• Joerg Roedel's avatar
    iommu/amd: Fix schedule-while-atomic BUG in initialization code · 74ddda71
    Joerg Roedel authored
    The register_syscore_ops() function takes a mutex and might
    sleep. In the IOMMU initialization code it is invoked during
    irq-remapping setup already, where irqs are disabled.
    
    This causes a schedule-while-atomic bug:
    
     BUG: sleeping function called from invalid context at kernel/locking/mutex.c:747
     in_atomic(): 0, irqs_disabled(): 1, pid: 1, name: swapper/0
     no locks held by swapper/0/1.
     irq event stamp: 304
     hardirqs last  enabled at (303): [<ffffffff818a87b6>] _raw_spin_unlock_irqrestore+0x36/0x60
     hardirqs last disabled at (304): [<ffffffff8235d440>] enable_IR_x2apic+0x79/0x196
     softirqs last  enabled at (36): [<ffffffff818ae75f>] __do_softirq+0x35f/0x4ec
     softirqs last disabled at (31): [<ffffffff810c1955>] irq_exit+0x105/0x120
     CPU: 0 PID: 1 Comm: swapper/0 Not tainted 4.13.0-rc2.1.el7a.test.x86_64.debug #1
     Hardware name:          PowerEdge C6145 /040N24, BIOS 3.5.0 10/28/2014
     Call Trace:
      dump_stack+0x85/0xca
      ___might_sleep+0x22a/0x260
      __might_sleep+0x4a/0x80
      __mutex_lock+0x58/0x960
      ? iommu_completion_wait.part.17+0xb5/0x160
      ? register_syscore_ops+0x1d/0x70
      ? iommu_flush_all_caches+0x120/0x150
      mutex_lock_nested+0x1b/0x20
      register_syscore_ops+0x1d/0x70
      state_next+0x119/0x910
      iommu_go_to_state+0x29/0x30
      amd_iommu_enable+0x13/0x23
    
    Fix it by moving the register_syscore_ops() call to the next
    initialization step, which runs with irqs enabled.
    Reported-by: default avatarArtem Savkov <asavkov@redhat.com>
    Tested-by: default avatarArtem Savkov <asavkov@redhat.com>
    Acked-by: default avatarThomas Gleixner <tglx@linutronix.de>
    Fixes: 2c0ae172 ('iommu/amd: Convert iommu initialization to state machine')
    Signed-off-by: default avatarJoerg Roedel <jroedel@suse.de>
    74ddda71
amd_iommu_init.c 68.6 KB