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2023-10-10cpu/SMT: Make SMT control more robust against enumeration failuresThomas Gleixner
The SMT control mechanism got added as speculation attack vector mitigation. The implemented logic relies on the primary thread mask to be set up properly. This turns out to be an issue with XEN/PV guests because their CPU hotplug mechanics do not enumerate APICs and therefore the mask is never correctly populated. This went unnoticed so far because by chance XEN/PV ends up with smp_num_siblings == 2. So smt_hotplug_control stays at its default value CPU_SMT_ENABLED and the primary thread mask is never evaluated in the context of CPU hotplug. This stopped "working" with the upcoming overhaul of the topology evaluation which legitimately provides a fake topology for XEN/PV. That sets smp_num_siblings to 1, which causes the core CPU hot-plug core to refuse to bring up the APs. This happens because smt_hotplug_control is set to CPU_SMT_NOT_SUPPORTED which causes cpu_smt_allowed() to evaluate the unpopulated primary thread mask with the conclusion that all non-boot CPUs are not valid to be plugged. Make cpu_smt_allowed() more robust and take CPU_SMT_NOT_SUPPORTED and CPU_SMT_NOT_IMPLEMENTED into account. Rename it to cpu_bootable() while at it as that makes it more clear what the function is about. The primary mask issue on x86 XEN/PV needs to be addressed separately as there are users outside of the CPU hotplug code too. Fixes: 05736e4ac13c ("cpu/hotplug: Provide knobs to control SMT") Reported-by: Juergen Gross <jgross@suse.com> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Tested-by: Juergen Gross <jgross@suse.com> Tested-by: Sohil Mehta <sohil.mehta@intel.com> Tested-by: Michael Kelley <mikelley@microsoft.com> Tested-by: Peter Zijlstra (Intel) <peterz@infradead.org> Tested-by: Zhang Rui <rui.zhang@intel.com> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org> Link: https://lore.kernel.org/r/20230814085112.149440843@linutronix.de
2023-10-10sched/numa: Move up the access pid reset logicRaghavendra K T
Recent NUMA hinting faulting activity is reset approximately every VMA_PID_RESET_PERIOD milliseconds. However, if the current task has not accessed a VMA then the reset check is missed and the reset is potentially deferred forever. Check if the PID activity information should be reset before checking if the current task recently trapped a NUMA hinting fault. [ mgorman@techsingularity.net: Rewrite changelog ] Suggested-by: Mel Gorman <mgorman@techsingularity.net> Signed-off-by: Raghavendra K T <raghavendra.kt@amd.com> Signed-off-by: Mel Gorman <mgorman@techsingularity.net> Signed-off-by: Ingo Molnar <mingo@kernel.org> Link: https://lore.kernel.org/r/20231010083143.19593-5-mgorman@techsingularity.net
2023-10-10sched/numa: Trace decisions related to skipping VMAsMel Gorman
NUMA balancing skips or scans VMAs for a variety of reasons. In preparation for completing scans of VMAs regardless of PID access, trace the reasons why a VMA was skipped. In a later patch, the tracing will be used to track if a VMA was forcibly scanned. Signed-off-by: Mel Gorman <mgorman@techsingularity.net> Signed-off-by: Ingo Molnar <mingo@kernel.org> Link: https://lore.kernel.org/r/20231010083143.19593-4-mgorman@techsingularity.net
2023-10-10sched/numa: Rename vma_numab_state::access_pids[] => ::pids_active[], ↵Mel Gorman
::next_pid_reset => ::pids_active_reset The access_pids[] field name is somewhat ambiguous as no PIDs are accessed. Similarly, it's not clear that next_pid_reset is related to access_pids[]. Rename the fields to more accurately reflect their purpose. [ mingo: Rename in the comments too. ] Signed-off-by: Mel Gorman <mgorman@techsingularity.net> Signed-off-by: Ingo Molnar <mingo@kernel.org> Link: https://lore.kernel.org/r/20231010083143.19593-3-mgorman@techsingularity.net
2023-10-09bpf: Fix verifier log for async callback return valuesDavid Vernet
The verifier, as part of check_return_code(), verifies that async callbacks such as from e.g. timers, will return 0. It does this by correctly checking that R0->var_off is in tnum_const(0), which effectively checks that it's in a range of 0. If this condition fails, however, it prints an error message which says that the value should have been in (0x0; 0x1). This results in possibly confusing output such as the following in which an async callback returns 1: At async callback the register R0 has value (0x1; 0x0) should have been in (0x0; 0x1) The fix is easy -- we should just pass the tnum_const(0) as the correct range to verbose_invalid_scalar(), which will then print the following: At async callback the register R0 has value (0x1; 0x0) should have been in (0x0; 0x0) Fixes: bfc6bb74e4f1 ("bpf: Implement verifier support for validation of async callbacks.") Signed-off-by: David Vernet <void@manifault.com> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Link: https://lore.kernel.org/bpf/20231009161414.235829-1-void@manifault.com
2023-10-09cgroup: use legacy_name for cgroup v1 disable infoKamalesh Babulal
cgroup v1 or v2 or both controller names can be passed as arguments to the 'cgroup_no_v1' kernel parameter, though most of the controller's names are the same for both cgroup versions. This can be confusing when both versions are used interchangeably, i.e., passing cgroup_no_v1=io $ sudo dmesg |grep cgroup ... cgroup: Disabling io control group subsystem in v1 mounts cgroup: Disabled controller 'blkio' Make it consistent across the pr_info()'s, by using ss->legacy_name, as the subsystem name, while printing the cgroup v1 controller disabling information in cgroup_init(). Signed-off-by: Kamalesh Babulal <kamalesh.babulal@oracle.com> Signed-off-by: Tejun Heo <tj@kernel.org>
2023-10-09cgroup: Remove duplicates in cgroup v1 tasks fileMichal Koutný
