Quoting Sebastian Andrzej Siewior (2019-09-04 04:00:38) > On 2019-08-22 15:55:19 [+1000], Herbert Xu wrote: > > Patch applied. Thanks. > [ ff296293b3538 ("random: Support freezable kthreads in add_hwgenerator_randomness()") ] > > and since kthread_freezable_should_stop() has might_sleep() in it, I get > this: > > |: do not call blocking ops when !TASK_RUNNING; state=1 set at [<00000000349d1489>] prepare_to_wait_event+0x5a/0x180 > |: WARNING: CPU: 0 PID: 828 at kernel/sched/core.c:6741 __might_sleep+0x6f/0x80 > |: Modules linked in: > |: > |: CPU: 0 PID: 828 Comm: hwrng Not tainted 5.3.0-rc7-next-20190903+ #46 > |: RIP: 0010:__might_sleep+0x6f/0x80 > … > |: Call Trace: > |: kthread_freezable_should_stop+0x1b/0x60 > |: add_hwgenerator_randomness+0xdd/0x130 > |: hwrng_fillfn+0xbf/0x120 > |: kthread+0x10c/0x140 > |: ret_from_fork+0x27/0x50 > Ugh ok. Thanks for the report. We're getting warnings because the task is in TASK_INTERRUPTIBLE state when we call kthread_freezable_should_stop() from deep within the wait event code. We shouldn't do that, and instead we should call wait_event_freezable() and kthread_should_stop() in the condition. This way we'll call into the freezer when the task is woken up by the suspend path. Can you try this? diff --git a/drivers/char/random.c b/drivers/char/random.c index 9b54cdb301d3..d3beed084c0a 100644 --- a/drivers/char/random.c +++ b/drivers/char/random.c @@ -327,6 +327,7 @@ #include <linux/percpu.h> #include <linux/cryptohash.h> #include <linux/fips.h> +#include <linux/freezer.h> #include <linux/ptrace.h> #include <linux/workqueue.h> #include <linux/irq.h> @@ -2429,7 +2430,6 @@ void add_hwgenerator_randomness(const char *buffer, size_t count, size_t entropy) { struct entropy_store *poolp = &input_pool; - bool frozen = false; if (unlikely(crng_init == 0)) { crng_fast_load(buffer, count); @@ -2440,13 +2440,11 @@ void add_hwgenerator_randomness(const char *buffer, size_t count, * We'll be woken up again once below random_write_wakeup_thresh, * or when the calling thread is about to terminate. */ - wait_event_interruptible(random_write_wait, - kthread_freezable_should_stop(&frozen) || + wait_event_freezable(random_write_wait, + kthread_should_stop() || ENTROPY_BITS(&input_pool) <= random_write_wakeup_bits); - if (!frozen) { - mix_pool_bytes(poolp, buffer, count); - credit_entropy_bits(poolp, entropy); - } + mix_pool_bytes(poolp, buffer, count); + credit_entropy_bits(poolp, entropy); } EXPORT_SYMBOL_GPL(add_hwgenerator_randomness);