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Introduce a new subprog_start field in bpf_prog_aux. This field may
be used by JIT compilers wanting to know the real absolute xlated
offset of the function being jitted. The func_info[func_id] may have
served this purpose, but func_info may be NULL, so JIT compilers
can't rely on it.
Signed-off-by: Anton Protopopov <a.s.protopopov@gmail.com>
Acked-by: Eduard Zingerman <eddyz87@gmail.com>
Link: https://lore.kernel.org/r/20251019202145.3944697-3-a.s.protopopov@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
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In [1] Eduard mentioned that on push_stack failure verifier code
should return -ENOMEM instead of -EFAULT. After checking with the
other call sites I've found that code randomly returns either -ENOMEM
or -EFAULT. This patch unifies the return values for the push_stack
(and similar push_async_cb) functions such that error codes are
always assigned properly.
[1] https://lore.kernel.org/bpf/20250615085943.3871208-1-a.s.protopopov@gmail.com
Signed-off-by: Anton Protopopov <a.s.protopopov@gmail.com>
Acked-by: Eduard Zingerman <eddyz87@gmail.com>
Link: https://lore.kernel.org/r/20251019202145.3944697-2-a.s.protopopov@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
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Fix a race where irq_work can be queued in bpf_ringbuf_commit()
but the ring buffer is freed before the work executes.
In the syzbot reproducer, a BPF program attached to sched_switch
triggers bpf_ringbuf_commit(), queuing an irq_work. If the ring buffer
is freed before this work executes, the irq_work thread may accesses
freed memory.
Calling `irq_work_sync(&rb->work)` ensures that all pending irq_work
complete before freeing the buffer.
Fixes: 457f44363a88 ("bpf: Implement BPF ring buffer and verifier support for it")
Reported-by: syzbot+2617fc732430968b45d2@syzkaller.appspotmail.com
Closes: https://syzkaller.appspot.com/bug?extid=2617fc732430968b45d2
Tested-by: syzbot+2617fc732430968b45d2@syzkaller.appspotmail.com
Signed-off-by: Noorain Eqbal <nooraineqbal@gmail.com>
Link: https://lore.kernel.org/r/20251020180301.103366-1-nooraineqbal@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
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propagate_to_outer_instance() calls get_outer_instance() and uses the
returned pointer to reset and commit stack write marks. Under normal
conditions, update_instance() guarantees that an outer instance exists,
so get_outer_instance() cannot return an ERR_PTR.
However, explicitly checking for IS_ERR(outer_instance) makes this code
more robust and self-documenting. It reduces cognitive load when reading
the control flow and silences potential false-positive reports from
static analysis or automated tooling.
No functional change intended.
Signed-off-by: Shardul Bankar <shardulsb08@gmail.com>
Acked-by: Eduard Zingerman <eddyz87@gmail.com>
Link: https://lore.kernel.org/r/20251021080849.860072-1-shardulsb08@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
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To simplify the code and make it more readable.
While at it, change thread_group_cputime() to use __for_each_thread(sig).
[peterz: update to new interface]
Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
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KCSAN reports:
BUG: KCSAN: data-race in do_raw_write_lock / do_raw_write_lock
write (marked) to 0xffff800009cf504c of 4 bytes by task 1102 on cpu 1:
do_raw_write_lock+0x120/0x204
_raw_write_lock_irq
do_exit
call_usermodehelper_exec_async
ret_from_fork
read to 0xffff800009cf504c of 4 bytes by task 1103 on cpu 0:
do_raw_write_lock+0x88/0x204
_raw_write_lock_irq
do_exit
call_usermodehelper_exec_async
ret_from_fork
value changed: 0xffffffff -> 0x00000001
Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 1103 Comm: kworker/u4:1 6.1.111
Commit 1a365e822372 ("locking/spinlock/debug: Fix various data races") has
adressed most of these races, but seems to be not consistent/not complete.
>From do_raw_write_lock() only debug_write_lock_after() part has been
converted to WRITE_ONCE(), but not debug_write_lock_before() part.
Do it now.
Fixes: 1a365e822372 ("locking/spinlock/debug: Fix various data races")
Reported-by: Adrian Freihofer <adrian.freihofer@siemens.com>
Signed-off-by: Alexander Sverdlin <alexander.sverdlin@siemens.com>
Signed-off-by: Boqun Feng <boqun.feng@gmail.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Paul E. McKenney <paulmck@kernel.org>
Acked-by: Waiman Long <longman@redhat.com>
Cc: stable@vger.kernel.org
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git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup
Pull cgroup fixes from Tejun Heo:
- Fix seqcount lockdep assertion failure in cgroup freezer on
PREEMPT_RT.