One PID may appear multiple times in a preloaded pidlist. (Possibly due to PID recycling but we have reports of the same task_struct appearing with different PIDs, thus possibly involving transfer of PID via de_thread().) Because v1 seq_file iterator uses PIDs as position, it leads to a message: > seq_file: buggy .next function kernfs_seq_next did not update position index Conservative and quick fix consists of removing duplicates from `tasks` file (as opposed to removing pidlists altogether). It doesn't affect correctness (it's sufficient to show a PID once), performance impact would be hidden by unconditional sorting of the pidlist already in place (asymptotically). Link: https://lore.kernel.org/r/20230823174804.23632-1-mkoutny@suse.com/ Suggested-by: Firo Yang <firo.yang@suse.com> Signed-off-by: Michal Koutný <mkoutny@suse.com> Signed-off-by: Tejun Heo <tj@kernel.org> Cc: stable@vger.kernel.org
2023-10-09Merge tag 'v6.6-rc5' into locking/core, to pick up fixesIngo Molnar
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2023-10-10tracing/eprobe: drop unneeded breaksJulia Lawall
Drop break after return. Link: https://lore.kernel.org/all/20230928104334.41215-1-Julia.Lawall@inria.fr/ Signed-off-by: Julia Lawall <Julia.Lawall@inria.fr> Acked-by: Masami Hiramatsu (Google) <mhiramat@kernel.org> Signed-off-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
2023-10-09sched/topology: Move the declaration of 'schedutil_gov' to kernel/sched/sched.hIngo Molnar
Move it out of the .c file into the shared scheduler-internal header file, to gain type-checking. Signed-off-by: Ingo Molnar <mingo@kernel.org> Cc: Shrikanth Hegde <sshegde@linux.vnet.ibm.com> Cc: Valentin Schneider <vschneid@redhat.com> Link: https://lore.kernel.org/r/20231009060037.170765-3-sshegde@linux.vnet.ibm.com
2023-10-09sched/topology: Change behaviour of the 'sched_energy_aware' sysctl, based ↵Shrikanth Hegde
on the platform The 'sched_energy_aware' sysctl is available for the admin to disable/enable energy aware scheduling(EAS). EAS is enabled only if few conditions are met by the platform. They are, asymmetric CPU capacity, no SMT, schedutil CPUfreq governor, frequency invariant load tracking etc. A platform may boot without EAS capability, but could gain such capability at runtime. For example, changing/registering the cpufreq governor to schedutil. At present, though platform doesn't support EAS, this sysctl returns 1 and it ends up calling build_perf_domains on write to 1 and NOP when writing to 0. That is confusing and un-necessary. Desired behavior would be to have this sysctl to enable/disable the EAS on supported platform. On non-supported platform write to the sysctl would return not supported error and read of the sysctl would return empty. So sched_energy_aware returns empty - EAS is not possible at this moment This will include EAS capable platforms which have at least one EAS condition false during startup, e.g. not using the schedutil cpufreq governor sched_energy_aware returns 0 - EAS is supported but disabled by admin. sched_energy_aware returns 1 - EAS is supported and enabled. User can find out the reason why EAS is not possible by checking info messages. sched_is_eas_possible returns true if the platform can do EAS at this moment. Signed-off-by: Shrikanth Hegde <sshegde@linux.vnet.ibm.com> Signed-off-by: Ingo Molnar <mingo@kernel.org> Tested-by: Pierre Gondois <pierre.gondois@arm.com> Reviewed-by: Valentin Schneider <vschneid@redhat.com> Link: https://lore.kernel.org/r/20231009060037.170765-3-sshegde@linux.vnet.ibm.com
2023-10-09bpf: Add ability to pin bpf timer to calling CPUDavid Vernet
BPF supports creating high resolution timers using bpf_timer_* helper functions. Currently, only the BPF_F_TIMER_ABS flag is supported, which specifies that the timeout should be interpreted as absolute time. It would also be useful to be able to pin that timer to a core. For example, if you wanted to make a subset of cores run without timer interrupts, and only have the timer be invoked on a single core. This patch adds support for this with a new BPF_F_TIMER_CPU_PIN flag. When specified, the HRTIMER_MODE_PINNED flag is passed to hrtimer_start(). A subsequent patch will update selftests to validate. Signed-off-by: David Vernet <void@manifault.com> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Acked-by: Song Liu <song@kernel.org> Acked-by: Hou Tao <houtao1@huawei.com> Link: https://lore.kernel.org/bpf/20231004162339.200702-2-void@manifault.com
2023-10-09perf/core: Allow reading package events from perf_event_read_localTero Kristo
Per-package perf events are typically registered with a single CPU only, however they can be read across all the CPUs within the package. Currently perf_event_read maps the event CPU according to the topology information to avoid an unnecessary SMP call, however perf_event_read_local deals with hard values and rejects a read with a failure if the CPU is not the one exactly registered. Allow similar mapping within the perf_event_read_local if the perf event in question can support this. This allows users like BPF code to read the package perf events properly across different CPUs within a package. Signed-off-by: Tero Kristo <tero.kristo@linux.intel.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Link: https://lkml.kernel.org/r/20230913125956.3652667-1-tero.kristo@linux.intel.com
2023-10-09alarmtimer: Use maximum alarm time for suspendGuenter Roeck
