commit 202b52b7fbf7 ("drm: Track drm_mm nodes with an interval tree") introduced a requirement that the special drm_mm.head_node was initialised and marked as not being allocated. It is a very special node that has no side but has a hole that represents the drm_mm address space, and holds the list of nodes. Since it is not a real node, it is not part of the node rbtree and we detect this as it being unallocated. This presumed that drm_mm_init() was initialising it to zero. It happens that i915 kzallocs its objects and so it was accidentally setting it, but for generic use we cannot make that assumption.
[ 22.981519] general protection fault: 0000 [#1] SMP [ 22.981521] Modules linked in: test_drm_mm(+) ctr ccm arc4 rt2800usb rt2x00usb rt2800lib rt2x00lib crc_ccitt mac80211 cmac rfcomm bnep snd_hda_codec_realtek snd_hda_codec_hdmi snd_hda_codec_generic snd_hda_intel dcdbas snd_hda_codec x86_pkg_temp_thermal intel_powerclamp btusb snd_hda_core coretemp crct10dif_pclmul cfg80211 btrtl btbcm btintel bluetooth crc32_pclmul ghash_clmulni_intel aesni_intel snd_pcm i2c_hid aes_x86_64 lrw gf128mul glue_helper ablk_helper cryptd snd_timer hid_multitouch snd joydev serio_raw lpc_ich mfd_core i2c_designware_platform i2c_designware_core 8250_dw binfmt_misc soundcore acpi_pad nls_iso8859_1 usbhid hid psmouse ahci libahci [last unloaded: test_drm_mm] [ 22.981544] CPU: 1 PID: 2088 Comm: drm_mm Tainted: G W 4.9.0-rc7+ #234 [ 22.981545] Hardware name: Dell Inc. XPS 13 9343/0310JH, BIOS A07 11/11/2015 [ 22.981546] task: ffff88020c971cc0 task.stack: ffffc90001728000 [ 22.981547] RIP: 0010:[<ffffffff814050f0>] [<ffffffff814050f0>] drm_mm_interval_tree_add_node+0xa0/0xd0 [ 22.981551] RSP: 0018:ffffc9000172ba98 EFLAGS: 00010202 [ 22.981552] RAX: 0f0000c69cf63d80 RBX: ffff88020be00000 RCX: ffff88020be00000 [ 22.981553] RDX: 0000000000000fff RSI: ffffc9000172bc48 RDI: ffffffff810ac4df [ 22.981553] RBP: ffffc9000172bb08 R08: ffffc9000172bc70 R09: 0000000000000fff [ 22.981554] R10: ffffffff810ac4d7 R11: 4dc04d8b4cffffe5 R12: 0000000000001000 [ 22.981555] R13: ffffc9000172bbd0 R14: ffffc9000172bbe0 R15: 0000000002000000 [ 22.981556] FS: 00007f80c9fab740(0000) GS:ffff88021f480000(0000) knlGS:0000000000000000 [ 22.981557] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 22.981558] CR2: 00007f80c9fd5000 CR3: 000000020c191000 CR4: 00000000003406e0 [ 22.981559] Stack: [ 22.981560] ffffffff81405d09 ffff88020be00000 ffffc9000172bbe0 000000000172bb08 [ 22.981562] ffffffffffffffff 0000000000000000 0000000000000000 0000000000000000 [ 22.981563] 0000000002000000 0000000002000000 ffffffffa02f3000 ffff88020be00000 [ 22.981565] Call Trace: [ 22.981568] [<ffffffff81405d09>] ? drm_mm_insert_node_generic+0x229/0x310 [ 22.981570] [<ffffffffa02f3000>] ? 