Plain seqcount_t expects preemption disabled, but PREEMPT_RT
spinlocks don't disable preemption. Switch to seqcount_spinlock_t to
properly associate css_set_lock with the freeze timing seqcount.
- Misc changes including kernel-doc warning fix for misc_res_type enum
and improved selftest diagnostics.
* tag 'cgroup-for-6.18-rc2-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup:
cgroup/misc: fix misc_res_type kernel-doc warning
selftests: cgroup: Use values_close_report in test_cpu
selftests: cgroup: add values_close_report helper
cgroup: Fix seqcount lockdep assertion in cgroup freezer
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The messages printed by swsusp_save() are basically only useful for
debug, so printing them every time a hibernation image is created at
the "info" log level is not particularly useful. Also printing a
message on a failing memory allocation is redundant.
Use pm_deferred_pr_dbg() for printing those messages so they will only
be printed when requested and the "deferred" variant is used because
this code runs in a deeply atomic context (one CPU with interrupts
off, no functional devices). Also drop the useless message printed
when memory allocations fails.
While at it, extend one of the messages in question so it is less
cryptic.
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
[ rjw: Dropped a useless colon at the end of one of the messages ]
Link: https://patch.msgid.link/10750389.nUPlyArG6x@rafael.j.wysocki
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The return value of irq_find_mapping() is only tested, not used for
anything else.
Replaced it by irq_resolve_mapping() which is internally used by
irq_find_mapping() and allows a simple boolean decision.
Signed-off-by: Christophe JAILLET <christophe.jaillet@wanadoo.fr>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://patch.msgid.link/1ce680114cdb8d40b072c54d7f015696a540e5a6.1760863194.git.christophe.jaillet@wanadoo.fr
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The loop in tk_aux_sysfs_init() uses `i <= MAX_AUX_CLOCKS` as the
termination condition, which results in 9 iterations (i=0 to 8) when
MAX_AUX_CLOCKS is defined as 8. However, the kernel is designed to support
only up to 8 auxiliary clocks.
This off-by-one error causes the creation of a 9th sysfs entry that exceeds
the intended auxiliary clock range.
Fix the loop bound to use `i < MAX_AUX_CLOCKS` to ensure exactly 8
auxiliary clock entries are created, matching the design specification.
Fixes: 7b95663a3d96 ("timekeeping: Provide interface to control auxiliary clocks")
Signed-off-by: Haofeng Li <lihaofeng@kylinos.cn>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://patch.msgid.link/tencent_2376993D9FC06A3616A4F981B3DE1C599607@qq.com
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The cpuset structure has a nr_subparts field which tracks the number
of child local partitions underneath a particular cpuset. Right now,
nr_subparts is only used in partition_is_populated() to avoid iteration
of child cpusets if the condition is right. So by always performing the
child iteration, we can avoid tracking the number of child partitions
and simplify the code a bit.
Signed-off-by: Waiman Long <longman@redhat.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
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There is no page fault without MMU. Compiling the rtapp/pagefault monitor
without CONFIG_MMU fails as page fault tracepoints' definitions are not
available.
Make rtapp/pagefault monitor depends on CONFIG_MMU.
Fixes: 9162620eb604 ("rv: Add rtapp_pagefault monitor")
Signed-off-by: Nam Cao <namcao@linutronix.de>
Reported-by: kernel test robot <lkp@intel.com>
Closes: https://lore.kernel.org/oe-kbuild-all/202509260455.6Z9Vkty4-lkp@intel.com/
Cc: stable@vger.kernel.org
Reviewed-by: Gabriele Monaco <gmonaco@redhat.com>
Link: https://lore.kernel.org/r/20251002082317.973839-1-namcao@linutronix.de
Signed-off-by: Gabriele Monaco <gmonaco@redhat.com>
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The callbacks in enabled_monitors_seq_ops are inconsistent. Some treat the
iterator as struct rv_monitor *, while others treat the iterator as struct
list_head *.
This causes a wrong type cast and crashes the system as reported by Nathan.
Convert everything to use struct list_head * as iterator. This also makes
enabled_monitors consistent with available_monitors.
