| From: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com> |
| Date: Tue, 16 Apr 2013 15:18:00 -0400 |
| Subject: xen/time: Fix kasprintf splat when allocating timer%d IRQ line. |
| |
| commit 7918c92ae9638eb8a6ec18e2b4a0de84557cccc8 upstream. |
| |
| When we online the CPU, we get this splat: |
| |
| smpboot: Booting Node 0 Processor 1 APIC 0x2 |
| installing Xen timer for CPU 1 |
| BUG: sleeping function called from invalid context at /home/konrad/ssd/konrad/linux/mm/slab.c:3179 |
| in_atomic(): 1, irqs_disabled(): 0, pid: 0, name: swapper/1 |
| Pid: 0, comm: swapper/1 Not tainted 3.9.0-rc6upstream-00001-g3884fad #1 |
| Call Trace: |
| [<ffffffff810c1fea>] __might_sleep+0xda/0x100 |
| [<ffffffff81194617>] __kmalloc_track_caller+0x1e7/0x2c0 |
| [<ffffffff81303758>] ? kasprintf+0x38/0x40 |
| [<ffffffff813036eb>] kvasprintf+0x5b/0x90 |
| [<ffffffff81303758>] kasprintf+0x38/0x40 |
| [<ffffffff81044510>] xen_setup_timer+0x30/0xb0 |
| [<ffffffff810445af>] xen_hvm_setup_cpu_clockevents+0x1f/0x30 |
| [<ffffffff81666d0a>] start_secondary+0x19c/0x1a8 |
| |
| The solution to that is use kasprintf in the CPU hotplug path |
| that 'online's the CPU. That is, do it in in xen_hvm_cpu_notify, |
| and remove the call to in xen_hvm_setup_cpu_clockevents. |
| |
| Unfortunatly the later is not a good idea as the bootup path |
| does not use xen_hvm_cpu_notify so we would end up never allocating |
| timer%d interrupt lines when booting. As such add the check for |
| atomic() to continue. |
| |
| Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com> |
| Signed-off-by: Ben Hutchings <ben@decadent.org.uk> |
| --- |
| arch/x86/xen/enlighten.c | 5 ++++- |
| arch/x86/xen/time.c | 6 +++++- |
| 2 files changed, 9 insertions(+), 2 deletions(-) |
| |
| --- a/arch/x86/xen/enlighten.c |
| +++ b/arch/x86/xen/enlighten.c |
| @@ -1391,8 +1391,11 @@ static int __cpuinit xen_hvm_cpu_notify( |
| switch (action) { |
| case CPU_UP_PREPARE: |
| xen_vcpu_setup(cpu); |
| - if (xen_have_vector_callback) |
| + if (xen_have_vector_callback) { |
| xen_init_lock_cpu(cpu); |
| + if (xen_feature(XENFEAT_hvm_safe_pvclock)) |
| + xen_setup_timer(cpu); |
| + } |
| break; |
| default: |
| break; |
| --- a/arch/x86/xen/time.c |
| +++ b/arch/x86/xen/time.c |
| @@ -497,7 +497,11 @@ static void xen_hvm_setup_cpu_clockevent |
| { |
| int cpu = smp_processor_id(); |
| xen_setup_runstate_info(cpu); |
| - xen_setup_timer(cpu); |
| + /* |
| + * xen_setup_timer(cpu) - snprintf is bad in atomic context. Hence |
| + * doing it xen_hvm_cpu_notify (which gets called by smp_init during |
| + * early bootup and also during CPU hotplug events). |
| + */ |
| xen_setup_cpu_clockevents(); |
| } |
| |