Some userspace applications use timerfd_create() to request wakeups after a long period of time. For example, a backup application may request a wakeup once per week. This is perfectly fine as long as the system does not try to suspend. However, if the system tries to suspend and the system's RTC does not support the required alarm timeout, the suspend operation will fail with an error such as rtc_cmos 00:01: Alarms can be up to one day in the future PM: dpm_run_callback(): platform_pm_suspend+0x0/0x4a returns -22 alarmtimer alarmtimer.4.auto: platform_pm_suspend+0x0/0x4a returned -22 after 117 usecs PM: Device alarmtimer.4.auto failed to suspend: error -22 This results in a refusal to suspend the system, causing substantial battery drain on affected systems. To fix the problem, use the maximum alarm time offset as reported by RTC drivers to set the maximum alarm time. While this may result in early wakeups from suspend, it is still much better than not suspending at all. Standardize system behavior if the requested alarm timeout is larger than the alarm timeout supported by the rtc chip. Currently, in this situation, the RTC driver will do one of the following: - It may return an error. - It may limit the alarm timeout to the maximum supported by the rtc chip. - It may mask the timeout by the maximum alarm timeout supported by the RTC chip (i.e. a requested timeout of 1 day + 1 minute may result in a 1 minute timeout). With this in place, if the RTC driver reports the maximum alarm timeout supported by the RTC chip, the system will always limit the alarm timeout to the maximum supported by the RTC chip. Signed-off-by: Guenter Roeck <linux@roeck-us.net> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Acked-by: John Stultz <jstultz@google.com> Link: https://lore.kernel.org/r/20230915152238.1144706-3-linux@roeck-us.net
2023-10-09Merge back earlier system-wide PM changes for v6.7.Rafael J. Wysocki
2023-10-09sched/psi: Change update_triggers() to a 'void' functionYang Yang
Update_triggers() always returns now + group->rtpoll_min_period, and the return value is only used by psi_rtpoll_work(), so change update_triggers() to a void function, let group->rtpoll_next_update = now + group->rtpoll_min_period directly. This will avoid unnecessary function return value passing & simplifies the function. [ mingo: Updated changelog ] Suggested-by: Suren Baghdasaryan <surenb@google.com> Signed-off-by: Yang Yang <yang.yang29@zte.com.cn> Signed-off-by: Ingo Molnar <mingo@kernel.org> Link: https://lore.kernel.org/r/202310092024289721617@zte.com.cn
2023-10-09sched/topology: Remove the EM_MAX_COMPLEXITY limitPierre Gondois
The Energy Aware Scheduler (EAS) estimates the energy consumption of placing a task on different CPUs. The goal is to minimize this energy consumption. Estimating the energy of different task placements is increasingly complex with the size of the platform. To avoid having a slow wake-up path, EAS is only enabled if this complexity is low enough. The current complexity limit was set in: b68a4c0dba3b1 ("sched/topology: Disable EAS on inappropriate platforms") ... based on the first implementation of EAS, which was re-computing the power of the whole platform for each task placement scenario, see: 390031e4c309 ("sched/fair: Introduce an energy estimation helper function") ... but the complexity of EAS was reduced in: eb92692b2544d ("sched/fair: Speed-up energy-aware wake-ups") ... and find_energy_efficient_cpu() (feec) algorithm was updated in: 3e8c6c9aac42 ("sched/fair: Remove task_util from effective utilization in feec()") find_energy_efficient_cpu() (feec) is now doing: feec() \_ for_each_pd(pd) [0] // get max_spare_cap_cpu and compute_prev_delta \_ for_each_cpu(pd) [1] \_ eenv_pd_busy_time(pd) [2] \_ for_each_cpu(pd) // compute_energy(pd) without the task \_ eenv_pd_max_util(pd, -1) [3.0] \_ for_each_cpu(pd) \_ em_cpu_energy(pd, -1) \_ for_each_ps(pd) // compute_energy(pd) with the task on prev_cpu \_ eenv_pd_max_util(pd, prev_cpu) [3.1] \_ for_each_cpu(pd) \_ em_cpu_energy(pd, prev_cpu) \_ for_each_ps(pd) // compute_energy(pd) with the task on max_spare_cap_cpu \_ eenv_pd_max_util(pd, max_spare_cap_cpu) [3.2] \_ for_each_cpu(pd) \_ em_cpu_energy(pd, max_spare_cap_cpu) \_ for_each_ps(pd) [3.1] happens only once since prev_cpu is unique. With the same definitions for nr_pd, nr_cpus and nr_ps, the complexity is of: nr_pd * (2 * [nr_cpus in pd] + 2 * ([nr_cpus in pd] + [nr_ps in pd])) + ([nr_cpus in pd] + [nr_ps in pd]) [0] * ( [1] + [2] + [3.0] + [3.2] ) + [3.1] = nr_pd * (4 * [nr_cpus in pd] + 2 * [nr_ps in pd]) + [nr_cpus in prev pd] + nr_ps The complexity limit was set to 2048 in: b68a4c0dba3b1 ("sched/topology: Disable EAS on inappropriate platforms") ... to make "EAS usable up to 16 CPUs with per-CPU DVFS and less than 8 performance states each". For the same platform, the complexity would actually be of: 16 * (4 + 2 * 7) + 1 + 7 = 296 Since the EAS complexity was greatly reduced since the limit was introduced, bigger platforms can handle EAS. For instance, a platform with 112 CPUs with 7 performance states each would not reach it: 112 * (4 + 2 * 7) + 1 + 7 = 2024 To reflect this improvement in the underlying EAS code, remove the EAS complexity check. Note that a limit on the number of CPUs still holds against EM_MAX_NUM_CPUS to avoid overflows during the energy estimation. [ mingo: Updates to the changelog. ] Signed-off-by: Pierre Gondois <Pierre.Gondois@arm.com> Signed-off-by: Ingo Molnar <mingo@kernel.org> Reviewed-by: Lukasz Luba <lukasz.luba@arm.com> Reviewed-by: Dietmar Eggemann <dietmar.eggemann@arm.com> Link: https://lore.kernel.org/r/20231009060037.170765-2-sshegde@linux.vnet.ibm.com
2023-10-09sched/topology: Consolidate and clean up access to a CPU's max compute capacityVincent Guittot
Remove the rq::cpu_capacity_orig field and use arch_scale_cpu_capacity() instead. The scheduler uses 3 methods to get access to a CPU's max compute capacity: - arch_scale_cpu_capacity(cpu) which is the default way to get a CPU's capacity. - cpu_capacity_orig field which is periodically updated with arch_scale_cpu_capacity(). - capacity_orig_of(cpu) which encapsulates rq->cpu_capacity_orig. There is no real need to save the value returned by arch_scale_cpu_capacity() in struct rq. arch_scale_cpu_capacity() returns: - either a per_cpu variable. - or a const value for systems which have only one capacity. Remove rq::cpu_capacity_orig and use arch_scale_cpu_capacity() everywhere. No functional changes. Some performance tests on Arm64: - small SMP device (hikey): no noticeable changes - HMP device (RB5): hackbench shows minor improvement (1-2%) - large smp (thx2): hackbench and tbench shows minor improvement (1%) Signed-off-by: Vincent Guittot <vincent.guittot@linaro.org> Signed-off-by: Ingo Molnar <mingo@kernel.org> Reviewed-by: Dietmar Eggemann <dietmar.eggemann@arm.com> Link: https://lore.kernel.org/r/20231009103621.374412-2-vincent.guittot@linaro.org