Fixes: de090d1ccae1 ("rv: Fix wrong type cast in enabled_monitors_next()")
Reported-by: Nathan Chancellor <nathan@kernel.org>
Closes: https://lore.kernel.org/linux-trace-kernel/20250923002004.GA2836051@ax162/
Signed-off-by: Nam Cao <namcao@linutronix.de>
Cc: stable@vger.kernel.org
Reviewed-by: Gabriele Monaco <gmonaco@redhat.com>
Link: https://lore.kernel.org/r/20251002082235.973099-1-namcao@linutronix.de
Signed-off-by: Gabriele Monaco <gmonaco@redhat.com>
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git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull scheduler fixes from Borislav Petkov:
- Make sure the check for lost pelt idle time is done unconditionally
to have correct lost idle time accounting
- Stop the deadline server task before a CPU goes offline
* tag 'sched_urgent_for_v6.18_rc2' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
sched/fair: Fix pelt lost idle time detection
sched/deadline: Stop dl_server before CPU goes offline
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git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull perf fixes from Borislav Petkov:
- Make sure perf reporting works correctly in setups using
overlayfs or FUSE
- Move the uprobe optimization to a better location logically
* tag 'perf_urgent_for_v6.18_rc2' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
perf/core: Fix MMAP2 event device with backing files
perf/core: Fix MMAP event path names with backing files
perf/core: Fix address filter match with backing files
uprobe: Move arch_uprobe_optimize right after handlers execution
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The vma->vm_mm might be NULL and it can be accessed outside of RCU. Thus,
we can mark it as trusted_or_null. With this change, BPF helpers can safely
access vma->vm_mm to retrieve the associated mm_struct from the VMA.
Then we can make policy decision from the VMA.
The "trusted" annotation enables direct access to vma->vm_mm within kfuncs
marked with KF_TRUSTED_ARGS or KF_RCU, such as bpf_task_get_cgroup1() and
bpf_task_under_cgroup(). Conversely, "null" enforcement requires all
callsites using vma->vm_mm to perform NULL checks.
The lsm selftest must be modified because it directly accesses vma->vm_mm
without a NULL pointer check; otherwise it will break due to this
change.
For the VMA based THP policy, the use case is as follows,
@mm = @vma->vm_mm; // vm_area_struct::vm_mm is trusted or null
if (!@mm)
return;
bpf_rcu_read_lock(); // rcu lock must be held to dereference the owner
@owner = @mm->owner; // mm_struct::owner is rcu trusted or null
if (!@owner)
goto out;
@cgroup1 = bpf_task_get_cgroup1(@owner, MEMCG_HIERARCHY_ID);
/* make the decision based on the @cgroup1 attribute */
bpf_cgroup_release(@cgroup1); // release the associated cgroup
out:
bpf_rcu_read_unlock();
PSI memory information can be obtained from the associated cgroup to inform
policy decisions. Since upstream PSI support is currently limited to cgroup
v2, the following example demonstrates cgroup v2 implementation:
@owner = @mm->owner;
if (@owner) {
// @ancestor_cgid is user-configured
@ancestor = bpf_cgroup_from_id(@ancestor_cgid);
if (bpf_task_under_cgroup(@owner, @ancestor)) {
@psi_group = @ancestor->psi;
/* Extract PSI metrics from @psi_group and
* implement policy logic based on the values
*/
}
}
The vma::vm_file can also be marked with __safe_trusted_or_null.
No additional selftests are required since vma->vm_file and vma->vm_mm are
already validated in the existing selftest suite.
Signed-off-by: Yafang Shao <laoar.shao@gmail.com>
Acked-by: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Cc: "Liam R. Howlett" <Liam.Howlett@oracle.com>
Link: https://lore.kernel.org/r/20251016063929.13830-3-laoar.shao@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
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When CONFIG_MEMCG is enabled, we can access mm->owner under RCU. The
owner can be NULL. With this change, BPF helpers can safely access
mm->owner to retrieve the associated task from the mm. We can then make
policy decision based on the task attribute.
The typical use case is as follows,
bpf_rcu_read_lock(); // rcu lock must be held for rcu trusted field
@owner = @mm->owner; // mm_struct::owner is rcu trusted or null
if (!@owner)
goto out;
/* Do something based on the task attribute */
out:
bpf_rcu_read_unlock();
Suggested-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Yafang Shao <laoar.shao@gmail.com>
Acked-by: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Link: https://lore.kernel.org/r/20251016063929.13830-2-laoar.shao@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
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Cross-merge BPF and other fixes after downstream PR.
