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| author | Konrad Rzeszutek Wilk <konrad.wilk@oracle.com> | 2012-02-01 21:56:54 +0100 |
|---|---|---|
| committer | Konrad Rzeszutek Wilk <konrad.wilk@oracle.com> | 2012-02-03 22:05:42 +0100 |
| commit | 41bd956de3dfdc3a43708fe2e0c8096c69064a1e (patch) | |
| tree | 1a2a31181c6c89dd754c46376fd82b3e0ba77e5e /drivers/ide/ide-pm.c | |
| parent | xen/bootup: During bootup suppress XENBUS: Unable to read cpu state (diff) | |
| download | linux-41bd956de3dfdc3a43708fe2e0c8096c69064a1e.tar.xz linux-41bd956de3dfdc3a43708fe2e0c8096c69064a1e.zip | |
xen/smp: Fix CPU online/offline bug triggering a BUG: scheduling while atomic.
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>
Diffstat (limited to 'drivers/ide/ide-pm.c')
0 files changed, 0 insertions, 0 deletions