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git://git.kernel.org/pub/scm/linux/kernel/git/tj/sched_ext
Pull sched_ext updates from Tejun Heo:
- Add support for cgroup "cpu.max" interface
- Code organization cleanup so that ext_idle.c doesn't depend on the
source-file-inclusion build method of sched/
- Drop UP paths in accordance with sched core changes
- Documentation and other misc changes
* tag 'sched_ext-for-6.17' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/sched_ext:
sched_ext: Fix scx_bpf_reenqueue_local() reference
sched_ext: Drop kfuncs marked for removal in 6.15
sched_ext, rcu: Eject BPF scheduler on RCU CPU stall panic
kernel/sched/ext.c: fix typo "occured" -> "occurred" in comments
sched_ext: Add support for cgroup bandwidth control interface
sched_ext, sched/core: Factor out struct scx_task_group
sched_ext: Return NULL in llc_span
sched_ext: Always use SMP versions in kernel/sched/ext_idle.h
sched_ext: Always use SMP versions in kernel/sched/ext_idle.c
sched_ext: Always use SMP versions in kernel/sched/ext.h
sched_ext: Always use SMP versions in kernel/sched/ext.c
sched_ext: Documentation: Clarify time slice handling in task lifecycle
sched_ext: Make scx_locked_rq() inline
sched_ext: Make scx_rq_bypassing() inline
sched_ext: idle: Make local functions static in ext_idle.c
sched_ext: idle: Remove unnecessary ifdef in scx_bpf_cpu_node()
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git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull scheduler updates from Ingo Molnar:
"Core scheduler changes:
- Better tracking of maximum lag of tasks in presence of different
slices duration, for better handling of lag in the fair scheduler
(Vincent Guittot)
- Clean up and standardize #if/#else/#endif markers throughout the
entire scheduler code base (Ingo Molnar)
- Make SMP unconditional: build the SMP scheduler's data structures
and logic on UP kernel too, even though they are not used, to
simplify the scheduler and remove around 200 #ifdef/[#else]/#endif
blocks from the scheduler (Ingo Molnar)
- Reorganize cgroup bandwidth control interface handling for better
interfacing with sched_ext (Tejun Heo)
Balancing:
- Bump sd->max_newidle_lb_cost when newidle balance fails (Chris
Mason)
- Remove sched_domain_topology_level::flags to simplify the code
(Prateek Nayak)
- Simplify and clean up build_sched_topology() (Li Chen)
- Optimize build_sched_topology() on large machines (Li Chen)
Real-time scheduling:
- Add initial version of proxy execution: a mechanism for
mutex-owning tasks to inherit the scheduling context of higher
priority waiters.
Currently limited to a single runqueue and conditional on
CONFIG_EXPERT, and other limitations (John Stultz, Peter Zijlstra,
Valentin Schneider)
- Deadline scheduler (Juri Lelli):
- Fix dl_servers initialization order (Juri Lelli)
- Fix DL scheduler's root domain reinitialization logic (Juri
Lelli)
- Fix accounting bugs after global limits change (Juri Lelli)
- Fix scalability regression by implementing less agressive
dl_server handling (Peter Zijlstra)
PSI:
- Improve scalability by optimizing psi_group_change() cpu_clock()
usage (Peter Zijlstra)
Rust changes:
- Make Task, CondVar and PollCondVar methods inline to avoid
unnecessary function calls (Kunwu Chan, Panagiotis Foliadis)
- Add might_sleep() support for Rust code: Rust's "#[track_caller]"
mechanism is used so that Rust's might_sleep() doesn't need to be
defined as a macro (Fujita Tomonori)
- Introduce file_from_location() (Boqun Feng)
Debugging & instrumentation:
- Make clangd usable with scheduler source code files again (Peter
Zijlstra)
- tools: Add root_domains_dump.py which dumps root domains info (Juri
Lelli)
- tools: Add dl_bw_dump.py for printing bandwidth accounting info
(Juri Lelli)
Misc cleanups & fixes:
- Remove play_idle() (Feng Lee)
- Fix check_preemption_disabled() (Sebastian Andrzej Siewior)
- Do not call __put_task_struct() on RT if pi_blocked_on is set (Luis
Claudio R. Goncalves)
- Correct the comment in place_entity() (wang wei)"
* tag 'sched-core-2025-07-28' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (84 commits)
sched/idle: Remove play_idle()
sched: Do not call __put_task_struct() on rt if pi_blocked_on is set
sched: Start blocked_on chain processing in find_proxy_task()
sched: Fix proxy/current (push,pull)ability
sched: Add an initial sketch of the find_proxy_task() function
sched: Fix runtime accounting w/ split exec & sched contexts
sched: Move update_curr_task logic into update_curr_se
locking/mutex: Add p->blocked_on wrappers for correctness checks
locking/mutex: Rework task_struct::blocked_on
sched: Add CONFIG_SCHED_PROXY_EXEC & boot argument to enable/disable
sched/topology: Remove sched_domain_topology_level::flags
x86/smpboot: avoid SMT domain attach/destroy if SMT is not enabled
x86/smpboot: moves x86_topology to static initialize and truncate
x86/smpboot: remove redundant CONFIG_SCHED_SMT
smpboot: introduce SDTL_INIT() helper to tidy sched topology setup
tools/sched: Add dl_bw_dump.py for printing bandwidth accounting info
tools/sched: Add root_domains_dump.py which dumps root domains info
sched/deadline: Fix accounting after global limits change
sched/deadline: Reset extra_bw to max_bw when clearing root domains
sched/deadline: Initialize dl_servers after SMP
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git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull futex updates from Thomas Gleixner:
- Switch the reference counting to a RCU based per-CPU reference to
address a performance bottleneck vs the single instance rcuref
variant
- Make the futex selftest build on 32-bit architectures which only
support 64-bit time_t, e.g. RISCV-32
- Cleanups and improvements in selftests and futex bench
* tag 'locking-futex-2025-07-29' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
selftests/futex: Fix spelling mistake "Succeffuly" -> "Successfully"
selftests/futex: Define SYS_futex on 32-bit architectures with 64-bit time_t
perf bench futex: Remove support for IMMUTABLE
selftests/futex: Remove support for IMMUTABLE
futex: Remove support for IMMUTABLE
futex: Make futex_private_hash_get() static
futex: Use RCU-based per-CPU reference counting instead of rcuref_t
selftests/futex: Adapt the private hash test to RCU related changes
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Add missing const qualifier to the non-CONFIG_THREAD_INFO_IN_TASK
version of end_of_stack() to match the CONFIG_THREAD_INFO_IN_TASK
version. Fixes a warning with CONFIG_KSTACK_ERASE=y on archs that don't
select THREAD_INFO_IN_TASK (such as LoongArch):
error: passing 'const struct task_struct *' to parameter of type 'struct task_struct *' discards qualifiers
The stackleak_task_low_bound() function correctly uses a const task
parameter, but the legacy end_of_stack() prototype didn't like that.
Build tested on loongarch (with CONFIG_KSTACK_ERASE=y) and m68k
(with CONFIG_DEBUG_STACK_USAGE=y).
Fixes: a45728fd4120 ("LoongArch: Enable HAVE_ARCH_STACKLEAK")
Reported-by: Nathan Chancellor <nathan@kernel.org>
Closes: https://lore.kernel.org/all/20250726004313.GA3650901@ax162
Cc: Youling Tang <tangyouling@kylinos.cn>
Cc: Huacai Chen <chenhuacai@loongson.cn>
Tested-by: Nathan Chancellor <nathan@kernel.org>
Signed-off-by: Kees Cook <kees@kernel.org>
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With PREEMPT_RT enabled, some of the calls to put_task_struct() coming
from rt_mutex_adjust_prio_chain() could happen in preemptible context and
with a mutex enqueued. That could lead to this sequence:
rt_mutex_adjust_prio_chain()
put_task_struct()
__put_task_struct()
sched_ext_free()
spin_lock_irqsave()
rtlock_lock() ---> TRIGGERS
lockdep_assert(!current->pi_blocked_on);
This is not a SCHED_EXT bug. The first cleanup function called by
__put_task_struct() is sched_ext_free() and it happens to take a
(RT) spin_lock, which in the scenario described above, would trigger
the lockdep assertion of "!current->pi_blocked_on".
Crystal Wood was able to identify the problem as __put_task_struct()
being called during rt_mutex_adjust_prio_chain(), in the context of
a process with a mutex enqueued.
Instead of adding more complex conditions to decide when to directly
call __put_task_struct() and when to defer the call, unconditionally
resort to the deferred call on PREEMPT_RT to simplify the code.
Fixes: 893cdaaa3977 ("sched: avoid false lockdep splat in put_task_struct()")
Suggested-by: Crystal Wood <crwood@redhat.com>
Signed-off-by: Luis Claudio R. Goncalves <lgoncalv@redhat.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Wander Lairson Costa <wander@redhat.com>
Reviewed-by: Valentin Schneider <vschneid@redhat.com>
Reviewed-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Link: https://lore.kernel.org/r/aGvTz5VaPFyj0pBV@uudg.org
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Support for overlapping domains added in commit e3589f6c81e4 ("sched:
Allow for overlapping sched_domain spans") also allowed forcefully
setting SD_OVERLAP for !NUMA domains via FORCE_SD_OVERLAP sched_feat().
Since NUMA domains had to be presumed overlapping to ensure correct
behavior, "sched_domain_topology_level::flags" was introduced. NUMA
domains added the SDTL_OVERLAP flag would ensure SD_OVERLAP was always
added during build_sched_domains() for these domains, even when
FORCE_SD_OVERLAP was off.
Condition for adding the SD_OVERLAP flag at the aforementioned commit
was as follows:
if (tl->flags & SDTL_OVERLAP || sched_feat(FORCE_SD_OVERLAP))
sd->flags |= SD_OVERLAP;
The FORCE_SD_OVERLAP debug feature was removed in commit af85596c74de
("sched/topology: Remove FORCE_SD_OVERLAP") which left the NUMA domains
as the exclusive users of SDTL_OVERLAP, SD_OVERLAP, and SD_NUMA flags.
Get rid of SDTL_OVERLAP and SD_OVERLAP as they have become redundant
and instead rely on SD_NUMA to detect the only overlapping domain
currently supported. Since SDTL_OVERLAP was the only user of
"tl->flags", get rid of "sched_domain_topology_level::flags" too.
Signed-off-by: K Prateek Nayak <kprateek.nayak@amd.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/ba4dbdf8-bc37-493d-b2e0-2efb00ea3e19@amd.com
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Define a small SDTL_INIT(maskfn, flagsfn, name) macro and use it to build the
sched_domain_topology_level array. Purely a cleanup; behaviour is unchanged.
