[bug report] drm/panthor: Expose size of driver internal BO's over fdinfo

[Adrián Larumbe]

Hi Dan, thanks for the bug report.

A fix is already being discussed at https://lore.kernel.org/dri-devel/20250215102807.7502e7ba@collabora.com/

On 17.02.2025 00:36, Dan Carpenter wrote:
> Hello Adrián Larumbe,
>
> Commit 434e5ca5b5d7 ("drm/panthor: Expose size of driver internal
> BO's over fdinfo") from Jan 30, 2025 (linux-next), leads to the
> following Smatch static checker warning:
>
> 	drivers/gpu/drm/panthor/panthor_mmu.c:1968 panthor_vm_heaps_sizes()
> 	warn: sleeping in atomic context
>
> drivers/gpu/drm/panthor/panthor_mmu.c
>     1956 void panthor_vm_heaps_sizes(struct panthor_file *pfile, struct drm_memory_stats *stats)
>     1957 {
>     1958         struct panthor_vm *vm;
>     1959         unsigned long i;
>     1960
>     1961         if (!pfile->vms)
>     1962                 return;
>     1963
>     1964         xa_lock(&pfile->vms->xa);
>                  ^^^^^^^
> This is a spinlock.
>
>     1965         xa_for_each(&pfile->vms->xa, i, vm) {
>     1966                 size_t size = 0;
>     1967
> --> 1968                 mutex_lock(&vm->heaps.lock);
>                          ^^^^^^^^^^
> So we can't take a mutex if we're holding a spinlock.
>
>     1969                 if (vm->heaps.pool)
>     1970                         size = panthor_heap_pool_size(vm->heaps.pool);
>     1971                 mutex_unlock(&vm->heaps.lock);
>     1972
>     1973                 stats->resident += size;
>     1974                 if (vm->as.id >= 0)
>     1975                         stats->active += size;
>     1976         }
>     1977         xa_unlock(&pfile->vms->xa);
>     1978 }
>
> regards,
> dan carpenter

Kind Regards,
Adrian Larumbe