No conflicts.
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
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Refactor pick_task_scx() adding a new argument to forcibly pick a
SCHED_EXT task, ignoring any higher-priority sched class activity.
This refactoring prepares the code for future scenarios, e.g., allowing
the ext dl_server to force a SCHED_EXT task selection.
No functional changes.
Suggested-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Andrea Righi <arighi@nvidia.com>
Reviewed-by: Emil Tsalapatis <emil@etsalapatis.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
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The CMA code, in addition to the reserved-memory regions in the device
tree, will also register a default CMA region if the device tree doesn't
provide any, with its size and position coming from either the kernel
command-line or configuration.
Let's register that one for use to create a heap for it.
Reviewed-by: T.J. Mercier <tjmercier@google.com>
Signed-off-by: Maxime Ripard <mripard@kernel.org>
Acked-by: Marek Szyprowski <m.szyprowski@samsung.com>
Signed-off-by: Sumit Semwal <sumit.semwal@linaro.org>
Link: https://lore.kernel.org/r/20251013-dma-buf-ecc-heap-v8-4-04ce150ea3d9@kernel.org
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In order to create a CMA dma-buf heap instance for each CMA heap region
in the system, we need to collect all of them during boot.
They are created from two main sources: the reserved-memory regions in
the device tree, and the default CMA region created from the
configuration or command line parameters, if no default region is
provided in the device tree.
Let's collect all the device-tree defined CMA regions flagged as
reusable.
Reviewed-by: T.J. Mercier <tjmercier@google.com>
Signed-off-by: Maxime Ripard <mripard@kernel.org>
Acked-by: Marek Szyprowski <m.szyprowski@samsung.com>
Signed-off-by: Sumit Semwal <sumit.semwal@linaro.org>
Link: https://lore.kernel.org/r/20251013-dma-buf-ecc-heap-v8-3-04ce150ea3d9@kernel.org
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The pm_vt_switch_required() function fails silently when memory
allocation fails, offering no indication to callers that the operation
was unsuccessful. This behavior prevents drivers from handling allocation
errors correctly or implementing retry mechanisms. By ensuring that
failures are reported back to the caller, drivers can make informed
decisions, improve robustness, and avoid unexpected behavior during
critical power management operations.
Change the function signature to return an integer error code and modify
the implementation to return -ENOMEM when kmalloc() fails. Update both
the function declaration and the inline stub in include/linux/pm.h to
maintain consistency across CONFIG_VT_CONSOLE_SLEEP configurations.
The function now returns:
- 0 on success (including when updating existing entries)
- -ENOMEM when memory allocation fails
This change improves error reporting without breaking existing callers,
as the current callers in drivers/video/fbdev/core/fbmem.c already
ignore the return value, making this a backward-compatible improvement.
Reviewed-by: Lyude Paul <lyude@redhat.com>
Signed-off-by: Malaya Kumar Rout <mrout@redhat.com>
Reviewed-by: Dhruva Gole <d-gole@ti.com>
Reviewed-by: Lyude Paul <lyude@redhat.com>
Link: https://patch.msgid.link/20251013193028.89570-1-mrout@redhat.com
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
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git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip into for-6.19
Pull in tip/sched/core to receive:
50653216e4ff ("sched: Add support to pick functions to take rf")
4c95380701f5 ("sched/ext: Fold balance_scx() into pick_task_scx()")
which will enable clean integration of DL server support among other things.
This conflicts with the following from sched_ext/for-6.18-fixes:
a8ad873113d3 ("sched_ext: defer queue_balance_callback() until after ops.dispatch")
which adds maybe_queue_balance_callback() to balance_scx() which is removed
by 50653216e4ff. Resolve by moving the invocation to pick_task_scx() in the
equivalent location.
Signed-off-by: Tejun Heo <tj@kernel.org>
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Pull sched_ext/for-6.18-fixes to sync trees to receive:
05e63305c85c ("sched_ext: Fix scx_kick_pseqs corruption on concurrent scheduler loads")
to avoid conflicts with planned cgroup sub-sched support.
Signed-off-by: Tejun Heo <tj@kernel.org>
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When scheduling the deferred balance callbacks, check SCX_RQ_BAL_CB_PENDING
instead of SCX_RQ_BAL_PENDING. This way schedule_deferred() properly tests
whether there is already a pending request for queue_balance_callback() to
be invoked at the end of .balance().
