[dm-devel] Regression: Disk corruption with dm-crypt and kernels >= 4.0

[Mike Snitzer]

On Fri, May 01 2015 at 12:37am -0400,
Abelardo Ricart III <aricart at memnix.com> wrote:

> I made sure to run a completely vanilla kernel when testing why I was suddenly
> seeing some nasty libata errors with all kernels >= v4.0. Here's a snippet:
> 
> -------------------->8--------------------
> [  165.592136] ata5.00: exception Emask 0x60 SAct 0x7000 SErr 0x800 action 0x6
> frozen
> [  165.592140] ata5.00: irq_stat 0x20000000, host bus error
> [  165.592143] ata5: SError: { HostInt }
> [  165.592145] ata5.00: failed command: READ FPDMA QUEUED
> [  165.592149] ata5.00: cmd 60/08:60:a0:0d:89/00:00:07:00:00/40 tag 12 ncq 4096
> in
>                         res 40/00:74:40:58:5d/00:00:00:00:00/40 Emask 0x60
> (host bus error)
> [  165.592151] ata5.00: status: { DRDY }
> -------------------->8--------------------
> 
> After a few dozen of these errors, I'd suddenly find my system in read-only
> mode with corrupted files throughout my encrypted filesystems (seemed like
> either a read or a write would corrupt a file, though I could be mistaken). I
> decided to do a git bisect with a random read-write-sync test to narrow down
> the culprit, which turned out to be this commit (part of a series):
> 
> # first bad commit: [cf2f1abfbd0dba701f7f16ef619e4d2485de3366] dm crypt: don't
> allocate pages for a partial request
> 
> Just to be sure, I created a patch to revert the entire nine patch series that
> commit belonged to... and the bad behavior disappeared. I've now been running
> kernel 4.0 for a few days without issue, and went so far as to stress test my
> poor SSD for a few hours to be 100% positive.
> 
> Here's some more info on my setup.
> 
> -------------------->8--------------------
> $ lsblk -f
> NAME         FSTYPE      LABEL MOUNTPOINT
> sda                  
> ├─sda1       vfat              /boot/EFI
> ├─sda2       ext4              /boot
> └─sda3       LVM2_member
>   ├─SSD-root crypto_LUKS
>   │ └─root   f2fs              /
>   └─SSD-home crypto_LUKS
>     └─home   f2fs              /home
> 
> $ cat /proc/cmdline
> BOOT_IMAGE=/vmlinuz-linux-memnix cryptdevice=/dev/SSD/root:root:allow-discards
> root=/dev/mapper/root acpi_osi=Linux security=tomoyo
> TOMOYO_trigger=/usr/lib/systemd/systemd intel_iommu=on
> modprobe.blacklist=nouveau rw quiet
> 
> $ cat /etc/lvm/lvm.conf | grep "issue_discards"
> issue_discards = 1
> -------------------->8--------------------
> 
> If there's anything else I can do to help diagnose the underlying problem, I'm
> more than willing.

The patchset in question was tested quite heavily so this is a
surprising report.  I'm noticing you are opting in to dm-crypt discard
support.  Have you tested without discards enabled?