2023-10-09sched/rt: Change the type of 'sysctl_sched_rt_period' from 'unsigned int' to ↵Yajun Deng
'int' Doing this matches the natural type of 'int' based calculus in sched_rt_handler(), and also enables the adding in of a correct upper bounds check on the sysctl interface. [ mingo: Rewrote the changelog. ] Signed-off-by: Yajun Deng <yajun.deng@linux.dev> Signed-off-by: Ingo Molnar <mingo@kernel.org> Link: https://lore.kernel.org/r/20231008021538.3063250-1-yajun.deng@linux.dev
2023-10-09sched/nohz: Remove unnecessarily complex error handling pattern from ↵Ingo Molnar
find_new_ilb() find_new_ilb() returns nr_cpu_ids on failure - which is the usual cpumask bitops return pattern, but is weird & unnecessary in this context: not only is it a global variable, it it is a +1 out of bounds CPU index and also has different signedness ... Its only user, kick_ilb(), then checks the return against nr_cpu_ids to decide to return. There's no other use. So instead of this, use a standard -1 return on failure to find an idle CPU, as the argument is signed already. Signed-off-by: Ingo Molnar <mingo@kernel.org> Reviewed-by: Joel Fernandes (Google) <joel@joelfernandes.org> Link: https://lore.kernel.org/r/20231006102518.2452758-4-mingo@kernel.org
2023-10-09sched/nohz: Use consistent variable names in find_new_ilb() and kick_ilb()Ingo Molnar
Use 'ilb_cpu' consistently in both functions. Signed-off-by: Ingo Molnar <mingo@kernel.org> Reviewed-by: Joel Fernandes (Google) <joel@joelfernandes.org> Link: https://lore.kernel.org/r/20231006102518.2452758-3-mingo@kernel.org
2023-10-09sched/nohz: Update idle load-balancing (ILB) commentsIngo Molnar
- Fix incorrect/misleading comments, - clarify some others, - fix typos & grammar, - and use more consistent style throughout. Signed-off-by: Ingo Molnar <mingo@kernel.org> Reviewed-by: Joel Fernandes (Google) <joel@joelfernandes.org> Link: https://lore.kernel.org/r/20231006102518.2452758-2-mingo@kernel.org
2023-10-09printk: flush consoles before checking progressJohn Ogness
Commit 9e70a5e109a4 ("printk: Add per-console suspended state") removed console lock usage during resume and replaced it with the clearly defined console_list_lock and srcu mechanisms. However, the console lock usage had an important side-effect of flushing the consoles. After its removal, consoles were no longer flushed before checking their progress. Add the console_lock/console_unlock dance to the beginning of __pr_flush() to actually flush the consoles before checking their progress. Also add comments to clarify this additional usage of the console lock. Note that console_unlock() does not guarantee flushing all messages since the commit dbdda842fe96f89 ("printk: Add console owner and waiter logic to load balance console writes"). Reported-by: Todd Brandt <todd.e.brandt@intel.com> Closes: https://bugzilla.kernel.org/show_bug.cgi?id=217955 Fixes: 9e70a5e109a4 ("printk: Add per-console suspended state") Co-developed-by: Petr Mladek <pmladek@suse.com> Signed-off-by: Petr Mladek <pmladek@suse.com> Signed-off-by: John Ogness <john.ogness@linutronix.de> Link: https://lore.kernel.org/r/20231006082151.6969-2-pmladek@suse.com
2023-10-09sched/eevdf: Fix pick_eevdf()Benjamin Segall
The old pick_eevdf() could fail to find the actual earliest eligible deadline when it descended to the right looking for min_deadline, but it turned out that that min_deadline wasn't actually eligible. In that case we need to go back and search through any left branches we skipped looking for the actual best _eligible_ min_deadline. This is more expensive, but still O(log n), and at worst should only involve descending two branches of the rbtree. I've run this through a userspace stress test (thank you tools/lib/rbtree.c), so hopefully this implementation doesn't miss any corner cases. Fixes: 147f3efaa241 ("sched/fair: Implement an EEVDF-like scheduling policy") Signed-off-by: Ben Segall <bsegall@google.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Link: https://lkml.kernel.org/r/xm261qego72d.fsf_-_@google.com
2023-10-09sched/eevdf: Fix min_deadline heap integrityPeter Zijlstra
Marek and Biju reported instances of: "EEVDF scheduling fail, picking leftmost" which Mike correlated with cgroup scheduling and the min_deadline heap getting corrupted; some trace output confirms: > And yeah, min_deadline is hosed somehow: > > validate_cfs_rq: --- / > __print_se: ffff88845cf48080 w: 1024 ve: -58857638 lag: 870381 vd: -55861854 vmd: -66302085 E (11372/tr) > __print_se: ffff88810d165800 w: 25 ve: -80323686 lag: 22336429 vd: -41496434 vmd: -66302085 E (-1//autogroup-31) > __print_se: ffff888108379000 w: 25 ve: 0 lag: -57987257 vd: 114632828 vmd: 114632828 N (-1//autogroup-33) > validate_cfs_rq: min_deadline: -55861854 avg_vruntime: -62278313462 / 1074 = -57987256 Turns out that reweight_entity(), which tries really hard to be fast, does not do the normal dequeue+update+enqueue pattern but *does* scale the deadline. However, it then fails to propagate the updated deadline value up the heap. Fixes: 147f3efaa241 ("sched/fair: Implement an EEVDF-like scheduling policy") Reported-by: Marek Szyprowski <m.szyprowski@samsung.com> Reported-by: Biju Das <biju.das.jz@bp.renesas.com> Reported-by: Mike Galbraith <efault@gmx.de> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Tested-by: Marek Szyprowski <m.szyprowski@samsung.com> Tested-by: Biju Das <biju.das.jz@bp.renesas.com> Tested-by: Mike Galbraith <efault@gmx.de> Link: https://lkml.kernel.org/r/20231006192445.GE743@noisy.programming.kicks-ass.net
2023-10-09kernel: watch_queue: copy user-array safelyPhilipp Stanner
