Wander Lairson Costa d243b34459 kernel/fork: beware of __put_task_struct() calling context ... Under PREEMPT_RT, __put_task_struct() indirectly acquires sleeping locks. Therefore, it can't be called from an non-preemptible context. One practical example is splat inside inactive_task_timer(), which is called in a interrupt context: CPU: 1 PID: 2848 Comm: life Kdump: loaded Tainted: G W --------- Hardware name: HP ProLiant DL388p Gen8, BIOS P70 07/15/2012 Call Trace: dump_stack_lvl+0x57/0x7d mark_lock_irq.cold+0x33/0xba mark_lock+0x1e7/0x400 mark_usage+0x11d/0x140 __lock_acquire+0x30d/0x930 lock_acquire.part.0+0x9c/0x210 rt_spin_lock+0x27/0xe0 refill_obj_stock+0x3d/0x3a0 kmem_cache_free+0x357/0x560 inactive_task_timer+0x1ad/0x340 __run_hrtimer+0x8a/0x1a0 __hrtimer_run_queues+0x91/0x130 hrtimer_interrupt+0x10f/0x220 __sysvec_apic_timer_interrupt+0x7b/0xd0 sysvec_apic_timer_interrupt+0x4f/0xd0 asm_sysvec_apic_timer_interrupt+0x12/0x20 RIP: 0033:0x7fff196bf6f5 Instead of calling __put_task_struct() directly, we defer it using call_rcu(). A more natural approach would use a workqueue, but since in PREEMPT_RT, we can't allocate dynamic memory from atomic context, the code would become more complex because we would need to put the work_struct instance in the task_struct and initialize it when we allocate a new task_struct. The issue is reproducible with stress-ng: while true; do stress-ng --sched deadline --sched-period 1000000000 \ --sched-runtime 800000000 --sched-deadline \ 1000000000 --mmapfork 23 -t 20 done Reported-by: Hu Chunyu <chuhu@redhat.com> Suggested-by: Oleg Nesterov <oleg@redhat.com> Suggested-by: Valentin Schneider <vschneid@redhat.com> Suggested-by: Peter Zijlstra <peterz@infradead.org> Signed-off-by: Wander Lairson Costa <wander@redhat.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Link: https://lore.kernel.org/r/20230614122323.37957-2-wander@redhat.com		2023-07-13 15:21:48 +02:00
..
bpf	bpf, btf: Warn but return no error for NULL btf from __register_btf_kfunc_id_set()	2023-07-03 18:48:09 +02:00
cgroup	- Yosry Ahmed brought back some cgroup v1 stats in OOM logs.	2023-06-28 10:28:11 -07:00
configs	mm/slab: rename CONFIG_SLAB to CONFIG_SLAB_DEPRECATED	2023-05-26 19:01:47 +02:00
debug	kdb: move kdb_send_sig() declaration to a better header file	2023-07-03 09:27:12 +01:00
dma	dma-mapping fixes for Linux 6.5	2023-07-09 10:24:22 -07:00
entry	ptrace: Provide set/get interface for syscall user dispatch	2023-04-16 14:23:07 +02:00
events	cxl for v6.5	2023-07-01 08:58:41 -07:00
futex	- Prevent the leaking of a debug timer in futex_waitv()	2023-01-01 11:15:05 -08:00
gcov	gcov: add support for checksum field	2022-12-21 14:31:52 -08:00
irq	irqdomain: Use return value of strreplace()	2023-06-30 11:13:44 +02:00
kcsan	kcsan: Don't expect 64 bits atomic builtins from 32 bits architectures	2023-06-09 23:29:50 +10:00
livepatch	livepatch: Make 'klp_stack_entries' static	2023-06-05 13:56:52 +02:00
