mm, oom: reintroduce /proc/pid/oom_adj
This is mostly a revert of 01dc52ebdf ("oom: remove deprecated oom_adj")
from Davidlohr Bueso.
It reintroduces /proc/pid/oom_adj for backwards compatibility with earlier
kernels. It simply scales the value linearly when /proc/pid/oom_score_adj
is written.
The major difference is that its scheduled removal is no longer included
in Documentation/feature-removal-schedule.txt. We do warn users with a
single printk, though, to suggest the more powerful and supported
/proc/pid/oom_score_adj interface.
Reported-by: Artem S. Tashkinov <t.artem@lycos.com>
Signed-off-by: David Rientjes <rientjes@google.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
David Rientjes
Linus Torvalds
parent
f4bcd79c88
commit
fa0cbbf145
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@ -33,7 +33,7 @@ Table of Contents
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2 Modifying System Parameters
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3 Per-Process Parameters
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3.1 /proc/<pid>/oom_score_adj - Adjust the oom-killer
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3.1 /proc/<pid>/oom_adj & /proc/<pid>/oom_score_adj - Adjust the oom-killer
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score
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3.2 /proc/<pid>/oom_score - Display current oom-killer score
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3.3 /proc/<pid>/io - Display the IO accounting fields
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@ -1320,10 +1320,10 @@ of the kernel.
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CHAPTER 3: PER-PROCESS PARAMETERS
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------------------------------------------------------------------------------
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3.1 /proc/<pid>/oom_score_adj- Adjust the oom-killer score
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3.1 /proc/<pid>/oom_adj & /proc/<pid>/oom_score_adj- Adjust the oom-killer score
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--------------------------------------------------------------------------------
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This file can be used to adjust the badness heuristic used to select which
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These file can be used to adjust the badness heuristic used to select which
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process gets killed in out of memory conditions.
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The badness heuristic assigns a value to each candidate task ranging from 0
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@ -1361,6 +1361,12 @@ same system, cpuset, mempolicy, or memory controller resources to use at least
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equivalent to discounting 50% of the task's allowed memory from being considered
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as scoring against the task.
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For backwards compatibility with previous kernels, /proc/<pid>/oom_adj may also
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be used to tune the badness score. Its acceptable values range from -16
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(OOM_ADJUST_MIN) to +15 (OOM_ADJUST_MAX) and a special value of -17
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(OOM_DISABLE) to disable oom killing entirely for that task. Its value is
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scaled linearly with /proc/<pid>/oom_score_adj.
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The value of /proc/<pid>/oom_score_adj may be reduced no lower than the last
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value set by a CAP_SYS_RESOURCE process. To reduce the value any lower
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requires CAP_SYS_RESOURCE.
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@ -1375,7 +1381,9 @@ minimal amount of work.
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-------------------------------------------------------------
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This file can be used to check the current score used by the oom-killer is for
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any given <pid>.
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any given <pid>. Use it together with /proc/<pid>/oom_score_adj to tune which
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process should be killed in an out-of-memory situation.
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3.3 /proc/<pid>/io - Display the IO accounting fields
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-------------------------------------------------------
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109
fs/proc/base.c
109
fs/proc/base.c
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@ -873,6 +873,113 @@ static const struct file_operations proc_environ_operations = {
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.release = mem_release,
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};
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static ssize_t oom_adj_read(struct file *file, char __user *buf, size_t count,
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loff_t *ppos)
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{
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struct task_struct *task = get_proc_task(file->f_path.dentry->d_inode);
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char buffer[PROC_NUMBUF];
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int oom_adj = OOM_ADJUST_MIN;
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size_t len;
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unsigned long flags;
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if (!task)
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return -ESRCH;
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if (lock_task_sighand(task, &flags)) {
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if (task->signal->oom_score_adj == OOM_SCORE_ADJ_MAX)
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oom_adj = OOM_ADJUST_MAX;
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else
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oom_adj = (task->signal->oom_score_adj * -OOM_DISABLE) /
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OOM_SCORE_ADJ_MAX;
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unlock_task_sighand(task, &flags);
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}
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put_task_struct(task);
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len = snprintf(buffer, sizeof(buffer), "%d\n", oom_adj);
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return simple_read_from_buffer(buf, count, ppos, buffer, len);
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}
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static ssize_t oom_adj_write(struct file *file, const char __user *buf,
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size_t count, loff_t *ppos)
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{
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struct task_struct *task;
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char buffer[PROC_NUMBUF];
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int oom_adj;
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unsigned long flags;
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int err;
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memset(buffer, 0, sizeof(buffer));
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if (count > sizeof(buffer) - 1)
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count = sizeof(buffer) - 1;
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if (copy_from_user(buffer, buf, count)) {
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err = -EFAULT;
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goto out;
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}
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err = kstrtoint(strstrip(buffer), 0, &oom_adj);
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if (err)
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goto out;
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if ((oom_adj < OOM_ADJUST_MIN || oom_adj > OOM_ADJUST_MAX) &&
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oom_adj != OOM_DISABLE) {
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err = -EINVAL;
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goto out;
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}
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task = get_proc_task(file->f_path.dentry->d_inode);
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if (!task) {
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err = -ESRCH;
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goto out;
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}
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task_lock(task);
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if (!task->mm) {
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err = -EINVAL;
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goto err_task_lock;
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}
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if (!lock_task_sighand(task, &flags)) {
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err = -ESRCH;
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goto err_task_lock;
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}
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/*
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* Scale /proc/pid/oom_score_adj appropriately ensuring that a maximum
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* value is always attainable.
