From mboxrd@z Thu Jan 1 00:00:00 1970 From: Zhenyu Wang Subject: Re: [PATCH 1/2] drm/i915: Don't deballoon unused ggtt drm_mm_node in linux guest Date: Wed, 21 Aug 2019 11:35:56 +0800 Message-ID: <20190821033556.GA11927@zhen-hp.sh.intel.com> References: <1566279978-9659-1-git-send-email-xiong.y.zhang@intel.com> Reply-To: Zhenyu Wang Mime-Version: 1.0 Content-Type: multipart/mixed; boundary="===============2006493856==" Return-path: In-Reply-To: <1566279978-9659-1-git-send-email-xiong.y.zhang@intel.com> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: intel-gfx-bounces@lists.freedesktop.org Sender: "Intel-gfx" To: Xiong Zhang Cc: intel-gfx@lists.freedesktop.org, intel-gvt-dev@lists.freedesktop.org, stable@vger.kernel.org List-Id: intel-gfx@lists.freedesktop.org --===============2006493856== Content-Type: multipart/signed; micalg=pgp-sha1; protocol="application/pgp-signature"; boundary="7JfCtLOvnd9MIVvH" Content-Disposition: inline --7JfCtLOvnd9MIVvH Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On 2019.08.20 13:46:17 +0800, Xiong Zhang wrote: > The following call trace may exist in linux guest dmesg when guest i915 > driver is unloaded. > [ 90.776610] [drm:vgt_deballoon_space.isra.0 [i915]] deballoon space: r= ange [0x0 - 0x0] 0 KiB. > [ 90.776621] BUG: unable to handle kernel NULL pointer dereference at 0= 0000000000000c0 > [ 90.776691] IP: drm_mm_remove_node+0x4d/0x320 [drm] > [ 90.776718] PGD 800000012c7d0067 P4D 800000012c7d0067 PUD 138e4c067 PM= D 0 > [ 90.777091] task: ffff9adab60f2f00 task.stack: ffffaf39c0fe0000 > [ 90.777142] RIP: 0010:drm_mm_remove_node+0x4d/0x320 [drm] > [ 90.777573] Call Trace: > [ 90.777653] intel_vgt_deballoon+0x4c/0x60 [i915] > [ 90.777729] i915_ggtt_cleanup_hw+0x121/0x190 [i915] > [ 90.777792] i915_driver_unload+0x145/0x180 [i915] > [ 90.777856] i915_pci_remove+0x15/0x20 [i915] > [ 90.777890] pci_device_remove+0x3b/0xc0 > [ 90.777916] device_release_driver_internal+0x157/0x220 > [ 90.777945] driver_detach+0x39/0x70 > [ 90.777967] bus_remove_driver+0x51/0xd0 > [ 90.777990] pci_unregister_driver+0x23/0x90 > [ 90.778019] SyS_delete_module+0x1da/0x240 > [ 90.778045] entry_SYSCALL_64_fastpath+0x24/0x87 > [ 90.778072] RIP: 0033:0x7f34312af067 > [ 90.778092] RSP: 002b:00007ffdea3da0d8 EFLAGS: 00000206 > [ 90.778297] RIP: drm_mm_remove_node+0x4d/0x320 [drm] RSP: ffffaf39c0fe= 3dc0 > [ 90.778344] ---[ end trace f4b1bc8305fc59dd ]--- >=20 > Four drm_mm_node are used to reserve guest ggtt space, but some of them > may be skipped and not initialised due to space constraints in > intel_vgt_balloon(). If drm_mm_remove_node() is called with > uninitialized drm_mm_node, the above call trace occurs. >=20 > This patch check drm_mm_node's validity before calling > drm_mm_remove_node(). >=20 > Fixes: ff8f797557c7("drm/i915: return the correct usable aperture size un= der gvt environment") > Cc: stable@vger.kernel.org > Signed-off-by: Xiong Zhang > --- > drivers/gpu/drm/i915/i915_vgpu.c | 3 +++ > 1 file changed, 3 insertions(+) >=20 > diff --git a/drivers/gpu/drm/i915/i915_vgpu.c b/drivers/gpu/drm/i915/i915= _vgpu.c > index bf2b837..d2fd66f 100644 > --- a/drivers/gpu/drm/i915/i915_vgpu.c > +++ b/drivers/gpu/drm/i915/i915_vgpu.c > @@ -119,6 +119,9 @@ static struct _balloon_info_ bl_info; > static void vgt_deballoon_space(struct i915_ggtt *ggtt, > struct drm_mm_node *node) > { > + if (!node->allocated) > + return; > + > DRM_DEBUG_DRIVER("deballoon space: range [0x%llx - 0x%llx] %llu KiB.\n", > node->start, > node->start + node->size, Searching shows this is pretty old one and also with r-b from Chris, but be ignored that nobody picked this up.. I think I hit this once too and tried to fix it another way, but this looks simpler to me. Acked-by: Zhenyu Wang --=20 Open Source Technology Center, Intel ltd. $gpg --keyserver wwwkeys.pgp.net --recv-keys 4D781827 --7JfCtLOvnd9MIVvH Content-Type: application/pgp-signature; name="signature.asc" -----BEGIN PGP SIGNATURE----- iF0EARECAB0WIQTXuabgHDW6LPt9CICxBBozTXgYJwUCXVy8HAAKCRCxBBozTXgY J7xcAJ9iqr4h7QnTx9tzdFbWg4y/mhDMZgCdHJaG2eTRmA8W3tkLza74nJ3bEiM= =RYoi -----END PGP SIGNATURE----- --7JfCtLOvnd9MIVvH-- --===============2006493856== Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: base64 Content-Disposition: inline X19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX18KSW50ZWwtZ2Z4 IG1haWxpbmcgbGlzdApJbnRlbC1nZnhAbGlzdHMuZnJlZWRlc2t0b3Aub3JnCmh0dHBzOi8vbGlz dHMuZnJlZWRlc2t0b3Aub3JnL21haWxtYW4vbGlzdGluZm8vaW50ZWwtZ2Z4 --===============2006493856==--