Bjorn Helgaas wrote:
> On Wed, Jul 26, 2023 at 11:29:42AM -0700, Ira Weiny wrote:
> > The following debug object splat was observed in testing.
> >
> > [ 14.061937] ------------[ cut here ]------------
> > [ 14.063899] ODEBUG: free active (active state 0) object: 0000000097d23782 object type: work_struct hint: doe_statemachine_work+0x0/0x510
> > [ 14.067480] WARNING: CPU: 1 PID: 71 at lib/debugobjects.c:514 debug_print_object+0x7d/0xb0
> > ...
> > [ 14.080951] Workqueue: pci 0000:36:00.0 DOE [1 doe_statemachine_work
> > [ 14.083485] RIP: 0010:debug_print_object+0x7d/0xb0
> > ...
> > [ 14.116231] Call Trace:
> > [ 14.117652] <TASK>
> > [ 14.118958] ? debug_print_object+0x7d/0xb0
> > [ 14.120782] ? __warn+0x7d/0x130
> > [ 14.122399] ? debug_print_object+0x7d/0xb0
> > [ 14.123746] ? report_bug+0x18d/0x1c0
> > [ 14.125025] ? handle_bug+0x3c/0x80
> > [ 14.126506] ? exc_invalid_op+0x13/0x60
> > [ 14.127796] ? asm_exc_invalid_op+0x16/0x20
> > [ 14.129380] ? debug_print_object+0x7d/0xb0
> > [ 14.130688] ? debug_print_object+0x7d/0xb0
> > [ 14.131997] ? __pfx_doe_statemachine_work+0x10/0x10
> > [ 14.133597] debug_object_free.part.0+0x11b/0x150
> > [ 14.134940] doe_statemachine_work+0x45e/0x510
> > [ 14.136348] process_one_work+0x1d4/0x3c0
> > ...
> > [ 14.161484] </TASK>
> > [ 14.162434] ---[ end trace 0000000000000000 ]---
> >
> > This occurs because destroy_work_on_stack() was called after signaling
> > the completion in the calling thread. This creates a race between
> > destroy_work_on_stack() and the task->work struct going of scope in the
> > pci_doe().
> >
> > Signal the work complete after destroying the work struct. This is safe
> > because signal_task_complete() is the final thing the work item does and
> > the workqueue code is careful not to access the work struct after.
> >
> > Fixes: abf04be0e707 ("PCI/DOE: Fix memory leak with CONFIG_DEBUG_OBJECTS=y")
> > Cc: Lukas Wunner <lukas@xxxxxxxxx>
> > Signed-off-by: Ira Weiny <ira.weiny@xxxxxxxxx>
>
> Thanks, applied to pci/misc with Lukas' reviewed-by and Dan's ack for
> v6.6. I edited out the timestamps and some of the call trace from the
> splat because they didn't seem relevant.
>
Thanks. I'll make sure to remove the timestamps in future.
Ira
