The @load_ve_lock spinlock guards manipulations of @ve_root_list, same time the calc_load_ve() is executed from irq context which triggers "invalid context wait" bug
| [ 5.195868] ============================= | [ 5.195877] [ BUG: Invalid wait context ] | [ 5.195887] 5.14.0.ovz9.10.1 #37 Tainted: G C X --------- --- | [ 5.195902] ----------------------------- | [ 5.195911] swapper/0/0 is trying to lock: | [ 5.196327] ffffffff872d8438 (load_ve_lock){....}-{3:3}, at: calc_load_ve+0x15/0x1c0 | [ 5.196742] other info that might help us debug this: | [ 5.196807] context-{2:2} | [ 5.196807] no locks held by swapper/0/0. | [ 5.196807] stack backtrace: | [ 5.196807] CPU: 0 PID: 0 Comm: swapper/0 ve: / Tainted: G C X --------- --- 5.14.0.ovz9.10.1 #37 10.1 | [ 5.196807] Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.14.0-4.fc34 04/01/2014 | [ 5.196807] Call Trace: | [ 5.196807] <IRQ> | [ 5.196807] dump_stack_lvl+0x57/0x7d | [ 5.196807] __lock_acquire.cold+0x28b/0x2cd | [ 5.196807] ? __lock_acquire+0x3b1/0x1f20 | [ 5.196807] lock_acquire+0xca/0x300 | [ 5.196807] ? calc_load_ve+0x15/0x1c0 | [ 5.196807] ? kvm_sched_clock_read+0x14/0x40 | [ 5.196807] ? sched_clock_local+0xe/0x80 | [ 5.196807] ? sched_clock_cpu+0xa5/0xc0 | [ 5.196807] _raw_spin_lock+0x34/0x80 | [ 5.196807] ? calc_load_ve+0x15/0x1c0 | [ 5.196807] calc_load_ve+0x15/0x1c0 | [ 5.196807] tick_do_update_jiffies64+0x115/0x150 | [ 5.196807] tick_irq_enter+0x6c/0xe0 | [ 5.196807] irq_enter_rcu+0x79/0x80 | [ 5.196807] sysvec_apic_timer_interrupt+0x95/0xd0 | [ 5.196807] </IRQ> | [ 5.196807] asm_sysvec_apic_timer_interrupt+0x12/0x20 | [ 5.196807] RIP: 0010:default_idle+0x10/0x20 | [ 5.196807] RSP: 0018:ffffffff87203ea8 EFLAGS: 00000202 | [ 5.196807] RAX: ffffffff86380df0 RBX: 0000000000000000 RCX: 0000000000000001 | [ 5.196807] RDX: 0000000000000000 RSI: ffffffff86ee3980 RDI: ffffffff86e1050e | [ 5.196807] RBP: ffffffff87260a00 R08: 0000000000000001 R09: 0000000000000001 | [ 5.196807] R10: 0000000000000001 R11: 0000000000000000 R12: 0000000000000000 | [ 5.196807] R13: 0000000000000000 R14: ffffffff87260120 R15: 0000000000000000 | [ 5.196807] ? mwait_idle+0x70/0x70 | [ 5.196807] ? mwait_idle+0x70/0x70 | [ 5.196807] default_idle_call+0x59/0x90 | [ 5.196807] do_idle+0x217/0x2b0 | [ 5.196807] cpu_startup_entry+0x19/0x20 | [ 5.196807] start_kernel+0x997/0x9bc | [ 5.196807] ? copy_bootdata+0x18/0x55 | [ 5.196807] secondary_startup_64_no_verify+0xc2/0xcb Note that the problem is rather coming from rt camp where splinlocks become sleepable thus can't be used in irq context (and for our kernel it requires the CONFIG_PROVE_RAW_LOCK_NESTING to be set), thus since we know that we're operating in irq context lets use raw spinlocks instead. Also I make unlock to happen earlier because there is no need to keep it once we've finished traversing the @ve_root_list list. https://jira.sw.ru/browse/PSBM-134756 CC: Kirill Tkhai <ktk...@virtuozzo.com> Signed-off-by: Cyrill Gorcunov <gorcu...@gmail.com> --- kernel/sched/core.c | 10 +++++----- kernel/sched/loadavg.c | 6 +++--- 2 files changed, 8 insertions(+), 8 deletions(-) --- vzkernel.orig/kernel/sched/core.c +++ vzkernel/kernel/sched/core.c @@ -10036,18 +10036,18 @@ static u64 cpu_shares_read_u64(struct cg #ifdef CONFIG_VE LIST_HEAD(ve_root_list); -DEFINE_SPINLOCK(load_ve_lock); +DEFINE_RAW_SPINLOCK(load_ve_lock); void link_ve_root_cpu_cgroup(struct cgroup_subsys_state *css) { struct task_group *tg = css_tg(css); unsigned long flags; - spin_lock_irqsave(&load_ve_lock, flags); + raw_spin_lock_irqsave(&load_ve_lock, flags); BUG_ON(!(css->flags & CSS_ONLINE)); if (list_empty(&tg->ve_root_list)) list_add(&tg->ve_root_list, &ve_root_list); - spin_unlock_irqrestore(&load_ve_lock, flags); + raw_spin_unlock_irqrestore(&load_ve_lock, flags); } void unlink_ve_root_cpu_cgroup(struct cgroup_subsys_state *css) @@ -10055,9 +10055,9 @@ void unlink_ve_root_cpu_cgroup(struct cg struct task_group *tg = css_tg(css); unsigned long flags; - spin_lock_irqsave(&load_ve_lock, flags); + raw_spin_lock_irqsave(&load_ve_lock, flags); list_del_init(&tg->ve_root_list); - spin_unlock_irqrestore(&load_ve_lock, flags); + raw_spin_unlock_irqrestore(&load_ve_lock, flags); } #endif /* CONFIG_VE */ --- vzkernel.orig/kernel/sched/loadavg.c +++ vzkernel/kernel/sched/loadavg.c @@ -110,7 +110,7 @@ long calc_load_fold_active(struct rq *th #ifdef CONFIG_VE extern struct list_head ve_root_list; -extern spinlock_t load_ve_lock; +extern raw_spinlock_t load_ve_lock; void calc_load_ve(void) { @@ -122,7 +122,7 @@ void calc_load_ve(void) * This is called without jiffies_lock, and here we protect * against very rare parallel execution on two or more cpus. */ - spin_lock(&load_ve_lock); + raw_spin_lock(&load_ve_lock); list_for_each_entry(tg, &ve_root_list, ve_root_list) { nr_active = 0; for_each_possible_cpu(i) { @@ -146,6 +146,7 @@ void calc_load_ve(void) tg->avenrun[1] = calc_load(tg->avenrun[1], EXP_5, nr_active); tg->avenrun[2] = calc_load(tg->avenrun[2], EXP_15, nr_active); } + raw_spin_unlock(&load_ve_lock); nr_unint = nr_uninterruptible() * FIXED_1; @@ -154,7 +155,6 @@ void calc_load_ve(void) calc_load(kstat_glob.nr_unint_avg[1], EXP_5, nr_unint); calc_load(kstat_glob.nr_unint_avg[2], EXP_15, nr_unint); write_seqcount_end(&kstat_glob.nr_unint_avg_seq); - spin_unlock(&load_ve_lock); } #endif /* CONFIG_VE */ _______________________________________________ Devel mailing list Devel@openvz.org https://lists.openvz.org/mailman/listinfo/devel