Currently, there is no overflow-check with memdup_user(). Use the new function memdup_array_user() instead of memdup_user() for duplicating the user-space array safely. Suggested-by: David Airlie <airlied@redhat.com> Signed-off-by: Philipp Stanner <pstanner@redhat.com> Reviewed-by: Kees Cook <keescook@chromium.org> Reviewed-by: Zack Rusin <zackr@vmware.com> Signed-off-by: Dave Airlie <airlied@redhat.com> Link: https://patchwork.freedesktop.org/patch/msgid/20230920123612.16914-5-pstanner@redhat.com
2023-10-09kernel: kexec: copy user-array safelyPhilipp Stanner
Currently, there is no overflow-check with memdup_user(). Use the new function memdup_array_user() instead of memdup_user() for duplicating the user-space array safely. Suggested-by: David Airlie <airlied@redhat.com> Signed-off-by: Philipp Stanner <pstanner@redhat.com> Acked-by: Baoquan He <bhe@redhat.com> Reviewed-by: Kees Cook <keescook@chromium.org> Reviewed-by: Zack Rusin <zackr@vmware.com> Signed-off-by: Dave Airlie <airlied@redhat.com> Link: https://patchwork.freedesktop.org/patch/msgid/20230920123612.16914-4-pstanner@redhat.com
2023-10-08Merge tag 'sched-urgent-2023-10-08' of ↵Linus Torvalds
git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip Pull misc scheduler fixes from Ingo Molnar: - Two EEVDF fixes: one to fix sysctl_sched_base_slice propagation, and to fix an avg_vruntime() corner-case. - A cpufreq frequency scaling fix * tag 'sched-urgent-2023-10-08' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: cpufreq: schedutil: Update next_freq when cpufreq_limits change sched/eevdf: Fix avg_vruntime() sched/eevdf: Also update slice on placement
2023-10-07sched/debug: Print 'tgid' in sched_show_task()Yajun Deng
Multiple blocked tasks are printed when the system hangs. They may have the same parent pid, but belong to different task groups. Printing tgid lets users better know whether these tasks are from the same task group or not. Signed-off-by: Yajun Deng <yajun.deng@linux.dev> Signed-off-by: Ingo Molnar <mingo@kernel.org> Link: https://lore.kernel.org/r/20230720080516.1515297-1-yajun.deng@linux.dev
2023-10-07sched/core: Update stale comment in try_to_wake_up()Ingo Molnar
The following commit: 9b3c4ab3045e ("sched,rcu: Rework try_invoke_on_locked_down_task()") ... renamed try_invoke_on_locked_down_task() to task_call_func(), but forgot to update the comment in try_to_wake_up(). But it turns out that the smp_rmb() doesn't live in task_call_func() either, it was moved to __task_needs_rq_lock() in: 91dabf33ae5d ("sched: Fix race in task_call_func()") Fix that now. Also fix the s/smb/smp typo while at it. Reported-by: Zhang Qiao <zhangqiao22@huawei.com> Signed-off-by: Ingo Molnar <mingo@kernel.org> Link: https://lore.kernel.org/r/20230731085759.11443-1-zhangqiao22@huawei.com
2023-10-07Merge branch 'sched/urgent' into sched/core, to pick up fixes and refresh ↵Ingo Molnar
the branch Signed-off-by: Ingo Molnar <mingo@kernel.org>
2023-10-06bpf: Refuse unused attributes in bpf_prog_{attach,detach}Lorenz Bauer
The recently added tcx attachment extended the BPF UAPI for attaching and detaching by a couple of fields. Those fields are currently only supported for tcx, other types like cgroups and flow dissector silently ignore the new fields except for the new flags. This is problematic once we extend bpf_mprog to older attachment types, since it's hard to figure out whether the syscall really was successful if the kernel silently ignores non-zero values. Explicitly reject non-zero fields relevant to bpf_mprog for attachment types which don't use the latter yet. Fixes: e420bed02507 ("bpf: Add fd-based tcx multi-prog infra with link support") Signed-off-by: Lorenz Bauer <lmb@isovalent.com> Co-developed-by: Daniel Borkmann <daniel@iogearbox.net> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Link: https://lore.kernel.org/r/20231006220655.1653-3-daniel@iogearbox.net Signed-off-by: Martin KaFai Lau <martin.lau@kernel.org>
2023-10-06bpf: Handle bpf_mprog_query with NULL entryDaniel Borkmann
Improve consistency for bpf_mprog_query() API and let the latter also handle a NULL entry as can be the case for tcx. Instead of returning -ENOENT, we copy a count of 0 and revision of 1 to user space, so that this can be fed into a subsequent bpf_mprog_attach() call as expected_revision. A BPF self- test as part of this series has been added to assert this case. Suggested-by: Lorenz Bauer <lmb@isovalent.com> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Link: https://lore.kernel.org/r/20231006220655.1653-2-daniel@iogearbox.net Signed-off-by: Martin KaFai Lau <martin.lau@kernel.org>
2023-10-06bpf: Fix BPF_PROG_QUERY last field checkDaniel Borkmann
While working on the ebpf-go [0] library integration for bpf_mprog and tcx, Lorenz noticed that two subsequent BPF_PROG_QUERY requests currently fail. A typical workflow is to first gather the bpf_mprog count without passing program/ link arrays, followed by the second request which contains the actual array pointers. The initial call populates count and revision fields. The second call gets rejected due to a BPF_PROG_QUERY_LAST_FIELD bug which should point to query.revision instead of query.link_attach_flags since the former is really the last member. It was not noticed in libbpf as bpf_prog_query_opts() always calls bpf(2) with an on-stack bpf_attr that is memset() each time (and therefore query.revision was reset to zero). [0] https://ebpf-go.dev Fixes: e420bed02507 ("bpf: Add fd-based tcx multi-prog infra with link support") Reported-by: Lorenz Bauer <lmb@isovalent.com> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Link: https://lore.kernel.org/r/20231006220655.1653-1-daniel@iogearbox.net Signed-off-by: Martin KaFai Lau <martin.lau@kernel.org>
2023-10-06Merge tag 'pm-6.6-rc5' of ↵Linus Torvalds
git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm Pull power management fix from Rafael Wysocki: "Fix a recently introduced hibernation crash (Pavankumar Kondeti)" * tag 'pm-6.6-rc5' of git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm: PM: hibernate: Fix copying the zero bitmap to safe pages
