Re: BUG: sleeping function called from atomic due to "Balance initial LPI affinity across CPUs"

[John Garry]

On 19/05/2020 23:09, Qian Cai wrote:
> Reverted the linux-next commit f068a62c548c ("irqchip/gic-v3-its:
> Balance initial LPI affinity across CPUs") fixed these warnings during
> boot,

Thanks for the notice. So we need the following set to see this:
CONFIG_CPUMASK_OFFSTACK=y
CONFIG_DEBUG_ATOMIC_SLEEP=y
CONFIG_DEBUG_PER_CPU_MAPS=y

> its_select_cpu at drivers/irqchip/irq-gic-v3-its.c:1572
>
> [  332.819381][ T3359] BUG: sleeping function called from invalid
> context at mm/slab.h:568
> [  332.827405][ T3359] in_atomic(): 1, irqs_disabled(): 128,
> non_block: 0, pid: 3359, name: irqbalance
> [  332.836455][ T3359] INFO: lockdep is turned off.
> [  332.841076][ T3359] irq event stamp: 0
> [  332.844836][ T3359] hardirqs last  enabled at (0): [<0000000000000000>] 0x0
> [  332.851828][ T3359] hardirqs last disabled at (0):
> [<ffff9000101ea65c>] copy_process+0x98c/0x1f34
> [  332.860710][ T3359] softirqs last  enabled at (0):
> [<ffff9000101ea690>] copy_process+0x9c0/0x1f34
> [  332.869586][ T3359] softirqs last disabled at (0): [<0000000000000000>] 0x0
> [  332.876560][ T3359] CPU: 155 PID: 3359 Comm: irqbalance Tainted: G
>        W    L    5.7.0-rc6-next-20200519 #1
> [  332.886563][ T3359] Hardware name: HPE Apollo 70
> /C01_APACHE_MB         , BIOS L50_5.13_1.11 06/18/2019
> [  332.897000][ T3359] Call trace:
> [  332.900151][ T3359]  dump_backtrace+0x0/0x22c
> [  332.904514][ T3359]  show_stack+0x28/0x34
> [  332.908543][ T3359]  dump_stack+0x104/0x194
> [  332.912738][ T3359]  ___might_sleep+0x314/0x328
> [  332.917274][ T3359]  __might_sleep+0x7c/0xe0
> [  332.921563][ T3359]  slab_pre_alloc_hook+0x44/0x8c
> [  332.926360][ T3359]  __kmalloc_node+0xb0/0x618
> [  332.930811][ T3359]  alloc_cpumask_var_node+0x48/0x94

We could use GFP_ATOMIC flag at the callsite here, but maybe there is a 
better solution.

> [  332.935868][ T3359]  alloc_cpumask_var+0x10/0x1c
> [  332.940496][ T3359]  its_select_cpu+0x58/0x2e4
> [  332.944945][ T3359]  its_set_affinity+0xe8/0x27c
> [  332.949576][ T3359]  msi_domain_set_affinity+0x78/0x114
> [  332.954813][ T3359]  irq_do_set_affinity+0x84/0x198
> [  332.959697][ T3359]  irq_set_affinity_locked+0x80/0x1a8
> [  332.964927][ T3359]  __irq_set_affinity+0x54/0x84
> [  332.969637][ T3359]  write_irq_affinity+0x16c/0x198
> [  332.974520][ T3359]  irq_affinity_proc_write+0x34/0x44
> [  332.979672][ T3359]  pde_write+0x5c/0x78
> [  332.983602][ T3359]  proc_reg_write+0x74/0xc0
> [  332.987974][ T3359]  __vfs_write+0x84/0x1d8
> [  332.992163][ T3359]  vfs_write+0x13c/0x1b8
> [  332.996265][ T3359]  ksys_write+0xb0/0x120
> [  333.000385][ T3359]  __arm64_sys_write+0x54/0x88
> [  333.005017][ T3359]  do_el0_svc+0x128/0x1dc
> [  333.009213][ T3359]  el0_sync_handler+0xd0/0x268
> [  333.013836][ T3359]  el0_sync+0x164/0x180
> [  336.527739][ T3356] mlx5_core 0000:0b:00.1 enp11s0f1np1: Link down
> .