[LU-6624] LBUG in osc_lru_reclaim

• Type: Bug
• Resolution: Fixed
• Priority: Critical
• Fix Version/s: Lustre 2.8.0
• Affects Version/s: Lustre 2.7.0
• Labels: patch
• Severity: 3
• Assignee: Jinshan Xiong (Inactive)
• Reporter: Hiroya Nozaki (Inactive)

Description

According to the existing code, I can guess that cl_client_cache->ccc_lru needs spin_lock when being referred but the below code looks violating the rule.

osc_lru_reclaim

long osc_lru_reclaim(struct client_obd *cli)
{
        struct cl_env_nest nest;
        struct lu_env *env;
        struct cl_client_cache *cache = cli->cl_cache;
        long rc = 0;
        int max_scans;
        ENTRY;

        LASSERT(cache != NULL);
        LASSERT(!list_empty(&cache->ccc_lru)); <--- HERE

        .....

        spin_lock(&cache->ccc_lru_lock);
                                  <---- The LASSERT should be here, isn't it ?
        cache->ccc_lru_shrinkers++;

        ....

Actually I sometimes see LBUG in osc_lru_reclaim when running multiple WRITEs in the same time. So I'm convinced this LASSERT should be moved to the locked section, or the LASSERT can touch ccc_lru while the other is doing linked list operation on ccc_lru.