Suggested-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Li Chen <chenl311@chinatelecom.cn>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: K Prateek Nayak <kprateek.nayak@amd.com>
Tested-by: K Prateek Nayak <kprateek.nayak@amd.com>
Link: https://lore.kernel.org/r/20250710105715.66594-2-me@linux.beauty
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The use of rcuref_t for reference counting introduces a performance bottleneck
when accessed concurrently by multiple threads during futex operations.
Replace rcuref_t with special crafted per-CPU reference counters. The
lifetime logic remains the same.
The newly allocate private hash starts in FR_PERCPU state. In this state, each
futex operation that requires the private hash uses a per-CPU counter (an
unsigned int) for incrementing or decrementing the reference count.
When the private hash is about to be replaced, the per-CPU counters are
migrated to a atomic_t counter mm_struct::futex_atomic.
The migration process:
- Waiting for one RCU grace period to ensure all users observe the
current private hash. This can be skipped if a grace period elapsed
since the private hash was assigned.
- futex_private_hash::state is set to FR_ATOMIC, forcing all users to
use mm_struct::futex_atomic for reference counting.
- After a RCU grace period, all users are guaranteed to be using the
atomic counter. The per-CPU counters can now be summed up and added to
the atomic_t counter. If the resulting count is zero, the hash can be
safely replaced. Otherwise, active users still hold a valid reference.
- Once the atomic reference count drops to zero, the next futex
operation will switch to the new private hash.
call_rcu_hurry() is used to speed up transition which otherwise might be
delay with RCU_LAZY. There is nothing wrong with using call_rcu(). The
side effects would be that on auto scaling the new hash is used later
and the SET_SLOTS prctl() will block longer.
[bigeasy: commit description + mm get/ put_async]
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lore.kernel.org/r/20250710110011.384614-3-bigeasy@linutronix.de
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sched_ext performed a kfunc renaming pass in 6.13 and kept the old names
around for compatibility with old binaries. These were scheduled for
cleanup in 6.15 but were missed. Submitting for cleanup in for-next.
Removed the kfuncs, their flags, and any references I could find to them
in doc comments. Left the entries in include/scx/compat.bpf.h as they're
still useful to make new binaries compatible with old kernels.
Tested by applying to my kernel. It builds and a modern version of
scx_lavd loads fine.
Signed-off-by: Jake Hillion <jake@hillion.co.uk>
Signed-off-by: Tejun Heo <tj@kernel.org>
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For systems using a sched_ext scheduler and has panic_on_rcu_stall
enabled, try kicking out the current scheduler before issuing a panic.
While there are numerous reasons for RCU CPU stalls that are not
directly attributed to the scheduler, deferring the panic gives
sched_ext an opportunity to provide additional debug info when ejecting
the current scheduler. Also, handling the event more gracefully allows
us to potentially recover the system instead of incurring additional
down time.
Suggested-by: Tejun Heo <tj@kernel.org>
Reviewed-by: Paul E. McKenney <paulmck@kernel.org>
Signed-off-by: David Dai <david.dai@linux.dev>
Signed-off-by: Tejun Heo <tj@kernel.org>
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From 077814f57f8acce13f91dc34bbd2b7e4911fbf25 Mon Sep 17 00:00:00 2001
From: Tejun Heo <tj@kernel.org>
Date: Fri, 13 Jun 2025 15:06:47 -1000
- Add CONFIG_GROUP_SCHED_BANDWIDTH which is selected by both
CONFIG_CFS_BANDWIDTH and EXT_GROUP_SCHED.
- Put bandwidth control interface files for both cgroup v1 and v2 under
CONFIG_GROUP_SCHED_BANDWIDTH.
- Update tg_bandwidth() to fetch configuration parameters from fair if
CONFIG_CFS_BANDWIDTH, SCX otherwise.
- Update tg_set_bandwidth() to update the parameters for both fair and SCX.
- Add bandwidth control parameters to struct scx_cgroup_init_args.
- Add sched_ext_ops.cgroup_set_bandwidth() which is invoked on bandwidth
control parameter updates.
- Update scx_qmap and maximal selftest to test the new feature.
Signed-off-by: Tejun Heo <tj@kernel.org>
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More sched_ext fields will be added to struct task_group. In preparation,
factor out sched_ext fields into struct scx_task_group to reduce clutter in
the common header. No functional changes.
Signed-off-by: Tejun Heo <tj@kernel.org>
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Simplify the scheduler making CONFIG_SMP=y sched_exec()
code unconditional.
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Acked-by: Peter Zijlstra <peterz@infradead.org>
Cc: Dietmar Eggemann <dietmar.eggemann@arm.com>
Cc: Juri Lelli <juri.lelli@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Cc: Shrikanth Hegde <sshegde@linux.ibm.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Valentin Schneider <vschneid@redhat.com>
Cc: Vincent Guittot <vincent.guittot@linaro.org>
Link: https://lore.kernel.org/r/20250528080924.2273858-27-mingo@kernel.org
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Simplify the scheduler by making CONFIG_SMP=y primitives and data
structures unconditional.
Introduce transitory wrappers for functionality not yet converted to SMP.
Note that this patch is pretty large, because there's no clear separation
between various aspects of the SMP scheduler, it's basically a huge block
of #ifdef CONFIG_SMP. A fair amount of it has to be switched on for it to
boot and work on UP systems.
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Acked-by: Peter Zijlstra <peterz@infradead.org>
Cc: Dietmar Eggemann <dietmar.eggemann@arm.com>
Cc: Juri Lelli <juri.lelli@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Cc: Shrikanth Hegde <sshegde@linux.ibm.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Valentin Schneider <vschneid@redhat.com>
Cc: Vincent Guittot <vincent.guittot@linaro.org>
Link: https://lore.kernel.org/r/20250528080924.2273858-21-mingo@kernel.org
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git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
Pull non-MM updates from Andrew Morton:
- "hung_task: extend blocking task stacktrace dump to semaphore" from
Lance Yang enhances the hung task detector.
The detector presently dumps the blocking tasks's stack when it is
blocked on a mutex. Lance's series extends this to semaphores
- "nilfs2: improve sanity checks in dirty state propagation" from
Wentao Liang addresses a couple of minor flaws in nilfs2
- "scripts/gdb: Fixes related to lx_per_cpu()" from Illia Ostapyshyn
fixes a couple of issues in the gdb scripts
- "Support kdump with LUKS encryption by reusing LUKS volume keys" from
Coiby Xu addresses a usability problem with kdump.
When the dump device is LUKS-encrypted, the kdump kernel may not have
the keys to the encrypted filesystem. A full writeup of this is in
the series [0/N] cover letter
- "sysfs: add counters for lockups and stalls" from Max Kellermann adds
/sys/kernel/hardlockup_count and /sys/kernel/hardlockup_count and
/sys/kernel/rcu_stall_count
- "fork: Page operation cleanups in the fork code" from Pasha Tatashin
implements a number of code cleanups in fork.c
- "scripts/gdb/symbols: determine KASLR offset on s390 during early
boot" from Ilya Leoshkevich fixes some s390 issues in the gdb
scripts
* tag 'mm-nonmm-stable-2025-05-31-15-28' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm: (67 commits)
llist: make llist_add_batch() a static inline
delayacct: remove redundant code and adjust indentation
squashfs: add optional full compressed block caching
crash_dump, nvme: select CONFIGFS_FS as built-in
scripts/gdb/symbols: determine KASLR offset on s390 during early boot
scripts/gdb/symbols: factor out pagination_off()
scripts/gdb/symbols: factor out get_vmlinux()
kernel/panic.c: format kernel-doc comments
mailmap: update and consolidate Casey Connolly's name and email
nilfs2: remove wbc->for_reclaim handling
fork: define a local GFP_VMAP_STACK
fork: check charging success before zeroing stack
fork: clean-up naming of vm_stack/vm_struct variables in vmap stacks code
fork: clean-up ifdef logic around stack allocation
kernel/rcu/tree_stall: add /sys/kernel/rcu_stall_count
kernel/watchdog: add /sys/kernel/{hard,soft}lockup_count
x86/crash: make the page that stores the dm crypt keys inaccessible
x86/crash: pass dm crypt keys to kdump kernel
Revert "x86/mm: Remove unused __set_memory_prot()"
crash_dump: retrieve dm crypt keys in kdump kernel
...
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Remove __HAVE_ARCH_KSTACK_END as it has been obsolete since removal of
metag architecture in v4.17.
Link: https://lkml.kernel.org/r/20250403-kstack-end-v1-1-7798e71f34d1@linaro.org
Signed-off-by: Pasha Tatashin <pasha.tatashin@soleen.com>
Link: https://lore.kernel.org/20240311164638.2015063-2-pasha.tatashin@soleen.com
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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A subset of AMD Processors supporting Preferred Core Rankings also
feature the ability to dynamically switch these rankings at runtime to
bias load balancing towards or away from the LLC domain with larger
cache.
To support dynamically updating "sg->asym_prefer_cpu" without needing to
rebuild the sched domain, introduce sched_update_asym_prefer_cpu() which
recomutes the "asym_prefer_cpu" when the core-ranking of a CPU changes.
sched_update_asym_prefer_cpu() swaps the "sg->asym_prefer_cpu" with the
CPU whose ranking has changed if the new ranking is greater than that of
the "asym_prefer_cpu". If CPU whose ranking has changed is the current
"asym_prefer_cpu", it scans the CPUs of the sched groups to find the new
"asym_prefer_cpu" and sets it accordingly.
get_group() for non-overlapping sched domains returns the sched group
for the first CPU in the sched_group_span() which ensures all CPUs in
the group see the updated value of "asym_prefer_cpu".
Overlapping groups are allocated differently and will require moving the
"asym_prefer_cpu" to "sg->sgc" but since the current implementations do
not set "SD_ASYM_PACKING" at NUMA domains, skip additional
indirection and place a SCHED_WARN_ON() to alert any future users.
