[v4.12-rc1 regression] mount ext4 fs results in kernel crash on PPC64le host

[Eryu Guan]

On Thu, Jun 29, 2017 at 06:47:50PM +1000, Balbir Singh wrote:
> On Thu, Jun 29, 2017 at 1:41 PM, Eryu Guan <eguan at redhat.com> wrote:
> > On Thu, Jun 29, 2017 at 03:16:10AM +1000, Balbir Singh wrote:
> >> On Wed, Jun 28, 2017 at 6:32 PM, Eryu Guan <eguan at redhat.com> wrote:
> <snip>
> >> Thanks for the excellent bug report, I am a little lost on the stack
> >> trace, it shows a bad page access that we think is triggered by the
> >> mmap changes? The patch changed the return type to integrate the call
> >> into trace-cmd. Could you point me to the tests that can help
> >> reproduce the crash. Could you also suggest how long to try the test
> >> cases for?
> >
> > Sorry, I should have provided it in the first place. It's as simple as
> > mounting an ext4 filesystem on my test ppc64le host, i.e.
> >
> > mkdir -p /mnt/ext4
> > mkfs -t ext4 -F /dev/sda5
> > mount /dev/sda5 /mnt/ext4
> >
> 
> I tried this test a few times with the kernel and could not reproduce it.
> Could you please share the config and compiler details, I'll retry with -rc7.
> 
> In the meanwhile, does enabling kmemleak, DEBUG_PAGE_ALLOC,
> slub/slab debug, list corruption, etc catch anything at the time of the
> corruption?

Testing with debug kernel (config file attached) didn't trigger kernel
crash, but only warnings

[   99.686770] ------------[ cut here ]------------
[   99.686868] WARNING: CPU: 1 PID: 2272 at ./include/linux/cpumask.h:121 try_to_wake_up+0x17c/0x8f0
[   99.686873] Modules linked in: ext4 jbd2 mbcache sg pseries_rng ghash_generic gf128mul xts vmx_crypto nfsd auth_rpcgss nfs_acl lockd grace sunrpc ip_tables xfs libcrc32c sd_mod ibmvscsi ibmveth scsi_transport_srp
[   99.686950] CPU: 1 PID: 2272 Comm: mount Not tainted 4.12.0-rc7.debug #28
[   99.686955] task: c0000003f00b7b00 task.stack: c0000003f25e0000
[   99.686959] NIP: c0000000001359ec LR: c000000000135ed4 CTR: c00000000016f940
[   99.686964] REGS: c0000003f25e3420 TRAP: 0700   Not tainted  (4.12.0-rc7.debug)
[   99.686968] MSR: 800000010282b033 <SF,VEC,VSX,EE,FP,ME,IR,DR,RI,LE,TM[E]>
[   99.686994]   CR: 28028822  XER: 00000001
[   99.687000] CFAR: c000000000135cb4 SOFTE: 0
[   99.687000] GPR00: c000000000135da0 c0000003f25e36a0 c000000001751800 00000000000000a0
[   99.687000] GPR04: 00000000000000a0 00000000000000c0 0000000000000000 0000000000000000
[   99.687000] GPR08: ffffffffffffffff 00000000000000a0 0000000000000000 00000000000041e0
[   99.687000] GPR12: 0000000000008800 c00000000fac0a80 0000000000000002 c0000003fd20b000
[   99.687000] GPR16: c0000003cabb0400 0000000000000000 0000000000000000 0000000000000002
[   99.687000] GPR20: 0000000000000000 c0000003f7a59d60 c000000001326300 c000000001795d00
[   99.687000] GPR24: c000000001799d48 0000000000000000 c00000000179a294 c0000003ec786be8
[   99.687000] GPR28: 0000000000000000 c0000003ec786680 00000000000000a0 c0000003ec786300
[   99.687083] NIP [c0000000001359ec] try_to_wake_up+0x17c/0x8f0
[   99.687088] LR [c000000000135ed4] try_to_wake_up+0x664/0x8f0
[   99.687092] Call Trace:
[   99.687095] [c0000003f25e36a0] [c000000000135da0] try_to_wake_up+0x530/0x8f0 (unreliable)
[   99.687104] [c0000003f25e3730] [c000000000114ea8] create_worker+0x148/0x220
[   99.687110] [c0000003f25e37d0] [c00000000011a418] alloc_unbound_pwq+0x4c8/0x620
[   99.687117] [c0000003f25e3830] [c00000000011a9c4] apply_wqattrs_prepare+0x1f4/0x340
[   99.687123] [c0000003f25e38a0] [c00000000011ab4c] apply_workqueue_attrs_locked+0x3c/0xa0
[   99.687130] [c0000003f25e38d0] [c00000000011b094] apply_workqueue_attrs+0x54/0x90
[   99.687137] [c0000003f25e3910] [c00000000011d674] __alloc_workqueue_key+0x184/0x5b0
[   99.687155] [c0000003f25e39d0] [d000000013dd1768] ext4_fill_super+0x1c68/0x33e0 [ext4]
[   99.687162] [c0000003f25e3b10] [c000000000390f7c] mount_bdev+0x22c/0x260
[   99.687178] [c0000003f25e3bb0] [d000000013dc9020] ext4_mount+0x20/0x40 [ext4]
[   99.687184] [c0000003f25e3bd0] [c0000000003923c4] mount_fs+0x74/0x210
[   99.687191] [c0000003f25e3c80] [c0000000003c0688] vfs_kern_mount+0x78/0x220
[   99.687197] [c0000003f25e3d00] [c0000000003c6044] do_mount+0x254/0xf70
[   99.687204] [c0000003f25e3de0] [c0000000003c7184] SyS_mount+0x94/0x100
[   99.687210] [c0000003f25e3e30] [c00000000000b190] system_call+0x38/0xe0
[   99.687215] Instruction dump:
[   99.687220] 409d000c 39200004 9121002c 387d0018 4803be2d 60000000 7fa3eb78 48911321
[   99.687236] 60000000 2fb70000 409e0124 480001e0 <0fe00000> 7fca3670 7d4a0194 57c906be
[   99.687252] ---[ end trace e80d5ad75ae4c2a0 ]---
[   99.691902] EXT4-fs (sda5): mounted filesystem with ordered data mode. Opts: (null)

Thanks,
Eryu
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