2023-10-06bpf: Annotate struct bpf_stack_map with __counted_byKees Cook
Prepare for the coming implementation by GCC and Clang of the __counted_by attribute. Flexible array members annotated with __counted_by can have their accesses bounds-checked at run-time via CONFIG_UBSAN_BOUNDS (for array indexing) and CONFIG_FORTIFY_SOURCE (for strcpy/memcpy-family functions). As found with Coccinelle [1], add __counted_by for struct bpf_stack_map. Signed-off-by: Kees Cook <keescook@chromium.org> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Acked-by: Stanislav Fomichev <sdf@google.com> Link: https://github.com/kees/kernel-tools/blob/trunk/coccinelle/examples/counted_by.cocci [1] Link: https://lore.kernel.org/bpf/20231006201657.work.531-kees@kernel.org
2023-10-06mm: add a NO_INHERIT flag to the PR_SET_MDWE prctlFlorent Revest
This extends the current PR_SET_MDWE prctl arg with a bit to indicate that the process doesn't want MDWE protection to propagate to children. To implement this no-inherit mode, the tag in current->mm->flags must be absent from MMF_INIT_MASK. This means that the encoding for "MDWE but without inherit" is different in the prctl than in the mm flags. This leads to a bit of bit-mangling in the prctl implementation. Link: https://lkml.kernel.org/r/20230828150858.393570-6-revest@chromium.org Signed-off-by: Florent Revest <revest@chromium.org> Reviewed-by: Kees Cook <keescook@chromium.org> Reviewed-by: Catalin Marinas <catalin.marinas@arm.com> Cc: Alexey Izbyshev <izbyshev@ispras.ru> Cc: Anshuman Khandual <anshuman.khandual@arm.com> Cc: Ayush Jain <ayush.jain3@amd.com> Cc: David Hildenbrand <david@redhat.com> Cc: Greg Thelen <gthelen@google.com> Cc: Joey Gouly <joey.gouly@arm.com> Cc: KP Singh <kpsingh@kernel.org> Cc: Mark Brown <broonie@kernel.org> Cc: Michal Hocko <mhocko@suse.com> Cc: Peter Xu <peterx@redhat.com> Cc: Ryan Roberts <ryan.roberts@arm.com> Cc: Szabolcs Nagy <Szabolcs.Nagy@arm.com> Cc: Topi Miettinen <toiwoton@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2023-10-06cpufreq: Rebuild sched-domains when removing cpufreq driverPierre Gondois
The Energy Aware Scheduler (EAS) relies on the schedutil governor. When moving to/from the schedutil governor, sched domains must be rebuilt to allow re-evaluating the enablement conditions of EAS. This is done through sched_cpufreq_governor_change(). Having a cpufreq governor assumes a cpufreq driver is running. Inserting/removing a cpufreq driver should trigger a re-evaluation of EAS enablement conditions, avoiding to see EAS enabled when removing a running cpufreq driver. Rebuild the sched domains in schedutil's sugov_init()/sugov_exit(), allowing to check EAS's enablement condition whenever schedutil governor is initialized/exited from. Move relevant code up in schedutil.c to avoid a split and conditional function declaration. Rename sched_cpufreq_governor_change() to sugov_eas_rebuild_sd(). Signed-off-by: Pierre Gondois <pierre.gondois@arm.com> Acked-by: Viresh Kumar <viresh.kumar@linaro.org> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
2023-10-06cpufreq: schedutil: Merge initialization code of sg_cpu in single loopLiao Chang
The initialization code of the per-cpu sg_cpu struct is currently split into two for-loop blocks. This can be simplified by merging the two blocks into a single loop. This will make the code more maintainable. Signed-off-by: Liao Chang <liaochang1@huawei.com> Acked-by: Viresh Kumar <viresh.kumar@linaro.org> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
2023-10-05Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/netJakub Kicinski
Cross-merge networking fixes after downstream PR. No conflicts (or adjacent changes of note). Signed-off-by: Jakub Kicinski <kuba@kernel.org>
2023-10-05cpufreq: schedutil: Update next_freq when cpufreq_limits changeXuewen Yan
When cpufreq's policy is 'single', there is a scenario that will cause sg_policy's next_freq to be unable to update. When the CPU's util is always max, the cpufreq will be max, and then if we change the policy's scaling_max_freq to be a lower freq, indeed, the sg_policy's next_freq need change to be the lower freq, however, because the cpu_is_busy, the next_freq would keep the max_freq. For example: The cpu7 is a single CPU: unisoc:/sys/devices/system/cpu/cpufreq/policy7 # while true;do done& [1] 4737 unisoc:/sys/devices/system/cpu/cpufreq/policy7 # taskset -p 80 4737 pid 4737's current affinity mask: ff pid 4737's new affinity mask: 80 unisoc:/sys/devices/system/cpu/cpufreq/policy7 # cat scaling_max_freq 2301000 unisoc:/sys/devices/system/cpu/cpufreq/policy7 # cat scaling_cur_freq 2301000 unisoc:/sys/devices/system/cpu/cpufreq/policy7 # echo 2171000 > scaling_max_freq unisoc:/sys/devices/system/cpu/cpufreq/policy7 # cat scaling_max_freq 2171000 At this time, the sg_policy's next_freq would stay at 2301000, which is wrong. To fix this, add a check for the ->need_freq_update flag. [ mingo: Clarified the changelog. ] Co-developed-by: Guohua Yan <guohua.yan@unisoc.com> Signed-off-by: Xuewen Yan <xuewen.yan@unisoc.com> Signed-off-by: Guohua Yan <guohua.yan@unisoc.com> Signed-off-by: Ingo Molnar <mingo@kernel.org> Acked-by: "Rafael J. Wysocki" <rafael@kernel.org> Link: https://lore.kernel.org/r/20230719130527.8074-1-xuewen.yan@unisoc.com
2023-10-05Merge tag 'net-6.6-rc5' of ↵Linus Torvalds