0xffffffffa02f3000 [ 22.981572] [<ffffffffa02903c1>] __subtest_insert_range.constprop.7+0xd1/0x5b0 [test_drm_mm] [ 22.981575] [<ffffffff81081222>] ? default_wake_function+0x12/0x20 [ 22.981576] [<ffffffff81096905>] ? __wake_up_common+0x55/0x90 [ 22.981578] [<ffffffff81085f42>] ? sched_clock_cpu+0x72/0xa0 [ 22.981581] [<ffffffff811308ad>] ? irq_work_queue+0xd/0x80 [ 22.981582] [<ffffffff810abcc4>] ? wake_up_klogd+0x34/0x40 [ 22.981584] [<ffffffff810ac19d>] ? console_unlock+0x4cd/0x530 [ 22.981585] [<ffffffff810ac4d7>] ? vprintk_emit+0x2d7/0x490 [ 22.981587] [<ffffffff810ac82f>] ? vprintk_default+0x1f/0x30 [ 22.981589] [<ffffffff81146e1c>] ? printk+0x4d/0x4f [ 22.981590] [<ffffffffa02f3000>] ? 0xffffffffa02f3000 [ 22.981592] [<ffffffffa02908b5>] subtest_insert_range+0x15/0x80 [test_drm_mm] [ 22.981594] [<ffffffffa02f3088>] test_drm_mm_init+0x88/0x1000 [test_drm_mm] [ 22.981597] [<ffffffff8100043d>] do_one_initcall+0x3d/0x150 [ 22.981600] [<ffffffff8119dfbf>] ? kfree+0x13f/0x180 [ 22.981602] [<ffffffff811471f2>] do_init_module+0x60/0x1f1 [ 22.981606] [<ffffffff810db878>] load_module+0x2228/0x2790 [ 22.981608] [<ffffffff810d8590>] ? __symbol_put+0x40/0x40 [ 22.981612] [<ffffffff811c52b1>] ? kernel_read+0x41/0x60 [ 22.981614] [<ffffffff810dbfb6>] SYSC_finit_module+0x96/0xd0 [ 22.981617] [<ffffffff810dc00e>] SyS_finit_module+0xe/0x10 [ 22.981620] [<ffffffff816e7aa4>] entry_SYSCALL_64_fastpath+0x17/0x98 [ 22.981622] Code: c7 41 30 00 00 00 00 48 89 e5 48 89 3a 48 c7 c2 20 4e 40 81 e8 b2 a1 f0 ff 5d c3 48 8d 56 78 45 31 d2 48 89 d6 eb 25 48 8b 51 58 <48> 39 50 38 73 04 48 89 50 38 4c 8b 58 28 4c 39 59 48 48 8d 50 [ 22.981651] RIP [<ffffffff814050f0>] drm_mm_interval_tree_add_node+0xa0/0xd0 [ 22.981655] RSP <ffffc9000172ba98>
Testcase: igt/drm_mm Fixes: 202b52b7fbf7 ("drm: Track drm_mm nodes with an interval tree") Signed-off-by: Chris Wilson chris@chris-wilson.co.uk Cc: David Herrmann dh.herrmann@gmail.com Cc: dri-devel@lists.freedesktop.org Cc: Daniel Vetter daniel.vetter@ffwll.ch Cc: drm-intel-fixes@lists.freedesktop.org # v4.9-rc1+ --- drivers/gpu/drm/drm_mm.c | 1 + 1 file changed, 1 insertion(+)
diff --git a/drivers/gpu/drm/drm_mm.c b/drivers/gpu/drm/drm_mm.c index b5b0b667677d..952e4594f181 100644 --- a/drivers/gpu/drm/drm_mm.c +++ b/drivers/gpu/drm/drm_mm.c @@ -902,6 +902,7 @@ void drm_mm_init(struct drm_mm * mm, u64 start, u64 size)
/* Clever trick to avoid a special case in the free hole tracking. */ INIT_LIST_HEAD(&mm->head_node.node_list); + mm->head_node.allocated = 0; mm->head_node.hole_follows = 1; mm->head_node.scanned_block = 0; mm->head_node.scanned_prev_free = 0;