[LU-6285] Assert fails in staging client module crashes kernel if CPUMASK_OFFSTACK set

• Type: Bug
• Resolution: Fixed
• Priority: Minor
• Fix Version/s: Lustre 2.8.0, Lustre 2.9.0
• Affects Version/s: Lustre 2.4.0

Epic/Theme

staging

• Severity: 3
• Assignee: Oleg Drokin
• Reporter: Tyson Whitehead (Inactive)

Description

Enabling CONFIG_CPUMASK_OFFSTACK in stock kernel 3.18.0 causes the staging ptlrpc module to emit the message

LustreError: 1203:0:(service.c:2796:ptlrpc_hr_init()) ASSERTION( hrp->hrp_nthrs > 0 ) failed:

followed by a backtrace and kernel lockup upon loading. I'll attach my dmesg dump and the .config file I used. I picked version 2.4.0 above as there doesn't seem to be anyway to indicate the staging client version.

Issue Links

• is related to: LU-8492 ptlrpc: Correctly calculate hrp->hrp_nthrs
• is related to: LU-6215 Sync Lustre external tree with lustre linux kernel client
• is related to: LU-4011 problems with upstream lustre client code

Comments

[Peter Jones]

Bulk of work landed for 2.9. Amir, please open a new ticket to track the landing of http://review.whamcloud.com/#/c/19106/

[Gerrit Updater]

Amir Shehata ([e-mail]) uploaded a new patch: http://review.whamcloud.com/19106
Subject: LU-6285 ptlrpc: Correctly calculate hrp->hrp_nthrs
Project: fs/lustre-release
Branch: master
Current Patch Set: 1
Commit: 2d6210842775e4fa7b0c7a6bce1dde8e948e56c9

[Amir Shehata (Inactive)]

There is still an issue which could cause the assert.

cpu_pattern can sepcify exactly 1 cpu in a partition:
"0[0]". That means CPT0 will have CPU 0. CPU 0 can have
hyperthreading enabled. This combination would result in

weight = cfs_cpu_ht_nsiblings(0);
hrp->hrp_nthrs = cfs_cpt_weight(ptlrpc_hr.hr_cpt_table, i);
hrp->hrp_nthrs /= weight;

evaluating to 0. Where

cfs_cpt_weight(ptlrpc_hr.hr_cpt_table, i) == 1
weight == 2

Therefore only divide out with weight if

hrp->hrp_nthrs >= weight

This will avoid the assert:

LASSERT(hrp->hrp_nthrs > 0);

[James A Simmons]

Please close this ticket

[Tyson Whitehead (Inactive)]

Excellent! Thanks everyone.

[James A Simmons]

All the patches have landed. We can close this ticket.

[Gerrit Updater]

Oleg Drokin ([e-mail]) merged in patch http://review.whamcloud.com/13926/
Subject: LU-6285 libcfs: get rid of deprecated cpumask function usage
Project: fs/lustre-release
Branch: master
Current Patch Set:
Commit: 3b3233792869e706fe1ebfb6605d93fbc0d0d63c

[Gerrit Updater]

Oleg Drokin ([e-mail]) merged in patch http://review.whamcloud.com/13925/
Subject: LU-6285 ptlrpc: Get rid of cpus_* calls as deprecated
Project: fs/lustre-release
Branch: master
Current Patch Set:
Commit: 61787e1cea610ba38ba917b73db0d43589c029df

[Gerrit Updater]

Oleg Drokin ([e-mail]) merged in patch http://review.whamcloud.com/13954/
Subject: LU-6285: o2iblnd: Do not use cpus_weight, it's deprecated
Project: fs/lustre-release
Branch: master
Current Patch Set:
Commit: b95db057d0501fb19f807cddf3a8ba3f7f47cb1a

[Gerrit Updater]

Oleg Drokin ([e-mail]) merged in patch http://review.whamcloud.com/13905/
Subject: LU-6285 ptlrpc: Do not recalculate siblings of CPU 0 in a loop
Project: fs/lustre-release
Branch: master
Current Patch Set:
Commit: 0eb4582d87e32dd3e5491e13ba659e625624bfe7