From 74ddda71f44c84af62f736a77fb9fcebe5bb436a Mon Sep 17 00:00:00 2001 From: Joerg Roedel Date: Wed, 26 Jul 2017 14:17:55 +0200 Subject: [PATCH] iommu/amd: Fix schedule-while-atomic BUG in initialization code 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): [] _raw_spin_unlock_irqrestore+0x36/0x60 hardirqs last disabled at (304): [] enable_IR_x2apic+0x79/0x196 softirqs last enabled at (36): [] __do_softirq+0x35f/0x4ec softirqs last disabled at (31): [] 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: Artem Savkov Tested-by: Artem Savkov Acked-by: Thomas Gleixner Fixes: 2c0ae1720c09 ('iommu/amd: Convert iommu initialization to state machine') Signed-off-by: Joerg Roedel --- drivers/iommu/amd_iommu_init.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/drivers/iommu/amd_iommu_init.c b/drivers/iommu/amd_iommu_init.c index 5cc597b383c7..372303700566 100644 --- a/drivers/iommu/amd_iommu_init.c +++ b/drivers/iommu/amd_iommu_init.c @@ -2440,11 +2440,11 @@ static int __init state_next(void) break; case IOMMU_ACPI_FINISHED: early_enable_iommus(); - register_syscore_ops(&amd_iommu_syscore_ops); x86_platform.iommu_shutdown = disable_iommus; init_state = IOMMU_ENABLED; break; case IOMMU_ENABLED: + register_syscore_ops(&amd_iommu_syscore_ops); ret = amd_iommu_init_pci(); init_state = ret ? IOMMU_INIT_ERROR : IOMMU_PCI_INIT; enable_iommus_v2(); -- GitLab