On Fri 20-07-18 17:09:02, Andrew Morton wrote: [...] > - Undocumented return value. > > - comment "failed to reap part..." is misleading - sounds like it's > referring to something which happened in the past, is in fact > referring to something which might happen in the future. > > - fails to call trace_finish_task_reaping() in one case > > - code duplication. > > - Increases mmap_sem hold time a little by moving > trace_finish_task_reaping() inside the locked region. So sue me ;) > > - Sharing the finish: path means that the trace event won't > distinguish between the two sources of finishing. > > Please take a look? oom_reap_task_mm should return false when __oom_reap_task_mm return false. This is what my patch did but it seems this changed by http://www.ozlabs.org/~akpm/mmotm/broken-out/mm-oom-remove-oom_lock-from-oom_reaper.patch so that one should be fixed. diff --git a/mm/oom_kill.c b/mm/oom_kill.c index 104ef4a01a55..88657e018714 100644 --- a/mm/oom_kill.c +++ b/mm/oom_kill.c @@ -565,7 +565,7 @@ static bool oom_reap_task_mm(struct task_struct *tsk, struct mm_struct *mm) /* failed to reap part of the address space. Try again later */ if (!__oom_reap_task_mm(mm)) { up_read(&mm->mmap_sem); - return true; + return false; } pr_info("oom_reaper: reaped process %d (%s), now anon-rss:%lukB, file-rss:%lukB, shmem-rss:%lukB\n", On top of that the proposed cleanup looks as follows: diff --git a/mm/oom_kill.c b/mm/oom_kill.c index 88657e018714..4e185a282b3d 100644 --- a/mm/oom_kill.c +++ b/mm/oom_kill.c @@ -541,8 +541,16 @@ bool __oom_reap_task_mm(struct mm_struct *mm) return ret; } +/* + * Reaps the address space of the give task. + * + * Returns true on success and false if none or part of the address space + * has been reclaimed and the caller should retry later. + */ static bool oom_reap_task_mm(struct task_struct *tsk, struct mm_struct *mm) { + bool ret = true; + if (!down_read_trylock(&mm->mmap_sem)) { trace_skip_task_reaping(tsk->pid); return false; @@ -555,28 +563,28 @@ static bool oom_reap_task_mm(struct task_struct *tsk, struct mm_struct *mm) * down_write();up_write() cycle in exit_mmap(). */ if (test_bit(MMF_OOM_SKIP, &mm->flags)) { - up_read(&mm->mmap_sem); trace_skip_task_reaping(tsk->pid); - return true; + goto out_unlock; } trace_start_task_reaping(tsk->pid); /* failed to reap part of the address space. Try again later */ - if (!__oom_reap_task_mm(mm)) { - up_read(&mm->mmap_sem); - return false; - } + ret = __oom_reap_task_mm(mm); + if (!ret) + goto out_finish; pr_info("oom_reaper: reaped process %d (%s), now anon-rss:%lukB, file-rss:%lukB, shmem-rss:%lukB\n", task_pid_nr(tsk), tsk->comm, K(get_mm_counter(mm, MM_ANONPAGES)), K(get_mm_counter(mm, MM_FILEPAGES)), K(get_mm_counter(mm, MM_SHMEMPAGES))); +out_finish: + trace_finish_task_reaping(tsk->pid); +out_unlock: up_read(&mm->mmap_sem); - trace_finish_task_reaping(tsk->pid); - return true; + return ret; } #define MAX_OOM_REAP_RETRIES 10 -- Michal Hocko SUSE Labs -- To unsubscribe from this list: send the line "unsubscribe linux-rdma" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
