On Thu, Jan 11, 2024 at 1:46 AM Greg KH <gregkh@xxxxxxxxxxxxxxxxxxx> wrote:
>
> On Tue, Jan 09, 2024 at 10:17:22AM -0800, John Sperbeck wrote:
> > With 5.10LTS (e.g., 5.10.206), on a machine using an NVME device, the
> > following tracing commands will trigger a crash due to a NULL pointer
> > dereference:
> >
> > KDIR=/sys/kernel/debug/tracing
> > echo 1 > $KDIR/tracing_on
> > echo 1 > $KDIR/events/nvme/enable
> > echo "Waiting for trace events..."
> > cat $KDIR/trace_pipe
> >
> > The backtrace looks something like this:
> >
> > Call Trace:
> > <IRQ>
> > ? __die_body+0x6b/0xb0
> > ? __die+0x9e/0xb0
> > ? no_context+0x3eb/0x460
> > ? ttwu_do_activate+0xf0/0x120
> > ? __bad_area_nosemaphore+0x157/0x200
> > ? select_idle_sibling+0x2f/0x410
> > ? bad_area_nosemaphore+0x13/0x20
> > ? do_user_addr_fault+0x2ab/0x360
> > ? exc_page_fault+0x69/0x180
> > ? asm_exc_page_fault+0x1e/0x30
> > ? trace_event_raw_event_nvme_complete_rq+0xba/0x170
> > ? trace_event_raw_event_nvme_complete_rq+0xa3/0x170
> > nvme_complete_rq+0x168/0x170
> > nvme_pci_complete_rq+0x16c/0x1f0
> > nvme_handle_cqe+0xde/0x190
> > nvme_irq+0x78/0x100
> > __handle_irq_event_percpu+0x77/0x1e0
> > handle_irq_event+0x54/0xb0
> > handle_edge_irq+0xdf/0x230
> > asm_call_irq_on_stack+0xf/0x20
> > </IRQ>
> > common_interrupt+0x9e/0x150
> > asm_common_interrupt+0x1e/0x40
> >
> > It looks to me like these two upstream commits were backported to 5.10:
> >
> > 679c54f2de67 ("nvme: use command_id instead of req->tag in trace_nvme_complete_rq()")
> > e7006de6c238 ("nvme: code command_id with a genctr for use-after-free validation")
> >
> > But they depend on this upstream commit to initialize the 'cmd' field in
> > some cases:
> >
> > f4b9e6c90c57 ("nvme: use driver pdu command for passthrough")
> >
> > Does it sound like I'm on the right track? The 5.15LTS and later seems to be okay.
> >
>
> If you apply that commit, does it solve the issue for you?
>
> thanks,
>
> greg k-h
The f4b9e6c90c57 ("nvme: use driver pdu command for passthrough")
upstream commit doesn't apply cleanly to 5.10LTS. If I adjust it to
fit, then the crash no longer occurs for me.
A revert of 706960d328f5 ("nvme: use command_id instead of req->tag in
trace_nvme_complete_rq()") from 5.10LTS also prevents the crash.
My leaning would be for a revert from 5.10LTS, but I think the
maintainers would have better insight then me. It's also possible
that this isn't serious enough to worry about in general. I don't
really know.