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*/
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if (oom_adj == OOM_ADJUST_MAX)
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oom_adj = OOM_SCORE_ADJ_MAX;
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else
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oom_adj = (oom_adj * OOM_SCORE_ADJ_MAX) / -OOM_DISABLE;
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if (oom_adj < task->signal->oom_score_adj &&
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!capable(CAP_SYS_RESOURCE)) {
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err = -EACCES;
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goto err_sighand;
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}
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/*
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* /proc/pid/oom_adj is provided for legacy purposes, ask users to use
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* /proc/pid/oom_score_adj instead.
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*/
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printk_once(KERN_WARNING "%s (%d): /proc/%d/oom_adj is deprecated, please use /proc/%d/oom_score_adj instead.\n",
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current->comm, task_pid_nr(current), task_pid_nr(task),
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task_pid_nr(task));
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task->signal->oom_score_adj = oom_adj;
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trace_oom_score_adj_update(task);
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err_sighand:
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unlock_task_sighand(task, &flags);
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err_task_lock:
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task_unlock(task);
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put_task_struct(task);
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out:
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return err < 0 ? err : count;
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}
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static const struct file_operations proc_oom_adj_operations = {
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.read = oom_adj_read,
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.write = oom_adj_write,
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.llseek = generic_file_llseek,
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};
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static ssize_t oom_score_adj_read(struct file *file, char __user *buf,
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size_t count, loff_t *ppos)
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{
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@ -2598,6 +2705,7 @@ static const struct pid_entry tgid_base_stuff[] = {
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REG("cgroup", S_IRUGO, proc_cgroup_operations),
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#endif
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INF("oom_score", S_IRUGO, proc_oom_score),
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REG("oom_adj", S_IRUGO|S_IWUSR, proc_oom_adj_operations),
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REG("oom_score_adj", S_IRUGO|S_IWUSR, proc_oom_score_adj_operations),
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#ifdef CONFIG_AUDITSYSCALL
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REG("loginuid", S_IWUSR|S_IRUGO, proc_loginuid_operations),
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@ -2964,6 +3072,7 @@ static const struct pid_entry tid_base_stuff[] = {
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REG("cgroup", S_IRUGO, proc_cgroup_operations),
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#endif
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INF("oom_score", S_IRUGO, proc_oom_score),
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REG("oom_adj", S_IRUGO|S_IWUSR, proc_oom_adj_operations),
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REG("oom_score_adj", S_IRUGO|S_IWUSR, proc_oom_score_adj_operations),
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#ifdef CONFIG_AUDITSYSCALL
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REG("loginuid", S_IWUSR|S_IRUGO, proc_loginuid_operations),
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@ -8,4 +8,13 @@
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#define OOM_SCORE_ADJ_MIN (-1000)
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#define OOM_SCORE_ADJ_MAX 1000
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/*
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* /proc/<pid>/oom_adj set to -17 protects from the oom killer for legacy
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* purposes.
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*/
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#define OOM_DISABLE (-17)
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/* inclusive */
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#define OOM_ADJUST_MIN (-16)
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#define OOM_ADJUST_MAX 15
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#endif /* _UAPI__INCLUDE_LINUX_OOM_H */
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