3.16.50-rc1 review patch. If anyone has any objections, please let me know.
------------------
From: Joerg Roedel <jroedel@xxxxxxx>
commit 74ddda71f44c84af62f736a77fb9fcebe5bb436a upstream.
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: Artem Savkov <asavkov@xxxxxxxxxx>
Tested-by: Artem Savkov <asavkov@xxxxxxxxxx>
Acked-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Fixes: 2c0ae1720c09 ('iommu/amd: Convert iommu initialization to state machine')
Signed-off-by: Joerg Roedel <jroedel@xxxxxxx>
Signed-off-by: Ben Hutchings <ben@xxxxxxxxxxxxxxx>
---
drivers/iommu/amd_iommu_init.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
--- a/drivers/iommu/amd_iommu_init.c
+++ b/drivers/iommu/amd_iommu_init.c
@@ -2027,11 +2027,11 @@ 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();