Hello Song, On 8/26/22 03:17, Song Chen wrote:
hi, 在 2022/8/25 23:23, Pierre Gondois 写道:In KvmTool, on a ThunderX2, when running a preemp_rt kernel based on v5.19-rc3-rt4, the following happens: [ 4.070739] [ BUG: Invalid wait context ] [ 4.070740] 5.19.0-rc3-rt4-00001-g1a6597c0bdcf #153 Not tainted [ 4.070742] ----------------------------- [ 4.070743] swapper/0/1 is trying to lock: [ 4.070744] ffff0000ab7405d8 ((&c->lock)){+.+.}-{3:3}, at: ___slab_alloc (mm/slub.c:2954) [ 4.070757] other info that might help us debug this: [ 4.070758] context-{5:5} [ 4.070759] 5 locks held by swapper/0/1: [ 4.070760] #0: ffff0000811491e0 (&dev->mutex){....}-{4:4}, at: __device_driver_lock (drivers/base/dd.c:1055) [ 4.070769] #1: ffff0000846c5670 (&desc->request_mutex){+.+.}-{4:4}, at: __setup_irq (kernel/irq/internals.h:147) [ 4.070778] #2: ffff0000846c54c8 (&irq_desc_lock_class){....}-{2:2}, at: __setup_irq (kernel/irq/manage.c:1612) [ 4.070784] #3: ffff80000b23ea78 (mask_lock){....}-{2:2}, at: irq_setup_affinity (./include/linux/irq.h:381) [ 4.070791] #4: ffff80000b23ea38 (tmp_mask_lock){....}-{2:2}, at: irq_do_set_affinity (./include/linux/irq.h:381) [ 4.070797] stack backtrace: [ 4.070801] CPU: 2 PID: 1 Comm: swapper/0 Not tainted 5.19.0-rc3-rt4-00001-g1a6597c0bdcf #153 [ 4.070805] Call trace: [ 4.070806] dump_backtrace (arch/arm64/kernel/stacktrace.c:200) [ 4.070811] show_stack (arch/arm64/kernel/stacktrace.c:207) [ 4.070813] dump_stack_lvl (lib/dump_stack.c:107) [ 4.070818] dump_stack (lib/dump_stack.c:114) [ 4.070820] __lock_acquire (kernel/locking/lockdep.c:4707) [ 4.070823] lock_acquire (kernel/locking/lockdep.c:466) [ 4.070825] rt_spin_lock (./arch/arm64/include/asm/current.h:19 (discriminator 4)) [ 4.070830] ___slab_alloc (mm/slub.c:2954) [ 4.070832] __slab_alloc.isra.0 (mm/slub.c:3116) [ 4.070835] __kmalloc_node (mm/slub.c:3207) [ 4.070837] alloc_cpumask_var_node (lib/cpumask.c:115) [ 4.070843] alloc_cpumask_var (lib/cpumask.c:147) [ 4.070846] its_select_cpu (drivers/irqchip/irq-gic-v3-its.c:1580) [ 4.070850] its_set_affinity (drivers/irqchip/irq-gic-v3-its.c:1659) [ 4.070853] msi_domain_set_affinity (kernel/irq/msi.c:501) [ 4.070857] irq_do_set_affinity (kernel/irq/manage.c:276) [ 4.070860] irq_setup_affinity (kernel/irq/manage.c:633) [ 4.070863] irq_startup (kernel/irq/chip.c:280) [ 4.070865] __setup_irq (kernel/irq/manage.c:1777) [ 4.070869] request_threaded_irq (kernel/irq/manage.c:2206) [ 4.070872] vp_find_vqs_msix (./include/linux/interrupt.h:168) [ 4.070876] vp_find_vqs (drivers/virtio/virtio_pci_common.c:400) [ 4.070878] vp_modern_find_vqs (drivers/virtio/virtio_pci_modern.c:259) [ 4.070880] init_vq (./include/linux/virtio_config.h:213) [ 4.070885] virtblk_probe (drivers/block/virtio_blk.c:936) [ 4.070887] virtio_dev_probe (drivers/virtio/virtio.c:303) [ 4.070892] really_probe (drivers/base/dd.c:555) [ 4.070895] __driver_probe_device (drivers/base/dd.c:764) [ 4.070897] driver_probe_device (drivers/base/dd.c:794) [ 4.070899] __driver_attach (drivers/base/dd.c:1164) [ 4.070901] bus_for_each_dev (drivers/base/bus.c:301) [ 4.070904] driver_attach (drivers/base/dd.c:1181) [ 4.070906] bus_add_driver (drivers/base/bus.c:618) [ 4.070908] driver_register (drivers/base/driver.c:240) [ 4.070910] register_virtio_driver (drivers/virtio/virtio.c:356 (discriminator 4)) [ 4.070913] virtio_blk_init (drivers/block/virtio_blk.c:1218) [ 4.070918] do_one_initcall (init/main.c:1295) [ 4.070921] kernel_init_freeable (init/main.c:1367) [ 4.070924] kernel_init (init/main.c:1503) [ 4.070927] ret_from_fork (arch/arm64/kernel/entry.S:868) commit cba4235e6031e ("genirq: Remove mask argument from