[BUG] I/O timeouts and system freezes on Kingston A2000 NVME with BCACHEFS

[Jens Axboe]

On 1/19/24 5:25 AM, Mia Kanashi wrote:
> This issue was originally reported here: https://github.com/koverstreet/bcachefs/issues/628
> 
> Transferring large amounts of files to the bcachefs from the btrfs
> causes I/O timeouts and freezes the whole system. This doesn't seem to
> be related to the btrfs, but rather to the heavy I/O on the drive, as
> it happens without btrfs being mounted. Transferring the files to the
> HDD, and then from it to the bcachefs on the NVME sometimes doesn't
> make the problem occur. The problem only happens on the bcachefs, not
> on btrfs or ext4. It doesn't happen on the HDD, I can't test with
> other NVME drives sadly. The behaviour when it is frozen is like this:
> all drive accesses can't process, when not cached in ram, so every app
> that is loaded in the ram, continues to function, but at the moment it
> tries to access the drive it freezes, until the drive is reset and
> those abort status messages appear in the dmesg, after that system is
> unfrozen for a moment, if you keep copying the files then the problem
> reoccurs once again.
> 
> This drive is known to have problems with the power management in the
> past:
> https://wiki.archlinux.org/title/Solid_state_drive/NVMe#Troubleshooting
> But those problems where since fixed with kernel workarounds /
> firmware updates. This issue is may be related, perhaps bcachefs does
> something different from the other filesystems, and workarounds don't
> apply, which causes the bug to occur only on it. It may be a problem
> in the nvme subsystem, or just some edge case in the bcachefs too, who
> knows. I tried to disable ASPM and setting latency to 0 like was
> suggested, it didn't fix the problem, so I don't know. If this is
> indeed related to that specific drive it would be hard to reproduce.

>From a quick look, looks like a broken drive/firmware. It is suspicious
that all failed IO is 256 blocks. You could try and limit the transfer
size and see if that helps:

# echo 64 > /sys/block/nvme0n1/queue/max_sectors_kb

Or maybe the transfer size is just a red herring, who knows. The error
code seems wonky:

> [  185.384762] nvme0n1: I/O Cmd(0x2) @ LBA 105272408, 256 blocks, I/O Error (sct 0x3 / sc 0x71)

-- 
Jens Axboe