Hi Pedro, On 6/25/24 12:12 오전, Pedro Tammela wrote: > On 22/06/2024 01:57, yskelg@xxxxxxxxx wrote: >> From: Yunseong Kim <yskelg@xxxxxxxxx> >> >> In the TRACE_EVENT(qdisc_reset) NULL dereference occurred from >> >> qdisc->dev_queue->dev <NULL> ->name >> >> [ 5301.595872] KASAN: null-ptr-deref in range >> [0x0000000000000130-0x0000000000000137] >> [ 5301.595877] Mem abort info: >> [ 5301.595881] ESR = 0x0000000096000006 >> [ 5301.595885] EC = 0x25: DABT (current EL), IL = 32 bits >> [ 5301.595889] SET = 0, FnV = 0 >> [ 5301.595893] EA = 0, S1PTW = 0 >> [ 5301.595896] FSC = 0x06: level 2 translation fault >> [ 5301.595900] Data abort info: >> [ 5301.595903] ISV = 0, ISS = 0x00000006, ISS2 = 0x00000000 >> [ 5301.595907] CM = 0, WnR = 0, TnD = 0, TagAccess = 0 >> [ 5301.595911] GCS = 0, Overlay = 0, DirtyBit = 0, Xs = 0 >> [ 5301.595915] [dfff800000000026] address between user and kernel >> address ranges >> [ 5301.595971] Internal error: Oops: 0000000096000006 [#1] SMP >> Link: >> https://lore.kernel.org/lkml/20240229143432.273b4871@xxxxxxxxxxxxxxxxxx/t/ >> Fixes: 51270d573a8d ("tracing/net_sched: Fix tracepoints that save >> qdisc_dev() as a string") >> Cc: netdev@xxxxxxxxxxxxxxx >> Cc: stable@xxxxxxxxxxxxxxx # +v6.7.10, +v6.8 >> Signed-off-by: Yunseong Kim <yskelg@xxxxxxxxx> >> Signed-off-by: Yeoreum Yun <yeoreum.yun@xxxxxxx> >> --- >> include/trace/events/qdisc.h | 2 +- >> 1 file changed, 1 insertion(+), 1 deletion(-) >> >> diff --git a/include/trace/events/qdisc.h b/include/trace/events/qdisc.h >> index f1b5e816e7e5..170b51fbe47a 100644 >> --- a/include/trace/events/qdisc.h >> +++ b/include/trace/events/qdisc.h >> @@ -81,7 +81,7 @@ TRACE_EVENT(qdisc_reset, >> TP_ARGS(q), >> TP_STRUCT__entry( >> - __string( dev, qdisc_dev(q)->name ) >> + __string(dev, qdisc_dev(q) ? qdisc_dev(q)->name : "noop_queue") >> __string( kind, q->ops->id ) >> __field( u32, parent ) >> __field( u32, handle ) > > You missed the __assign_str portion (see below). Also let's just say > "(null)" as it's the correct device name. "noop_queue" could be misleading. Thanks for the code review Pedro, I agree your advice. > diff --git a/include/trace/events/qdisc.h b/include/trace/events/qdisc.h > index 1f4258308b96..f54e0b4dbcf4 100644 > --- a/include/trace/events/qdisc.h > +++ b/include/trace/events/qdisc.h > @@ -81,14 +81,14 @@ TRACE_EVENT(qdisc_reset, > TP_ARGS(q), > > TP_STRUCT__entry( > - __string( dev, qdisc_dev(q)->name ) > + __string( dev, qdisc_dev(q) ? > qdisc_dev(q)->name : "(null)" ) > __string( kind, q->ops->id ) > __field( u32, parent ) > __field( u32, handle ) > ), It looks better to align the name with the current convention. Link: https://lore.kernel.org/linux-trace-kernel/20240222211442.634192653@xxxxxxxxxxx/ > TP_fast_assign( > - __assign_str(dev, qdisc_dev(q)->name); > + __assign_str(dev, qdisc_dev(q) ? qdisc_dev(q)->name : > "(null)"); > __assign_str(kind, q->ops->id); > __entry->parent = q->parent; > __entry->handle = q->handle; > > The second part you mentioned, Steve recently worked on it and changed it. Link: https://lore.kernel.org/linux-trace-kernel/20240516133454.681ba6a0@xxxxxxxxxxxxxxxxxxxx/ If it hadn't, I don't think I would have been able to prevent the panic by just applying my patch. Link: https://lore.kernel.org/all/e2f9da4e-919d-4a98-919d-167726ef6bc7@xxxxxxxxx/ Warm Regards, Yunseong Kim
