[52794.911008] lowmemorykiller: Killing 'FinalizerDaemon' (17589), adj 904,
[52794.911008]    to free 53160kB on behalf of 'kworker/3:4' (18339) because
[52794.911008]    cache 199320kB is below limit 221184kB for oom_score_adj 900
[52794.911008]    Free memory is 24024kB above reserved.
[52794.911008]    Free CMA is 0kB
[52794.911008]    Total reserve is 42396kB
[52794.911008]    Total free pages is 32556kB
[52794.911008]    Total file cache is 234748kB
[52794.911008]    Total zcache is 0kB
[52794.911008]    GFP mask is 0x24080c0



1, choose oom_score_adj


221184kB : 55296 pages
129024kB : 32256 pages

other_free: 24024kB 
other_file: 199320kB 
1.1 choose condition:
other_file > lowmem_minfree[i-1] || other file > lowmem_minfree[i-1]
and
other_file < lowmem_minfree[i] && other file > lowmem_minfree[i]

        for (i = 0; i < array_size; i++) {
                minfree = lowmem_minfree[i];
                if (other_free < minfree && other_file < minfree) {
                        min_score_adj = lowmem_adj[i];
                        break;
                }
        }


1.2

cache 199320kB is below limit 221184kB for oom_score_adj 900


root@ailsa_ii:/sys/module/lowmemorykiller/parameters # cat adj
0,58,117,176,900,1000

root@ailsa_ii:/sys/module/lowmemorykiller/parameters # cat minfree
18432,23040,27648,32256,55296,80640





221184kB : 55296 pages
129024kB : 32256 pages

other_free: 24024kB 
other_file: 199320kB 

selected_oom_score_adj = 900


2, choose the process which have largest oom_score_adj with largest tasksize .


        for_each_process(tsk) {
                struct task_struct *p;
                short oom_score_adj;

...
                oom_score_adj = p->signal->oom_score_adj;
                if (oom_score_adj < min_score_adj) {
                        task_unlock(p);
                        continue;
                }
                tasksize = get_mm_rss(p->mm);
                task_unlock(p);
                if (tasksize <= 0)
                        continue;
                if (selected) {
                        if (oom_score_adj < selected_oom_score_adj)
                                continue;
                        if (oom_score_adj == selected_oom_score_adj &&
                            tasksize <= selected_tasksize)
                                continue;
                }
                selected = p;
                selected_tasksize = tasksize;
                selected_oom_score_adj = oom_score_adj;
                lowmem_print(3, "select '%s' (%d), adj %hd, size %d, to kill\n",
                             p->comm, p->pid, oom_score_adj, tasksize);
        }



3, kill

        if (selected) {                                                                                                                                                                                                                        
                long cache_size, cache_limit, free;
                task_lock(selected);
                send_sig(SIGKILL, selected, 0);
...
                task_unlock(selected);
                cache_size = other_file * (long)(PAGE_SIZE / 1024);
                cache_limit = minfree * (long)(PAGE_SIZE / 1024);
                free = other_free * (long)(PAGE_SIZE / 1024);
                trace_lowmemory_kill(selected, cache_size, cache_limit, free);
                lowmem_print(1, "Killing '%s' (%d), adj %hd,\n" \
                                "   to free %ldkB on behalf of '%s' (%d) because\n" \
                                "   cache %ldkB is below limit %ldkB for oom_score_adj %hd\n" \
                                "   Free memory is %ldkB above reserved.\n" \
                                "   Free CMA is %ldkB\n" \
                                "   Total reserve is %ldkB\n" \
                                "   Total free pages is %ldkB\n" \
                                "   Total file cache is %ldkB\n" \
                                "   Total zcache is %ldkB\n" \
                                "   GFP mask is 0x%x\n",
                             selected->comm, selected->pid,
                             selected_oom_score_adj,
                             selected_tasksize * (long)(PAGE_SIZE / 1024),
                             current->comm, current->pid,
                             cache_size, cache_limit,
                             min_score_adj,
                             free,
                             global_page_state(NR_FREE_CMA_PAGES) *
                                (long)(PAGE_SIZE / 1024),
                             totalreserve_pages * (long)(PAGE_SIZE / 1024),
                             global_page_state(NR_FREE_PAGES) *
                                (long)(PAGE_SIZE / 1024),
                             global_page_state(NR_FILE_PAGES) *
                                (long)(PAGE_SIZE / 1024),
                             (long)zcache_pages() * (long)(PAGE_SIZE / 1024),
                             sc->gfp_mask);