From 7918c92ae9638eb8a6ec18e2b4a0de84557cccc8 Mon Sep 17 00:00:00 2001 From: Konrad Rzeszutek Wilk Date: Tue, 16 Apr 2013 15:18:00 -0400 Subject: [PATCH] xen/time: Fix kasprintf splat when allocating timer%d IRQ line. 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: [] __might_sleep+0xda/0x100 [] __kmalloc_track_caller+0x1e7/0x2c0 [] ? kasprintf+0x38/0x40 [] kvasprintf+0x5b/0x90 [] kasprintf+0x38/0x40 [] xen_setup_timer+0x30/0xb0 [] xen_hvm_setup_cpu_clockevents+0x1f/0x30 [] 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. CC: stable@vger.kernel.org Signed-off-by: Konrad Rzeszutek Wilk --- arch/x86/xen/enlighten.c | 5 ++++- arch/x86/xen/time.c | 6 +++++- 2 files changed, 9 insertions(+), 2 deletions(-) diff --git a/arch/x86/xen/enlighten.c b/arch/x86/xen/enlighten.c index 47d32434d0b6b2..ddbd54a9b845d0 100644 --- a/arch/x86/xen/enlighten.c +++ b/arch/x86/xen/enlighten.c @@ -1641,8 +1641,11 @@ static int __cpuinit xen_hvm_cpu_notify(struct notifier_block *self, 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; diff --git a/arch/x86/xen/time.c b/arch/x86/xen/time.c index 0296a952250179..054cc01bb849ac 100644 --- a/arch/x86/xen/time.c +++ b/arch/x86/xen/time.c @@ -497,7 +497,11 @@ static void xen_hvm_setup_cpu_clockevents(void) { 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(); }