Re: [PATCH/RFC] driver core: Postpone DMA tear-down until after devres release
From: John Garry
Date: Thu Mar 07 2019 - 09:58:52 EST
On 07/03/2019 14:52, Robin Murphy wrote:
Hi John,
Hi Robin,
ok, fine.
It's a pain bisecting another rmmod issue with it...
Cheers,
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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