Signed-off-by: K Prateek Nayak <kprateek.nayak@amd.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lore.kernel.org/r/20250409053446.23367-3-kprateek.nayak@amd.com
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git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull objtool fixes from Ingo Molnar:
"These are objtool fixes and updates by Josh Poimboeuf, centered around
the fallout from the new CONFIG_OBJTOOL_WERROR=y feature, which,
despite its default-off nature, increased the profile/impact of
objtool warnings:
- Improve error handling and the presentation of warnings/errors
- Revert the new summary warning line that some test-bot tools
interpreted as new regressions
- Fix a number of objtool warnings in various drivers, core kernel
code and architecture code. About half of them are potential
problems related to out-of-bounds accesses or potential undefined
behavior, the other half are additional objtool annotations
- Update objtool to latest (known) compiler quirks and objtool bugs
triggered by compiler code generation
- Misc fixes"
* tag 'objtool-urgent-2025-04-01' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (36 commits)
objtool/loongarch: Add unwind hints in prepare_frametrace()
rcu-tasks: Always inline rcu_irq_work_resched()
context_tracking: Always inline ct_{nmi,irq}_{enter,exit}()
sched/smt: Always inline sched_smt_active()
objtool: Fix verbose disassembly if CROSS_COMPILE isn't set
objtool: Change "warning:" to "error: " for fatal errors
objtool: Always fail on fatal errors
Revert "objtool: Increase per-function WARN_FUNC() rate limit"
objtool: Append "()" to function name in "unexpected end of section" warning
objtool: Ignore end-of-section jumps for KCOV/GCOV
objtool: Silence more KCOV warnings, part 2
objtool, drm/vmwgfx: Don't ignore vmw_send_msg() for ORC
objtool: Fix STACK_FRAME_NON_STANDARD for cold subfunctions
objtool: Fix segfault in ignore_unreachable_insn()
objtool: Fix NULL printf() '%s' argument in builtin-check.c:save_argv()
objtool, lkdtm: Obfuscate the do_nothing() pointer
objtool, regulator: rk808: Remove potential undefined behavior in rk806_set_mode_dcdc()
objtool, ASoC: codecs: wcd934x: Remove potential undefined behavior in wcd934x_slim_irq_handler()
objtool, Input: cyapa - Remove undefined behavior in cyapa_update_fw_store()
objtool, panic: Disable SMAP in __stack_chk_fail()
...
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sched_smt_active() can be called from noinstr code, so it should always
be inlined. The CONFIG_SCHED_SMT version already has __always_inline.
Do the same for its !CONFIG_SCHED_SMT counterpart.
Fixes the following warning:
vmlinux.o: error: objtool: intel_idle_ibrs+0x13: call to sched_smt_active() leaves .noinstr.text section
Fixes: 321a874a7ef8 ("sched/smt: Expose sched_smt_present static key")
Reported-by: kernel test robot <lkp@intel.com>
Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Link: https://lore.kernel.org/r/1d03907b0a247cf7fb5c1d518de378864f603060.1743481539.git.jpoimboe@kernel.org
Closes: https://lore.kernel.org/r/202503311434.lyw2Tveh-lkp@intel.com/
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git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull timer core updates from Thomas Gleixner:
- Fix a memory ordering issue in posix-timers
Posix-timer lookup is lockless and reevaluates the timer validity
under the timer lock, but the update which validates the timer is not
protected by the timer lock. That allows the store to be reordered
against the initialization stores, so that the lookup side can
observe a partially initialized timer. That's mostly a theoretical
problem, but incorrect nevertheless.
- Fix a long standing inconsistency of the coarse time getters
The coarse time getters read the base time of the current update
cycle without reading the actual hardware clock. NTP frequency
adjustment can set the base time backwards. The fine grained
interfaces compensate this by reading the clock and applying the new
conversion factor, but the coarse grained time getters use the base
time directly. That allows the user to observe time going backwards.
Cure it by always forwarding base time, when NTP changes the
frequency with an immediate step.
- Rework of posix-timer hashing
The posix-timer hash is not scalable and due to the CRIU timer
restore mechanism prone to massive contention on the global hash
bucket lock.
Replace the global hash lock with a fine grained per bucket locking
scheme to address that.
- Rework the proc/$PID/timers interface.
/proc/$PID/timers is provided for CRIU to be able to restore a timer.
The printout happens with sighand lock held and interrupts disabled.
That's not required as this can be done with RCU protection as well.
- Provide a sane mechanism for CRIU to restore a timer ID
CRIU restores timers by creating and deleting them until the kernel
internal per process ID counter reached the requested ID. That's
horribly slow for sparse timer IDs.
Provide a prctl() which allows CRIU to restore a timer with a given
ID. When enabled the ID pointer is used as input pointer to read the
requested ID from user space. When disabled, the normal allocation
scheme (next ID) is active as before. This is backwards compatible
for both kernel and user space.
- Make hrtimer_update_function() less expensive.
The sanity checks are valuable, but expensive for high frequency
usage in io/uring. Make the debug checks conditional and enable them
only when lockdep is enabled.
- Small updates, cleanups and improvements
* tag 'timers-core-2025-03-23' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (27 commits)
selftests/timers: Improve skew_consistency by testing with other clockids
timekeeping: Fix possible inconsistencies in _COARSE clockids
posix-timers: Drop redundant memset() invocation
selftests/timers/posix-timers: Add a test for exact allocation mode
posix-timers: Provide a mechanism to allocate a given timer ID
posix-timers: Dont iterate /proc/$PID/timers with sighand:: Siglock held
posix-timers: Make per process list RCU safe
posix-timers: Avoid false cacheline sharing
posix-timers: Switch to jhash32()
posix-timers: Improve hash table performance
posix-timers: Make signal_struct:: Next_posix_timer_id an atomic_t
posix-timers: Make lock_timer() use guard()
posix-timers: Rework timer removal
posix-timers: Simplify lock/unlock_timer()
posix-timers: Use guards in a few places
posix-timers: Remove SLAB_PANIC from kmem cache
posix-timers: Remove a few paranoid warnings
posix-timers: Cleanup includes
posix-timers: Add cond_resched() to posix_timer_add() search loop
posix-timers: Initialise timer before adding it to the hash table
...
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|
git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull scheduler updates from Ingo Molnar:
"Core & fair scheduler changes:
- Cancel the slice protection of the idle entity (Zihan Zhou)
- Reduce the default slice to avoid tasks getting an extra tick
(Zihan Zhou)
- Force propagating min_slice of cfs_rq when {en,de}queue tasks
(Tianchen Ding)
- Refactor can_migrate_task() to elimate looping (I Hsin Cheng)
- Add unlikey branch hints to several system calls (Colin Ian King)
- Optimize current_clr_polling() on certain architectures (Yujun
Dong)
Deadline scheduler: (Juri Lelli)
- Remove redundant dl_clear_root_domain call
- Move dl_rebuild_rd_accounting to cpuset.h
Uclamp:
- Use the uclamp_is_used() helper instead of open-coding it (Xuewen
Yan)
- Optimize sched_uclamp_used static key enabling (Xuewen Yan)
Scheduler topology support: (Juri Lelli)
- Ignore special tasks when rebuilding domains
- Add wrappers for sched_domains_mutex
- Generalize unique visiting of root domains
- Rebuild root domain accounting after every update
- Remove partition_and_rebuild_sched_domains
- Stop exposing partition_sched_domains_locked
RSEQ: (Michael Jeanson)
- Update kernel fields in lockstep with CONFIG_DEBUG_RSEQ=y
- Fix segfault on registration when rseq_cs is non-zero
- selftests: Add rseq syscall errors test
- selftests: Ensure the rseq ABI TLS is actually 1024 bytes
Membarriers:
- Fix redundant load of membarrier_state (Nysal Jan K.A.)
Scheduler debugging:
- Introduce and use preempt_model_str() (Sebastian Andrzej Siewior)
- Make CONFIG_SCHED_DEBUG unconditional (Ingo Molnar)
Fixes and cleanups:
- Always save/restore x86 TSC sched_clock() on suspend/resume
(Guilherme G. Piccoli)
- Misc fixes and cleanups (Thorsten Blum, Juri Lelli, Sebastian
Andrzej Siewior)"
* tag 'sched-core-2025-03-22' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (40 commits)
cpuidle, sched: Use smp_mb__after_atomic() in current_clr_polling()
sched/debug: Remove CONFIG_SCHED_DEBUG
sched/debug: Remove CONFIG_SCHED_DEBUG from self-test config files
sched/debug, Documentation: Remove (most) CONFIG_SCHED_DEBUG references from documentation
sched/debug: Make CONFIG_SCHED_DEBUG functionality unconditional
sched/debug: Make 'const_debug' tunables unconditional __read_mostly
sched/debug: Change SCHED_WARN_ON() to WARN_ON_ONCE()
rseq/selftests: Fix namespace collision with rseq UAPI header
include/{topology,cpuset}: Move dl_rebuild_rd_accounting to cpuset.h
sched/topology: Stop exposing partition_sched_domains_locked
cgroup/cpuset: Remove partition_and_rebuild_sched_domains
sched/topology: Remove redundant dl_clear_root_domain call
sched/deadline: Rebuild root domain accounting after every update
sched/deadline: Generalize unique visiting of root domains
sched/topology: Wrappers for sched_domains_mutex
sched/deadline: Ignore special tasks when rebuilding domains
tracing: Use preempt_model_str()
xtensa: Rely on generic printing of preemption model
x86: Rely on generic printing of preemption model
s390: Rely on generic printing of preemption model
...
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git://git.kernel.org/pub/scm/linux/kernel/git/tj/sched_ext
Pull sched_ext updates from Tejun Heo:
- Add mechanism to count and report internal events. This significantly
improves visibility on subtle corner conditions.
- The default idle CPU selection logic is revamped and improved in
multiple ways including being made topology aware.
- sched_ext was disabling ttwu_queue for simplicity, which can be
costly when hardware topology is more complex. Implement
SCX_OPS_ALLOWED_QUEUED_WAKEUP so that BPF schedulers can selectively
enable ttwu_queue.
- tools/sched_ext updates to improve compatibility among others.
- Other misc updates and fixes.
- sched_ext/for-6.14-fixes were pulled a few times to receive
prerequisite fixes and resolve conflicts.
* tag 'sched_ext-for-6.15' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/sched_ext: (42 commits)
sched_ext: idle: Refactor scx_select_cpu_dfl()
sched_ext: idle: Honor idle flags in the built-in idle selection policy
sched_ext: Skip per-CPU tasks in scx_bpf_reenqueue_local()
sched_ext: Add trace point to track sched_ext core events
sched_ext: Change the event type from u64 to s64
sched_ext: Documentation: add task lifecycle summary
tools/sched_ext: Provide a compatible helper for scx_bpf_events()
selftests/sched_ext: Add NUMA-aware scheduler test
tools/sched_ext: Provide consistent access to scx flags
sched_ext: idle: Fix scx_bpf_pick_any_cpu_node() behavior
sched_ext: idle: Introduce scx_bpf_nr_node_ids()
sched_ext: idle: Introduce node-aware idle cpu kfunc helpers
sched_ext: idle: Per-node idle cpumasks
sched_ext: idle: Introduce SCX_OPS_BUILTIN_IDLE_PER_NODE
sched_ext: idle: Make idle static keys private
sched/topology: Introduce for_each_node_numadist() iterator
mm/numa: Introduce nearest_node_nodemask()
nodemask: numa: reorganize inclusion path
nodemask: add nodes_copy()
tools/sched_ext: Sync with scx repo
...
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|
In architectures that use the polling bit, current_clr_polling() employs
smp_mb() to ensure that the clearing of the polling bit is visible to
other cores before checking TIF_NEED_RESCHED.
However, smp_mb() can be costly. Given that clear_bit() is an atomic
operation, replacing smp_mb() with smp_mb__after_atomic() is appropriate.
