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Date: Mon, 30 May 2016 15:05:52 +0200
From: Michal Hocko <mhocko@...nel.org>
To: <linux-mm@...ck.org>
Cc: Tetsuo Handa <penguin-kernel@...ove.SAKURA.ne.jp>,
David Rientjes <rientjes@...gle.com>,
Oleg Nesterov <oleg@...hat.com>,
Vladimir Davydov <vdavydov@...allels.com>,
Andrew Morton <akpm@...ux-foundation.org>,
LKML <linux-kernel@...r.kernel.org>,
Michal Hocko <mhocko@...e.com>
Subject: [PATCH 2/6] proc, oom_adj: extract oom_score_adj setting into a helper
From: Michal Hocko <mhocko@...e.com>
Currently we have two proc interfaces to set oom_score_adj. The legacy
/proc/<pid>/oom_adj and /proc/<pid>/oom_score_adj which both have their
specific handlers. Big part of the logic is duplicated so extract the
common code into __set_oom_adj helper. Legacy knob still expects some
details slightly different so make sure those are handled same way - e.g.
the legacy mode ignores oom_score_adj_min and it warns about the usage.
This patch shouldn't introduce any functional changes.
Signed-off-by: Michal Hocko <mhocko@...e.com>
---
fs/proc/base.c | 112 +++++++++++++++++++++++++++------------------------------
1 file changed, 52 insertions(+), 60 deletions(-)
diff --git a/fs/proc/base.c b/fs/proc/base.c
index a6014e45c516..0afc77d4d84a 100644
--- a/fs/proc/base.c
+++ b/fs/proc/base.c
@@ -1041,6 +1041,56 @@ static ssize_t oom_adj_read(struct file *file, char __user *buf, size_t count,
return simple_read_from_buffer(buf, count, ppos, buffer, len);
}
+static int __set_oom_adj(struct file *file, int oom_adj, bool legacy)
+{
+ struct task_struct *task;
+ unsigned long flags;
+ int err = 0;
+
+ task = get_proc_task(file_inode(file));
+ if (!task) {
+ err = -ESRCH;
+ goto out;
+ }
+
+ if (!lock_task_sighand(task, &flags)) {
+ err = -ESRCH;
+ goto err_put_task;
+ }
+
+ if (legacy) {
+ if (oom_adj < task->signal->oom_score_adj &&
+ !capable(CAP_SYS_RESOURCE)) {
+ err = -EACCES;
+ goto err_sighand;
+ }
+ /*
+ * /proc/pid/oom_adj is provided for legacy purposes, ask users to use
+ * /proc/pid/oom_score_adj instead.
+ */
+ pr_warn_once("%s (%d): /proc/%d/oom_adj is deprecated, please use /proc/%d/oom_score_adj instead.\n",
+ current->comm, task_pid_nr(current), task_pid_nr(task),
+ task_pid_nr(task));
+ } else {
+ if ((short)oom_adj < task->signal->oom_score_adj_min &&
+ !capable(CAP_SYS_RESOURCE)) {
+ err = -EACCES;
+ goto err_sighand;
+ }
+ }
+
+ task->signal->oom_score_adj = oom_adj;
+ if (!legacy && has_capability_noaudit(current, CAP_SYS_RESOURCE))
+ task->signal->oom_score_adj_min = (short)oom_adj;
+ trace_oom_score_adj_update(task);
+err_sighand:
+ unlock_task_sighand(task, &flags);
+err_put_task:
+ put_task_struct(task);
+out:
+ return err;
+}
+
/*
* /proc/pid/oom_adj exists solely for backwards compatibility with previous
* kernels. The effective policy is defined by oom_score_adj, which has a
@@ -1054,10 +1104,8 @@ static ssize_t oom_adj_read(struct file *file, char __user *buf, size_t count,
static ssize_t oom_adj_write(struct file *file, const char __user *buf,
size_t count, loff_t *ppos)
{
- struct task_struct *task;
char buffer[PROC_NUMBUF];
int oom_adj;
- unsigned long flags;
int err;
memset(buffer, 0, sizeof(buffer));
@@ -1077,17 +1125,6 @@ static ssize_t oom_adj_write(struct file *file, const char __user *buf,
goto out;
}
- task = get_proc_task(file_inode(file));
- if (!task) {
- err = -ESRCH;
- goto out;
- }
-
- if (!lock_task_sighand(task, &flags)) {
- err = -ESRCH;
- goto err_put_task;
- }
-
/*
* Scale /proc/pid/oom_score_adj appropriately ensuring that a maximum
* value is always attainable.
@@ -1097,26 +1134,8 @@ static ssize_t oom_adj_write(struct file *file, const char __user *buf,
else
oom_adj = (oom_adj * OOM_SCORE_ADJ_MAX) / -OOM_DISABLE;
- if (oom_adj < task->signal->oom_score_adj &&
- !capable(CAP_SYS_RESOURCE)) {
- err = -EACCES;
- goto err_sighand;
- }
+ err = __set_oom_adj(file, oom_adj, true);
- /*
- * /proc/pid/oom_adj is provided for legacy purposes, ask users to use
- * /proc/pid/oom_score_adj instead.
- */
- pr_warn_once("%s (%d): /proc/%d/oom_adj is deprecated, please use /proc/%d/oom_score_adj instead.\n",
- current->comm, task_pid_nr(current), task_pid_nr(task),
- task_pid_nr(task));
-
- task->signal->oom_score_adj = oom_adj;
- trace_oom_score_adj_update(task);
-err_sighand:
- unlock_task_sighand(task, &flags);
-err_put_task:
- put_task_struct(task);
out:
return err < 0 ? err : count;
}
@@ -1150,9 +1169,7 @@ static ssize_t oom_score_adj_read(struct file *file, char __user *buf,
static ssize_t oom_score_adj_write(struct file *file, const char __user *buf,
size_t count, loff_t *ppos)
{
- struct task_struct *task;
char buffer[PROC_NUMBUF];
- unsigned long flags;
int oom_score_adj;
int err;
@@ -1173,32 +1190,7 @@ static ssize_t oom_score_adj_write(struct file *file, const char __user *buf,
goto out;
}
- task = get_proc_task(file_inode(file));
- if (!task) {
- err = -ESRCH;
- goto out;
- }
-
- if (!lock_task_sighand(task, &flags)) {
- err = -ESRCH;
- goto err_put_task;
- }
-
- if ((short)oom_score_adj < task->signal->oom_score_adj_min &&
- !capable(CAP_SYS_RESOURCE)) {
- err = -EACCES;
- goto err_sighand;
- }
-
- task->signal->oom_score_adj = (short)oom_score_adj;
- if (has_capability_noaudit(current, CAP_SYS_RESOURCE))
- task->signal->oom_score_adj_min = (short)oom_score_adj;
- trace_oom_score_adj_update(task);
-
-err_sighand:
- unlock_task_sighand(task, &flags);
-err_put_task:
- put_task_struct(task);
+ err = __set_oom_adj(file, oom_score_adj, false);
out:
return err < 0 ? err : count;
}
--
2.8.1
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