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When a user offlines a VCPU and then onlines it, we get: NMI watchdog disabled (cpu2): hardware events not enabled BUG: scheduling while atomic: swapper/2/0/0x00000002 Modules linked in: dm_multipath dm_mod xen_evtchn iscsi_boot_sysfs iscsi_tcp libiscsi_tcp libiscsi scsi_transport_iscsi scsi_mod libcrc32c crc32c radeon fbco ttm bitblit softcursor drm_kms_helper xen_blkfront xen_netfront xen_fbfront fb_sys_fops sysimgblt sysfillrect syscopyarea xen_kbdfront xenfs [last unloaded: Pid: 0, comm: swapper/2 Tainted: G O 3.2.0phase15.1-00003-gd6f7f5b-dirty #4 Call Trace: [<ffffffff81070571>] __schedule_bug+0x61/0x70 [<ffffffff8158eb78>] __schedule+0x798/0x850 [<ffffffff8158ed6a>] schedule+0x3a/0x50 [<ffffffff810349be>] cpu_idle+0xbe/0xe0 [<ffffffff81583599>] cpu_bringup_and_idle+0xe/0x10 The reason for this should be obvious from this call-chain: cpu_bringup_and_idle: \- cpu_bringup | \-[preempt_disable] | |- cpu_idle \- play_dead [assuming the user offlined the VCPU] | \ | +- (xen_play_dead) | \- HYPERVISOR_VCPU_off [so VCPU is dead, once user | | onlines it starts from here] | \- cpu_bringup [preempt_disable] | +- preempt_enable_no_reschedule() +- schedule() \- preempt_enable() So we have two preempt_disble() and one preempt_enable(). Calling preempt_enable() after the cpu_bringup() in the xen_play_dead fixes the imbalance. Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com> |
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| .. | ||
| debugfs.c | ||
| debugfs.h | ||
| enlighten.c | ||
| grant-table.c | ||
| irq.c | ||
| Kconfig | ||
| Makefile | ||
| mmu.c | ||
| mmu.h | ||
| multicalls.c | ||
| multicalls.h | ||
| p2m.c | ||
| pci-swiotlb-xen.c | ||
| platform-pci-unplug.c | ||
| setup.c | ||
| smp.c | ||
| spinlock.c | ||
| suspend.c | ||
| time.c | ||
| trace.c | ||
| vdso.h | ||
| vga.c | ||
| xen-asm_32.S | ||
| xen-asm_64.S | ||
| xen-asm.h | ||
| xen-asm.S | ||
| xen-head.S | ||
| xen-ops.h | ||