[
{
"CollectPEBSRecord": "1",
"PublicDescription": "Counts the number of times the machine was unable to find a translation in the Instruction Translation Lookaside Buffer (ITLB) for a linear address of an instruction fetch. It counts when new translation are filled into the ITLB. The event is speculative in nature, but will not count translations (page walks) that are begun and not finished, or translations that are finished but not filled into the ITLB.",
"EventCode": "0x81",
"Counter": "0,1,2,3",
"UMask": "0x4",
"EventName": "ITLB.MISS",
"SampleAfterValue": "200003",
"BriefDescription": "ITLB misses"
},
{
"PEBS": "2",
"CollectPEBSRecord": "2",
"PublicDescription": "Counts load uops retired that caused a DTLB miss.",
"EventCode": "0xD0",
"Counter": "0,1,2,3",
"UMask": "0x11",
"EventName": "MEM_UOPS_RETIRED.DTLB_MISS_LOADS",
"SampleAfterValue": "200003",
"BriefDescription": "Load uops retired that missed the DTLB (Precise event capable)"
},
{
"PEBS": "2",
"CollectPEBSRecord": "2",
"PublicDescription": "Counts store uops retired that caused a DTLB miss.",
"EventCode": "0xD0",
"Counter": "0,1,2,3",
"UMask": "0x12",
"EventName": "MEM_UOPS_RETIRED.DTLB_MISS_STORES",
"SampleAfterValue": "200003",
"BriefDescription": "Store uops retired that missed the DTLB (Precise event capable)"
},
{
"PEBS": "2",
"CollectPEBSRecord": "2",
"PublicDescription": "Counts uops retired that had a DTLB miss on load, store or either. Note that when two distinct memory operations to the same page miss the DTLB, only one of them will be recorded as a DTLB miss.",
"EventCode": "0xD0",
"Counter": "0,1,2,3",
"UMask": "0x13",
"EventName": "MEM_UOPS_RETIRED.DTLB_MISS",
"SampleAfterValue": "200003",
"BriefDescription": "Memory uops retired that missed the DTLB (Precise event capable)"
},
{
"CollectPEBSRecord": "1",
"PublicDescription": "Counts every core cycle when a Data-side (walks due to a data operation) page walk is in progress.",
"EventCode": "0x05",
"Counter": "0,1,2,3",
"UMask": "0x1",
"EventName": "PAGE_WALKS.D_SIDE_CYCLES",
"SampleAfterValue": "200003",
"BriefDescription": "Duration of D-side page-walks in cycles"
},
{
"CollectPEBSRecord": "1",
"PublicDescription": "Counts every core cycle when a Instruction-side (walks due to an instruction fetch) page walk is in progress.",
"EventCode": "0x05",
"Counter": "0,1,2,3",
"UMask": "0x2",
"EventName": "PAGE_WALKS.I_SIDE_CYCLES",
"SampleAfterValue": "200003",
"BriefDescription": "Duration of I-side pagewalks in cycles"
},
{
"CollectPEBSRecord": "1",
"PublicDescription": "Counts every core cycle a page-walk is in progress due to either a data memory operation or an instruction fetch.",
"EventCode": "0x05",
"Counter": "0,1,2,3",
"UMask": "0x3",
"EventName": "PAGE_WALKS.CYCLES",
"SampleAfterValue": "200003",
"BriefDescription": "Duration of page-walks in cycles"
}
]n>
drm/i915: Check for NULL i915_vma in intel_unpin_fb_obj()
I've seen this trigger twice now, where the i915_gem_object_to_ggtt()
call in intel_unpin_fb_obj() returns NULL, resulting in an oops
immediately afterwards as the (inlined) call to i915_vma_unpin_fence()
tries to dereference it.
It seems to be some race condition where the object is going away at
shutdown time, since both times happened when shutting down the X
server. The call chains were different:
- VT ioctl(KDSETMODE, KD_TEXT):
intel_cleanup_plane_fb+0x5b/0xa0 [i915]
drm_atomic_helper_cleanup_planes+0x6f/0x90 [drm_kms_helper]
intel_atomic_commit_tail+0x749/0xfe0 [i915]
intel_atomic_commit+0x3cb/0x4f0 [i915]
drm_atomic_commit+0x4b/0x50 [drm]
restore_fbdev_mode+0x14c/0x2a0 [drm_kms_helper]
drm_fb_helper_restore_fbdev_mode_unlocked+0x34/0x80 [drm_kms_helper]
drm_fb_helper_set_par+0x2d/0x60 [drm_kms_helper]
intel_fbdev_set_par+0x18/0x70 [i915]
fb_set_var+0x236/0x460
fbcon_blank+0x30f/0x350
do_unblank_screen+0xd2/0x1a0
vt_ioctl+0x507/0x12a0
tty_ioctl+0x355/0xc30
do_vfs_ioctl+0xa3/0x5e0
SyS_ioctl+0x79/0x90
entry_SYSCALL_64_fastpath+0x13/0x94
- i915 unpin_work workqueue:
intel_unpin_work_fn+0x58/0x140 [i915]
process_one_work+0x1f1/0x480
worker_thread+0x48/0x4d0
kthread+0x101/0x140
and this patch purely papers over the issue by adding a NULL pointer
check and a WARN_ON_ONCE() to avoid the oops that would then generally
make the machine unresponsive.
Other callers of i915_gem_object_to_ggtt() seem to also check for the
returned pointer being NULL and warn about it, so this clearly has
happened before in other places.
[ Reported it originally to the i915 developers on Jan 8, applying the
ugly workaround on my own now after triggering the problem for the
second time with no feedback.
This is likely to be the same bug reported as
https://bugs.freedesktop.org/show_bug.cgi?id=98829
https://bugs.freedesktop.org/show_bug.cgi?id=99134
which has a patch for the underlying problem, but it hasn't gotten to
me, so I'm applying the workaround. ]
Cc: Daniel Vetter <daniel.vetter@intel.com>
Cc: Jani Nikula <jani.nikula@linux.intel.com>
Cc: Ville Syrjälä <ville.syrjala@linux.intel.com>
Cc: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
Cc: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Cc: Imre Deak <imre.deak@intel.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>