| Message ID | ba25ffe3-9db7-2311-51c7-91fce0ce8cfa@gmail.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On Wed, Jun 07, 2017 at 11:36:14AM +0800, Joseph Qi wrote: > From: Joseph Qi <qijiang.qj@alibaba-inc.com> > > 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. > > Fixes: 297e3d854784 ("blk-throttle: make throtl_slice tunable") > Signed-off-by: Joseph Qi <qijiang.qj@alibaba-inc.com> Thanks! Reviewed-by: Shaohua Li <shli@fb.com> > --- > block/blk-throttle.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/block/blk-throttle.c b/block/blk-throttle.c > index fc13dd0..3b751f7 100644 > --- a/block/blk-throttle.c > +++ b/block/blk-throttle.c > @@ -698,7 +698,7 @@ static void throtl_dequeue_tg(struct throtl_grp *tg) > static void throtl_schedule_pending_timer(struct throtl_service_queue *sq, > unsigned long expires) > { > - unsigned long max_expire = jiffies + 8 * sq_to_tg(sq)->td->throtl_slice; > + unsigned long max_expire = jiffies + 8 * sq_to_td(sq)->throtl_slice; > > /* > * Since we are adjusting the throttle limit dynamically, the sleep > -- > 1.9.4
On 06/06/2017 09:36 PM, Joseph Qi wrote: > From: Joseph Qi <qijiang.qj@alibaba-inc.com> > > 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.
diff --git a/block/blk-throttle.c b/block/blk-throttle.c index fc13dd0..3b751f7 100644 --- a/block/blk-throttle.c +++ b/block/blk-throttle.c @@ -698,7 +698,7 @@ static void throtl_dequeue_tg(struct throtl_grp *tg) static void throtl_schedule_pending_timer(struct throtl_service_queue *sq, unsigned long expires) { - unsigned long max_expire = jiffies + 8 * sq_to_tg(sq)->td->throtl_slice; + unsigned long max_expire = jiffies + 8 * sq_to_td(sq)->throtl_slice; /* * Since we are adjusting the throttle limit dynamically, the sleep