RDMA/rxe: Fix soft lockup problem due to using tasklets in softirq
authorZhu Yanjun <yanjunz@mellanox.com>
Wed, 12 Feb 2020 07:26:33 +0000 (09:26 +0200)
committerJason Gunthorpe <jgg@mellanox.com>
Thu, 13 Feb 2020 14:51:09 +0000 (10:51 -0400)
commit8ac0e6641c7ca14833a2a8c6f13d8e0a435e535c
tree00de5588fd13d073c0afd968e4c6ece95ae2d494
parent9b6d3bbc1335404b331f4f11dc896066bdf1c752
RDMA/rxe: Fix soft lockup problem due to using tasklets in softirq

When run stress tests with RXE, the following Call Traces often occur

  watchdog: BUG: soft lockup - CPU#2 stuck for 22s! [swapper/2:0]
  ...
  Call Trace:
  <IRQ>
  create_object+0x3f/0x3b0
  kmem_cache_alloc_node_trace+0x129/0x2d0
  __kmalloc_reserve.isra.52+0x2e/0x80
  __alloc_skb+0x83/0x270
  rxe_init_packet+0x99/0x150 [rdma_rxe]
  rxe_requester+0x34e/0x11a0 [rdma_rxe]
  rxe_do_task+0x85/0xf0 [rdma_rxe]
  tasklet_action_common.isra.21+0xeb/0x100
  __do_softirq+0xd0/0x298
  irq_exit+0xc5/0xd0
  smp_apic_timer_interrupt+0x68/0x120
  apic_timer_interrupt+0xf/0x20
  </IRQ>
  ...

The root cause is that tasklet is actually a softirq. In a tasklet
handler, another softirq handler is triggered. Usually these softirq
handlers run on the same cpu core. So this will cause "soft lockup Bug".

Fixes: 8700e3e7c485 ("Soft RoCE driver")
Link: https://lore.kernel.org/r/20200212072635.682689-8-leon@kernel.org
Signed-off-by: Zhu Yanjun <yanjunz@mellanox.com>
Signed-off-by: Leon Romanovsky <leonro@mellanox.com>
Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>
drivers/infiniband/sw/rxe/rxe_comp.c