[4.8.0-14/ppc64el regression] rmmod scsi_debug keeps causing kernel oops
Affects | Status | Importance | Assigned to | Milestone | |
---|---|---|---|---|---|
linux (Ubuntu) |
Invalid
|
Medium
|
Unassigned | ||
systemd (Ubuntu) |
Fix Released
|
Medium
|
Martin Pitt |
Bug Description
Since upgrading to 4.8.0-14, the "storage" autopkgtest of systemd is broken. This uses scsi_debug to get a test hard drive, which is reset between the test through unloading/reloading the module. This has worked fine so far (and still works on amd64/i386), but now regularly triggers a kernel oops:
[ 161.120362] Unable to handle kernel paging request for data at address 0x00000000
[ 161.120468] Faulting instruction address: 0xc000000000538ecc
[ 161.120517] Oops: Kernel access of bad area, sig: 11 [#1]
[ 161.120555] SMP NR_CPUS=2048 NUMA pSeries
[ 161.120595] Modules linked in: dm_crypt dm_mod xts algif_skcipher af_alg sd_mod sg xt_TCPMSS xt_tcpudp iptable_mangle ghash_generic gf128mul vmx_crypto virtio_balloon ip_tables x_tables autofs4 ext4 crc16 jbd2 fscrypto mbcache crc32c_generic btrfs xor raid6_pq ohci_pci ehci_pci ohci_hcd virtio_blk virtio_net ehci_hcd usbcore crc32c_vpmsum usb_common virtio_pci virtio_ring virtio [last unloaded: scsi_debug]
[ 161.121016] CPU: 0 PID: 5473 Comm: rmmod Not tainted 4.8.0-15-generic #16-Ubuntu
[ 161.121067] task: c00000005ae51980 task.stack: c00000005ef58000
[ 161.121110] NIP: c000000000538ecc LR: c000000000538ee0 CTR: c0000000000f7250
[ 161.121162] REGS: c00000005ef5b9f0 TRAP: 0300 Not tainted (4.8.0-15-generic)
[ 161.121213] MSR: 800000010280b033 <SF,VEC,
[ 161.121390] CFAR: c00000000009a8e0 DAR: 0000000000000000 DSISR: 40000000 SOFTE: 1
[ 161.122099] NIP [c000000000538ecc] ddebug_
[ 161.122143] LR [c000000000538ee0] ddebug_
[ 161.122186] Call Trace:
[ 161.122205] [c00000005ef5bc70] [c000000000538e98] ddebug_
[ 161.122280] [c00000005ef5bd10] [c00000000018961c] free_module+
[ 161.122333] [c00000005ef5bd60] [c000000000189a38] SyS_delete_
[ 161.122394] [c00000005ef5be30] [c0000000000095e0] system_
[ 161.122445] Instruction dump:
[ 161.122472] 3d42fff5 e92a63b8 7fa9e000 7d3d4b78 ebe90000 419e00bc 7d3e4b78 3b40fffe
[ 161.122561] 48000018 7fbfe000 7ffdfb78 7ffefb78 <ebff0000> 419e0060 e87e0010 7f64db78
[ 161.122651] ---[ end trace 5f19b96c7077a0e0 ]---
This isn't reproducible by merely loading and unloading the module, it apparently needs to get some actual exercise. I'll find a simpler reproducer than running the systemd test tomorrow morning.
tags: | added: bot-stop-nagging |
summary: |
- [4.8 regression] rmmod scsi_debug keeps causing kernel oops + [4.8.0-14/ppc64el regression] rmmod scsi_debug keeps causing kernel oops |
Changed in linux (Ubuntu): | |
status: | New → Confirmed |
tags: | added: kernel-4.8 |
Changed in linux (Ubuntu): | |
importance: | Undecided → Medium |
I adjusted the test to avoid "rmmod scsi_debug": https:/ /anonscm. debian. org/cgit/ pkg-systemd/ systemd. git/commit/ ?id=be77e470d8
So there's still a bug there, but it won't block testing any more at least. And rmmod is always a bit brittle anyway, so let's avoid it.