Re: kern/57833: kernel panic on xorg exit

[Taylor R Campbell <riastradh%NetBSD.org@localhost>]

The following reply was made to PR kern/57833; it has been noted by GNATS.

From: Taylor R Campbell <riastradh%NetBSD.org@localhost>
To: Ramiro Aceves <ea1abz%gmail.com@localhost>,
	"David H. Gutteridge" <david%gutteridge.ca@localhost>
Cc: gnats-bugs%NetBSD.org@localhost, netbsd-bugs%NetBSD.org@localhost
Subject: Re: kern/57833: kernel panic on xorg exit
Date: Thu, 11 Jan 2024 03:35:34 +0000

 This is a multi-part message in MIME format.
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 Aside from working around the symptom -- do you get a core dump, and do you
 have netbsd.gdb for a kernel which produces it?
 
 If so, can you go to the i915_gem_object_release_mmap_offset frame,
 and print some information?
 
 # gdb ./netbsd.gdb
 (gdb) target kvm netbsd.42.core
 (gdb) frame 3            # or whatever the frame number is
 (gdb) info locals
 (gdb) print *obj
 (gdb) print *obj->mm.pages
 (gdb) print obj->mm.pages->sgl->sg_pgs[0]
 
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 Content-Type: text/plain; charset="ISO-8859-1"; name="pr57833-i915gemrelmmapoffnullpage"
 Content-Transfer-Encoding: quoted-printable
 Content-Disposition: attachment; filename="pr57833-i915gemrelmmapoffnullpage.patch"
 
 diff --git a/sys/external/bsd/drm2/dist/drm/i915/gem/i915_gem_mman.c b/sys/=
 external/bsd/drm2/dist/drm/i915/gem/i915_gem_mman.c
 index 8e592f008ef7..276ebbdbc234 100644
 --- a/sys/external/bsd/drm2/dist/drm/i915/gem/i915_gem_mman.c
 +++ b/sys/external/bsd/drm2/dist/drm/i915/gem/i915_gem_mman.c
 @@ -677,6 +677,8 @@ void i915_gem_object_release_mmap_offset(struct drm_i91=
 5_gem_object *obj)
  		return;
  	for (i =3D 0; i < obj->base.size >> PAGE_SHIFT; i++) {
  		page =3D obj->mm.pages->sgl->sg_pgs[i];
 +		if (page =3D=3D NULL)
 +			continue;
  		vm_page =3D &page->p_vmp;
  		pmap_page_protect(vm_page, VM_PROT_NONE);
  	}
 
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