On 14/06/2022 12:02, Michal Orzel wrote:
Hi Julien,
Hi Michal,
On 14.06.2022 11:41, Julien Grall wrote:
From: Julien Grall <[email protected]>
Commit 5047cd1d5dea "xen/common: Use enhanced ASSERT_ALLOC_CONTEXT in
xmalloc()" extended the checks in _xmalloc() to catch any use of the
helpers from context with interrupts disabled.
Unfortunately, the rule is not followed when allocating the CPU
sibling/core maps.
(XEN) Xen call trace:
(XEN) [<00238a5c>] _xmalloc+0xfc/0x314 (PC)
(XEN) [<00000000>] 00000000 (LR)
(XEN) [<00238c8c>] _xzalloc+0x18/0x4c
(XEN) [<00288cb4>] smpboot.c#setup_cpu_sibling_map+0x38/0x138
(XEN) [<00289024>] start_secondary+0x1b4/0x270
(XEN) [<40010170>] 40010170
(XEN)
(XEN)
(XEN) ****************************************
(XEN) Panic on CPU 2:
(XEN) Assertion '!in_irq() && (local_irq_is_enabled() || num_online_cpus() <=
1)' failed at common/xmalloc_tlsf.c:601
(XEN) ****************************************
This is happening because zalloc_cpumask_var() may allocate memory
if NR_CPUS is > 2 * sizeof(unsigned long).
Avoid the problem by allocate the per-CPU IRQs while preparing the
CPU.
Shouldn't this be "by allocating the CPU sibling/core maps while ..."
to reflect the commit title and to distinguish between this change and the IRQ
one?
Yes. I will update it.
[...]
static void remove_cpu_sibling_map(int cpu)
@@ -292,9 +294,14 @@ smp_get_max_cpus (void)
void __init
smp_prepare_cpus(void)
{
+ int rc;
Here you are leaving rc uninitialized (which is ok) but ...
+
cpumask_copy(&cpu_present_map, &cpu_possible_map);
- setup_cpu_sibling_map(0);
+ rc = setup_cpu_sibling_map(0);
+ if ( rc )
+ panic("Unable to allocate CPU sibling/core maps\n");
+
}
/* Boot the current CPU */
@@ -361,8 +368,6 @@ void start_secondary(void)
set_current(idle_vcpu[cpuid]);
- setup_cpu_sibling_map(cpuid);
-
/* Run local notifiers */
notify_cpu_starting(cpuid);
/*
@@ -530,9 +535,19 @@ static int cpu_smpboot_callback(struct notifier_block *nfb,
void *hcpu)
{
unsigned int cpu = (unsigned long)hcpu;
+ unsigned int rc = 0;
... here you are setting rc to 0 even though it will be reassigned.
Furthermore, if rc is used only in case of CPU_UP_PREPARE, why not moving the
definition there?
Because I forgot to replace "return NOTIFY_DONE;" with :
return !rc ? NOTIFY_DONE : notifier_from_errno(rc);
In this case, we would need to initialize rc to 0 so it doesn't get used
initialized.
Cheers,
--
Julien Grall
