On 4/17/20 01:09, Sebastian Andrzej Siewior wrote:
> On 2020-04-13 12:18:17 [+0800], Liwei Song wrote:
>> Interrupts are off during resume from RAM, this will triger a warning
>> when allocate memory in non-preemptible context on RT since commit
>> b5d5bc970f209 ("mm: Warn on memory allocation in non-preemptible
>> context on RT"), exclude suspend from this warning check.
>
> Is this the ACPI backtrace or do you have something else?
Yes, there are two backtrace here include one ACPI Calltrace, another one
is from iommu:
1).
[ 88.992342] ? acpi_os_allocate_zeroed+0x28/0x2a
[ 88.992349] acpi_os_allocate_zeroed+0x28/0x2a
[ 88.992351] acpi_ns_internalize_name+0x4b/0xa0
[ 88.992354] ? trace_preempt_on+0x2a/0x120
[ 88.992360] acpi_ns_get_node_unlocked+0x6f/0xd7
[ 88.992362] ? _raw_spin_unlock_irqrestore+0x42/0x90
[ 88.992367] ? down_timeout+0x3c/0x60
[ 88.992372] ? acpi_os_wait_semaphore+0x4d/0x70
[ 88.992378] acpi_ns_get_node+0x43/0x5d
2).
[ 88.991560] Call Trace:
[ 88.991561] ? _raw_spin_unlock_irqrestore+0x42/0x90
[ 88.991563] ? iommu_suspend+0x4f/0x1c0
[ 88.991569] iommu_suspend+0x4f/0x1c0
[ 88.991572] syscore_suspend+0x9b/0x3e0
[ 88.991575] suspend_devices_and_enter+0x1fb/0xec0
[ 88.991579] ? rcu_read_lock_sched_held+0x4f/0x80
[ 88.991580] ? prb_unlock+0x18/0x80
[ 88.991585] pm_suspend.cold+0x326/0x37b
During suspend phase the only way to make preemptible() happy is
enable interrupt before kcalloc/kmalloc/kzalloc, but enable interrupt
may cause some unknown issue if device access I/O address which already
suspend, so I think it's better and safe to exclude suspend from this
warning check.
Thanks,
Liwei.
>
> I'm currently not 100% sure if we can skip the warning.
>
>> Fixes: b5d5bc970f209 ("mm: Warn on memory allocation in non-preemptible context on RT")
>> Signed-off-by: Liwei Song <liwei.song@xxxxxxxxxxxxx>
>> ---
>> mm/slub.c | 6 ++++--
>> 1 file changed, 4 insertions(+), 2 deletions(-)
>>
>> diff --git a/mm/slub.c b/mm/slub.c
>> index 1929645daa53..ebff24ae50ea 100644
>> --- a/mm/slub.c
>> +++ b/mm/slub.c
>> @@ -2771,7 +2771,8 @@ static __always_inline void *slab_alloc_node(struct kmem_cache *s,
>> unsigned long tid;
>>
>> if (IS_ENABLED(CONFIG_PREEMPT_RT) && IS_ENABLED(CONFIG_DEBUG_ATOMIC_SLEEP))
>> - WARN_ON_ONCE(!preemptible() && system_state >= SYSTEM_SCHEDULING);
>> + WARN_ON_ONCE(!preemptible() && system_state >= SYSTEM_SCHEDULING &&
>> + system_state != SYSTEM_SUSPEND);
>>
>> s = slab_pre_alloc_hook(s, gfpflags);
>> if (!s)
>> @@ -3236,7 +3237,8 @@ int kmem_cache_alloc_bulk(struct kmem_cache *s, gfp_t flags, size_t size,
>> int i;
>>
>> if (IS_ENABLED(CONFIG_PREEMPT_RT) && IS_ENABLED(CONFIG_DEBUG_ATOMIC_SLEEP))
>> - WARN_ON_ONCE(!preemptible() && system_state >= SYSTEM_SCHEDULING);
>> + WARN_ON_ONCE(!preemptible() && system_state >= SYSTEM_SCHEDULING &&
>> + system_state != SYSTEM_SUSPEND);
>>
>> /* memcg and kmem_cache debug support */
>> s = slab_pre_alloc_hook(s, flags);
>
> Sebastian
>
