits them when scx_enabled() is true. A fork
that fails in the enable window (between releasing scx_fork_rwsem and
setting __scx_enabled) runs ops.init_task() but never ops.exit_task().
Gate scx_cancel_fork() on scx_init_task_enabled.
Fixes: 4269c603cc26 ("sched_ext: Enable scx_ops_init_task() separately")
Cc: stable@vger.kernel.org # v6.12+
Signed-off-by: fangqiurong <fangqiurong@kylinos.cn>
Signed-off-by: Tejun Heo <tj@kernel.org>
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- inlines.h: scx_bpf_dispatch() doesn't exist; the comment means
scx_bpf_sub_dispatch()
- internal.h: name %SCX_DEQ_SCHED_CHANGE instead of the never-defined
%SCX_DEQ_SAVE
- internal.h: @name shows up in the ops file in the scheduler's sysfs
directory, not a "kernel.sched_ext_ops" sysctl
Signed-off-by: Tao Cui <cuitao@kylinos.cn>
Signed-off-by: Tejun Heo <tj@kernel.org>
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scx_process_sync_ecaps() sets up the dispatch context for
ops.sub_ecaps_updated() in the target cpu's pcpu context recovered from the
llist node. However, the context is per executing cpu: the dispatch kfuncs
resolve it with this_cpu_ptr() and the dispatch buffer lives in it. What the
dispatches target is determined by the rq recorded in the context, not by
which cpu's context it is. Under core scheduling the pick runs balance_one()
for sibling rqs, so a sync processed for a sibling invokes the op with the
executing cpu's context not set up and its dispatch kfuncs misoperate on a
NULL or stale rq.
Set up the executing cpu's dsp_ctx instead, matching scx_dispatch_sched().
The recorded rq keeps the dispatches targeting the synced cpu.
Fixes: b81a6c018cde ("sched_ext: Add sub_ecaps_updated() effective-cap change notifier")
Reported-by: David Carlier <devnexen@gmail.com>
Link: https://lore.kernel.org/all/20260813045931.8691-1-devnexen@gmail.com/
Signed-off-by: Tejun Heo <tj@kernel.org>
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ring_buffer_per_cpu::mapped tracks if a ring-buffer is either mapped by
user-space or if it is a persistent buffer. We already have user_mapped
for the former and ring_meta for the latter. Get rid of mapped and
instead create rb_is_static(). A static ring-buffer cannot be resized,
swapped or have its pages extracted.
Link: https://patch.msgid.link/20260813131152.3589632-10-vdonnefort@google.com
Signed-off-by: Vincent Donnefort <vdonnefort@google.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
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The 'cpus' field in struct trace_buffer became useless in commit
8e7b58c27b3c ("ring-buffer: Just update the subbuffers when changing their
allocation order"). Remove it
Link: https://patch.msgid.link/20260813131152.3589632-9-vdonnefort@google.com
Fixes: 8e7b58c27b3c ("ring-buffer: Just update the subbuffers when changing their allocation order")
Signed-off-by: Vincent Donnefort <vdonnefort@google.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
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The ring buffer order can be dynamically modified and temporarily
disables writing to do so. It is therefore safe to use the updated value
to calculate the maximum event size which can be written onto the ring
buffer.
However, notice it is hardly making any difference for trace_marker
because of the TRACE_MARKER_MAX_SIZE limit. For an 8KiB subbuf size,
trace_marker can take 4096 characters while it can 'only' take 4054
bytes for smaller subbufs.
Link: https://patch.msgid.link/20260813131152.3589632-8-vdonnefort@google.com
Signed-off-by: Vincent Donnefort <vdonnefort@google.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
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ring_buffer_alloc_read_page() is racy with ring_buffer_subbuf_order_set,
it can allocate a reader page with an outdated order. This isn't a big
issue, the user can still re-allocate a new reader page and try again.
However, what is more problematic is if the value of subbuf_order
changes in the middle of ring_buffer_alloc_read_page(). In that case,
bpage->order might not match the actual allocated memory.