locking	- Arnd Bergmann has fixed a bunch of -Wmissing-prototypes in	2023-06-28 10:59:38 -07:00
module	module: fix init_module_from_file() error handling	2023-07-04 10:17:11 -07:00
power	- Yosry Ahmed brought back some cgroup v1 stats in OOM logs.	2023-06-28 10:28:11 -07:00
printk	seqlock/latch: Provide raw_read_seqcount_latch_retry()	2023-06-05 21:11:03 +02:00
rcu	Merge branches 'doc.2023.05.10a', 'fixes.2023.05.11a', 'kvfree.2023.05.10a', 'nocb.2023.05.11a', 'rcu-tasks.2023.05.10a', 'torture.2023.05.15a' and 'rcu-urgent.2023.06.06a' into HEAD	2023-06-07 13:44:06 -07:00
sched	cgroup: Changes for v6.5	2023-06-27 16:54:21 -07:00
time	hardening updates for v6.5-rc1	2023-06-27 21:24:18 -07:00
trace	Tracing fixes for 6.5:	2023-07-06 19:07:15 -07:00
.gitignore
acct.c	acct: fix potential integer overflow in encode_comp_t()	2022-11-30 16:13:18 -08:00
async.c
audit_fsnotify.c	audit: fix potential double free on error path from fsnotify_add_inode_mark	2022-08-22 18:50:06 -04:00
audit_tree.c
audit_watch.c	audit_init_parent(): constify path	2022-09-01 17:39:30 -04:00
audit.c	audit: use time_after to compare time	2022-08-29 19:47:03 -04:00
audit.h	audit: avoid missing-prototype warnings	2023-05-17 11:34:55 -04:00
auditfilter.c
auditsc.c	capability: just use a 'u64' instead of a 'u32[2]' array	2023-03-01 10:01:22 -08:00
backtracetest.c
bounds.c	mm: multi-gen LRU: minimal implementation	2022-09-26 19:46:09 -07:00
capability.c	capability: fix kernel-doc warnings in capability.c	2023-05-22 14:30:52 -04:00
cfi.c	cfi: Switch to -fsanitize=kcfi	2022-09-26 10:13:13 -07:00
compat.c	sched_getaffinity: don't assume 'cpumask_size()' is fully initialized	2023-03-14 19:32:38 -07:00
configs.c
context_tracking.c	locking/atomic: treewide: use raw_atomic*_<op>()	2023-06-05 09:57:20 +02:00
cpu_pm.c	cpuidle, cpu_pm: Remove RCU fiddling from cpu_pm_{enter,exit}()	2023-01-13 11:48:15 +01:00
cpu.c	cpu/hotplug: Fix off by one in cpuhp_bringup_mask()	2023-05-23 18:06:40 +02:00
crash_core.c	mm, treewide: redefine MAX_ORDER sanely	2023-04-05 19:42:46 -07:00
crash_dump.c
cred.c	cred: Do not default to init_cred in prepare_kernel_cred()	2022-11-01 10:04:52 -07:00
delayacct.c	delayacct: track delays from IRQ/SOFTIRQ	2023-04-18 16:39:34 -07:00
dma.c
exec_domain.c
exit.c	fork, vhost: Use CLONE_THREAD to fix freezer/ps regression	2023-06-01 17:15:33 -04:00
extable.c	context_tracking: Take NMI eqs entrypoints over RCU	2022-07-05 13:32:59 -07:00
fail_function.c	kernel/fail_function: fix memory leak with using debugfs_lookup()	2023-02-08 13:36:22 +01:00
fork.c	kernel/fork: beware of __put_task_struct() calling context	2023-07-13 15:21:48 +02:00
freezer.c	freezer,sched: Rewrite core freezer logic	2022-09-07 21:53:50 +02:00
gen_kheaders.sh	Revert "kheaders: substituting --sort in archive creation"	2023-05-28 16:20:21 +09:00
groups.c	security: Add LSM hook to setgroups() syscall	2022-07-15 18:21:49 +00:00
hung_task.c	kernel/hung_task.c: set some hung_task.c variables storage-class-specifier to static	2023-04-08 13:45:37 -07:00
