Re: [BUG][2.6.38] IRQ Lock Inversion / i915 fails
From: Knut Petersen
Date: Thu Mar 17 2011 - 19:34:07 EST
Am 17.03.2011 17:55, schrieb Linus Torvalds:
> Ok, so the lock inversion seems to be due to the sound/drivers/aloop.c
> file, where the function "loopback_pos_update()" gets called from
> within a softirq context. And it takes a lock (cable->lock) that is
> also taken unprotected by loopback_trigger(). So that's liable to
> deadlock as per lockdep. Jaroslav? Takashi?
Takashi Iwai already gave a solution for the irq inversion problem.
> The X problem seems to be something unrelated. You have those "GPU
> hung" messages, along with i2c/EDID problems. But the actual oops is
> at the very beginning of intel_release_load_detect_pipe(), here:
> 0: 55 push %ebp
> 1: 89 e5 mov %esp,%ebp
> 3: 57 push %edi
> 4: 89 cf mov %ecx,%edi
> 6: 56 push %esi
> 7: 53 push %ebx
> 8: 89 c3 mov %eax,%ebx
> a: 83 ec 0c sub $0xc,%esp
> d: 8b 00 mov (%eax),%eax
> f: 8b 73 20 mov 0x20(%ebx),%esi
> 12: 80 7b 30 00 cmpb $0x0,0x30(%ebx)
> 16: 8b 4b 28 mov 0x28(%ebx),%ecx
> 19: 89 45 f0 mov %eax,-0x10(%ebp)
> 1c:* 8b 86 e0 01 00 00 mov 0x1e0(%esi),%eax <-- trapping
> 22: 89 45 ec mov %eax,-0x14(%ebp)
> 25: 74 2d je 0x54
> 27: c7 43 20 00 00 00 00 movl $0x0,0x20(%ebx)
> 2e: 89 f0 mov %esi,%eax
> where %esi is NULL. I think that is the "crtc->helper_private" load,
> and crtc is NULL.
> That code does look broken. The very same function explicitly sets
> crtc to NULL, so clearly it _can_ be NULL. That said, this is all old
> code. I suspect the thing that made it start trigger may be commit
> f5afcd3dd0dc ("drm/i915/crt: Check for a analog monitor in case of
> DVI-I"), which is the only real change to the crt_detect logic I can
Well, I think there are two i915 problems that are independent.
The i2c/edid thing might be related to the f5a...commit, but reverting
that commit alone does not help. i2c/edid error messages might be before
or after the "gpu hung" problem, Xorg seems to be able to cope with that.
But after a gpu lockup it's time to reboot.
If nobody has a better idea I'll try to bisect ... tomorrow.
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