Use bpage->order for the allocation to prevent this race.
Cc: stable@vger.kernel.org
Link: https://patch.msgid.link/20260813131152.3589632-6-vdonnefort@google.com
Fixes: bce761d75745 ("ring-buffer: Read and write to ring buffers with custom sub buffer size")
Reported-by: Sashiko <sashiko-bot@kernel.org>
Signed-off-by: Vincent Donnefort <vdonnefort@google.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
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trace_buffer subbuf_size is read lockless in ring_buffer_read_page() and
ring_buffer_read_start(), while it can simultaneously be resized with
ring_buffer_subbuf_order_set().
Instead of trace_buffer::subbuf_size, use bpage::order in
ring_buffer_read_start() and ring_buffer_read_page().
In ring_buffer_read_start(), even with resize_disabled, there is still a
possibility of a race with a buffer modification. Hold the trace_buffer
mutex to synchronise with any pending ring buffer order modification.
trace_buffer::subbuf_size is now actually useless, remove it. Also,
create accessors rb_subbuf_capacity() and rb_page_capacity() which
return the actual size available for storing events, while
rb_subbuf_size() returns the actual subbuf page-size.
Cc: stable@vger.kernel.org
Link: https://patch.msgid.link/20260813131152.3589632-5-vdonnefort@google.com
Fixes: f9b94daa542a ("ring-buffer: Set new size of the ring buffer sub page")
Reported-by: Sashiko <sashiko-bot@kernel.org>
Closes: https://sashiko.dev/#/patchset/20260805153225.2096152-1-vdonnefort%40google.com # patch 1
Acked-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Signed-off-by: Vincent Donnefort <vdonnefort@google.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
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Discarding a cached reader page after a concurrent ring buffer resize
uses the new global subbuf_order for the free_pages() call. This
mismatched order may crashes the kernel or leaks memory because the cached
page was allocated under the old size.
Save the actual free_page order alongside the page address to ensure we
always refer to the correct value and do not rely on the potentially
stalled cpu_buffer->subbuf_order value. The simplest is to make
free_page a buffer_data_read_page which already covers exactly what we
need: a page address and a page order.
Cc: stable@vger.kernel.org
Link: https://patch.msgid.link/20260813131152.3589632-4-vdonnefort@google.com
Fixes: 8e7b58c27b3c ("ring-buffer: Just update the subbuffers when changing their allocation order")
Signed-off-by: Vincent Donnefort <vdonnefort@google.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
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Because, ring_buffer_subbuf_order_set() can clear cpu_buffer->free_page,
hold cpu_buffer->lock to prevent races with
ring_buffer_alloc_read_page() and ring_buffer_free_read_page().
Cc: stable@vger.kernel.org
Link: https://patch.msgid.link/20260813131152.3589632-3-vdonnefort@google.com
Fixes: 8e7b58c27b3c ("ring-buffer: Just update the subbuffers when changing their allocation order")
Reported-by: Sashiko <sashiko-bot@kernel.org>
Closes: https://sashiko.dev/#/patchset/20260810125633.3344684-1-vdonnefort%40google.com # patch 3
Signed-off-by: Vincent Donnefort <vdonnefort@google.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
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When sub-buffers use an order greater than 0, cpu_buffer->free_page is
allocated with subbuf_order. Use the correct order for
cpu_buffer->free_page.
Cc: stable@vger.kernel.org
Link: https://patch.msgid.link/20260813131152.3589632-2-vdonnefort@google.com
Fixes: f9b94daa542a ("ring-buffer: Set new size of the ring buffer sub page")
Reported-by: Sashiko <sashiko-bot@kernel.org>
Closes: https://sashiko.dev/#/patchset/20260806211306.3704194-1-vdonnefort%40google.com # patch 3
Signed-off-by: Vincent Donnefort <vdonnefort@google.com>
Reviewed-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
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arm64 passes zero as the stack pointer while walking BPF frames, so
bpf_throw() leaves stale KASAN stack poison after jumping to the
exception callback.
Use the frame pointer as the fallback stack watermark.
