Messages in this thread | | | Date | Fri, 26 Aug 2022 09:17:16 +0800 | Subject | Re: [PATCH] irqchip/gic-v3-its: Remove cpumask_var_t allocation | From | Song Chen <> |
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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@arm.com> > --- > 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?
Song
> if (!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;
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