On Mon, 23 Jan 2023 16:33:36 -0800
Ira Weiny <ira.weiny@xxxxxxxxx> wrote:
> Lukas Wunner wrote:
> > Gregory Price reports a WARN splat with CONFIG_DEBUG_OBJECTS=y upon CXL
> > probing because pci_doe_submit_task() invokes INIT_WORK() instead of
> > INIT_WORK_ONSTACK() for a work_struct that was allocated on the stack.
> >
> > All callers of pci_doe_submit_task() allocate the work_struct on the
> > stack, so replace INIT_WORK() with INIT_WORK_ONSTACK() as a backportable
> > short-term fix.
> >
> > Stacktrace for posterity:
> >
> > WARNING: CPU: 0 PID: 23 at lib/debugobjects.c:545 __debug_object_init.cold+0x18/0x183
> > CPU: 0 PID: 23 Comm: kworker/u2:1 Not tainted 6.1.0-0.rc1.20221019gitaae703b02f92.17.fc38.x86_64 #1
> > Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS rel-1.16.0-0-gd239552ce722-prebuilt.qemu.org 04/01/2014
> > Call Trace:
> > pci_doe_submit_task+0x5d/0xd0
> > pci_doe_discovery+0xb4/0x100
> > pcim_doe_create_mb+0x219/0x290
> > cxl_pci_probe+0x192/0x430
> > local_pci_probe+0x41/0x80
> > pci_device_probe+0xb3/0x220
> > really_probe+0xde/0x380
> > __driver_probe_device+0x78/0x170
> > driver_probe_device+0x1f/0x90
> > __driver_attach_async_helper+0x5c/0xe0
> > async_run_entry_fn+0x30/0x130
> > process_one_work+0x294/0x5b0
> >
> > Fixes: 9d24322e887b ("PCI/DOE: Add DOE mailbox support functions")
> > Link: https://lore.kernel.org/linux-cxl/Y1bOniJliOFszvIK@xxxxxxxxxxxx/
> > Reported-by: Gregory Price <gregory.price@xxxxxxxxxxxx>
> > Tested-by: Ira Weiny <ira.weiny@xxxxxxxxx>
>
> Reviewed-by: Ira Weiny <ira.weiny@xxxxxxxxx>
It's an unusual requirement, but this is indeed the minimal fix
given current users. Obviously becomes more sensible later in the
series once you make the API synchronous only.
Reviewed-by: Jonathan Cameron <Jonathan.Cameron@xxxxxxxxx>
>
> > Signed-off-by: Lukas Wunner <lukas@xxxxxxxxx>
> > Cc: stable@xxxxxxxxxxxxxxx # v6.0+
> > Cc: Jonathan Cameron <Jonathan.Cameron@xxxxxxxxxx>
> > ---
> > Changes v1 -> v2:
> > * Add note in kernel-doc of pci_doe_submit_task() that pci_doe_task must
> > be allocated on the stack (Jonathan)
> >
> > drivers/pci/doe.c | 4 +++-
> > 1 file changed, 3 insertions(+), 1 deletion(-)
> >
> > diff --git a/drivers/pci/doe.c b/drivers/pci/doe.c
> > index 66d9ab288646..12a6752351bf 100644
> > --- a/drivers/pci/doe.c
> > +++ b/drivers/pci/doe.c
> > @@ -520,6 +520,8 @@ EXPORT_SYMBOL_GPL(pci_doe_supports_prot);
> > * task->complete will be called when the state machine is done processing this
> > * task.
> > *
> > + * @task must be allocated on the stack.
> > + *
> > * Excess data will be discarded.
> > *
> > * RETURNS: 0 when task has been successfully queued, -ERRNO on error
> > @@ -541,7 +543,7 @@ int pci_doe_submit_task(struct pci_doe_mb *doe_mb, struct pci_doe_task *task)
> > return -EIO;
> >
> > task->doe_mb = doe_mb;
> > - INIT_WORK(&task->work, doe_statemachine_work);
> > + INIT_WORK_ONSTACK(&task->work, doe_statemachine_work);
> > queue_work(doe_mb->work_queue, &task->work);
> > return 0;
> > }
> > --
> > 2.39.1
> >
>
>