Fixes: e74cb1b42213 ("arm64: stacktrace: Implement arch_bpf_stack_walk() for the BPF JIT")
Signed-off-by: Mykyta Yatsenko <yatsenko@meta.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Tested-by: Ihor Solodrai <ihor.solodrai@linux.dev>
Link: https://lore.kernel.org/bpf/20260812-hello_world-v1-1-c3c2ddcb362d@meta.com
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Pull vfs fixes from Christian Brauner:
- Don't warn when a mount is completed from another user namespace.
fsopen() records the caller's user namespace in fc->user_ns and
hands back an ordinary file descriptor. The task that calls
fsconfig(FSCONFIG_CMD_CREATE) doesn't have to be the one that
created the context, and mount_capable() lets it through as long
as the caller has CAP_SYS_ADMIN over fc->user_ns, which anyone in
an ancestor namespace does. So fc->user_ns != current_user_ns()
is something an unprivileged user can arrange.
Both overlayfs and binfmt_misc WARN_ON() that. Overlayfs already
has the same check as a plain error return in ovl_parse_param().
Drop the WARN_ON() and just refuse. Add selftests for both cases.
- Reject pid allocations through dead ancestor pid namespaces.
Require PIDNS_ADDING in every namespace that will receive the pid
before publishing any of them. That preserves the invariant that
free_pid() never decrements pid_allocated in a namespace whose
child_reaper is no longer live. The existing ENOMEM behavior is
unchanged.
* tag 'vfs-7.2-rc8.fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs:
pid: reject allocations through dead ancestor pid namespaces
selftests/filesystems: test completing a context from another user namespace
binfmt_misc: don't warn when the mount is completed from another user namespace
ovl: don't warn when the mount is completed from another user namespace
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When a fair task is enqueued, we must update curr and more precisely
its vruntime before placing the enqueued task so avg vruntime will take
into account the last exec phase.
Example:
TA is an always running task in cgroup G0.
TB is a short running task (cyclictest) in cgroup G1.
The lag of TB always increases up the clamp limit because TB is placed
before TA(curr) is updated (since the last tick). When curr(TA) is
finally updated, its last exec phase provide positive lag to TB
Because TA and TB don't belong to the same group, enqueue_hierarchy() will not
update TA's entity when updating curr but only G0's entity at root level.
The same applies when dequeuing.
This is because update_curr() uses ->h_curr, rather than ->curr, and therefore,
while it is invoked on the root cfs_rq, which contains all the eevdf bits, it
does not do the right thing.
Fixes: 85570f10a4c6 ("sched/eevdf: Move to a single runqueue")
Signed-off-by: Vincent Guittot <vincent.guittot@linaro.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://patch.msgid.link/20260812125039.1717249-1-vincent.guittot@linaro.org
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Pull in dependents, the flat hierarchy fix depends on this.
Signed-off-by: Peter Zijlstra <peterz@infradead.org>
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In order to compute the right lag, it is required to update time to 'now'.
Without this, the delayed entity might appear younger than it really is and
receive less compensation for having waited.
Signed-off-by: Vincent Guittot <vincent.guittot@linaro.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
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The function trace_event_update_all() does a scan of events looking to
replace enums with their values in the strings that get exported to the
event format files. It's run at boot up on all events and again when a
module loads.
The issue is that when a module loads, it still runs on *all* events.
There's no reason to process every event when a module loads as the
previous events have already been processed. Only execute on the events
that are loaded with the module.
Link: https://patch.msgid.link/20260813204226.29563591@gandalf.local.home
Fixes: 3673b8e4ce723 ("tracing: Allow for modules to convert their enums to values")
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
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The check that prevents userspace from sending siginfo with si_code values
reserved to the kernel is duplicated across do_rt_sigqueueinfo(),
do_rt_tgsigqueueinfo() and do_pidfd_send_signal(). Move the check into a
helper so the rule lives in one place.
