[PATCH] arm64: cache: Lower ARCH_DMA_MINALIGN to 64 (L1_CACHE_BYTES)
Will Deacon
will at kernel.org
Mon Jun 7 13:39:54 UTC 2021
[Adding VC4 folks -- please see the KASAN splat below!]
Background here is that reducing ARCH_DMA_MINALIGN to 64 on arm64 (queued in
-next) is causing vc4 to hang on Rpi3b due to a probable driver bug.
Will
On Mon, Jun 07, 2021 at 02:08:59PM +0100, Mark Rutland wrote:
> On Mon, Jun 07, 2021 at 01:01:18PM +0100, Mark Rutland wrote:
> > On Mon, Jun 07, 2021 at 11:58:32AM +0200, Marek Szyprowski wrote:
> > > I've just checked with the latest firmware from
> > > https://github.com/raspberrypi/firmware (master branch, just copied
> > > everything to /boot) and the issue is still there.
> > >
> > > If you start from arm64/defconfig without modules, please make sure you
> > > have enabled all RPi drivers, otherwise VC4 DRM won't come up. I've
> > > managed to reproduce the issue without the modules with the following
> > > changes to arm64's defconfig:
> > >
> > > ./scripts/config -e DRM -e DRM_VC4 -e CONFIG_CLK_RASPBERRYPI -e
> > > CONFIG_SENSORS_RASPBERRYPI_HWMON -e CONFIG_I2C_BCM2835 -e
> > > CONFIG_ARM_RASPBERRYPI_CPUFREQ
> >
> > Thanks for this!
> >
> > With that config on commit 65688d2a05deb9f0 I also see a hang at the end
> > of boot, but before reaching userspace, with the last messages in dmesg
> > as below.
> >
> > I'll go check that the ARCH_DMA_MINALIGN affects this, then I'll go play
> > with debug options.
>
> I can confirm that with the ARCH_DMA_MINALIGN change reverted, the hang
> goes away. Running with that reverted andwith KASAN, I get the
> slab-out-of-bounds splat below, which occurs at the time the hang would
> otherwise occur, and is possibly the problem:
>
> [ 3.609515] vc4-drm soc:gpu: bound 3f902000.hdmi (ops vc4_hdmi_ops)
> [ 3.621451] vc4-drm soc:gpu: bound 3f806000.vec (ops vc4_vec_ops)
> [ 3.628344] vc4-drm soc:gpu: bound 3f400000.hvs (ops vc4_hvs_ops)
> [ 3.635904] vc4-drm soc:gpu: bound 3f004000.txp (ops vc4_txp_ops)
> [ 3.643351] vc4-drm soc:gpu: bound 3f206000.pixelvalve (ops vc4_crtc_ops)
> [ 3.651238] vc4-drm soc:gpu: bound 3f207000.pixelvalve (ops vc4_crtc_ops)
> [ 3.659167] vc4-drm soc:gpu: bound 3f807000.pixelvalve (ops vc4_crtc_ops)
> [ 3.666499] vc4-drm soc:gpu: bound 3fc00000.v3d (ops vc4_v3d_ops)
> [ 3.688560] [drm] Initialized vc4 0.0.0 20140616 for soc:gpu on minor 0
> [ 3.728010] ==================================================================
> [ 3.728042] BUG: KASAN: slab-out-of-bounds in vc4_atomic_commit_tail+0x1cc/0x910
> [ 3.728123] Read of size 8 at addr ffff000007360440 by task kworker/u8:0/7
> [ 3.728153]
> [ 3.728169] CPU: 2 PID: 7 Comm: kworker/u8:0 Not tainted 5.13.0-rc3-00009-g694c523e7267 #3
> [ 3.728203] Hardware name: Raspberry Pi 3 Model B (DT)
> [ 3.728225] Workqueue: events_unbound deferred_probe_work_func
> [ 3.728290] Call trace:
> [ 3.728301] dump_backtrace+0x0/0x2b4
> [ 3.728358] show_stack+0x1c/0x30
> [ 3.728407] dump_stack+0xfc/0x168
> [ 3.728445] print_address_description.constprop.0+0x2c/0x2c0
> [ 3.728495] kasan_report+0x1dc/0x240
> [ 3.728529] __asan_load8+0x98/0xd4
> [ 3.728565] vc4_atomic_commit_tail+0x1cc/0x910
> [ 3.728621] commit_tail+0x100/0x210
> [ 3.728675] drm_atomic_helper_commit+0x1c4/0x3dc
> [ 3.728730] drm_atomic_commit+0x80/0x94
> [ 3.728768] drm_client_modeset_commit_atomic+0x2f4/0x3a0
> [ 3.728821] drm_client_modeset_commit_locked+0x8c/0x230
> [ 3.728872] drm_fb_helper_pan_display+0x164/0x3a0
> [ 3.728924] fb_pan_display+0x12c/0x1fc
> [ 3.728963] bit_update_start+0x34/0xa0
> [ 3.729013] fbcon_switch+0x678/0x920
> [ 3.729058] redraw_screen+0x17c/0x35c
> [ 3.729095] fbcon_prepare_logo+0x484/0x5bc
> [ 3.729143] fbcon_init+0x77c/0x970
> [ 3.729187] visual_init+0x14c/0x1e4
> [ 3.729239] do_bind_con_driver.isra.0+0x2c4/0x530
> [ 3.729279] do_take_over_console+0x200/0x2e0
> [ 3.729317] do_fbcon_takeover+0x90/0x120
> [ 3.729363] fbcon_fb_registered+0x14c/0x164
> [ 3.729412] register_framebuffer+0x308/0x4e0
> [ 3.729451] __drm_fb_helper_initial_config_and_unlock+0x538/0x7d0
> [ 3.729506] drm_fbdev_client_hotplug+0x204/0x374
> [ 3.729556] drm_fbdev_generic_setup+0xf4/0x24c