iomem.c
irq_work.c	trace: Add trace_ipi_send_cpu()	2023-03-24 11:01:29 +01:00
jump_label.c	jump_label: Prevent key->enabled int overflow	2022-12-01 15:53:05 -08:00
kallsyms_internal.h	kallsyms: Reduce the memory occupied by kallsyms_seqs_of_names[]	2022-11-12 18:47:36 -08:00
kallsyms_selftest.c	kallsyms: Delete an unused parameter related to {module_}kallsyms_on_each_symbol()	2023-03-19 13:27:19 -07:00
kallsyms_selftest.h	kallsyms: Add self-test facility	2022-11-15 00:42:02 -08:00
kallsyms.c	v6.5-rc1-modules-next	2023-06-28 15:51:08 -07:00
kcmp.c
Kconfig.freezer
Kconfig.hz
Kconfig.locks
Kconfig.preempt
kcov.c	kcov: add prototypes for helper functions	2023-06-09 17:44:17 -07:00
kexec_core.c	kexec: enable kexec_crash_size to support two crash kernel regions	2023-06-09 17:44:24 -07:00
kexec_elf.c
kexec_file.c	- Arnd Bergmann has fixed a bunch of -Wmissing-prototypes in	2023-06-28 10:59:38 -07:00
kexec_internal.h	panic, kexec: make __crash_kexec() NMI safe	2022-09-11 21:55:06 -07:00
kexec.c	kexec: introduce sysctl parameters kexec_load_limit_*	2023-02-02 22:50:05 -08:00
kheaders.c	kheaders: Use array declaration instead of char	2023-03-24 20:10:59 -07:00
kprobes.c	fprobe: Pass return address to the handlers	2023-06-06 21:39:55 +09:00
ksyms_common.c	kallsyms: make kallsyms_show_value() as generic function	2023-06-08 12:27:20 -07:00
ksysfs.c	kernel/ksysfs.c: use sysfs_emit for sysfs show handlers	2023-03-24 17:09:14 +01:00
kthread.c	- Arnd Bergmann has fixed a bunch of -Wmissing-prototypes in	2023-06-28 10:59:38 -07:00
latencytop.c	latencytop: use the last element of latency_record of system	2022-09-11 21:55:12 -07:00
Makefile	v6.5-rc1-modules-next	2023-06-28 15:51:08 -07:00
module_signature.c
notifier.c	notifiers: add tracepoints to the notifiers infrastructure	2023-04-08 13:45:38 -07:00
nsproxy.c	convert setns(2) to fdget()/fdput()	2023-04-20 22:55:35 -04:00
padata.c	padata: use alignment when calculating the number of worker threads	2023-03-14 17:06:44 +08:00
panic.c	panic: hide unused global functions	2023-06-09 17:44:15 -07:00
params.c	kallsyms: Replace all non-returning strlcpy with strscpy	2023-06-14 12:27:38 -07:00
pid_namespace.c	pid: use struct_size_t() helper	2023-07-01 08:26:23 -07:00
pid_sysctl.h	kernel: pid_namespace: remove unused set_memfd_noexec_scope()	2023-06-19 16:19:28 -07:00
pid.c	pid: use struct_size_t() helper	2023-07-01 08:26:23 -07:00
profile.c	kernel/profile.c: simplify duplicated code in profile_setup()	2022-09-11 21:55:12 -07:00
ptrace.c	ptrace: Provide set/get interface for syscall user dispatch	2023-04-16 14:23:07 +02:00
range.c
reboot.c	kernel/reboot: Add SYS_OFF_MODE_RESTART_PREPARE mode	2022-10-04 15:59:36 +02:00
regset.c
relay.c	relayfs: fix out-of-bounds access in relay_file_read	2023-05-02 17:23:27 -07:00
resource_kunit.c
resource.c	dax/kmem: Fix leak of memory-hotplug resources	2023-02-17 14:58:01 -08:00
