On 06/06/2017 09:36 PM, Joseph Qi wrote: > From: Joseph Qi <qijiang.qj@xxxxxxxxxxxxxxx> > > I have encountered a NULL pointer dereference in > throtl_schedule_pending_timer: > [ 413.735396] BUG: unable to handle kernel NULL pointer dereference at 0000000000000038 > [ 413.735535] IP: [<ffffffff812ebbbf>] throtl_schedule_pending_timer+0x3f/0x210 > [ 413.735643] PGD 22c8cf067 PUD 22cb34067 PMD 0 > [ 413.735713] Oops: 0000 [#1] SMP > ...... > > This is caused by the following case: > blk_throtl_bio > throtl_schedule_next_dispatch <= sq is top level one without parent > throtl_schedule_pending_timer > sq_to_tg(sq)->td->throtl_slice <= sq_to_tg(sq) returns NULL > > Fix it by using sq_to_td instead of sq_to_tg(sq)->td, which will always > return a valid td. Applied, thanks. -- Jens Axboe