Fixes: a8ad873113d3 ("sched_ext: defer queue_balance_callback() until after ops.dispatch")
Signed-off-by: Emil Tsalapatis <emil@etsalapatis.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
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When __lookup_instance() allocates a func_instance structure but fails
to allocate the must_write_set array, it returns an error without freeing
the previously allocated func_instance. This causes a memory leak of 192
bytes (sizeof(struct func_instance)) each time this error path is triggered.
Fix by freeing 'result' on must_write_set allocation failure.
Fixes: b3698c356ad9 ("bpf: callchain sensitive stack liveness tracking using CFG")
Reported-by: BPF Runtime Fuzzer (BRF)
Signed-off-by: Shardul Bankar <shardulsb08@gmail.com>
Signed-off-by: Martin KaFai Lau <martin.lau@kernel.org>
Acked-by: Eduard Zingerman <eddyz87@gmail.com>
Link: https://patch.msgid.link/20251016063330.4107547-1-shardulsb08@gmail.com
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With pick_task() having an rf argument, it is possible to do the
lock-break there, get rid of the weird balance/pick_task hack.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Tejun Heo <tj@kernel.org>
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Some pick functions like the internal pick_next_task_fair() already take
rf but some others dont. We need this for scx's server pick function.
Prepare for this by having pick functions accept it.
[peterz: - added RETRY_TASK handling
- removed pick_next_task_fair indirection]
Signed-off-by: Joel Fernandes <joelagnelf@nvidia.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Tejun Heo <tj@kernel.org>
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Have enqueue/dequeue set a per-class bit in rq->queue_mask. This then
enables easy tracking of which runqueues are modified over a
lock-break.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Tejun Heo <tj@kernel.org>
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Shrikanth noted that sched_change pattern relies on using shared
flags.
Suggested-by: Shrikanth Hegde <sshegde@linux.ibm.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
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Teach the sched_change pattern how to do update_rq_clock(); this
allows for some simplifications / cleanups.
Suggested-by: K Prateek Nayak <kprateek.nayak@amd.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Juri Lelli <juri.lelli@redhat.com>
Acked-by: Tejun Heo <tj@kernel.org>
Acked-by: Vincent Guittot <vincent.guittot@linaro.org>
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In preparation to adding more rules to __task_rq_lock(), such that
__task_rq_unlock() will no longer be equivalent to rq_unlock(),
make sure every __task_rq_lock() is matched by a __task_rq_unlock()
and vice-versa.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Juri Lelli <juri.lelli@redhat.com>
Acked-by: Tejun Heo <tj@kernel.org>
Acked-by: Vincent Guittot <vincent.guittot@linaro.org>
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'Document' the locking context the various sched_class methods are
called under.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Juri Lelli <juri.lelli@redhat.com>
Acked-by: Tejun Heo <tj@kernel.org>
Acked-by: Vincent Guittot <vincent.guittot@linaro.org>
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Now that do_set_cpus_allowed() holds all the regular locks, convert it
to use the sched_change pattern helper.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Juri Lelli <juri.lelli@redhat.com>
Acked-by: Tejun Heo <tj@kernel.org>
Acked-by: Vincent Guittot <vincent.guittot@linaro.org>
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Hopefully saner naming.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Juri Lelli <juri.lelli@redhat.com>
Acked-by: Tejun Heo <tj@kernel.org>
Acked-by: Vincent Guittot <vincent.guittot@linaro.org>
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All callers of do_set_cpus_allowed() only take p->pi_lock, which is
not sufficient to actually change the cpumask. Again, this is mostly
ok in these cases, but it results in unnecessarily complicated
reasoning.
Furthermore, there is no reason what so ever to not just take all the
required locks, so do just that.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Juri Lelli <juri.lelli@redhat.com>
Acked-by: Tejun Heo <tj@kernel.org>
Acked-by: Vincent Guittot <vincent.guittot@linaro.org>
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For some reason migrate_disable_switch() was more complicated than it
needs to be, resulting in mind bending locking of dubious quality.
Recognise that migrate_disable_switch() must be called before a
context switch, but any place before that switch is equally good.
Since the current place results in troubled locking, simply move the
thing before taking rq->lock.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Juri Lelli <juri.lelli@redhat.com>
Acked-by: Tejun Heo <tj@kernel.org>
Acked-by: Vincent Guittot <vincent.guittot@linaro.org>
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Move sched_class::prio_changed() into the change pattern.
