Messages in this thread | | | Date | Tue, 23 Aug 2022 17:54:35 -0700 | From | Jerry Snitselaar <> | Subject | Re: [PATCH v2] dmaengine: idxd: avoid deadlock in process_misc_interrupts() |
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On Tue, Aug 23, 2022 at 09:46:19AM -0700, Dave Jiang wrote: > > On 8/23/2022 9:37 AM, Jerry Snitselaar wrote: > > idxd_device_clear_state() now grabs the idxd->dev_lock > > itself, so don't grab the lock prior to calling it. > > > > This was seen in testing after dmar fault occurred on system, > > resulting in lockup stack traces. > > > > Cc: Fenghua Yu <fenghua.yu@intel.com> > > Cc: Dave Jiang <dave.jiang@intel.com> > > Cc: Vinod Koul <vkoul@kernel.org> > > Cc: dmaengine@vger.kernel.org > > Fixes: cf4ac3fef338 ("dmaengine: idxd: fix lockdep warning on device driver removal") > > Signed-off-by: Jerry Snitselaar <jsnitsel@redhat.com> > > Thanks Jerry! > > Reviewed-by: Dave Jiang <dave.jiang@intel.com> >
I noticed another problem while looking at this. When the device ends up in the halted state, and needs an flr or system reset, it calls idxd_wqs_unmap_portal(). Then if you do a modprobe -r idxd, you hit the WARN_ON in devm_iounmap(), because the remove code path calls idxd_wq_portal_unmap(), and wq->portal is null. I'm not sure if it just needs a simple sanity check in drv_disable_wq() to avoid the call in the case that it has already been unmapped, or if more cleanup needs to be done, and possibly a state to differentiate between halted + soft reset possible, versus halted + flr or system reset needed. You get multiple "Device is HALTED" messages during the removal as well.
Regards, Jerry
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