2015-07-13 9:23 GMT+02:00 Maarten Lankhorst maarten.lankhorst@linux.intel.com:
Op 13-07-15 om 08:22 schreef Daniel Vetter:
On Sun, Jul 12, 2015 at 09:52:51AM -0700, Linus Torvalds wrote:
On Sun, Jul 12, 2015 at 1:03 AM, Jörg Otte jrg.otte@gmail.com wrote:
BUG: unable to handle kernel NULL pointer dereference at 0000000000000009 IP: [<ffffffffbd3447bb>] 0xffffffffbd3447bb
Ugh. Please enable KALLSYMS to get sane symbols.
But yes, "crtc_state->base.active" is at offset 9 from "crtc_state", so it's pretty clearly just that change frm
if (intel_crtc->active) {
if (crtc_state->base.active) {and "crtc_state" is NULL.
And the code very much knows that crtc_state can be NULL, since it's initialized with
crtc_state = state->base.state ? intel_atomic_get_crtc_state(state->base.state,intel_crtc) : NULL;
Tssk. Daniel? Should I just revert that commit dec4f799d0a4 ("drm/i915: Use crtc_state->active in primary check_plane func") for now, or is there a better fix? Like just checking crtc_state for NULL?
Indeed embarrassing. I've missed that we still have 1 caller left that's using the transitional helpers, and those don't fill out plane_state->state backpointers to the global atomic update since there is no global atomic update for transitional helpers. Below diff should fix this - we need to preferentially check crts_state->active and if that's not set intel_crtc->active should yield the right result for the one remaining caller (it's in the crtc_disable paths).
For cheap excuses why i915 is so crap in 4.2: Thanks to a hipshot decision to transition to a different QA team ("we'll do this in 1 week without upfront planing") I essentially don't have proper QA support for 1-2 months by now. The other trouble in this area specifically is that this code is already completely changed in -next again, so any testing done on integration trees (like -next or drm-intel-nightly) won't test any patches for 4.2. -Daniel
Oh and Signed-off-by: Daniel Vetter daniel.vetter@intel.com in case you decide to apply this right away.
Well your version has the benefit of compiling without errors. :-)
Reviewed-by: Maarten Lankhorst maarten.lankhorst@linux.intel.com
Just noticed another problem: On each resume I get the following error: -----------[ cut here ]------------ WARNING: CPU: 2 PID: 2663 at /data/kernel/linux/drivers/gpu/drm/i915/intel_display.c:6319 0xffffffff9a33d5e9() WARN_ON(!crtc->state->enable) CPU: 2 PID: 2663 Comm: kworker/u8:80 Not tainted 4.2.0-rc2 #15 ardware name: FUJITSU LIFEBOOK AH532/FJNBB1C, BIOS Version 1.09 05/22/2012 orkqueue: events_unbound 0xffffffff9a055750 0000000000000000 ffffffff9a98ea28 ffffffff9a6d84d2 0000000000000000 ffffffff9a03c416 ffff88020951c4e0 0000000000000000 0000000000000000 ffff8802141cb800 ffff88021630c000 ffffffff9a03c4d5 ffffffff9a9c3664 all Trace: [<ffffffff9a6d84d2>] ? 0xffffffff9a6d84d2 [<ffffffff9a03c416>] ? 0xffffffff9a03c416 [<ffffffff9a03c4d5>] ? 0xffffffff9a03c4d5 [<ffffffff9a33d5e9>] ? 0xffffffff9a33d5e9 [<ffffffff9a343ac3>] ? 0xffffffff9a343ac3 [<ffffffff9a34444a>] ? 0xffffffff9a34444a [<ffffffff9a345518>] ? 0xffffffff9a345518 [<ffffffff9a3246f0>] ? 0xffffffff9a3246f0 [<ffffffff9a2e1ce8>] ? 0xffffffff9a2e1ce8 [<ffffffff9a236170>] ? 0xffffffff9a236170 [<ffffffff9a38b28d>] ? 0xffffffff9a38b28d [<ffffffff9a38b784>] ? 0xffffffff9a38b784 [<ffffffff9a38baa4>] ? 0xffffffff9a38baa4 [<ffffffff9a05577d>] ? 0xffffffff9a05577d [<ffffffff9a04dc47>] ? 0xffffffff9a04dc47 [<ffffffff9a04dfab>] ? 0xffffffff9a04dfab [<ffffffff9a04dea0>] ? 0xffffffff9a04dea0 [<ffffffff9a05331c>] ? 0xffffffff9a05331c [<ffffffff9a053260>] ? 0xffffffff9a053260 [<ffffffff9a6dfa0f>] ? 0xffffffff9a6dfa0f [<ffffffff9a053260>] ? 0xffffffff9a053260 --[ end trace 1b6d28ee34071679 ]---
Nervertheless resume works, so it doesn't hurt me.
BTW: I get also up to 40..50! compile warnings like: i915/i915_drv.h: In function 'i915_debugfs_connector_add': i915/i915_drv.h:3119:53: warning: no return statement in function returning non-void [-Wreturn-type]
which may cause yet uncovered troubles.
Thanks, Jörg