[LU-11075] suspicious code in ldlm_prepare_lru_list()

• Status: Resolved
• Project: Lustre
• Fix Version/s: Lustre 2.12.0
• Type: Bug
• Priority: Minor
• Reporter: John Hammond
• Assignee: John Hammond
• Resolution: Fixed
• Severity: 3

Description

There is some suspicious code in ldlm_prepare_lru_list() which should be fixed:

static int ldlm_prepare_lru_list(struct ldlm_namespace *ns,
                                 struct list_head *cancels, int count, int max,
                                 enum ldlm_lru_flags lru_flags)
...
                        if (!ldlm_is_canceling(lock) || /* XXX '||' should be '&&' */
                            !ldlm_is_converting(lock))
                                break;
...
                if (result == LDLM_POLICY_SKIP_LOCK) {
                        lu_ref_del(&lock->l_reference, __func__, current);
                        LDLM_LOCK_RELEASE(lock); /* XXX release should follow if block. */
                        if (no_wait) {
                                spin_lock(&ns->ns_lock);
                                if (!list_empty(&lock->l_lru) &&
                                    lock->l_lru.prev == ns->ns_last_pos)
                                        ns->ns_last_pos = &lock->l_lru;
                                spin_unlock(&ns->ns_lock);
                        }
                        continue;
                }

Issue Links

• is related to: LU-11092 NMI watchdog: BUG: soft lockup - CPU#...
• is related to: LU-10537 softlockup in ldlm_prepare_lru_list()

Comments

[Gerrit Updater]

John L. Hammond ([e-mail]) uploaded a new patch: https://review.whamcloud.com/32660
Subject: LU-11075 ldlm: correct logic in ldlm_prepare_lru_list()
Project: fs/lustre-release
Branch: master
Current Patch Set: 1
Commit: 8fe6f74a2a7fcb2b8ac1af4e00b21d04ed7f5951

[Andreas Dilger]

Could this be the root cause of LU-11092 and numerous other LDLM LRU overflow problems?

[John Hammond]

It's possible.

[Gerrit Updater]

Oleg Drokin ([e-mail]) merged in patch https://review.whamcloud.com/32660/
Subject: LU-11075 ldlm: correct logic in ldlm_prepare_lru_list()
Project: fs/lustre-release
Branch: master
Current Patch Set:
Commit: aecafb57d5b60ea430ce9ef13783eb74ad4f6936

[Peter Jones]

Landed for 2.12