Many architectures implement smp_mb__after_atomic() as a lighter-weight
barrier compared to smp_mb(), leading to performance improvements.
For instance, on x86, smp_mb__after_atomic() is a no-op. This change
eliminates a smp_mb() instruction in the cpuidle wake-up path, saving
several CPU cycles and thereby reducing wake-up latency.
Architectures that do not use the polling bit will retain the original
smp_mb() behavior to ensure that existing dependencies remain unaffected.
Signed-off-by: Yujun Dong <yujundong@pascal-lab.net>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Link: https://lore.kernel.org/r/20241230141624.155356-1-yujundong@pascal-lab.net
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All the big Linux distros enable CONFIG_SCHED_DEBUG, because
the various features it provides help not just with kernel
development, but with system administration and user-space
software development as well.
Reflect this reality and enable this functionality
unconditionally.
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Tested-by: Shrikanth Hegde <sshegde@linux.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Juri Lelli <juri.lelli@redhat.com>
Cc: Vincent Guittot <vincent.guittot@linaro.org>
Cc: Dietmar Eggemann <dietmar.eggemann@arm.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Ben Segall <bsegall@google.com>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Valentin Schneider <vschneid@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Link: https://lore.kernel.org/r/20250317104257.3496611-4-mingo@kernel.org
|
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dl_rebuild_rd_accounting() is defined in cpuset.c, so it makes more
sense to move related declarations to cpuset.h.
Implement the move.
Suggested-by: Waiman Long <llong@redhat.com>
Signed-off-by: Juri Lelli <juri.lelli@redhat.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Waiman Long <llong@redhat.com>
Reviewed-by: Valentin Schneider <vschneid@redhat.com>
Reviewed-by: Dietmar Eggemann <dietmar.eggemann@arm.com>
Tested-by: Waiman Long <longman@redhat.com>
Tested-by: Jon Hunter <jonathanh@nvidia.com>
Tested-by: Dietmar Eggemann <dietmar.eggemann@arm.com>
Link: https://lore.kernel.org/r/Z9MSOVMpU7jpVrMU@jlelli-thinkpadt14gen4.remote.csb
|
|
The are no callers of partition_sched_domains_locked() outside
topology.c.
Stop exposing such function.
Suggested-by: Waiman Long <llong@redhat.com>
Signed-off-by: Juri Lelli <juri.lelli@redhat.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Valentin Schneider <vschneid@redhat.com>
Reviewed-by: Dietmar Eggemann <dietmar.eggemann@arm.com>
Tested-by: Waiman Long <longman@redhat.com>
Tested-by: Jon Hunter <jonathanh@nvidia.com>
Tested-by: Dietmar Eggemann <dietmar.eggemann@arm.com>
Link: https://lore.kernel.org/r/Z9MSC96a8FcqWV3G@jlelli-thinkpadt14gen4.remote.csb
|
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Rebuilding of root domains accounting information (total_bw) is
currently broken on some cases, e.g. suspend/resume on aarch64. Problem
is that the way we keep track of domain changes and try to add bandwidth
back is convoluted and fragile.
Fix it by simplify things by making sure bandwidth accounting is cleared
and completely restored after root domains changes (after root domains
are again stable).
To be sure we always call dl_rebuild_rd_accounting while holding
cpuset_mutex we also add cpuset_reset_sched_domains() wrapper.
Fixes: 53916d5fd3c0 ("sched/deadline: Check bandwidth overflow earlier for hotplug")
Reported-by: Jon Hunter <jonathanh@nvidia.com>
Co-developed-by: Waiman Long <llong@redhat.com>
Signed-off-by: Waiman Long <llong@redhat.com>
Signed-off-by: Juri Lelli <juri.lelli@redhat.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Dietmar Eggemann <dietmar.eggemann@arm.com>
Tested-by: Dietmar Eggemann <dietmar.eggemann@arm.com>
Link: https://lore.kernel.org/r/Z9MRfeJKJUOyUSto@jlelli-thinkpadt14gen4.remote.csb
|
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Bandwidth checks and updates that work on root domains currently employ
a cookie mechanism for efficiency. This mechanism is very much tied to
when root domains are first created and initialized.
Generalize the cookie mechanism so that it can be used also later at
runtime while updating root domains. Also, additionally guard it with
sched_domains_mutex, since domains need to be stable while updating them
(and it will be required for further dynamic changes).
Fixes: 53916d5fd3c0 ("sched/deadline: Check bandwidth overflow earlier for hotplug")
Reported-by: Jon Hunter <jonathanh@nvidia.com>
Signed-off-by: Juri Lelli <juri.lelli@redhat.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Valentin Schneider <vschneid@redhat.com>
Reviewed-by: Dietmar Eggemann <dietmar.eggemann@arm.com>
Tested-by: Waiman Long <longman@redhat.com>
Tested-by: Jon Hunter <jonathanh@nvidia.com>
Tested-by: Dietmar Eggemann <dietmar.eggemann@arm.com>
Link: https://lore.kernel.org/r/Z9MQaiXPvEeW_v7x@jlelli-thinkpadt14gen4.remote.csb
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Checkpoint/Restore in Userspace (CRIU) requires to reconstruct posix timers
with the same timer ID on restore. It uses sys_timer_create() and relies on
the monotonic increasing timer ID provided by this syscall. It creates and
deletes timers until the desired ID is reached. This is can loop for a long
time, when the checkpointed process had a very sparse timer ID range.
It has been debated to implement a new syscall to allow the creation of
timers with a given timer ID, but that's tideous due to the 32/64bit compat
issues of sigevent_t and of dubious value.
The restore mechanism of CRIU creates the timers in a state where all
threads of the restored process are held on a barrier and cannot issue
syscalls. That means the restorer task has exclusive control.
This allows to address this issue with a prctl() so that the restorer
thread can do:
if (prctl(PR_TIMER_CREATE_RESTORE_IDS, PR_TIMER_CREATE_RESTORE_IDS_ON))
goto linear_mode;
create_timers_with_explicit_ids();
prctl(PR_TIMER_CREATE_RESTORE_IDS, PR_TIMER_CREATE_RESTORE_IDS_OFF);
This is backwards compatible because the prctl() fails on older kernels and
CRIU can fall back to the linear timer ID mechanism. CRIU versions which do
not know about the prctl() just work as before.
Implement the prctl() and modify timer_create() so that it copies the
requested timer ID from userspace by utilizing the existing timer_t
pointer, which is used to copy out the allocated timer ID on success.
If the prctl() is disabled, which it is by default, timer_create() works as
before and does not try to read from the userspace pointer.
There is no problem when a broken or rogue user space application enables
the prctl(). If the user space pointer does not contain a valid ID, then
timer_create() fails. If the data is not initialized, but constains a
random valid ID, timer_create() will create that random timer ID or fail if
the ID is already given out.
As CRIU must use the raw syscall to avoid manipulating the internal state
of the restored process, this has no library dependencies and can be
adopted by CRIU right away.
Recreating two timers with IDs 1000000 and 2000000 takes 1.5 seconds with
the create/delete method. With the prctl() it takes 3 microseconds.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Frederic Weisbecker <frederic@kernel.org>
Reviewed-by: Cyrill Gorcunov <gorcunov@gmail.com>
Tested-by: Cyrill Gorcunov <gorcunov@gmail.com>
Link: https://lore.kernel.org/all/87jz8vz0en.ffs@tglx
|
|
The global hash_lock protecting the posix timer hash table can be heavily
contended especially when there is an extensive linear search for a timer
ID.
Timer IDs are handed out by monotonically increasing next_posix_timer_id
and then validating that there is no timer with the same ID in the hash
table. Both operations happen with the global hash lock held.
To reduce the hash lock contention the hash will be reworked to a scaled
hash with per bucket locks, which requires to handle the ID counter
lockless.
Prepare for this by making next_posix_timer_id an atomic_t, which can be
used lockless with atomic_inc_return().
[ tglx: Adopted from Eric's series, massaged change log and simplified it ]
Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Frederic Weisbecker <frederic@kernel.org>
Acked-by: Frederic Weisbecker <frederic@kernel.org>
Link: https://lore.kernel.org/all/20250219125522.2535263-2-edumazet@google.com
Link: https://lore.kernel.org/all/20250308155624.151545978@linutronix.de
|
|
Signed-off-by: Ingo Molnar <mingo@kernel.org>
|
|
On architectures where ARCH_HAS_SYNC_CORE_BEFORE_USERMODE
is not selected, sync_core_before_usermode() is a no-op.
In membarrier_mm_sync_core_before_usermode() the compiler does not
eliminate redundant branches and load of mm->membarrier_state
for this case as the atomic_read() cannot be optimized away.
Here's a snippet of the code generated for finish_task_switch() on powerpc
prior to this change:
1b786c: ld r26,2624(r30) # mm = rq->prev_mm;
.......
1b78c8: cmpdi cr7,r26,0
1b78cc: beq cr7,1b78e4 <finish_task_switch+0xd0>
1b78d0: ld r9,2312(r13) # current
1b78d4: ld r9,1888(r9) # current->mm
1b78d8: cmpd cr7,r26,r9
1b78dc: beq cr7,1b7a70 <finish_task_switch+0x25c>
1b78e0: hwsync
1b78e4: cmplwi cr7,r27,128
.......
1b7a70: lwz r9,176(r26) # atomic_read(&mm->membarrier_state)
1b7a74: b 1b78e0 <finish_task_switch+0xcc>
This was found while analyzing "perf c2c" reports on kernels prior
to commit c1753fd02a00 ("mm: move mm_count into its own cache line")
where mm_count was false sharing with membarrier_state.
There is a minor improvement in the size of finish_task_switch().
The following are results from bloat-o-meter for ppc64le:
GCC 7.5.0
---------
add/remove: 0/0 grow/shrink: 0/1 up/down: 0/-32 (-32)
Function old new delta
finish_task_switch 884 852 -32
GCC 12.2.1
----------
add/remove: 0/0 grow/shrink: 0/1 up/down: 0/-32 (-32)
Function old new delta
finish_task_switch.isra 852 820 -32
LLVM 17.0.6
-----------
add/remove: 0/0 grow/shrink: 0/2 up/down: 0/-36 (-36)
Function old new delta
rt_mutex_schedule 120 104 -16
finish_task_switch 792 772 -20
Results on aarch64:
GCC 14.1.1
----------
add/remove: 0/2 grow/shrink: 1/1 up/down: 4/-60 (-56)
Function old new delta
get_nohz_timer_target 352 356 +4
e843419@0b02_0000d7e7_408 8 - -8
e843419@01bb_000021d2_868 8 - -8
finish_task_switch.isra 592 548 -44
Signed-off-by: Nysal Jan K.A. <nysal@linux.ibm.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Reviewed-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Reviewed-by: Michael Ellerman <mpe@ellerman.id.au>
Reviewed-by: Segher Boessenkool <segher@kernel.crashing.org>
Link: https://lore.kernel.org/r/20250303060457.531293-1-nysal@linux.ibm.com
|
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Add a core event, SCX_EV_SELECT_CPU_FALLBACK, which represents how many times
ops.select_cpu() returns a CPU that the task can't use.
