diff options
| -rw-r--r-- | mm/oom_kill.c | 30 |
1 files changed, 24 insertions, 6 deletions
diff --git a/mm/oom_kill.c b/mm/oom_kill.c index 326dd14..dfb1ab6 100644 --- a/mm/oom_kill.c +++ b/mm/oom_kill.c @@ -443,13 +443,29 @@ static bool __oom_reap_task(struct task_struct *tsk) { struct mmu_gather tlb; struct vm_area_struct *vma; - struct mm_struct *mm; + struct mm_struct *mm = NULL; struct task_struct *p; struct zap_details details = {.check_swap_entries = true, .ignore_dirty = true}; bool ret = true; /* + * We have to make sure to not race with the victim exit path + * and cause premature new oom victim selection: + * __oom_reap_task exit_mm + * atomic_inc_not_zero + * mmput + * atomic_dec_and_test + * exit_oom_victim + * [...] + * out_of_memory + * select_bad_process + * # no TIF_MEMDIE task selects new victim + * unmap_page_range # frees some memory + */ + mutex_lock(&oom_lock); + + /* * Make sure we find the associated mm_struct even when the particular * thread has already terminated and cleared its mm. * We might have race with exit path so consider our work done if there @@ -457,19 +473,19 @@ static bool __oom_reap_task(struct task_struct *tsk) */ p = find_lock_task_mm(tsk); if (!p) - return true; + goto unlock_oom; mm = p->mm; if (!atomic_inc_not_zero(&mm->mm_users)) { task_unlock(p); - return true; + goto unlock_oom; } task_unlock(p); if (!down_read_trylock(&mm->mmap_sem)) { ret = false; - goto out; + goto unlock_oom; } tlb_gather_mmu(&tlb, mm, 0, -1); @@ -511,13 +527,15 @@ static bool __oom_reap_task(struct task_struct *tsk) * to release its memory. */ set_bit(MMF_OOM_REAPED, &mm->flags); -out: +unlock_oom: + mutex_unlock(&oom_lock); /* * Drop our reference but make sure the mmput slow path is called from a * different context because we shouldn't risk we get stuck there and * put the oom_reaper out of the way. */ - mmput_async(mm); + if (mm) + mmput_async(mm); return ret; } |