setup_affinity()") and commit 11ea68f553e24 ("genirq, sched/isolation: Isolate from handling managed interrupts") overcome this issue by defining a static struct cpumask and protecting it by a raw spinlock. The code in these commits is executed with IRQs disabled. its_select_cpu() can be executed with IRQs enabled or disabled. Thus disabling IRQs is necesserary to avoid deadlocking. This patch: - makes tmpmask a 'static struct cpumask'. This prevents storing it on the stack and having to dynamically allocate it - protects tmpmask with a raw spinlock - disables IRQs around the spinlock for the case its_select_cpu() is called with IRQs enabled Signed-off-by: Pierre Gondois <pierre.gondois@xxxxxxx> --- drivers/irqchip/irq-gic-v3-its.c | 34 +++++++++++++++++--------------- 1 file changed, 18 insertions(+), 16 deletions(-) diff --git a/drivers/irqchip/irq-gic-v3-its.c b/drivers/irqchip/irq-gic-v3-its.c index 5ff09de6c48f..3cf89e59b036 100644 --- a/drivers/irqchip/irq-gic-v3-its.c +++ b/drivers/irqchip/irq-gic-v3-its.c @@ -1574,14 +1574,15 @@ static int its_select_cpu(struct irq_data *d, const struct cpumask *aff_mask) { struct its_device *its_dev = irq_data_get_irq_chip_data(d); - cpumask_var_t tmpmask; + static DEFINE_RAW_SPINLOCK(tmpmask_lock); + static struct cpumask tmpmask; + unsigned long flags; int cpu, node; - - if (!alloc_cpumask_var(&tmpmask, GFP_ATOMIC)) - return -ENOMEM; - node = its_dev->its->numa_node;+ local_irq_save(flags);+ raw_spin_lock(&tmpmask_lock); +why not call raw_spin_lock_irqsave and raw_spin_unlock_irqrestore?
Yes indeed, raw_spin_unlock_irqrestore() would fit perfectly, this is a mistake. Thanks for the review, Pierre
Songif (!irqd_affinity_is_managed(d)) { /* First try the NUMA node */ if (node != NUMA_NO_NODE) { @@ -1589,8 +1590,8 @@ static int its_select_cpu(struct irq_data *d, * Try the intersection of the affinity mask and the * node mask (and the online mask, just to be safe). */ - cpumask_and(tmpmask, cpumask_of_node(node), aff_mask); - cpumask_and(tmpmask, tmpmask, cpu_online_mask); + cpumask_and(&tmpmask, cpumask_of_node(node), aff_mask); + cpumask_and(&tmpmask, &tmpmask, cpu_online_mask);/** Ideally, we would check if the mask is empty, and @@ -1604,7 +1605,7 @@ static int its_select_cpu(struct irq_data *d, * Instead, just fallback on the online mask. This * diverges from Thomas' suggestion above. */ - cpu = cpumask_pick_least_loaded(d, tmpmask); + cpu = cpumask_pick_least_loaded(d, &tmpmask); if (cpu < nr_cpu_ids) goto out;@@ -1616,25 +1617,26 @@ static int its_select_cpu(struct irq_data *d,}/* Try the intersection of the affinity and online masks */- cpumask_and(tmpmask, aff_mask, cpu_online_mask); + cpumask_and(&tmpmask, aff_mask, cpu_online_mask);/* If that doesn't fly, the online mask is the last resort */- if (cpumask_empty(tmpmask)) - cpumask_copy(tmpmask, cpu_online_mask); + if (cpumask_empty(&tmpmask)) + cpumask_copy(&tmpmask, cpu_online_mask);- cpu = cpumask_pick_least_loaded(d, tmpmask);+ cpu = cpumask_pick_least_loaded(d, &tmpmask); } else { - cpumask_copy(tmpmask, aff_mask); + cpumask_copy(&tmpmask, aff_mask);/* If we cannot cross sockets, limit the search to that node */if ((its_dev->its->flags & ITS_FLAGS_WORKAROUND_CAVIUM_23144) && node != NUMA_NO_NODE) - cpumask_and(tmpmask, tmpmask, cpumask_of_node(node)); + cpumask_and(&tmpmask, &tmpmask, cpumask_of_node(node));- cpu = cpumask_pick_least_loaded(d, tmpmask);+ cpu = cpumask_pick_least_loaded(d, &tmpmask); } out: - free_cpumask_var(tmpmask); + raw_spin_unlock(&tmpmask_lock); + local_irq_restore(flags);pr_debug("IRQ%d -> %*pbl CPU%d\n", d->irq, cpumask_pr_args(aff_mask), cpu);return cpu;