__scx_add_event() is used since the caller holds an rq lock,
so the preemption has already been disabled.
Signed-off-by: Changwoo Min <changwoo@igalia.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
|
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Tejun reported the following race between fork() and cgroup.kill at [1].
Tejun:
I was looking at cgroup.kill implementation and wondering whether there
could be a race window. So, __cgroup_kill() does the following:
k1. Set CGRP_KILL.
k2. Iterate tasks and deliver SIGKILL.
k3. Clear CGRP_KILL.
The copy_process() does the following:
c1. Copy a bunch of stuff.
c2. Grab siglock.
c3. Check fatal_signal_pending().
c4. Commit to forking.
c5. Release siglock.
c6. Call cgroup_post_fork() which puts the task on the css_set and tests
CGRP_KILL.
The intention seems to be that either a forking task gets SIGKILL and
terminates on c3 or it sees CGRP_KILL on c6 and kills the child. However, I
don't see what guarantees that k3 can't happen before c6. ie. After a
forking task passes c5, k2 can take place and then before the forking task
reaches c6, k3 can happen. Then, nobody would send SIGKILL to the child.
What am I missing?
This is indeed a race. One way to fix this race is by taking
cgroup_threadgroup_rwsem in write mode in __cgroup_kill() as the fork()
side takes cgroup_threadgroup_rwsem in read mode from cgroup_can_fork()
to cgroup_post_fork(). However that would be heavy handed as this adds
one more potential stall scenario for cgroup.kill which is usually
called under extreme situation like memory pressure.
To fix this race, let's maintain a sequence number per cgroup which gets
incremented on __cgroup_kill() call. On the fork() side, the
cgroup_can_fork() will cache the sequence number locally and recheck it
against the cgroup's sequence number at cgroup_post_fork() site. If the
sequence numbers mismatch, it means __cgroup_kill() can been called and
we should send SIGKILL to the newly created task.
Reported-by: Tejun Heo <tj@kernel.org>
Closes: https://lore.kernel.org/all/Z5QHE2Qn-QZ6M-KW@slm.duckdns.org/ [1]
Fixes: 661ee6280931 ("cgroup: introduce cgroup.kill")
Cc: stable@vger.kernel.org # v5.14+
Signed-off-by: Shakeel Butt <shakeel.butt@linux.dev>
Reviewed-by: Michal Koutný <mkoutny@suse.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
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git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
Pull MM updates from Andrew Morton:
"The various patchsets are summarized below. Plus of course many
indivudual patches which are described in their changelogs.
- "Allocate and free frozen pages" from Matthew Wilcox reorganizes
the page allocator so we end up with the ability to allocate and
free zero-refcount pages. So that callers (ie, slab) can avoid a
refcount inc & dec
- "Support large folios for tmpfs" from Baolin Wang teaches tmpfs to
use large folios other than PMD-sized ones
- "Fix mm/rodata_test" from Petr Tesarik performs some maintenance
and fixes for this small built-in kernel selftest
- "mas_anode_descend() related cleanup" from Wei Yang tidies up part
of the mapletree code
- "mm: fix format issues and param types" from Keren Sun implements a
few minor code cleanups
- "simplify split calculation" from Wei Yang provides a few fixes and
a test for the mapletree code
- "mm/vma: make more mmap logic userland testable" from Lorenzo
Stoakes continues the work of moving vma-related code into the
(relatively) new mm/vma.c
- "mm/page_alloc: gfp flags cleanups for alloc_contig_*()" from David
Hildenbrand cleans up and rationalizes handling of gfp flags in the
page allocator
- "readahead: Reintroduce fix for improper RA window sizing" from Jan
Kara is a second attempt at fixing a readahead window sizing issue.
It should reduce the amount of unnecessary reading
- "synchronously scan and reclaim empty user PTE pages" from Qi Zheng
addresses an issue where "huge" amounts of pte pagetables are
accumulated:
https://lore.kernel.org/lkml/cover.1718267194.git.zhengqi.arch@bytedance.com/
Qi's series addresses this windup by synchronously freeing PTE
memory within the context of madvise(MADV_DONTNEED)
- "selftest/mm: Remove warnings found by adding compiler flags" from
Muhammad Usama Anjum fixes some build warnings in the selftests
code when optional compiler warnings are enabled
- "mm: don't use __GFP_HARDWALL when migrating remote pages" from
David Hildenbrand tightens the allocator's observance of
__GFP_HARDWALL
- "pkeys kselftests improvements" from Kevin Brodsky implements
various fixes and cleanups in the MM selftests code, mainly
pertaining to the pkeys tests
- "mm/damon: add sample modules" from SeongJae Park enhances DAMON to
estimate application working set size
- "memcg/hugetlb: Rework memcg hugetlb charging" from Joshua Hahn
provides some cleanups to memcg's hugetlb charging logic
- "mm/swap_cgroup: remove global swap cgroup lock" from Kairui Song
removes the global swap cgroup lock. A speedup of 10% for a
tmpfs-based kernel build was demonstrated
- "zram: split page type read/write handling" from Sergey Senozhatsky
has several fixes and cleaups for zram in the area of
zram_write_page(). A watchdog softlockup warning was eliminated
- "move pagetable_*_dtor() to __tlb_remove_table()" from Kevin
Brodsky cleans up the pagetable destructor implementations. A rare
use-after-free race is fixed
- "mm/debug: introduce and use VM_WARN_ON_VMG()" from Lorenzo Stoakes
simplifies and cleans up the debugging code in the VMA merging
logic
- "Account page tables at all levels" from Kevin Brodsky cleans up
and regularizes the pagetable ctor/dtor handling. This results in
improvements in accounting accuracy
- "mm/damon: replace most damon_callback usages in sysfs with new
core functions" from SeongJae Park cleans up and generalizes
DAMON's sysfs file interface logic
- "mm/damon: enable page level properties based monitoring" from
SeongJae Park increases the amount of information which is
presented in response to DAMOS actions
- "mm/damon: remove DAMON debugfs interface" from SeongJae Park
removes DAMON's long-deprecated debugfs interfaces. Thus the
migration to sysfs is completed
- "mm/hugetlb: Refactor hugetlb allocation resv accounting" from
Peter Xu cleans up and generalizes the hugetlb reservation
accounting
- "mm: alloc_pages_bulk: small API refactor" from Luiz Capitulino
removes a never-used feature of the alloc_pages_bulk() interface
- "mm/damon: extend DAMOS filters for inclusion" from SeongJae Park
extends DAMOS filters to support not only exclusion (rejecting),
but also inclusion (allowing) behavior
- "Add zpdesc memory descriptor for zswap.zpool" from Alex Shi
introduces a new memory descriptor for zswap.zpool that currently
overlaps with struct page for now. This is part of the effort to
reduce the size of struct page and to enable dynamic allocation of
memory descriptors
- "mm, swap: rework of swap allocator locks" from Kairui Song redoes
and simplifies the swap allocator locking. A speedup of 400% was
demonstrated for one workload. As was a 35% reduction for kernel
build time with swap-on-zram
- "mm: update mips to use do_mmap(), make mmap_region() internal"
from Lorenzo Stoakes reworks MIPS's use of mmap_region() so that
mmap_region() can be made MM-internal
- "mm/mglru: performance optimizations" from Yu Zhao fixes a few
MGLRU regressions and otherwise improves MGLRU performance
- "Docs/mm/damon: add tuning guide and misc updates" from SeongJae
Park updates DAMON documentation
- "Cleanup for memfd_create()" from Isaac Manjarres does that thing
- "mm: hugetlb+THP folio and migration cleanups" from David
Hildenbrand provides various cleanups in the areas of hugetlb
folios, THP folios and migration
- "Uncached buffered IO" from Jens Axboe implements the new
RWF_DONTCACHE flag which provides synchronous dropbehind for
pagecache reading and writing. To permite userspace to address
issues with massive buildup of useless pagecache when
reading/writing fast devices
- "selftests/mm: virtual_address_range: Reduce memory" from Thomas
Weißschuh fixes and optimizes some of the MM selftests"
* tag 'mm-stable-2025-01-26-14-59' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm: (321 commits)
mm/compaction: fix UBSAN shift-out-of-bounds warning
s390/mm: add missing ctor/dtor on page table upgrade
kasan: sw_tags: use str_on_off() helper in kasan_init_sw_tags()
tools: add VM_WARN_ON_VMG definition
mm/damon/core: use str_high_low() helper in damos_wmark_wait_us()
seqlock: add missing parameter documentation for raw_seqcount_try_begin()
mm/page-writeback: consolidate wb_thresh bumping logic into __wb_calc_thresh
mm/page_alloc: remove the incorrect and misleading comment
zram: remove zcomp_stream_put() from write_incompressible_page()
mm: separate move/undo parts from migrate_pages_batch()
mm/kfence: use str_write_read() helper in get_access_type()
selftests/mm/mkdirty: fix memory leak in test_uffdio_copy()
kasan: hw_tags: Use str_on_off() helper in kasan_init_hw_tags()
selftests/mm: virtual_address_range: avoid reading from VM_IO mappings
selftests/mm: vm_util: split up /proc/self/smaps parsing
selftests/mm: virtual_address_range: unmap chunks after validation
selftests/mm: virtual_address_range: mmap() without PROT_WRITE
selftests/memfd/memfd_test: fix possible NULL pointer dereference
mm: add FGP_DONTCACHE folio creation flag
mm: call filemap_fdatawrite_range_kick() after IOCB_DONTCACHE issue
...
