Re: [PATCH/RFC] driver core: Postpone DMA tear-down until after devres release

[Robin Murphy <robin.murphy@arm.com>]

Hi John,

On 07/03/2019 14:45, John Garry wrote:
[...]
> Hi guys,
> 
> Any idea what happened to this fix?

It's been in -next for a while (commit 376991db4b64) - I assume it will 
land shortly and hit stable thereafter, at which point somebody gets to 
sort out the manual backport past 4.20.

Robin.

> I have this on 5.0:
> 
> [    0.000000] Linux version 5.0.0 (john@htsatcamb-server) (gcc version 
> 4.8.5 (Linaro GCC 4.8-2015.06)) #121 SMP PREEMPT Thu Mar 7 14:28:39 GMT 
> 2019
> [    0.000000] Kernel command line: BOOT_IMAGE=/john/Image rdinit=/init 
> crashkernel=256M@32M earlycon console=ttyAMA0,115200 acpi=force 
> pcie_aspm=off scsi_mod.use_blk_mq=y no_console_suspend pcie-hisi.disable=1
> 
> ...
> 
> [   26.806856] pci_bus 000c:20: 2-byte config write to 000c:20:00.0 
> offset 0x44 may corrupt adjacent RW1C bits
> [   26.817521] pcieport 0002:f8:00.0: can't derive routing for PCI INT B
> [   26.837167] pci_bus 000c:20: 2-byte config write to 000c:20:00.0 
> offset 0x44 may corrupt adjacent RW1C bits
> [   26.850091] serial 0002:f9:00.1: PCI INT B: no GSI
> [   26.879364] serial 0002:f9:00.1: enabling device (0000 -> 0003)
> [   26.913131] 0002:f9:00.1: ttyS3 at I/O 0x1008 (irq = 0, base_baud = 
> 115200) is a ST16650V2
> [   26.992897] rtc-efi rtc-efi: setting system clock to 
> 2019-03-07T14:41:48 UTC (1551969708)
> [   27.009380] ALSA device list:
> [   27.015326]   No soundcards found.
> [   27.022549] Freeing unused kernel memory: 1216K
> [   27.055567] Run /init as init process
> root@(none)$ cd /sys/devices/platform/HISI0162:01
> root@(none)$ echo HISI0162:01 > driver/unbind
> [   36.488040] hisi_sas_v2_hw HISI0162:01: dev[9:1] is gone
> [   36.561077] hisi_sas_v2_hw HISI0162:01: dev[8:1] is gone
> [   36.621061] hisi_sas_v2_hw HISI0162:01: dev[7:1] is gone
> [   36.693074] hisi_sas_v2_hw HISI0162:01: dev[6:1] is gone
> [   36.753066] hisi_sas_v2_hw HISI0162:01: dev[5:1] is gone
> [   36.764276] sd 0:0:3:0: [sdd] Synchronizing SCSI cache
> [   36.821106] hisi_sas_v2_hw HISI0162:01: dev[4:1] is gone
> [   36.889048] hisi_sas_v2_hw HISI0162:01: dev[3:1] is gone
> [   36.993002] hisi_sas_v2_hw HISI0162:01: dev[1:1] is gone
> [   37.004276] sd 0:0:0:0: [sda] Synchronizing SCSI cache
> [   37.014768] sd 0:0:0:0: [sda] Stopping disk
> [   37.709094] hisi_sas_v2_hw HISI0162:01: dev[2:5] is gone
> [   37.721231] hisi_sas_v2_hw HISI0162:01: dev[0:2] is gone
> [   37.803774] BUG: Bad page state in process sh  pfn:11356
> [   37.814444] page:ffff7e000044d580 count:1 mapcount:0 
> mapping:0000000000000000 index:0x0
> [   37.830525] flags: 0xfffc00000001000(reserved)
> [   37.839443] raw: 0fffc00000001000 ffff7e000044d588 ffff7e000044d588 
> 0000000000000000
> [   37.854998] raw: 0000000000000000 0000000000000000 00000001ffffffff 
> 0000000000000000
> [   37.870552] page dumped because: PAGE_FLAGS_CHECK_AT_FREE flag(s) set
> [   37.883485] bad because of flags: 0x1000(reserved)
> [   37.893098] Modules linked in:
> [   37.899221] CPU: 5 PID: 2691 Comm: sh Not tainted 5.0.0 #121
