4.9-stable review patch. If anyone has any objections, please let me know. ------------------ From: Miaoqing Pan <miaoqing@xxxxxxxxxxxxxx> commit 07246c115801c27652700e3679bb58661ef7ed65 upstream. The bug was triggered when do suspend/resuming continuously on Dell XPS L322X/0PJHXN version 9333 (2013) with kernel 4.12.0-041200rc4-generic. But can't reproduce on DELL E5440 + AR9300 PCIE chips. The warning is caused by accessing invalid pointer sc->rng_task. sc->rng_task is not be cleared after kthread_stop(sc->rng_task) be called in ath9k_rng_stop(). Because the kthread is stopped before ath9k_rng_kthread() be scheduled. So set sc->rng_task to null after kthread_stop(sc->rng_task) to resolve this issue. WARNING: CPU: 0 PID: 984 at linux/kernel/kthread.c:71 kthread_stop+0xf1/0x100 CPU: 0 PID: 984 Comm: NetworkManager Not tainted 4.12.0-041200rc4-generic #201706042031 Hardware name: Dell Inc. Dell System XPS L322X/0PJHXN, BIOS A09 05/15/2013 task: ffff950170fdda00 task.stack: ffffa22c01538000 RIP: 0010:kthread_stop+0xf1/0x100 RSP: 0018:ffffa22c0153b5b0 EFLAGS: 00010246 RAX: ffffffffa6257800 RBX: ffff950171b79560 RCX: 0000000000000000 RDX: 0000000080000000 RSI: 000000007fffffff RDI: ffff9500ac9a9680 RBP: ffffa22c0153b5c8 R08: 0000000000000000 R09: 0000000000000000 R10: ffffa22c0153b648 R11: ffff9501768004b8 R12: ffff9500ac9a9680 R13: ffff950171b79f70 R14: ffff950171b78780 R15: ffff9501749dc018 FS: 00007f0d6bfd5540(0000) GS:ffff95017f200000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007fc190161a08 CR3: 0000000232906000 CR4: 00000000001406f0 Call Trace: ath9k_rng_stop+0x1a/0x20 [ath9k] ath9k_stop+0x3b/0x1d0 [ath9k] drv_stop+0x33/0xf0 [mac80211] ieee80211_stop_device+0x43/0x50 [mac80211] ieee80211_do_stop+0x4f2/0x810 [mac80211] Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=196043 Reported-by: Giulio Genovese <giulio.genovese@xxxxxxxxx> Tested-by: Giulio Genovese <giulio.genovese@xxxxxxxxx> Signed-off-by: Miaoqing Pan <miaoqing@xxxxxxxxxxxxxx> Signed-off-by: Kalle Valo <kvalo@xxxxxxxxxxxxxxxx> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- drivers/net/wireless/ath/ath9k/rng.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) --- a/drivers/net/wireless/ath/ath9k/rng.c +++ b/drivers/net/wireless/ath/ath9k/rng.c @@ -120,6 +120,8 @@ void ath9k_rng_start(struct ath_softc *s void ath9k_rng_stop(struct ath_softc *sc) { - if (sc->rng_task) + if (sc->rng_task) { kthread_stop(sc->rng_task); + sc->rng_task = NULL; + } }