> [ 3.729604] vc4_drm_bind+0x1d4/0x1f0
> [ 3.729654] try_to_bring_up_master+0x254/0x2dc
> [ 3.729709] __component_add+0x10c/0x240
> [ 3.729759] component_add+0x18/0x24
> [ 3.729807] vc4_v3d_dev_probe+0x20/0x30
> [ 3.729854] platform_probe+0x90/0x110
> [ 3.729907] really_probe+0x148/0x744
> [ 3.729952] driver_probe_device+0x8c/0xfc
> [ 3.729998] __device_attach_driver+0x120/0x180
> [ 3.730048] bus_for_each_drv+0xf4/0x15c
> [ 3.730091] __device_attach+0x168/0x250
> [ 3.730137] device_initial_probe+0x18/0x24
> [ 3.730186] bus_probe_device+0xec/0x100
> [ 3.730230] deferred_probe_work_func+0xe8/0x130
> [ 3.730279] process_one_work+0x3b8/0x650
> [ 3.730319] worker_thread+0x3cc/0x72c
> [ 3.730356] kthread+0x21c/0x224
> [ 3.730402] ret_from_fork+0x10/0x38
> [ 3.730442]
> [ 3.730453] Allocated by task 7:
> [ 3.730470] kasan_save_stack+0x2c/0x60
> [ 3.730526] __kasan_kmalloc+0x90/0xb4
> [ 3.730577] vc4_hvs_channels_duplicate_state+0x60/0x1a0
> [ 3.730637] drm_atomic_get_private_obj_state+0x144/0x230
> [ 3.730680] vc4_atomic_check+0x40/0x73c
> [ 3.730732] drm_atomic_check_only+0x998/0xe60
> [ 3.730769] drm_atomic_commit+0x34/0x94
> [ 3.730804] drm_client_modeset_commit_atomic+0x2f4/0x3a0
> [ 3.730854] drm_client_modeset_commit_locked+0x8c/0x230
> [ 3.730904] drm_client_modeset_commit+0x38/0x60
> [ 3.730951] drm_fb_helper_set_par+0x104/0x17c
> [ 3.730998] fbcon_init+0x43c/0x970
> [ 3.731041] visual_init+0x14c/0x1e4
> [ 3.731090] do_bind_con_driver.isra.0+0x2c4/0x530
> [ 3.731128] do_take_over_console+0x200/0x2e0
> [ 3.731165] do_fbcon_takeover+0x90/0x120
> [ 3.731210] fbcon_fb_registered+0x14c/0x164
> [ 3.731258] register_framebuffer+0x308/0x4e0
> [ 3.731296] __drm_fb_helper_initial_config_and_unlock+0x538/0x7d0
> [ 3.731349] drm_fbdev_client_hotplug+0x204/0x374
> [ 3.731398] drm_fbdev_generic_setup+0xf4/0x24c
> [ 3.731446] vc4_drm_bind+0x1d4/0x1f0
> [ 3.731493] try_to_bring_up_master+0x254/0x2dc
> [ 3.731546] __component_add+0x10c/0x240
> [ 3.731594] component_add+0x18/0x24
> [ 3.731642] vc4_v3d_dev_probe+0x20/0x30
> [ 3.731686] platform_probe+0x90/0x110
> [ 3.731737] really_probe+0x148/0x744
> [ 3.731781] driver_probe_device+0x8c/0xfc
> [ 3.731827] __device_attach_driver+0x120/0x180
> [ 3.731875] bus_for_each_drv+0xf4/0x15c
> [ 3.731916] __device_attach+0x168/0x250
> [ 3.731962] device_initial_probe+0x18/0x24
> [ 3.732009] bus_probe_device+0xec/0x100
> [ 3.732052] deferred_probe_work_func+0xe8/0x130
> [ 3.732100] process_one_work+0x3b8/0x650
> [ 3.732137] worker_thread+0x3cc/0x72c
> [ 3.732172] kthread+0x21c/0x224
> [ 3.732215] ret_from_fork+0x10/0x38
> [ 3.732253]
> [ 3.732262] The buggy address belongs to the object at ffff000007360400
> [ 3.732262] which belongs to the cache kmalloc-128 of size 128
> [ 3.732293] The buggy address is located 64 bytes inside of
> [ 3.732293] 128-byte region [ffff000007360400, ffff000007360480)
> [ 3.732329] The buggy address belongs to the page:
> [ 3.732344] page:(____ptrval____) refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x7360
> [ 3.732380] flags: 0x3fffc0000000200(slab|node=0|zone=0|lastcpupid=0xffff)
> [ 3.732442] raw: 03fffc0000000200 dead000000000100 dead000000000122 ffff000004c02300
> [ 3.732478] raw: 0000000000000000 0000000000100010 00000001ffffffff 0000000000000000
> [ 3.732501] page dumped because: kasan: bad access detected
> [ 3.732518]
> [ 3.732527] Memory state around the buggy address:
> [ 3.732549] ffff000007360300: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
> [ 3.732579] ffff000007360380: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
> [ 3.732608] >ffff000007360400: 00 00 00 00 00 00 00 fc fc fc fc fc fc fc fc fc
> [ 3.732629] ^
> [ 3.732652] ffff000007360480: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
> [ 3.732682] ffff000007360500: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
> [ 3.732703] ==================================================================
> [ 3.732718] Disabling lock debugging due to kernel taint
> [ 3.769129] Console: switching to colour frame buffer device 90x30
> [ 5.148699] vc4-drm soc:gpu: [drm] fb0: vc4drmfb frame buffer device
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