> [   37.910578] Hardware name: Huawei Taishan 2280 /D05, BIOS Hisilicon 
> D05 IT21 Nemo 2.0 RC0 04/18/2018
> [   37.928924] Call trace:
> [   37.933825]  dump_backtrace+0x0/0x150
> [   37.941166]  show_stack+0x14/0x1c
> [   37.947808]  dump_stack+0x8c/0xb0
> [   37.954451]  bad_page+0xe4/0x144
> [   37.960918]  free_pages_check_bad+0x7c/0x84
> [   37.969307]  __free_pages_ok+0x284/0x290
> [   37.977173]  __free_pages+0x30/0x44
> [   37.984163]  __dma_direct_free_pages+0x68/0x6c
> [   37.993076]  dma_direct_free+0x24/0x38
> [   38.000591]  dma_free_attrs+0x84/0xc0
> [   38.007930]  dmam_release+0x20/0x28
> [   38.014924]  release_nodes+0x128/0x1f8
> [   38.022439]  devres_release_all+0x34/0x4c
> [   38.030478]  device_release_driver_internal+0x190/0x208
> [   38.040963]  device_release_driver+0x14/0x1c
> [   38.049526]  unbind_store+0xbc/0xf4
> [   38.056517]  drv_attr_store+0x20/0x30
> [   38.063859]  sysfs_kf_write+0x44/0x4c
> [   38.071200]  kernfs_fop_write+0xd0/0x1c4
> [   38.079065]  __vfs_write+0x2c/0x158
> [   38.086055]  vfs_write+0xa8/0x19c
> [   38.092696]  ksys_write+0x44/0xa0
> [   38.099338]  __arm64_sys_write+0x1c/0x24
> [   38.107203]  el0_svc_common+0xb0/0x100
> [   38.114718]  el0_svc_handler+0x70/0x88
> [   38.122232]  el0_svc+0x8/0x7c0
> [   38.128356] Disabling lock debugging due to kernel taint
> [   38.139019] BUG: Bad page state in process sh  pfn:11355
> [   38.149682] page:ffff7e000044d540 count:0 mapcount:0 
> mapping:0000000000000000 index:0x0
> [   38.165760] flags: 0xfffc00000001000(reserved)
> [   38.174676] raw: 0fffc00000001000 ffff7e000044d548 ffff7e000044d548 
> 0000000000000000
> [   38.190230] raw: 0000000000000000 0000000000000000 00000000ffffffff 
> 0000000000000000
> [   38.205783] page dumped because: PAGE_FLAGS_CHECK_AT_FREE flag(s) set
> [   38.218716] bad because of flags: 0x1000(reserved)
> [   38.228329] Modules linked in:
> [   38.234451] CPU: 5 PID: 2691 Comm: sh Tainted: G    B 5.0.0 #121
> [   38.248604] Hardware name: Huawei Taishan 2280 /D05, BIOS Hisilicon 
> D05 IT21 Nemo 2.0 RC0 04/18/2018
> [   38.266949] Call trace:
> [   38.271844]  dump_backtrace+0x0/0x150
> [   38.279185]  show_stack+0x14/0x1c
> [   38.285826]  dump_stack+0x8c/0xb0
> [   38.292468]  bad_page+0xe4/0x144
> [   38.298936]  free_pages_check_bad+0x7c/0x84
> 
> ...
> 
> Thanks,
> John
> 
>> Thanks,
>> Robin.
>>
>>>> There aren't many drivers using dmam_alloc_*(), let alone which would
>>>> also find themselves behind an IOMMU on an Arm system, but it turns out
>>>> I actually have another one which can reproduce the BUG() with 5.0-rc.
>>>
>>> SATA core uses dmam_alloc_*().
>>>
>>>> I've tried a 4.12 kernel with a bit of instrumentation[1] and sure
>>>> enough the devres-managed buffer is freed with the wrong ops[2] even
>>>> then. How it manages not to blow up more catastrophically I have no
>>>> idea... I guess at best it just leaks the buffers and IOMMU mappings,
>>>> and at worst quietly frees random other pages instead.
>>>
>>> May depend on the actual ops, and whether CMA is used or not.
>>>
>>> Gr{oetje,eeting}s,
>>>
>>>                          Geert
>>>
>>
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>>
>> .
>>
> 
>