And while there, extend it with sched_class::get_prio() in order to
fix the deadline sitation.
Suggested-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Juri Lelli <juri.lelli@redhat.com>
Acked-by: Tejun Heo <tj@kernel.org>
Acked-by: Vincent Guittot <vincent.guittot@linaro.org>
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Use the new sched_class::switching_from() method to dequeue delayed
tasks before switching to another class.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Vincent Guittot <vincent.guittot@linaro.org>
Reviewed-by: Juri Lelli <juri.lelli@redhat.com>
Acked-by: Tejun Heo <tj@kernel.org>
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Add {DE,EN}QUEUE_CLASS and fold the sched_class::switch* methods into
the change pattern. This completes and makes the pattern more
symmetric.
This changes the order of callbacks slightly:
OLD NEW
|
| switching_from()
dequeue_task(); | dequeue_task()
put_prev_task(); | put_prev_task()
| switched_from()
|
... change task ... | ... change task ...
|
switching_to(); | switching_to()
enqueue_task(); | enqueue_task()
set_next_task(); | set_next_task()
prev_class->switched_from() |
switched_to() | switched_to()
|
Notably, it moves the switched_from() callback right after the
dequeue/put. Existing implementations don't appear to be affected by
this change in location -- specifically the task isn't enqueued on the
class in question in either location.
Make (CLASS)^(SAVE|MOVE), because there is nothing to save-restore
when changing scheduling classes.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Juri Lelli <juri.lelli@redhat.com>
Acked-by: Tejun Heo <tj@kernel.org>
Acked-by: Vincent Guittot <vincent.guittot@linaro.org>
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Prepare for the sched_class::switch*() methods getting folded into the
change pattern. As a result of that, the location of switched_from
will change slightly. SCHED_DEADLINE is affected by this change in
location:
OLD NEW
|
| switching_from()
dequeue_task(); | dequeue_task()
put_prev_task(); | put_prev_task()
| switched_from()
|
... change task ... | ... change task ...
|
switching_to(); | switching_to()
enqueue_task(); | enqueue_task()
set_next_task(); | set_next_task()
prev_class->switched_from() |
switched_to() | switched_to()
|
Notably, where switched_from() was called *after* the change to the
task, it will get called before it. Specifically, switched_from_dl()
uses dl_task(p) which uses p->prio; which is changed when switching
class (it might be the reason to switch class in case of PI).
When switched_from_dl() gets called, the task will have left the
deadline class and dl_task() must be false, while when doing
dequeue_dl_entity() the task must be a dl_task(), otherwise we'd have
called a different dequeue method.
Reported-by: Dietmar Eggemann <dietmar.eggemann@arm.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
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Ensure the matched flags are in the low word while the unmatched flags
go into the second word.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Juri Lelli <juri.lelli@redhat.com>
Acked-by: Tejun Heo <tj@kernel.org>
Acked-by: Vincent Guittot <vincent.guittot@linaro.org>
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As proposed a long while ago -- and half done by scx -- wrap the
scheduler's 'change' pattern in a guard helper.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Juri Lelli <juri.lelli@redhat.com>
Acked-by: Tejun Heo <tj@kernel.org>
Acked-by: Vincent Guittot <vincent.guittot@linaro.org>
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Load imbalance is observed when the workload frequently forks new threads.
Due to CPU affinity, the workload can run on CPU 0-7 in the first
group, and only on CPU 8-11 in the second group. CPU 12-15 are always idle.
{ 0 1 2 3 4 5 6 7 } {8 9 10 11 12 13 14 15}
* * * * * * * * * * * *
When looking for dst group for newly forked threads, in many times
update_sg_wakeup_stats() reports the second group has more idle CPUs
than the first group. The scheduler thinks the second group is less
busy. Then it selects least busy CPUs among CPU 8-11. Therefore CPU 8-11
can be crowded with newly forked threads, at the same time CPU 0-7
can be idle.
A task may not use all the CPUs in a schedule group due to CPU affinity.
Only update schedule group statistics for allowed CPUs.
Signed-off-by: Adam Li <adamli@os.amperecomputing.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
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Allow architecture specific sched domain NUMA distances that are
modified from actual NUMA node distances for the purpose of building
NUMA sched domains.
Keep actual NUMA distances separately if modified distances
are used for building sched domains. Such distances
are still needed as NUMA balancing benefits from finding the
NUMA nodes that are actually closer to a task numa_group.
