On Fri, Aug 21, 2020 at 07:42:55PM +0200, Rafael J. Wysocki wrote:
> From: Rafael J. Wysocki <rafael.j.wysocki@xxxxxxxxx>
>
> After commit 1757659d022b ("ACPI: OSL: Implement deferred unmapping
> of ACPI memory") in some cases acpi_release_memory() may return
> before the target memory mappings actually go away, because they
> are released asynchronously now.
>
> Prevent it from returning prematurely by making it wait for the next
> RCU grace period to elapse, for all of the RCU callbacks to complete
> and for all of the scheduled work items to be flushed before
> returning.
>
> Fixes: 1757659d022b ("ACPI: OSL: Implement deferred unmapping of ACPI memory")
> Reported-by: Kenneth R. Crudup <kenny@xxxxxxxxx>
> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@xxxxxxxxx>
FWIW:
Reviewed-by: Heikki Krogerus <heikki.krogerus@xxxxxxxxxxxxxxx>
> ---
> drivers/acpi/osl.c | 19 +++++++++++++++++--
> 1 file changed, 17 insertions(+), 2 deletions(-)
>
> Index: linux-pm/drivers/acpi/osl.c
> ===================================================================
> --- linux-pm.orig/drivers/acpi/osl.c
> +++ linux-pm/drivers/acpi/osl.c
> @@ -1575,11 +1575,26 @@ static acpi_status acpi_deactivate_mem_r
> acpi_status acpi_release_memory(acpi_handle handle, struct resource *res,
> u32 level)
> {
> + acpi_status status;
> +
> if (!(res->flags & IORESOURCE_MEM))
> return AE_TYPE;
>
> - return acpi_walk_namespace(ACPI_TYPE_REGION, handle, level,
> - acpi_deactivate_mem_region, NULL, res, NULL);
> + status = acpi_walk_namespace(ACPI_TYPE_REGION, handle, level,
> + acpi_deactivate_mem_region, NULL,
> + res, NULL);
> + if (ACPI_FAILURE(status))
> + return status;
> +
> + /*
> + * Wait for all of the mappings queued up for removal by
> + * acpi_deactivate_mem_region() to actually go away.
> + */
> + synchronize_rcu();
> + rcu_barrier();
> + flush_scheduled_work();
> +
> + return AE_OK;
> }
> EXPORT_SYMBOL_GPL(acpi_release_memory);
thanks,
--
heikki