Link: https://lore.kernel.org/20260806133013.4341-1-include@grrlz.net
Signed-off-by: Bradley Morgan <include@grrlz.net>
Reviewed-by: Andrew Morton <akpm@linux-foundation.org>
Acked-by: Oleg Nesterov <oleg@redhat.com>
Cc: Christian Brauner <brauner@kernel.org>
Cc: Thomas Gleixner <tglx@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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cmd_attr_register_cpumask() and cmd_attr_deregister_cpumask() differed
only in which attribute they parsed and which action they passed on, so
take both as arguments. __free(free_cpumask_var) then removes the goto.
No functional change.
Link: https://lore.kernel.org/20260728202104.17839-3-include@grrlz.net
Signed-off-by: Bradley Morgan <include@grrlz.net>
Cc: Balbir Singh <bsingharora@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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Patch series "taskstats: tidy up the cpumask command path".
Two small cleanups from reading kernel/taskstats.c. No functional change in
either one.
This patch (of 2):
taskstats_user_cmd() only calls the cpumask handlers after checking the
same info->attrs[] entry, so parse() never sees a NULL attribute. Drop
the check and its odd "return 1", which no caller tested for anyway.
No functional change.
Link: https://lore.kernel.org/20260728202104.17839-1-include@grrlz.net
Link: https://lore.kernel.org/20260728202104.17839-2-include@grrlz.net
Signed-off-by: Bradley Morgan <include@grrlz.net>
Cc: Balbir Singh <bsingharora@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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The verifier keeps per-subprogram metadata in three parallel arrays:
subprog_info, func_info, and func_info_aux. Dead code elimination can
remove whole subprograms, and adjust_subprog_starts_after_remove()
shifts subprog_info and func_info to close the gap, but leaves
func_info_aux in place. From that point on, func_info_aux[i] no longer
describes subprogram i.
Shift func_info_aux together with func_info so the three arrays stay
aligned after subprogram removal.
Reported-by: Sashiko <sashiko-bot@kernel.org>
Signed-off-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20260808064523.DE3E71F000E9@smtp.kernel.org
Link: https://lore.kernel.org/bpf/20260812231506.3558128-1-memxor@gmail.com
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The following sequence may leads race between event_define_fields()
and update_event_fields():
CPU0 (loads module A) CPU1 (loads module B)
=============================== ===============================
load_module(A) load_module(B)
notifier_call_chain notifier_call_chain
trace_module_notify trace_module_notify
mutex_lock(&event_mutex) trace_event_update_all()
trace_module_add_events(A) down_write(&trace_event_sem)
__register_event(call_A)
__add_event_to_tracers(call_A)
event_define_fields(call_A)
for each f: list_for_each_entry(field,
list_add(&f->link, &class->fields, link)
&class->fields) field = class->fields->next;
Where access to the class->fields is not protected by the event_mutex in
trace_event_update_all().
This produces the following panic:
Unable to handle kernel access ... at virtual address 0000000000000018
pc : update_event_fields+0xf8/0x368
Call trace:
update_event_fields+0xf8/0x368
trace_event_update_all+0x7c/0x2b4
trace_module_notify+0x4c/0x1dc
notifier_call_chain+0x84/0x168
blocking_notifier_call_chain_robust+0x64/0xd4
load_module+0x10c8/0x123c
__arm64_sys_finit_module+0x230/0x31c
Fix by taking event_mutex in trace_event_update_all() before
trace_event_sem.
Cc: stable@vger.kernel.org
Fixes: b3bc8547d3be ("tracing: Have TRACE_DEFINE_ENUM affect trace event types as well")
Link: https://patch.msgid.link/2e5730d2-c631-da41-3a3a-ae35bb4895f3@allwinnertech.com
Signed-off-by: Michael Wu <michael@allwinnertech.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
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A module-only event filter such as ":mod:foo" is cached with a NULL
event_mod->match when foo has not been loaded. If a later write tries to
remove a specific match from the same module, remove_cache_mod() passes
the NULL cached match to strcmp(), causing a NULL pointer dereference.