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git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull scheduler updates from Ingo Molnar:
"Fair scheduler (SCHED_FAIR) enhancements:
- Behavioral improvements:
- Untangle NEXT_BUDDY and pick_next_task() (Peter Zijlstra)
- Delayed-dequeue enhancements & fixes: (Vincent Guittot)
- Rename h_nr_running into h_nr_queued
- Add new cfs_rq.h_nr_runnable
- Use the new cfs_rq.h_nr_runnable
- Removed unsued cfs_rq.h_nr_delayed
- Rename cfs_rq.idle_h_nr_running into h_nr_idle
- Remove unused cfs_rq.idle_nr_running
- Rename cfs_rq.nr_running into nr_queued
- Do not try to migrate delayed dequeue task
- Fix variable declaration position
- Encapsulate set custom slice in a __setparam_fair() function
- Fixes:
- Fix race between yield_to() and try_to_wake_up() (Tianchen Ding)
- Fix CPU bandwidth limit bypass during CPU hotplug (Vishal
Chourasia)
- Cleanups:
- Clean up in migrate_degrades_locality() to improve readability
(Peter Zijlstra)
- Mark m*_vruntime() with __maybe_unused (Andy Shevchenko)
- Update comments after sched_tick() rename (Sebastian Andrzej
Siewior)
- Remove CONFIG_CFS_BANDWIDTH=n definition of cfs_bandwidth_used()
(Valentin Schneider)
Deadline scheduler (SCHED_DL) enhancements:
- Restore dl_server bandwidth on non-destructive root domain changes
(Juri Lelli)
- Correctly account for allocated bandwidth during hotplug (Juri
Lelli)
- Check bandwidth overflow earlier for hotplug (Juri Lelli)
- Clean up goto label in pick_earliest_pushable_dl_task() (John
Stultz)
- Consolidate timer cancellation (Wander Lairson Costa)
Load-balancer enhancements:
- Improve performance by prioritizing migrating eligible tasks in
sched_balance_rq() (Hao Jia)
- Do not compute NUMA Balancing stats unnecessarily during
load-balancing (K Prateek Nayak)
- Do not compute overloaded status unnecessarily during
load-balancing (K Prateek Nayak)
Generic scheduling code enhancements:
- Use READ_ONCE() in task_on_rq_queued(), to consistently use the
WRITE_ONCE() updated ->on_rq field (Harshit Agarwal)
Isolated CPUs support enhancements: (Waiman Long)
- Make "isolcpus=nohz" equivalent to "nohz_full"
- Consolidate housekeeping cpumasks that are always identical
- Remove HK_TYPE_SCHED
- Unify HK_TYPE_{TIMER|TICK|MISC} to HK_TYPE_KERNEL_NOISE
RSEQ enhancements:
- Validate read-only fields under DEBUG_RSEQ config (Mathieu
Desnoyers)
PSI enhancements:
- Fix race when task wakes up before psi_sched_switch() adjusts flags
(Chengming Zhou)
IRQ time accounting performance enhancements: (Yafang Shao)
- Define sched_clock_irqtime as static key
- Don't account irq time if sched_clock_irqtime is disabled
Virtual machine scheduling enhancements:
- Don't try to catch up excess steal time (Suleiman Souhlal)
Heterogenous x86 CPU scheduling enhancements: (K Prateek Nayak)
- Convert "sysctl_sched_itmt_enabled" to boolean
- Use guard() for itmt_update_mutex
- Move the "sched_itmt_enabled" sysctl to debugfs
- Remove x86_smt_flags and use cpu_smt_flags directly
- Use x86_sched_itmt_flags for PKG domain unconditionally
Debugging code & instrumentation enhancements:
- Change need_resched warnings to pr_err() (David Rientjes)
- Print domain name in /proc/schedstat (K Prateek Nayak)
- Fix value reported by hot tasks pulled in /proc/schedstat (Peter
Zijlstra)
- Report the different kinds of imbalances in /proc/schedstat
(Swapnil Sapkal)
- Move sched domain name out of CONFIG_SCHED_DEBUG (Swapnil Sapkal)
- Update Schedstat version to 17 (Swapnil Sapkal)"
* tag 'sched-core-2025-01-21' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (48 commits)
rseq: Fix rseq unregistration regression
psi: Fix race when task wakes up before psi_sched_switch() adjusts flags
sched, psi: Don't account irq time if sched_clock_irqtime is disabled
sched: Don't account irq time if sched_clock_irqtime is disabled
sched: Define sched_clock_irqtime as static key
sched/fair: Do not compute overloaded status unnecessarily during lb
sched/fair: Do not compute NUMA Balancing stats unnecessarily during lb
x86/topology: Use x86_sched_itmt_flags for PKG domain unconditionally
x86/topology: Remove x86_smt_flags and use cpu_smt_flags directly
x86/itmt: Move the "sched_itmt_enabled" sysctl to debugfs
x86/itmt: Use guard() for itmt_update_mutex
x86/itmt: Convert "sysctl_sched_itmt_enabled" to boolean
sched/core: Prioritize migrating eligible tasks in sched_balance_rq()
sched/debug: Change need_resched warnings to pr_err
sched/fair: Encapsulate set custom slice in a __setparam_fair() function
sched: Fix race between yield_to() and try_to_wake_up()
docs: Update Schedstat version to 17
sched/stats: Print domain name in /proc/schedstat
sched: Move sched domain name out of CONFIG_SCHED_DEBUG
sched: Report the different kinds of imbalances in /proc/schedstat
...
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CPU unplug first calls __cpu_disable(), and that's where powerpc calls
cleanup_cpu_mmu_context(), which clears this CPU from mm_cpumask() of all
mms in the system.
However this CPU may still be using a lazy tlb mm, and its mm_cpumask bit
will be cleared from it. The CPU does not switch away from the lazy tlb
mm until arch_cpu_idle_dead() calls idle_task_exit().
If that user mm exits in this window, it will not be subject to the lazy
tlb mm shootdown and may be freed while in use as a lazy mm by the CPU
that is being unplugged.
cleanup_cpu_mmu_context() could be moved later, but it looks better to
move the lazy tlb mm switching earlier. The problem with doing the lazy
mm switching in idle_task_exit() is explained in commit bf2c59fce4074
("sched/core: Fix illegal RCU from offline CPUs"), which added a wart to
switch away from the mm but leave it set in active_mm to be cleaned up
later.
So instead, switch away from the lazy tlb mm at sched_cpu_wait_empty(),
which is the last hotplug state before teardown
(CPUHP_AP_SCHED_WAIT_EMPTY). This CPU will never switch to a user thread
from this point, so it has no chance to pick up a new lazy tlb mm. This
removes the lazy tlb mm handling wart in CPU unplug.
With this, idle_task_exit() is not needed anymore and can be cleaned up.
This leaves the prototype alone, to be cleaned after this change.
herton: took the suggestions from https://lore.kernel.org/all/87jzvyprsw.ffs@tglx/
and made adjustments on the initial patch proposed by Nicholas.
Link: https://lkml.kernel.org/r/20230524060455.147699-1-npiggin@gmail.com
Link: https://lore.kernel.org/all/20230525205253.E2FAEC433EF@smtp.kernel.org/
Link: https://lkml.kernel.org/r/20241104142318.3295663-1-herton@redhat.com
Fixes: 2655421ae69f ("lazy tlb: shoot lazies, non-refcounting lazy tlb mm reference handling scheme")
Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Signed-off-by: Herton R. Krzesinski <herton@redhat.com>
Suggested-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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A common pattern seen when wake_qs are used to defer a wakeup
until after a lock is released is something like:
preempt_disable();
raw_spin_unlock(lock);
wake_up_q(wake_q);
preempt_enable();
So create some raw_spin_unlock*_wake() helper functions to clean
this up.
Applies on top of the fix I submitted here:
https://lore.kernel.org/lkml/20241212222138.2400498-1-jstultz@google.com/
NOTE: I recognise the unlock()/unlock_irq()/unlock_irqrestore()
variants creates its own duplication, which we could use a macro
to generate the similar functions, but I often dislike how those
generation macros making finding the actual implementation
harder, so I left the three functions as is. If folks would
prefer otherwise, let me know and I'll switch it.
Suggested-by: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: John Stultz <jstultz@google.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/20241217040803.243420-1-jstultz@google.com
|
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/proc/schedstat file shows cpu and sched domain level scheduler
statistics. It does not show domain name instead shows domain level.
It will be very useful for tools like `perf sched stats`[1] to
aggragate domain level stats if domain names are shown in /proc/schedstat.
But sched domain name is guarded by CONFIG_SCHED_DEBUG. As per the
discussion[2], move sched domain name out of CONFIG_SCHED_DEBUG.
[1] https://lore.kernel.org/lkml/20241122084452.1064968-1-swapnil.sapkal@amd.com/
[2] https://lore.kernel.org/lkml/fcefeb4d-3acb-462d-9c9b-3df8d927e522@amd.com/
Suggested-by: "Gautham R. Shenoy" <gautham.shenoy@amd.com>
Signed-off-by: Swapnil Sapkal <swapnil.sapkal@amd.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lore.kernel.org/r/20241220063224.17767-5-swapnil.sapkal@amd.com
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In /proc/schedstat, lb_imbalance reports the sum of imbalances
discovered in sched domains with each call to sched_balance_rq(), which is
not very useful because lb_imbalance does not mention whether the imbalance
is due to load, utilization, nr_tasks or misfit_tasks. Remove this field
from /proc/schedstat.
Currently there is no field in /proc/schedstat to report different types
of imbalances. Introduce new fields in /proc/schedstat to report the
total imbalances in load, utilization, nr_tasks or misfit_tasks.
Added fields to /proc/schedstat:
- lb_imbalance_load: Total imbalance due to load.
- lb_imbalance_util: Total imbalance due to utilization.
- lb_imbalance_task: Total imbalance due to number of tasks.
- lb_imbalance_misfit: Total imbalance due to misfit tasks.
Signed-off-by: Swapnil Sapkal <swapnil.sapkal@amd.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Shrikanth Hegde <sshegde@linux.ibm.com>
Link: https://lore.kernel.org/r/20241220063224.17767-4-swapnil.sapkal@amd.com
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The housekeeping cpumasks are only set by two boot commandline
parameters: "nohz_full" and "isolcpus". When there is more than one of
"nohz_full" or "isolcpus", the extra ones must have the same CPU list
or the setup will fail partially.
The HK_TYPE_DOMAIN and HK_TYPE_MANAGED_IRQ types are settable by
"isolcpus" only and their settings can be independent of the other
types. The other housekeeping types are all set by "nohz_full" or
"isolcpus=nohz" without a way to set them individually. So they all
have identical cpumasks.
There is actually no point in having different cpumasks for these
"nohz_full" only housekeeping types. Consolidate these types to use the
same cpumask by aliasing them to the same value. If there is a need to
set any of them independently in the future, we can break them out to
their own cpumasks again.
With this change, the number of cpumasks in the housekeeping structure
drops from 9 to 3. Other than that, there should be no other functional
change.
Signed-off-by: Waiman Long <longman@redhat.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Frederic Weisbecker <frederic@kernel.org>
Link: https://lore.kernel.org/r/20241030175253.125248-4-longman@redhat.com
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The HK_TYPE_SCHED housekeeping type is defined but not set anywhere. So
any code that try to use HK_TYPE_SCHED are essentially dead code. So
remove HK_TYPE_SCHED and any code that use it.
Signed-off-by: Waiman Long <longman@redhat.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Frederic Weisbecker <frederic@kernel.org>
Link: https://lore.kernel.org/r/20241030175253.125248-2-longman@redhat.com
|
|
git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
Pull MM updates from Andrew Morton:
- The series "zram: optimal post-processing target selection" from
Sergey Senozhatsky improves zram's post-processing selection
algorithm. This leads to improved memory savings.
