[LU-16633] obd_get_mod_rpc_slot() is vulnerable to races

• Status: Resolved
• Project: Lustre
• Affects Version/s: Lustre 2.16.0
• Fix Version/s: Lustre 2.16.0
• Type: Bug
• Priority: Minor
• Reporter: Alex Zhuravlev
• Assignee: Alex Zhuravlev
• Resolution: Fixed
• Severity: 3

Description

wait_woken() called from obd_get_mod_rpc_slot() resets WQ_FLAG_WOKEN flag, but leaves the corresponding wq_entry on the list.
__wake_up_locked_key() (called from obd_put_mod_rpc() in another thread) finds that wq_entry on the list w/o WQ_FLAG_WOKEN set, consumes one more slot (cl_mod_rpcs_in_flight++).
this way we leak slots.
this can be catched with sanity/182b.

Issue Links

• is related to: LU-15947 Spinlock contention during wake_up_al...
• is related to: LU-16404 sanity test_230n: lfs mirror: cannot ...

Comments

[Alex Zhuravlev]

confirmed with AT with https://review.whamcloud.com/#/c/fs/lustre-release/+/50261/2: https://testing.whamcloud.com/test_sets/2df6460e-17a8-4b75-9abe-313301f0a9dc

[Andreas Dilger]

"Alex Zhuravlev <[e-mail]>" uploaded a new patch: https://review.whamcloud.com/50261
Subject: LU-16633 obdclass: fix rpc slot leakage
Project: fs/lustre-release
Branch: master
Current Patch Set: 11
Commit: 238afb52dc57bbfe4db6c3736d9d651903b8ad05

[Gerrit Updater]

"Oleg Drokin <[e-mail]>" merged in patch https://review.whamcloud.com/c/fs/lustre-release/+/50261/
Subject: LU-16633 obdclass: fix rpc slot leakage
Project: fs/lustre-release
Branch: master
Current Patch Set:
Commit: 91a3726f313df33e099320d171039f8371fec27f

[Peter Jones]

Landed for 2.16

[Gerrit Updater]

"Etienne AUJAMES <[e-mail]>" uploaded a new patch: https://review.whamcloud.com/c/fs/lustre-release/+/51539
Subject: LU-16633 obdclass: fix rpc slot leakage
Project: fs/lustre-release
Branch: b2_15
Current Patch Set: 1
Commit: 1fb91b79be498564e6c537228fd4d411b58dcda3