The issue can be reproduced from userspace:
echo ':mod:trace_events_kunit_missing' > /sys/kernel/tracing/set_event
echo '!foo_bar:mod:trace_events_kunit_missing' >> /sys/kernel/tracing/set_event
The second write must be a concatenation (">>") to not include O_TRUNC as
that would cause ftrace_clear_events() to clear the cached modules lines.
The crash was reproduced on x86_64 QEMU while KUnit workers contended on
the event tracing path:
BUG: kernel NULL pointer dereference, address: 0000000000000000
#PF: supervisor read access in kernel mode
RIP: 0010:strcmp+0x10/0x30
Call Trace:
__ftrace_set_clr_event_nolock+0x373/0x4a0
ftrace_set_clr_event+0xf0/0x180
ftrace_event_write+0xdf/0x110
vfs_write+0xf6/0x440
ksys_write+0x68/0xe0
do_syscall_64+0xf9/0x540
entry_SYSCALL_64_after_hwframe+0x77/0x7f
Check event_mod->match before comparing it, consistent with the existing
NULL checks for the cached system and event fields. The mismatched removal
continues to return -EINVAL; a broad cached module filter is removed with
"!:mod:<module>".
Cc: stable@vger.kernel.org
Link: https://patch.msgid.link/20260811173902.1927376-2-sh_def@163.com
Fixes: b355247df104 ("tracing: Cache \":mod:\" events for modules not loaded yet")
Reported-by: syzbot+4d3143c8e28f6266c636@syzkaller.appspotmail.com
Closes: https://lore.kernel.org/lkml/6a7a6b7f.9c11d2ce.289b96.00f8.GAE@google.com/
Signed-off-by: Hui Su <sh_def@163.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
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Cross-merge networking fixes after downstream PR (net-7.2-rc8).
No conflicts.
Adjacent changes:
drivers/net/ethernet/wangxun/ngbe/ngbe_main.c
5f3a13e0bb5e ("net: ngbe: fix NULL pointer dereference in non-MSI-X interrupt enabling")
d661abdc30c2 ("net: ngbe: correct misleading interrupt comment")
drivers/net/ipvlan/ipvlan_main.c
e16e960d55a4 ("ipvlan: inherit needed_headroom and needed_tailroom from phy_dev")
00a40d809207 ("ipvlan: Support per-netns netdev unregistration.")
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
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Introduce global percpu data, inspired by the commit
6316f78306c1 ("Merge branch 'support-global-data'"). It enables the
definition of global percpu variables in BPF, similar to the
include/linux/percpu-defs.h::DEFINE_PER_CPU() macro.
For example, in BPF, it is able to define a global percpu variable like:
int data SEC(".percpu");
With this patch, tools like retsnoop [1] and bpfsnoop [2] can simplify
their BPF code for handling LBRs. The code can be updated from
static struct perf_branch_entry lbrs[1][MAX_LBR_ENTRIES] SEC(".data.lbrs");
to
static struct perf_branch_entry lbrs[MAX_LBR_ENTRIES] SEC(".percpu.lbrs");
This eliminates the need to retrieve the CPU ID using the
bpf_get_smp_processor_id() helper.
Additionally, by reusing global percpu data map, sharing information
between tail callers and callees or freplace callers and callees becomes
simpler compared to reusing percpu_array maps.
Links:
[1] https://github.com/anakryiko/retsnoop
[2] https://github.com/bpfsnoop/bpfsnoop
Signed-off-by: Leon Hwang <leon.hwang@linux.dev>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Acked-by: Eduard Zingerman <eddyz87@gmail.com>
Link: https://lore.kernel.org/bpf/20260813152324.97937-4-leon.hwang@linux.dev
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Hui Su
Tejun Heo
Tao Cui
Paul E. McKenney
Song Liu
Israel Téllez García
Joel Fernandes
Kunwu Chan
fangqiurong
Vincent Donnefort
Mykyta Yatsenko
Linus Torvalds
Vincent Guittot
Peter Zijlstra
Steven Rostedt
Bradley Morgan
Kumar Kartikeya Dwivedi
Michael Wu
Jakub Kicinski
Leon Hwang