On Mon, Apr 25, 2016 at 05:20:10PM -0400, Dan Streetman wrote:
> Add a work_struct to struct zpool, and change zpool_destroy_pool to
> defer calling the pool implementation destroy.
>
> The zsmalloc pool destroy function, which is one of the zpool
> implementations, may sleep during destruction of the pool. However
> zswap, which uses zpool, may call zpool_destroy_pool from atomic
> context. So we need to defer the call to the zpool implementation
> to destroy the pool.
>
> This is essentially the same as Yu Zhao's proposed patch to zsmalloc,
> but moved to zpool.
Thanks, Dan. Sergey also mentioned another call path that triggers the
same problem (BUG: scheduling while atomic):
rcu_process_callbacks()
__zswap_pool_release()
zswap_pool_destroy()
zswap_cpu_comp_destroy()
cpu_notifier_register_begin()
mutex_lock(&cpu_add_remove_lock);
So I was thinking zswap_pool_destroy() might be done in workqueue in zswap.c.
This way we fix both call paths.
Or you have another patch to fix the second call path?