git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net Pull networking fixes from Jakub Kicinski: "Including fixes from Bluetooth, netfilter, BPF and WiFi. I didn't collect precise data but feels like we've got a lot of 6.5 fixes here. WiFi fixes are most user-awaited. Current release - regressions: - Bluetooth: fix hci_link_tx_to RCU lock usage Current release - new code bugs: - bpf: mprog: fix maximum program check on mprog attachment - eth: ti: icssg-prueth: fix signedness bug in prueth_init_tx_chns() Previous releases - regressions: - ipv6: tcp: add a missing nf_reset_ct() in 3WHS handling - vringh: don't use vringh_kiov_advance() in vringh_iov_xfer(), it doesn't handle zero length like we expected - wifi: - cfg80211: fix cqm_config access race, fix crashes with brcmfmac - iwlwifi: mvm: handle PS changes in vif_cfg_changed - mac80211: fix mesh id corruption on 32 bit systems - mt76: mt76x02: fix MT76x0 external LNA gain handling - Bluetooth: fix handling of HCI_QUIRK_STRICT_DUPLICATE_FILTER - l2tp: fix handling of transhdrlen in __ip{,6}_append_data() - dsa: mv88e6xxx: avoid EEPROM timeout when EEPROM is absent - eth: stmmac: fix the incorrect parameter after refactoring Previous releases - always broken: - net: replace calls to sock->ops->connect() with kernel_connect(), prevent address rewrite in kernel_bind(); otherwise BPF hooks may modify arguments, unexpectedly to the caller - tcp: fix delayed ACKs when reads and writes align with MSS - bpf: - verifier: unconditionally reset backtrack_state masks on global func exit - s390: let arch_prepare_bpf_trampoline return program size, fix struct_ops offsets - sockmap: fix accounting of available bytes in presence of PEEKs - sockmap: reject sk_msg egress redirects to non-TCP sockets - ipv4/fib: send netlink notify when delete source address routes - ethtool: plca: fix width of reads when parsing netlink commands - netfilter: nft_payload: rebuild vlan header on h_proto access - Bluetooth: hci_codec: fix leaking memory of local_codecs - eth: intel: ice: always add legacy 32byte RXDID in supported_rxdids - eth: stmmac: - dwmac-stm32: fix resume on STM32 MCU - remove buggy and unneeded stmmac_poll_controller, depend on NAPI - ibmveth: always recompute TCP pseudo-header checksum, fix use of the driver with Open vSwitch - wifi: - rtw88: rtw8723d: fix MAC address offset in EEPROM - mt76: fix lock dependency problem for wed_lock - mwifiex: sanity check data reported by the device - iwlwifi: ensure ack flag is properly cleared - iwlwifi: mvm: fix a memory corruption due to bad pointer arithm - iwlwifi: mvm: fix incorrect usage of scan API Misc: - wifi: mac80211: work around Cisco AP 9115 VHT MPDU length" * tag 'net-6.6-rc5' of git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net: (99 commits) MAINTAINERS: update Matthieu's email address mptcp: userspace pm allow creating id 0 subflow mptcp: fix delegated action races net: stmmac: remove unneeded stmmac_poll_controller net: lan743x: also select PHYLIB net: ethernet: mediatek: disable irq before schedule napi net: mana: Fix oversized sge0 for GSO packets net: mana: Fix the tso_bytes calculation net: mana: Fix TX CQE error handling netlink: annotate data-races around sk->sk_err sctp: update hb timer immediately after users change hb_interval sctp: update transport state when processing a dupcook packet tcp: fix delayed ACKs for MSS boundary condition tcp: fix quick-ack counting to count actual ACKs of new data page_pool: fix documentation typos tipc: fix a potential deadlock on &tx->lock net: stmmac: dwmac-stm32: fix resume on STM32 MCU ipv4: Set offload_failed flag in fibmatch results netfilter: nf_tables: nft_set_rbtree: fix spurious insertion failure netfilter: nf_tables: Deduplicate nft_register_obj audit logs ...
2023-10-05tracing: Make system_callback() function staticSteven Rostedt (Google)
The system_callback() function in trace_events.c is only used within that file. The "static" annotation was missed. Fixes: 5790b1fb3d672 ("eventfs: Remove eventfs_file and just use eventfs_inode") Reported-by: kernel test robot <lkp@intel.com> Closes: https://lore.kernel.org/oe-kbuild-all/202310051743.y9EobbUr-lkp@intel.com/ Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
2023-10-05eventfs: Use eventfs_remove_events_dir()Steven Rostedt (Google)
The update to removing the eventfs_file changed the way the events top level directory was handled. Instead of returning a dentry, it now returns the eventfs_inode. In this changed, the removing of the events top level directory is not much different than removing any of the other directories. Because of this, the removal just called eventfs_remove_dir() instead of eventfs_remove_events_dir(). Although eventfs_remove_dir() does the clean up, it misses out on the dget() of the ei->dentry done in eventfs_create_events_dir(). It makes more sense to match eventfs_create_events_dir() with a specific function eventfs_remove_events_dir() and this specific function can then perform the dput() to the dentry that had the dget() when it was created. Fixes: 5790b1fb3d67 ("eventfs: Remove eventfs_file and just use eventfs_inode") Reported-by: kernel test robot <lkp@intel.com> Closes: https://lore.kernel.org/oe-kbuild-all/202310051743.y9EobbUr-lkp@intel.com/ Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
2023-10-05resource: Unify next_resource() and next_resource_skip_children()Andy Shevchenko
We have the next_resource() is used once and no user for the next_resource_skip_children() outside of the for_each_resource(). Unify them by adding skip_children parameter to the next_resource(). Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com> Link: https://lore.kernel.org/r/20230912165312.402422-2-andriy.shevchenko@linux.intel.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2023-10-05resource: Reuse for_each_resource() macroAndy Shevchenko
We have a few places where for_each_resource() is open coded. Replace that by the macro. This makes code easier to read and understand. With this, compile r_next() only for CONFIG_PROC_FS=y. Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com> Link: https://lore.kernel.org/r/20230912165312.402422-1-andriy.shevchenko@linux.intel.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2023-10-05perf/core: Rename perf_proc_update_handler() -> ↵Xiu Jianfeng
perf_event_max_sample_rate_handler(), for readability Follow the naming pattern of the other sysctl handlers in perf. Signed-off-by: Xiu Jianfeng <xiujianfeng@huawei.com> Signed-off-by: Ingo Molnar <mingo@kernel.org> Link: https://lore.kernel.org/r/20230721090607.172002-1-xiujianfeng@huawei.com