- Wei Yang has gone to town on the mapletree code, contributing several
series which clean up the implementation:
- "refine mas_mab_cp()"
- "Reduce the space to be cleared for maple_big_node"
- "maple_tree: simplify mas_push_node()"
- "Following cleanup after introduce mas_wr_store_type()"
- "refine storing null"
- The series "selftests/mm: hugetlb_fault_after_madv improvements" from
David Hildenbrand fixes this selftest for s390.
- The series "introduce pte_offset_map_{ro|rw}_nolock()" from Qi Zheng
implements some rationaizations and cleanups in the page mapping
code.
- The series "mm: optimize shadow entries removal" from Shakeel Butt
optimizes the file truncation code by speeding up the handling of
shadow entries.
- The series "Remove PageKsm()" from Matthew Wilcox completes the
migration of this flag over to being a folio-based flag.
- The series "Unify hugetlb into arch_get_unmapped_area functions" from
Oscar Salvador implements a bunch of consolidations and cleanups in
the hugetlb code.
- The series "Do not shatter hugezeropage on wp-fault" from Dev Jain
takes away the wp-fault time practice of turning a huge zero page
into small pages. Instead we replace the whole thing with a THP. More
consistent cleaner and potentiall saves a large number of pagefaults.
- The series "percpu: Add a test case and fix for clang" from Andy
Shevchenko enhances and fixes the kernel's built in percpu test code.
- The series "mm/mremap: Remove extra vma tree walk" from Liam Howlett
optimizes mremap() by avoiding doing things which we didn't need to
do.
- The series "Improve the tmpfs large folio read performance" from
Baolin Wang teaches tmpfs to copy data into userspace at the folio
size rather than as individual pages. A 20% speedup was observed.
- The series "mm/damon/vaddr: Fix issue in
damon_va_evenly_split_region()" fro Zheng Yejian fixes DAMON
splitting.
- The series "memcg-v1: fully deprecate charge moving" from Shakeel
Butt removes the long-deprecated memcgv2 charge moving feature.
- The series "fix error handling in mmap_region() and refactor" from
Lorenzo Stoakes cleanup up some of the mmap() error handling and
addresses some potential performance issues.
- The series "x86/module: use large ROX pages for text allocations"
from Mike Rapoport teaches x86 to use large pages for
read-only-execute module text.
- The series "page allocation tag compression" from Suren Baghdasaryan
is followon maintenance work for the new page allocation profiling
feature.
- The series "page->index removals in mm" from Matthew Wilcox remove
most references to page->index in mm/. A slow march towards shrinking
struct page.
- The series "damon/{self,kunit}tests: minor fixups for DAMON debugfs
interface tests" from Andrew Paniakin performs maintenance work for
DAMON's self testing code.
- The series "mm: zswap swap-out of large folios" from Kanchana Sridhar
improves zswap's batching of compression and decompression. It is a
step along the way towards using Intel IAA hardware acceleration for
this zswap operation.
- The series "kasan: migrate the last module test to kunit" from
Sabyrzhan Tasbolatov completes the migration of the KASAN built-in
tests over to the KUnit framework.
- The series "implement lightweight guard pages" from Lorenzo Stoakes
permits userapace to place fault-generating guard pages within a
single VMA, rather than requiring that multiple VMAs be created for
this. Improved efficiencies for userspace memory allocators are
expected.
- The series "memcg: tracepoint for flushing stats" from JP Kobryn uses
tracepoints to provide increased visibility into memcg stats flushing
activity.
- The series "zram: IDLE flag handling fixes" from Sergey Senozhatsky
fixes a zram buglet which potentially affected performance.
- The series "mm: add more kernel parameters to control mTHP" from
Maíra Canal enhances our ability to control/configuremultisize THP
from the kernel boot command line.
- The series "kasan: few improvements on kunit tests" from Sabyrzhan
Tasbolatov has a couple of fixups for the KASAN KUnit tests.
- The series "mm/list_lru: Split list_lru lock into per-cgroup scope"
from Kairui Song optimizes list_lru memory utilization when lockdep
is enabled.
* tag 'mm-stable-2024-11-18-19-27' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm: (215 commits)
cma: enforce non-zero pageblock_order during cma_init_reserved_mem()
mm/kfence: add a new kunit test test_use_after_free_read_nofault()
zram: fix NULL pointer in comp_algorithm_show()
memcg/hugetlb: add hugeTLB counters to memcg
vmstat: call fold_vm_zone_numa_events() before show per zone NUMA event
mm: mmap_lock: check trace_mmap_lock_$type_enabled() instead of regcount
zram: ZRAM_DEF_COMP should depend on ZRAM
MAINTAINERS/MEMORY MANAGEMENT: add document files for mm
Docs/mm/damon: recommend academic papers to read and/or cite
mm: define general function pXd_init()
kmemleak: iommu/iova: fix transient kmemleak false positive
mm/list_lru: simplify the list_lru walk callback function
mm/list_lru: split the lock to per-cgroup scope
mm/list_lru: simplify reparenting and initial allocation
mm/list_lru: code clean up for reparenting
mm/list_lru: don't export list_lru_add
mm/list_lru: don't pass unnecessary key parameters
kasan: add kunit tests for kmalloc_track_caller, kmalloc_node_track_caller
kasan: change kasan_atomics kunit test as KUNIT_CASE_SLOW
kasan: use EXPORT_SYMBOL_IF_KUNIT to export symbols
...
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git://git.kernel.org/pub/scm/linux/kernel/git/tj/sched_ext
Pull sched_ext updates from Tejun Heo:
- Improve the default select_cpu() implementation making it topology
aware and handle WAKE_SYNC better.
- set_arg_maybe_null() was used to inform the verifier which ops args
could be NULL in a rather hackish way. Use the new __nullable CFI
stub tags instead.
- On Sapphire Rapids multi-socket systems, a BPF scheduler, by
hammering on the same queue across sockets, could live-lock the
system to the point where the system couldn't make reasonable forward
progress.
This could lead to soft-lockup triggered resets or stalling out
bypass mode switch and thus BPF scheduler ejection for tens of
minutes if not hours. After trying a number of mitigations, the
following set worked reliably:
- Injecting artificial cpu_relax() loops in two places while
sched_ext is trying to turn on the bypass mode.
- Triggering scheduler ejection when soft-lockup detection is
imminent (a quarter of threshold left).
While not the prettiest, the impact both in terms of code complexity
and overhead is minimal.
- A common complaint on the API is the overuse of the word "dispatch"
and the confusion around "consume". This is due to how the dispatch
queues became more generic over time. Rename the affected kfuncs for
clarity. Thanks to BPF's compatibility features, this change can be
made in a way that's both forward and backward compatible. The
compatibility code will be dropped in a few releases.
- Other misc changes
* tag 'sched_ext-for-6.13' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/sched_ext: (21 commits)
sched_ext: Replace scx_next_task_picked() with switch_class() in comment
sched_ext: Rename scx_bpf_dispatch[_vtime]_from_dsq*() -> scx_bpf_dsq_move[_vtime]*()
sched_ext: Rename scx_bpf_consume() to scx_bpf_dsq_move_to_local()
sched_ext: Rename scx_bpf_dispatch[_vtime]() to scx_bpf_dsq_insert[_vtime]()
sched_ext: scx_bpf_dispatch_from_dsq_set_*() are allowed from unlocked context
sched_ext: add a missing rcu_read_lock/unlock pair at scx_select_cpu_dfl()
sched_ext: Clarify sched_ext_ops table for userland scheduler
sched_ext: Enable the ops breather and eject BPF scheduler on softlockup
sched_ext: Avoid live-locking bypass mode switching
sched_ext: Fix incorrect use of bitwise AND
sched_ext: Do not enable LLC/NUMA optimizations when domains overlap
sched_ext: Introduce NUMA awareness to the default idle selection policy
sched_ext: Replace set_arg_maybe_null() with __nullable CFI stub tags
sched_ext: Rename CFI stubs to names that are recognized by BPF
sched_ext: Introduce LLC awareness to the default idle selection policy
sched_ext: Clarify ops.select_cpu() for single-CPU tasks
sched_ext: improve WAKE_SYNC behavior for default idle CPU selection
sched_ext: Use btf_ids to resolve task_struct
sched/ext: Use tg_cgroup() to elieminate duplicate code
sched/ext: Fix unmatch trailing comment of CONFIG_EXT_GROUP_SCHED
...
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git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull timer updates from Thomas Gleixner:
"A rather large update for timekeeping and timers:
- The final step to get rid of auto-rearming posix-timers
posix-timers are currently auto-rearmed by the kernel when the
signal of the timer is ignored so that the timer signal can be
delivered once the corresponding signal is unignored.
This requires to throttle the timer to prevent a DoS by small
intervals and keeps the system pointlessly out of low power states
for no value. This is a long standing non-trivial problem due to
the lock order of posix-timer lock and the sighand lock along with
life time issues as the timer and the sigqueue have different life
time rules.
Cure this by:
- Embedding the sigqueue into the timer struct to have the same
life time rules. Aside of that this also avoids the lookup of
the timer in the signal delivery and rearm path as it's just a
always valid container_of() now.
- Queuing ignored timer signals onto a seperate ignored list.
- Moving queued timer signals onto the ignored list when the
signal is switched to SIG_IGN before it could be delivered.
- Walking the ignored list when SIG_IGN is lifted and requeue the
signals to the actual signal lists. This allows the signal
delivery code to rearm the timer.
This also required to consolidate the signal delivery rules so they
are consistent across all situations. With that all self test
scenarios finally succeed.
- Core infrastructure for VFS multigrain timestamping
This is required to allow the kernel to use coarse grained time
stamps by default and switch to fine grained time stamps when inode
attributes are actively observed via getattr().
These changes have been provided to the VFS tree as well, so that
the VFS specific infrastructure could be built on top.
- Cleanup and consolidation of the sleep() infrastructure
- Move all sleep and timeout functions into one file
- Rework udelay() and ndelay() into proper documented inline
functions and replace the hardcoded magic numbers by proper
defines.
- Rework the fsleep() implementation to take the reality of the
timer wheel granularity on different HZ values into account.
Right now the boundaries are hard coded time ranges which fail
to provide the requested accuracy on different HZ settings.
- Update documentation for all sleep/timeout related functions
and fix up stale documentation links all over the place
- Fixup a few usage sites
- Rework of timekeeping and adjtimex(2) to prepare for multiple PTP
clocks
A system can have multiple PTP clocks which are participating in
seperate and independent PTP clock domains. So far the kernel only
considers the PTP clock which is based on CLOCK TAI relevant as
that's the clock which drives the timekeeping adjustments via the
various user space daemons through adjtimex(2).
The non TAI based clock domains are accessible via the file
descriptor based posix clocks, but their usability is very limited.
They can't be accessed fast as they always go all the way out to
the hardware and they cannot be utilized in the kernel itself.
