[LU-3650] osc_ldlm_blocking_ast() LBUG

• Type: Bug
• Status: In Progress
• Priority: Major
• Resolution: Unresolved
• Affects Version/s: Lustre 2.4.1, Lustre 2.5.0
• Labels: llnl
• Environment: Lustre [2.4.0-RC1_3chaos|http://github.com/chaos/lustre/tree/2.4.0-RC1_3chaos], PPC64 client
• Severity: 3
• Assignee: Lai Siyao
• Reporter: Christopher Morrone

Description

We are hitting the LBUG in osc_ldlm_blocking_ast() that says "This should never happen". The backtrace looks like:

PID: 29660  TASK: c00000098d26bab0  CPU: 42  COMMAND: "ldlm_bl_44"
 #0 [c000000dc9f3f7c0] .crash_kexec at c0000000000e5aa4
 #1 [c000000dc9f3f9c0] .panic at c0000000005c4f40
 #2 [c000000dc9f3fa50] .lbug_with_loc at d00000000acd14e0 [libcfs]
 #3 [c000000dc9f3fae0] .osc_ldlm_blocking_ast at d00000000afbe1d8 [osc]
 #4 [c000000dc9f3fbc0] .ldlm_cancel_callback at d00000000bf3148c [ptlrpc]
 #5 [c000000dc9f3fc60] .ldlm_cli_cancel_local at d00000000bf4db78 [ptlrpc]
 #6 [c000000dc9f3fd20] .ldlm_cli_cancel_list_local at d00000000bf4f80c [ptlrpc]
 #7 [c000000dc9f3fe40] .ldlm_bl_thread_main at d00000000bf5c07c [ptlrpc]
 #8 [c000000dc9f3ff90] .kernel_thread at c000000000032fd4

Both times we have seen this (that I am aware of), the LBUG was preceded shortly before by a kernel page allocation error, so that may be part of the recipe for triggering this bug.

This is a PPC64 client running lustre 2.4.0-RC1_3chaos.