Re: dvb usb issues since kernel 4.9

[Hanna Hawa]

Hi,

I'm a software developer working in Marvell SoC team.
I'm facing kernel panic issue while running raid 5 on sata disks 
connected to Macchiatobin (Marvell community board with Armada-8040 SoC 
with 4 ARMv8 cores of CA72)
Raid 5 built with Marvell DMA engine and async_tx mechanism 
(ASYNC_TX_DMA [=y]); the DMA driver (mv_xor_v2) uses a tasklet to clean 
the done descriptors from the queue.

The panic (see below) occurs while building the RAID-5 (mdadm) or while 
writing/reading to the raid partition.

After some debug/bisect/diff, found that patch "softirq: Let ksoftirqd 
do its job" is problematic patch.

- Using v4.14.0 and problematic patch reverted - no timout issue.
- Using v4.14.0 (including softirq patch) and the additional fix 
proposed by Linus - no timeout issue.

As others have reported in this thread, the softirq change is causing 
some regression.
Would it be possible to either revert the patch or apply a fix such as 
the one proposed by Linus ?

Below panic message:
[   25.371495] mv_xor_v2 f0400000.xor: dma_sync_wait: timeout!
[   25.377101] Kernel panic - not syncing: async_tx_quiesce: DMA error 
waiting for transaction
[   25.377101]
[   25.386973] CPU: 0 PID: 1417 Comm: md0_raid5 Not tainted 4.14.0 #16
[   25.393264] Hardware name: Marvell Armada 8040 DB board (DT)
[   25.398946] Call trace:
[   25.401410] [<ffff000008089310>] dump_backtrace+0x0/0x380
[   25.406831] [<ffff0000080896a4>] show_stack+0x14/0x20
[   25.411904] [<ffff00000890fa78>] dump_stack+0x98/0xb8
[   25.416976] [<ffff0000080c8ef0>] panic+0x118/0x280
[   25.421788] [<ffff000008386a44>] async_tx_quiesce+0x74/0x78
[   25.427382] [<ffff000008386ca4>] async_memcpy+0x1a4/0x2a0
[   25.432806] [<ffff000008747f9c>] async_copy_data.isra.16+0x1b4/0x280
[   25.439186] [<ffff00000874b6fc>] raid_run_ops+0x514/0x1320
[   25.444694] [<ffff000008751550>] handle_stripe+0x1040/0x2848
[   25.450377] [<ffff000008752f98>] 
handle_active_stripes.isra.28+0x240/0x460
[   25.457279] [<ffff000008753468>] raid5d+0x2b0/0x450
[   25.462177] [<ffff00000875ead4>] md_thread+0x104/0x160
[   25.467338] [<ffff0000080e638c>] kthread+0xfc/0x128
[   25.472234] [<ffff000008085354>] ret_from_fork+0x10/0x1c
[   25.477571] Kernel Offset: disabled
[   25.481073] CPU features: 0x002000
[   25.484487] Memory Limit: none
[   25.487556] ---[ end Kernel panic - not syncing: async_tx_quiesce: 
DMA error waiting for transaction
[   25.487556]

Thanks,
Hanna