Consolidate the recording of unique NUMA distances in an array to
sched_record_numa_dist() so the function can be reused to record NUMA
distances when the NUMA distance metric is changed.
No functional change and additional distance array
allocated if there're no arch specific NUMA distances
being defined.
Co-developed-by: Vinicius Costa Gomes <vinicius.gomes@intel.com>
Signed-off-by: Vinicius Costa Gomes <vinicius.gomes@intel.com>
Signed-off-by: Tim Chen <tim.c.chen@linux.intel.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Chen Yu <yu.c.chen@intel.com>
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|
Commit 16b269436b72 ("sched/deadline: Modify cpudl::free_cpus
to reflect rd->online") introduced the cpudl_set/clear_freecpu
functions to allow the cpu_dl::free_cpus mask to be manipulated
by the deadline scheduler class rq_on/offline callbacks so the
mask would also reflect this state.
Commit 9659e1eeee28 ("sched/deadline: Remove cpu_active_mask
from cpudl_find()") removed the check of the cpu_active_mask to
save some processing on the premise that the cpudl::free_cpus
mask already reflected the runqueue online state.
Unfortunately, there are cases where it is possible for the
cpudl_clear function to set the free_cpus bit for a CPU when the
deadline runqueue is offline. When this occurs while a CPU is
connected to the default root domain the flag may retain the bad
state after the CPU has been unplugged. Later, a different CPU
that is transitioning through the default root domain may push a
deadline task to the powered down CPU when cpudl_find sees its
free_cpus bit is set. If this happens the task will not have the
opportunity to run.
One example is outlined here:
https://lore.kernel.org/lkml/20250110233010.2339521-1-opendmb@gmail.com
Another occurs when the last deadline task is migrated from a
CPU that has an offlined runqueue. The dequeue_task member of
the deadline scheduler class will eventually call cpudl_clear
and set the free_cpus bit for the CPU.
This commit modifies the cpudl_clear function to be aware of the
online state of the deadline runqueue so that the free_cpus mask
can be updated appropriately.
It is no longer necessary to manage the mask outside of the
cpudl_set/clear functions so the cpudl_set/clear_freecpu
functions are removed. In addition, since the free_cpus mask is
now only updated under the cpudl lock the code was changed to
use the non-atomic __cpumask functions.
Signed-off-by: Doug Berger <opendmb@gmail.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
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|
If a task yields, the scheduler may decide to pick it again. The task in
turn may decide to yield immediately or shortly after, leading to a tight
loop of yields.
If there's another runnable task as this point, the deadline will be
increased by the slice at each loop. This can cause the deadline to runaway
pretty quickly, and subsequent elevated run delays later on as the task
doesn't get picked again. The reason the scheduler can pick the same task
again and again despite its deadline increasing is because it may be the
only eligible task at that point.
Fix this by making the task forfeiting its remaining vruntime and pushing
the deadline one slice ahead. This implements yield behavior more
authentically.
We limit the forfeiting to eligible tasks. This is because core scheduling
prefers running ineligible tasks rather than force idling. As such, without
the condition, we can end up on a yield loop which makes the vruntime
increase rapidly, leading to anomalous run delays later down the line.
Fixes: 147f3efaa24182 ("sched/fair: Implement an EEVDF-like scheduling policy")
Signed-off-by: Fernand Sieber <sieberf@amazon.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lore.kernel.org/r/20250401123622.584018-1-sieberf@amazon.com
Link: https://lore.kernel.org/r/20250911095113.203439-1-sieberf@amazon.com
Link: https://lore.kernel.org/r/20250916140228.452231-1-sieberf@amazon.com
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Commit 370645f41e6e ("dma-mapping: force bouncing if the kmalloc() size is
not cache-line-aligned") introduced DMA_BOUNCE_UNALIGNED_KMALLOC feature
and permitted architecture specific code configure kmalloc slabs with
sizes smaller than the value of dma_get_cache_alignment().
When that feature is enabled, the physical address of some small
kmalloc()-ed buffers might be not aligned to the CPU cachelines, thus not
really suitable for typical DMA. To properly handle that case a SWIOTLB
buffer bouncing is used, so no CPU cache corruption occurs. When that
happens, there is no point reporting a false-positive DMA-API warning that
the buffer is not properly aligned, as this is not a client driver fault.
