> -----Original Message----- > From: Baolu Lu <baolu.lu@xxxxxxxxxxxxxxx> > Sent: Sunday, March 16, 2025 8:04 AM > To: Borah, Chaitanya Kumar <chaitanya.kumar.borah@xxxxxxxxx> > Cc: intel-gfx@xxxxxxxxxxxxxxxxxxxxx; intel-xe@xxxxxxxxxxxxxxxxxxxxx; > iommu@xxxxxxxxxxxxxxx > Subject: Re: Regression on drm-tip > > On 3/14/25 17:04, Borah, Chaitanya Kumar wrote: > > > > > >> -----Original Message----- > >> From: Baolu Lu <baolu.lu@xxxxxxxxxxxxxxx> > >> Sent: Thursday, March 13, 2025 7:53 PM > >> To: Borah, Chaitanya Kumar <chaitanya.kumar.borah@xxxxxxxxx> > >> Cc: baolu.lu@xxxxxxxxxxxxxxx; intel-gfx@xxxxxxxxxxxxxxxxxxxxx; intel- > >> xe@xxxxxxxxxxxxxxxxxxxxx; iommu@xxxxxxxxxxxxxxx > >> Subject: Re: Regression on drm-tip > >> > >> On 2025/3/13 16:51, Borah, Chaitanya Kumar wrote: > >>> Hello Lu, > >>> > >>> Hope you are doing well. I am Chaitanya from the linux graphics team > >>> in > >> Intel. > >>> > >>> This mail is regarding a regression we are seeing in our CI runs[1] > >>> on drm-tip > >> repository. > >>> > >>> ```````````````````````````````````````````````````````````````````` > >>> `` ``````````` <4>[ 2.856622] WARNING: possible circular locking > >>> dependency detected <4>[ 2.856631] > >>> 6.14.0-rc5-CI_DRM_16217-gc55ef90b69d3+ #1 Tainted: G I <4>[ > >>> 2.856642] ------------------------------------------------------ > >>> <4>[ 2.856650] swapper/0/1 is trying to acquire lock: > >>> <4>[ 2.856657] ffffffff8360ecc8 > >>> (iommu_probe_device_lock){+.+.}-{3:3}, at: > >>> iommu_probe_device+0x1d/0x70 <4>[ 2.856679] > >>> but task is already holding lock: > >>> <4>[ 2.856686] ffff888102ab6fa8 > >>> (&device->physical_node_lock){+.+.}-{3:3}, at: > >>> intel_iommu_init+0xea1/0x1220 > >>> ```````````````````````````````````````````````````````````````````` > >>> `` > >>> ``````````` > >>> Details log can be found in [2]. > >>> > >>> After bisecting the tree, the following patch [3] seems to be the > >>> first "bad" commit > >>> > >>> ```````````````````````````````````````````````````````````````````` > >>> `` > >>> ``````````````````````````````````` > >>> commit b150654f74bf0df8e6a7936d5ec51400d9ec06d8 > >>> Author: Lu Baolumailto:baolu.lu@xxxxxxxxxxxxxxx > >>> Date: Fri Feb 28 18:27:26 2025 +0800 > >>> > >>> iommu/vt-d: Fix suspicious RCU usage > >>> > >>> ```````````````````````````````````````````````````````````````````` > >>> `` > >>> ``````````````````````````````````` > >>> > >>> We also verified that if we revert the patch the issue is not seen. > >>> > >>> Could you please check why the patch causes this regression and > >>> provide a > >> fix if necessary? > >> > >> Can you please take a quick test to check if the following fix works? > >> > >> diff --git a/drivers/iommu/intel/dmar.c b/drivers/iommu/intel/dmar.c > >> index > >> e540092d664d..06debeaec643 100644 > >> --- a/drivers/iommu/intel/dmar.c > >> +++ b/drivers/iommu/intel/dmar.c > >> @@ -2051,8 +2051,13 @@ int enable_drhd_fault_handling(unsigned int > cpu) > >> if (iommu->irq || iommu->node != cpu_to_node(cpu)) > >> continue; > >> > >> + /* > >> + * Call dmar_alloc_hwirq() with dmar_global_lock held, > >> + * could cause possible lock race condition. > >> + */ > >> + up_read(&dmar_global_lock); > >> ret = dmar_set_interrupt(iommu); > >> - > >> + down_read(&dmar_global_lock); > >> if (ret) { > >> pr_err("DRHD %Lx: failed to enable fault, interrupt, ret > %d\n", > >> (unsigned long > >> long)drhd->reg_base_addr, ret); > >> > >> Thanks, > >> baolu > > > > We still see the issue with this change. > > I am attempting to reproduce this issue with my MTL machine. I pulled the > test branch from: > > https://anongit.freedesktop.org/git/drm-tip.git > > and built the test kernel image using the configuration file from: > > https://intel-gfx-ci.01.org/tree/drm-tip/CI_DRM_16217/kconfig.txt > > But I did not observe the lockdep splat mentioned above after booting. > > Is there anything I might have missed? > +Suresh, Jani, Lucas We are seeing this only the skykale and kabylake on our CI runs. https://intel-gfx-ci.01.org/tree/drm-tip/igt@runner@xxxxxxxxxxxx Regards Chaitanya > Thanks, > baolu