2023-10-04eventfs: Remove eventfs_file and just use eventfs_inodeSteven Rostedt (Google)
Instead of having a descriptor for every file represented in the eventfs directory, only have the directory itself represented. Change the API to send in a list of entries that represent all the files in the directory (but not other directories). The entry list contains a name and a callback function that will be used to create the files when they are accessed. struct eventfs_inode *eventfs_create_events_dir(const char *name, struct dentry *parent, const struct eventfs_entry *entries, int size, void *data); is used for the top level eventfs directory, and returns an eventfs_inode that will be used by: struct eventfs_inode *eventfs_create_dir(const char *name, struct eventfs_inode *parent, const struct eventfs_entry *entries, int size, void *data); where both of the above take an array of struct eventfs_entry entries for every file that is in the directory. The entries are defined by: typedef int (*eventfs_callback)(const char *name, umode_t *mode, void **data, const struct file_operations **fops); struct eventfs_entry { const char *name; eventfs_callback callback; }; Where the name is the name of the file and the callback gets called when the file is being created. The callback passes in the name (in case the same callback is used for multiple files), a pointer to the mode, data and fops. The data will be pointing to the data that was passed in eventfs_create_dir() or eventfs_create_events_dir() but may be overridden to point to something else, as it will be used to point to the inode->i_private that is created. The information passed back from the callback is used to create the dentry/inode. If the callback fills the data and the file should be created, it must return a positive number. On zero or negative, the file is ignored. This logic may also be used as a prototype to convert entire pseudo file systems into just-in-time allocation. The "show_events_dentry" file has been updated to show the directories, and any files they have. With just the eventfs_file allocations: Before after deltas for meminfo (in kB): MemFree: -14360 MemAvailable: -14260 Buffers: 40 Cached: 24 Active: 44 Inactive: 48 Inactive(anon): 28 Active(file): 44 Inactive(file): 20 Dirty: -4 AnonPages: 28 Mapped: 4 KReclaimable: 132 Slab: 1604 SReclaimable: 132 SUnreclaim: 1472 Committed_AS: 12 Before after deltas for slabinfo: <slab>: <objects> [ * <size> = <total>] ext4_inode_cache 27 [* 1184 = 31968 ] extent_status 102 [* 40 = 4080 ] tracefs_inode_cache 144 [* 656 = 94464 ] buffer_head 39 [* 104 = 4056 ] shmem_inode_cache 49 [* 800 = 39200 ] filp -53 [* 256 = -13568 ] dentry 251 [* 192 = 48192 ] lsm_file_cache 277 [* 32 = 8864 ] vm_area_struct -14 [* 184 = -2576 ] trace_event_file 1748 [* 88 = 153824 ] kmalloc-1k 35 [* 1024 = 35840 ] kmalloc-256 49 [* 256 = 12544 ] kmalloc-192 -28 [* 192 = -5376 ] kmalloc-128 -30 [* 128 = -3840 ] kmalloc-96 10581 [* 96 = 1015776 ] kmalloc-64 3056 [* 64 = 195584 ] kmalloc-32 1291 [* 32 = 41312 ] kmalloc-16 2310 [* 16 = 36960 ] kmalloc-8 9216 [* 8 = 73728 ] Free memory dropped by 14,360 kB Available memory dropped by 14,260 kB Total slab additions in size: 1,771,032 bytes With this change: Before after deltas for meminfo (in kB): MemFree: -12084 MemAvailable: -11976 Buffers: 32 Cached: 32 Active: 72 Inactive: 168 Inactive(anon): 176 Active(file): 72 Inactive(file): -8 Dirty: 24 AnonPages: 196 Mapped: 8 KReclaimable: 148 Slab: 836 SReclaimable: 148 SUnreclaim: 688 Committed_AS: 324 Before after deltas for slabinfo: <slab>: <objects> [ * <size> = <total>] tracefs_inode_cache 144 [* 656 = 94464 ] shmem_inode_cache -23 [* 800 = -18400 ] filp -92 [* 256 = -23552 ] dentry 179 [* 192 = 34368 ] lsm_file_cache -3 [* 32 = -96 ] vm_area_struct -13 [* 184 = -2392 ] trace_event_file 1748 [* 88 = 153824 ] kmalloc-1k -49 [* 1024 = -50176 ] kmalloc-256 -27 [* 256 = -6912 ] kmalloc-128 1864 [* 128 = 238592 ] kmalloc-64 4685 [* 64 = 299840 ] kmalloc-32 -72 [* 32 = -2304 ] kmalloc-16 256 [* 16 = 4096 ] total = 721352 Free memory dropped by 12,084 kB Available memory dropped by 11,976 kB Total slab additions in size: 721,352 bytes That's over 2 MB in savings per instance for free and available memory, and over 1 MB in savings per instance of slab memory. Link: https://lore.kernel.org/linux-trace-kernel/20231003184059.4924468e@gandalf.local.home Link: https://lore.kernel.org/linux-trace-kernel/20231004165007.43d79161@gandalf.local.home Cc: Masami Hiramatsu <mhiramat@kernel.org> Cc: Mark Rutland <mark.rutland@arm.com> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Ajay Kaher <akaher@vmware.com> Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
2023-10-04rcu: Comment why callbacks migration can't wait for CPUHP_RCUTREE_PREPFrederic Weisbecker
The callbacks migration is performed through an explicit call from the hotplug control CPU right after the death of the target CPU and before proceeding with the CPUHP_ teardown functions. This is unusual but necessary and yet uncommented. Summarize the reason as explained in the changelog of: a58163d8ca2c (rcu: Migrate callbacks earlier in the CPU-offline timeline) Reviewed-by: Paul E. McKenney <paulmck@kernel.org> Signed-off-by: Frederic Weisbecker <frederic@kernel.org>
2023-10-04rcu: Standardize explicit CPU-hotplug callsFrederic Weisbecker
rcu_report_dead() and rcutree_migrate_callbacks() have their headers in rcupdate.h while those are pure rcutree calls, like the other CPU-hotplug functions. Also rcu_cpu_starting() and rcu_report_dead() have different naming conventions while they mirror each other's effects. Fix the headers and propose a naming that relates both functions and aligns with the prefix of other rcutree CPU-hotplug functions. Reviewed-by: Paul E. McKenney <paulmck@kernel.org> Signed-off-by: Frederic Weisbecker <frederic@kernel.org>