rseq.c	rseq: Extend struct rseq with per-memory-map concurrency ID	2022-12-27 12:52:12 +01:00
scftorture.c
scs.c	scs: add support for dynamic shadow call stacks	2022-11-09 18:06:35 +00:00
seccomp.c	seccomp: simplify sysctls with register_sysctl_init()	2023-04-13 11:49:20 -07:00
signal.c	v6.5-rc1-sysctl-next	2023-06-28 16:05:21 -07:00
smp.c	trace,smp: Add tracepoints for scheduling remotelly called functions	2023-06-16 22:08:09 +02:00
smpboot.c	cpu/hotplug: Remove unused state functions	2023-05-15 13:45:00 +02:00
smpboot.h
softirq.c	Revert "softirq: Let ksoftirqd do its job"	2023-05-09 21:50:27 +02:00
stackleak.c	stackleak: allow to specify arch specific stackleak poison function	2023-04-20 11:36:35 +02:00
stacktrace.c
static_call_inline.c	static_call: Add call depth tracking support	2022-10-17 16:41:16 +02:00
static_call.c
stop_machine.c	Scheduler changes in this cycle were:	2022-05-24 11:11:13 -07:00
sys_ni.c	asm-generic updates for 6.5	2023-07-06 10:06:04 -07:00
sys.c	riscv: Add prctl controls for userspace vector management	2023-06-08 07:16:53 -07:00
sysctl-test.c	kernel/sysctl-test: use SYSCTL_{ZERO/ONE_HUNDRED} instead of i_{zero/one_hundred}	2022-09-08 16:56:45 -07:00
sysctl.c	v6.5-rc1-sysctl-next	2023-06-28 16:05:21 -07:00
task_work.c	task_work: use try_cmpxchg in task_work_add, task_work_cancel_match and task_work_run	2022-09-11 21:55:10 -07:00
taskstats.c	genetlink: start to validate reserved header bytes	2022-08-29 12:47:15 +01:00
torture.c	torture: Fix hang during kthread shutdown phase	2023-01-05 12:10:35 -08:00
tracepoint.c	tracepoint: Allow livepatch module add trace event	2023-02-18 14:34:36 -05:00
tsacct.c
ucount.c	ucounts: Split rlimit and ucount values and max values	2022-05-18 18:24:57 -05:00
uid16.c
uid16.h
umh.c	sysctl: fix unused proc_cap_handler() function warning	2023-06-29 15:19:43 -07:00
up.c
user_namespace.c	userns: fix a struct's kernel-doc notation	2023-02-02 22:50:04 -08:00
user-return-notifier.c
user.c	kernel/user: Allow user_struct::locked_vm to be usable for iommufd	2022-11-30 20:16:49 -04:00
usermode_driver.c	blob_to_mnt(): kern_unmount() is needed to undo kern_mount()	2022-05-19 23:25:47 -04:00
utsname_sysctl.c	utsname: simplify one-level sysctl registration for uts_kern_table	2023-04-13 11:49:35 -07:00
utsname.c
vhost_task.c	vhost: Fix worker hangs due to missed wake up calls	2023-06-08 15:43:09 -04:00
watch_queue.c	watch_queue: prevent dangling pipe pointer	2023-06-06 10:47:04 +02:00
watchdog_buddy.c	watchdog/hardlockup: move SMP barriers from common code to buddy code	2023-06-19 16:25:28 -07:00
watchdog_perf.c	watchdog/perf: add a weak function for an arch to detect if perf can use NMIs	2023-06-09 17:44:21 -07:00
watchdog.c	watchdog/sparc64: define HARDLOCKUP_DETECTOR_SPARC64	2023-06-19 16:25:29 -07:00
workqueue_internal.h	workqueue: Automatically mark CPU-hogging work items CPU_INTENSIVE	2023-05-17 17:02:08 -10:00
workqueue.c	workqueue: Changes for v6.5	2023-06-27 16:32:52 -07:00