Date:   Tue, 9 Aug 2022 08:03:11 +0200
From:   Jiri Slaby <jirislaby@...nel.org>
To:     Linus Torvalds <torvalds@...ux-foundation.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Cc:     minchan@...nel.org, ngupta@...are.org,
        Sergey Senozhatsky <senozhatsky@...omium.org>,
        Jan Kara <jack@...e.com>, Ted Ts'o <tytso@....edu>,
        Andreas Dilger <adilger.kernel@...ger.ca>,
        Ext4 Developers List <linux-ext4@...r.kernel.org>
Subject: ext2/zram issue [was: Linux 5.19]

Hi,

On 31. 07. 22, 23:43, Linus Torvalds wrote:
> So here we are, one week late, and 5.19 is tagged and pushed out.
> 
> The full shortlog (just from rc8, obviously not all of 5.19) is below,
> but I can happily report that there is nothing really interesting in
> there. A lot of random small stuff.

Note: I originally reported this downstream for tracking at:
https://bugzilla.suse.com/show_bug.cgi?id=1202203

5.19 behaves pretty weird in openSUSE's openQA (opposing to 5.18, or 
5.18.15). It's all qemu-kvm "HW"¹⁾:
https://openqa.opensuse.org/tests/2502148
loop2: detected capacity change from 0 to 72264
EXT4-fs warning (device zram0): ext4_end_bio:343: I/O error 10 writing 
to inode 57375 starting block 137216)
Buffer I/O error on device zram0, logical block 137216
Buffer I/O error on device zram0, logical block 137217
...
SQUASHFS error: xz decompression failed, data probably corrupt
SQUASHFS error: Failed to read block 0x2e41680: -5
SQUASHFS error: xz decompression failed, data probably corrupt
SQUASHFS error: Failed to read block 0x2e41680: -5
Bus error



https://openqa.opensuse.org/tests/2502145
FS-Cache: Loaded
begin 644 ldconfig.core.pid_2094.sig_7.time_1659859442



https://openqa.opensuse.org/tests/2502146
FS-Cache: Loaded
begin 644 Xorg.bin.core.pid_3733.sig_6.time_1659858784



https://openqa.opensuse.org/tests/2502148
EXT4-fs warning (device zram0): ext4_end_bio:343: I/O error 10 writing 
to inode 57375 starting block 137216)
Buffer I/O error on device zram0, logical block 137216
Buffer I/O error on device zram0, logical block 137217



https://openqa.opensuse.org/tests/2502154
[   13.158090][  T634] FS-Cache: Loaded
...
[  525.627024][    C0] sysrq: Show State



Those are various failures -- crashes of ldconfig, Xorg; I/O failures on 
zram; the last one is a lockup likely, something invoked sysrq after 
500s stall.

Interestingly, I've also hit this twice locally:
 > init[1]: segfault at 18 ip 00007fb6154b4c81 sp 00007ffc243ed600 error 
6 in libc.so.6[7fb61543f000+185000]
 > Code: 41 5f c3 66 0f 1f 44 00 00 42 f6 44 10 08 01 0f 84 04 01 00 00 
48 83 e1 fe 48 89 48 08 49 8b 47 70 49 89 5f 70 66 48 0f 6e c0 <48> 89 
58 18 0f 16 44 24 08 48 81 fd ff 03 00 00 76 08 66 0f ef c9
 > ***  signal 11 ***
 > malloc(): unsorted double linked list corrupted
 > traps: init[1] general protection fault ip:7fb61543f8b9 
sp:7ffc243ebf40 error:0 in libc.so.6[7fb61543f000+185000]
 > Kernel panic - not syncing: Attempted to kill init! exitcode=0x0000000b
 > CPU: 0 PID: 1 Comm: init Not tainted 5.19.0-1-default #1 openSUSE 
Tumbleweed e1df13166a33f423514290c702e43cfbb2b5b575

KASAN is not helpful either, so it's unlikely a memory corruption 
(unless it is "HW" related; should I try to turn on IOMMU in qemu?):
> kasan: KernelAddressSanitizer initialized
> ...
> zram: module verification failed: signature and/or required key missing - tainting kernel
> zram: Added device: zram0
> zram0: detected capacity change from 0 to 2097152
> EXT4-fs (zram0): mounting ext2 file system using the ext4 subsystem
> EXT4-fs (zram0): mounted filesystem without journal. Quota mode: none.
> EXT4-fs warning (device zram0): ext4_end_bio:343: I/O error 10 writing to inode 16386 starting block 159744)
> Buffer I/O error on device zram0, logical block 159744
> Buffer I/O error on device zram0, logical block 159745



They all occur to me like a zram failure. The installer apparently 
creates an ext2 FS and after it mounts it using ext4 module, the issue 
starts occurring.

Any tests I/you could run on 5.19 to exercise zram and ext2? Otherwise I 
am unable to reproduce easily, except using the openSUSE installer :/.

Any other ideas? Or is this known already?

¹⁾ main are uefi boot and virtio-blk (it likely happens with virtio-scsi 
too). The cmdline _I_ use: qemu-kvm -device intel-hda -device hda-duplex 
-drive file=/tmp/pokus.qcow2,if=none,id=hd -device 
virtio-blk-pci,drive=hd -drive 
if=pflash,format=raw,unit=0,readonly=on,file=/usr/share/qemu/ovmf-x86_64-opensuse-code.bin 
-drive if=pflash,format=raw,unit=1,file=/tmp/vars.bin -cdrom 
/tmp/cd1.iso  -m 1G -smp 1 -net user -net nic,model=virtio -serial pty 
-device virtio-rng-pci -device qemu-xhci,p2=4,p3=4 -usbdevice tablet


thanks,
-- 
js
suse labs

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