[m.szyprowski@samsung.com: replace is_swiotlb_allocated() with is_swiotlb_active(), per Catalin]
Link: https://lkml.kernel.org/r/20251010173009.3916215-1-m.szyprowski@samsung.com
Link: https://lkml.kernel.org/r/20251009141508.2342138-1-m.szyprowski@samsung.com
Fixes: 370645f41e6e ("dma-mapping: force bouncing if the kmalloc() size is not cache-line-aligned")
Signed-off-by: Marek Szyprowski <m.szyprowski@samsung.com>
Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Inki Dae <m.szyprowski@samsung.com>
Cc: Robin Murohy <robin.murphy@arm.com>
Cc: "Isaac J. Manjarres" <isaacmanjarres@google.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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|
The builtin DSQ queue data structures are meant to be used by a wide
range of different sched_ext schedulers with different demands on these
data structures. They might be per-cpu with low-contention, or
high-contention shared queues. Unfortunately, DSQs have a coarse-grained
lock around the whole data structure. Without going all the way to a
lock-free, more scalable implementation, a small step we can take to
reduce lock contention is to allow a lockless, small-fixed-cost peek at
the head of the queue.
This change allows certain custom SCX schedulers to cheaply peek at
queues, e.g. during load balancing, before locking them. But it
represents a few extra memory operations to update the pointer each
time the DSQ is modified, including a memory barrier on ARM so the write
appears correctly ordered.
This commit adds a first_task pointer field which is updated
atomically when the DSQ is modified, and allows any thread to peek at
the head of the queue without holding the lock.
Signed-off-by: Ryan Newton <newton@meta.com>
Reviewed-by: Andrea Righi <arighi@nvidia.com>
Reviewed-by: Christian Loehle <christian.loehle@arm.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
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When there is only one function of the same name, old_sympos of 0 and 1
are logically identical. Match them in klp_find_func().
This is to avoid a corner case with different toolchain behavior.
In this specific issue, two versions of kpatch-build were used to
build livepatch for the same kernel. One assigns old_sympos == 0 for
unique local functions, the other assigns old_sympos == 1 for unique
local functions. Both versions work fine by themselves. (PS: This
behavior change was introduced in a downstream version of kpatch-build.
This change does not exist in upstream kpatch-build.)
However, during livepatch upgrade (with the replace flag set) from a
patch built with one version of kpatch-build to the same fix built with
the other version of kpatch-build, livepatching fails with errors like:
[ 14.218706] sysfs: cannot create duplicate filename 'xxx/somefunc,1'
...
[ 14.219466] Call Trace:
[ 14.219468] <TASK>
[ 14.219469] dump_stack_lvl+0x47/0x60
[ 14.219474] sysfs_warn_dup.cold+0x17/0x27
[ 14.219476] sysfs_create_dir_ns+0x95/0xb0
[ 14.219479] kobject_add_internal+0x9e/0x260
[ 14.219483] kobject_add+0x68/0x80
[ 14.219485] ? kstrdup+0x3c/0xa0
[ 14.219486] klp_enable_patch+0x320/0x830
[ 14.219488] patch_init+0x443/0x1000 [ccc_0_6]
[ 14.219491] ? 0xffffffffa05eb000
[ 14.219492] do_one_initcall+0x2e/0x190
[ 14.219494] do_init_module+0x67/0x270
[ 14.219496] init_module_from_file+0x75/0xa0
[ 14.219499] idempotent_init_module+0x15a/0x240
[ 14.219501] __x64_sys_finit_module+0x61/0xc0
[ 14.219503] do_syscall_64+0x5b/0x160
[ 14.219505] entry_SYSCALL_64_after_hwframe+0x4b/0x53
[ 14.219507] RIP: 0033:0x7f545a4bd96d
...
[ 14.219516] kobject: kobject_add_internal failed for somefunc,1 with
-EEXIST, don't try to register things with the same name ...
This happens because klp_find_func() thinks somefunc with old_sympos==0
is not the same as somefunc with old_sympos==1, and klp_add_object_nops
adds another xxx/func,1 to the list of functions to patch.
Signed-off-by: Song Liu <song@kernel.org>
Acked-by: Josh Poimboeuf <jpoimboe@kernel.org>
[pmladek@suse.com: Fixed some typos.]
Reviewed-by: Petr Mladek <pmladek@suse.com>
Tested-by: Petr Mladek <pmladek@suse.com>
Signed-off-by: Petr Mladek <pmladek@suse.com>
|