As Time Sensitive Networking (TSN) gains traction it is required to
provide fast user and kernel space access to these clocks.
The approach taken is to utilize the timekeeping and adjtimex(2)
infrastructure to provide this access in a similar way how the
kernel provides access to clock MONOTONIC, REALTIME etc.
Instead of creating a duplicated infrastructure this rework
converts timekeeping and adjtimex(2) into generic functionality
which operates on pointers to data structures instead of using
static variables.
This allows to provide time accessors and adjtimex(2) functionality
for the independent PTP clocks in a subsequent step.
- Consolidate hrtimer initialization
hrtimers are set up by initializing the data structure and then
seperately setting the callback function for historical reasons.
That's an extra unnecessary step and makes Rust support less
straight forward than it should be.
Provide a new set of hrtimer_setup*() functions and convert the
core code and a few usage sites of the less frequently used
interfaces over.
The bulk of the htimer_init() to hrtimer_setup() conversion is
already prepared and scheduled for the next merge window.
- Drivers:
- Ensure that the global timekeeping clocksource is utilizing the
cluster 0 timer on MIPS multi-cluster systems.
Otherwise CPUs on different clusters use their cluster specific
clocksource which is not guaranteed to be synchronized with
other clusters.
- Mostly boring cleanups, fixes, improvements and code movement"
* tag 'timers-core-2024-11-18' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (140 commits)
posix-timers: Fix spurious warning on double enqueue versus do_exit()
clocksource/drivers/arm_arch_timer: Use of_property_present() for non-boolean properties
clocksource/drivers/gpx: Remove redundant casts
clocksource/drivers/timer-ti-dm: Fix child node refcount handling
dt-bindings: timer: actions,owl-timer: convert to YAML
clocksource/drivers/ralink: Add Ralink System Tick Counter driver
clocksource/drivers/mips-gic-timer: Always use cluster 0 counter as clocksource
clocksource/drivers/timer-ti-dm: Don't fail probe if int not found
clocksource/drivers:sp804: Make user selectable
clocksource/drivers/dw_apb: Remove unused dw_apb_clockevent functions
hrtimers: Delete hrtimer_init_on_stack()
alarmtimer: Switch to use hrtimer_setup() and hrtimer_setup_on_stack()
io_uring: Switch to use hrtimer_setup_on_stack()
sched/idle: Switch to use hrtimer_setup_on_stack()
hrtimers: Delete hrtimer_init_sleeper_on_stack()
wait: Switch to use hrtimer_setup_sleeper_on_stack()
timers: Switch to use hrtimer_setup_sleeper_on_stack()
net: pktgen: Switch to use hrtimer_setup_sleeper_on_stack()
futex: Switch to use hrtimer_setup_sleeper_on_stack()
fs/aio: Switch to use hrtimer_setup_sleeper_on_stack()
...
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git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull scheduler updates from Ingo Molnar:
"Core facilities:
- Add the "Lazy preemption" model (CONFIG_PREEMPT_LAZY=y), which
optimizes fair-class preemption by delaying preemption requests to
the tick boundary, while working as full preemption for
RR/FIFO/DEADLINE classes. (Peter Zijlstra)
- x86: Enable Lazy preemption (Peter Zijlstra)
- riscv: Enable Lazy preemption (Jisheng Zhang)
- Initialize idle tasks only once (Thomas Gleixner)
- sched/ext: Remove sched_fork() hack (Thomas Gleixner)
Fair scheduler:
- Optimize the PLACE_LAG when se->vlag is zero (Huang Shijie)
Idle loop:
- Optimize the generic idle loop by removing unnecessary memory
barrier (Zhongqiu Han)
RSEQ:
- Improve cache locality of RSEQ concurrency IDs for intermittent
workloads (Mathieu Desnoyers)
Waitqueues:
- Make wake_up_{bit,var} less fragile (Neil Brown)
PSI:
- Pass enqueue/dequeue flags to psi callbacks directly (Johannes
Weiner)
Preparatory patches for proxy execution:
- Add move_queued_task_locked helper (Connor O'Brien)
- Consolidate pick_*_task to task_is_pushable helper (Connor O'Brien)
- Split out __schedule() deactivate task logic into a helper (John
Stultz)
- Split scheduler and execution contexts (Peter Zijlstra)
- Make mutex::wait_lock irq safe (Juri Lelli)
- Expose __mutex_owner() (Juri Lelli)
- Remove wakeups from under mutex::wait_lock (Peter Zijlstra)
Misc fixes and cleanups:
- Remove unused __HAVE_THREAD_FUNCTIONS hook support (David
Disseldorp)
- Update the comment for TIF_NEED_RESCHED_LAZY (Sebastian Andrzej
Siewior)
- Remove unused bit_wait_io_timeout (Dr. David Alan Gilbert)
- remove the DOUBLE_TICK feature (Huang Shijie)
- fix the comment for PREEMPT_SHORT (Huang Shijie)
- Fix unnused variable warning (Christian Loehle)
- No PREEMPT_RT=y for all{yes,mod}config"
* tag 'sched-core-2024-11-18' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (33 commits)
sched, x86: Update the comment for TIF_NEED_RESCHED_LAZY.
sched: No PREEMPT_RT=y for all{yes,mod}config
riscv: add PREEMPT_LAZY support
sched, x86: Enable Lazy preemption
sched: Enable PREEMPT_DYNAMIC for PREEMPT_RT
sched: Add Lazy preemption model
sched: Add TIF_NEED_RESCHED_LAZY infrastructure
sched/ext: Remove sched_fork() hack
sched: Initialize idle tasks only once
sched: psi: pass enqueue/dequeue flags to psi callbacks directly
sched/uclamp: Fix unnused variable warning
sched: Split scheduler and execution contexts
sched: Split out __schedule() deactivate task logic into a helper
sched: Consolidate pick_*_task to task_is_pushable helper
sched: Add move_queued_task_locked helper
locking/mutex: Expose __mutex_owner()
locking/mutex: Make mutex::wait_lock irq safe
locking/mutex: Remove wakeups from under mutex::wait_lock
sched: Improve cache locality of RSEQ concurrency IDs for intermittent workloads
sched: idle: Optimize the generic idle loop by removing needless memory barrier
...
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When CONFIG_KASAN_SW_TAGS and CONFIG_KASAN_STACK are enabled, the
object_is_on_stack() function may produce incorrect results due to the
presence of tags in the obj pointer, while the stack pointer does not have
tags. This discrepancy can lead to incorrect stack object detection and
subsequently trigger warnings if CONFIG_DEBUG_OBJECTS is also enabled.
Example of the warning:
ODEBUG: object 3eff800082ea7bb0 is NOT on stack ffff800082ea0000, but annotated.
------------[ cut here ]------------
WARNING: CPU: 0 PID: 1 at lib/debugobjects.c:557 __debug_object_init+0x330/0x364
Modules linked in:
CPU: 0 UID: 0 PID: 1 Comm: swapper/0 Not tainted 6.12.0-rc5 #4
Hardware name: linux,dummy-virt (DT)
pstate: 600000c5 (nZCv daIF -PAN -UAO -TCO -DIT -SSBS BTYPE=--)
pc : __debug_object_init+0x330/0x364
lr : __debug_object_init+0x330/0x364
sp : ffff800082ea7b40
x29: ffff800082ea7b40 x28: 98ff0000c0164518 x27: 98ff0000c0164534
x26: ffff800082d93ec8 x25: 0000000000000001 x24: 1cff0000c00172a0
x23: 0000000000000000 x22: ffff800082d93ed0 x21: ffff800081a24418
x20: 3eff800082ea7bb0 x19: efff800000000000 x18: 0000000000000000
x17: 00000000000000ff x16: 0000000000000047 x15: 206b63617473206e
x14: 0000000000000018 x13: ffff800082ea7780 x12: 0ffff800082ea78e
x11: 0ffff800082ea790 x10: 0ffff800082ea79d x9 : 34d77febe173e800
x8 : 34d77febe173e800 x7 : 0000000000000001 x6 : 0000000000000001
x5 : feff800082ea74b8 x4 : ffff800082870a90 x3 : ffff80008018d3c4
x2 : 0000000000000001 x1 : ffff800082858810 x0 : 0000000000000050
Call trace:
__debug_object_init+0x330/0x364
debug_object_init_on_stack+0x30/0x3c
schedule_hrtimeout_range_clock+0xac/0x26c
schedule_hrtimeout+0x1c/0x30
wait_task_inactive+0x1d4/0x25c
kthread_bind_mask+0x28/0x98
init_rescuer+0x1e8/0x280
workqueue_init+0x1a0/0x3cc
kernel_init_freeable+0x118/0x200
kernel_init+0x28/0x1f0
ret_from_fork+0x10/0x20
---[ end trace 0000000000000000 ]---
ODEBUG: object 3eff800082ea7bb0 is NOT on stack ffff800082ea0000, but annotated.
------------[ cut here ]------------
Link: https://lkml.kernel.org/r/20241113042544.19095-1-qun-wei.lin@mediatek.com
Signed-off-by: Qun-Wei Lin <qun-wei.lin@mediatek.com>
Cc: Andrew Yang <andrew.yang@mediatek.com>
Cc: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>
Cc: Casper Li <casper.li@mediatek.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Chinwen Chang <chinwen.chang@mediatek.com>
Cc: Kent Overstreet <kent.overstreet@linux.dev>
Cc: Matthias Brugger <matthias.bgg@gmail.com>
Cc: Pasha Tatashin <pasha.tatashin@soleen.com>
Cc: Shakeel Butt <shakeel.butt@linux.dev>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
|
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On 2 x Intel Sapphire Rapids machines with 224 logical CPUs, a poorly
behaving BPF scheduler can live-lock the system by making multiple CPUs bang
on the same DSQ to the point where soft-lockup detection triggers before
SCX's own watchdog can take action. It also seems possible that the machine
can be live-locked enough to prevent scx_ops_helper, which is an RT task,
from running in a timely manner.
Implement scx_softlockup() which is called when three quarters of
soft-lockup threshold has passed. The function immediately enables the ops
breather and triggers an ops error to initiate ejection of the BPF
scheduler.
The previous and this patch combined enable the kernel to reliably recover
the system from live-lock conditions that can be triggered by a poorly
behaving BPF scheduler on Intel dual socket systems.
Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Douglas Anderson <dianders@chromium.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
|
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To prepare for handling posix timer signals on sigaction(SIG_IGN) properly,
add a list to task::signal.
This list will be used to queue posix timers so their signal can be
requeued when SIG_IGN is lifted later.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Frederic Weisbecker <frederic@kernel.org>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lore.kernel.org/all/20241105064213.920101900@linutronix.de
|
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Remove the leftovers of sigqueue preallocation as it's not longer used.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Frederic Weisbecker <frederic@kernel.org>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lore.kernel.org/all/20241105064213.786506636@linutronix.de
|
