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Date: Mon, 17 Aug 2020 10:08:27 -0400
From: Waiman Long <longman@...hat.com>
To: Andrew Morton <akpm@...ux-foundation.org>,
Johannes Weiner <hannes@...xchg.org>,
Michal Hocko <mhocko@...nel.org>,
Vladimir Davydov <vdavydov.dev@...il.com>,
Jonathan Corbet <corbet@....net>,
Alexey Dobriyan <adobriyan@...il.com>,
Ingo Molnar <mingo@...nel.org>,
Peter Zijlstra <peterz@...radead.org>,
Juri Lelli <juri.lelli@...hat.com>,
Vincent Guittot <vincent.guittot@...aro.org>
Cc: linux-kernel@...r.kernel.org, linux-doc@...r.kernel.org,
linux-fsdevel@...r.kernel.org, cgroups@...r.kernel.org,
linux-mm@...ck.org, Waiman Long <longman@...hat.com>
Subject: [RFC PATCH 4/8] fs/proc: Support a new procfs memctl file
To allow system administrators to view and modify the over-high action
settings of a running application, a new /proc/<pid>/memctl file is
now added to show the over-high action parameters as well as allowing
their modification.
Signed-off-by: Waiman Long <longman@...hat.com>
---
fs/proc/base.c | 109 +++++++++++++++++++++++++++++++++++++++++++++++++
1 file changed, 109 insertions(+)
diff --git a/fs/proc/base.c b/fs/proc/base.c
index 617db4e0faa0..3c9349ad1e37 100644
--- a/fs/proc/base.c
+++ b/fs/proc/base.c
@@ -88,6 +88,8 @@
#include <linux/user_namespace.h>
#include <linux/fs_struct.h>
#include <linux/slab.h>
+#include <linux/prctl.h>
+#include <linux/ctype.h>
#include <linux/sched/autogroup.h>
#include <linux/sched/mm.h>
#include <linux/sched/coredump.h>
@@ -3145,6 +3147,107 @@ static int proc_stack_depth(struct seq_file *m, struct pid_namespace *ns,
}
#endif /* CONFIG_STACKLEAK_METRICS */
+#ifdef CONFIG_MEMCG
+/*
+ * Memory cgroup control parameters
+ * <over_high_action> <limit1> <limit2>
+ */
+static ssize_t proc_memctl_read(struct file *file, char __user *buf,
+ size_t count, loff_t *ppos)
+{
+ struct task_struct *task = get_proc_task(file_inode(file));
+ unsigned long action, limit1, limit2;
+ char buffer[80];
+ ssize_t len;
+
+ if (!task)
+ return -ESRCH;
+
+ action = task->memcg_over_high_action |
+ (task->memcg_over_high_signal << PR_MEMACT_SIG_SHIFT) |
+ (task->memcg_over_high_flags << PR_MEMACT_FLG_SHIFT);
+ limit1 = (unsigned long)task->memcg_over_high_climit * PAGE_SIZE;
+ limit2 = (unsigned long)task->memcg_over_high_plimit * PAGE_SIZE;
+
+ put_task_struct(task);
+ len = snprintf(buffer, sizeof(buffer), "%ld %ld %ld\n",
+ action, limit1, limit2);
+ return simple_read_from_buffer(buf, count, ppos, buffer, len);
+}
+
+static ssize_t proc_memctl_write(struct file *file, const char __user *buf,
+ size_t count, loff_t *offs)
+{
+ struct task_struct *task = get_proc_task(file_inode(file));
+ unsigned long vals[3];
+ char buffer[80];
+ char *ptr, *next;
+ int i, err;
+ unsigned int action, signal, flags;
+
+ if (!task)
+ return -ESRCH;
+ if (count > sizeof(buffer) - 1)
+ count = sizeof(buffer) - 1;
+ if (copy_from_user(buffer, buf, count)) {
+ err = -EFAULT;
+ goto out;
+ }
+ buffer[count] = '\0';
+ next = buffer;
+
+ /*
+ * Expect to find 3 numbers
+ */
+ for (i = 0, ptr = buffer; i < 3; i++) {
+ ptr = skip_spaces(next);
+ if (!*ptr) {
+ err = -EINVAL;
+ goto out;
+ }
+
+ /* Skip non-space characters for next */
+ for (next = ptr; *next && !isspace(*next); next++)
+ ;
+ if (isspace(*next))
+ *next++ = '\0';
+
+ err = kstrtoul(ptr, 0, &vals[i]);
+ if (err)
+ break;
+ }
+ action = vals[0] & PR_MEMACT_MASK;
+ signal = (vals[0] >> PR_MEMACT_SIG_SHIFT) & PR_MEMACT_MASK;
+ flags = vals[0] >> PR_MEMACT_FLG_SHIFT;
+
+ /* Round up limits to number of pages */
+ vals[1] = DIV_ROUND_UP(vals[1], PAGE_SIZE);
+ vals[2] = DIV_ROUND_UP(vals[2], PAGE_SIZE);
+
+ /* Check input values */
+ if ((action > PR_MEMACT_MAX) || (signal >= _NSIG) ||
+ (flags & ~PR_MEMFLAG_MASK)) {
+ err = -EINVAL;
+ goto out;
+ }
+
+ WRITE_ONCE(task->memcg_over_high_action, action);
+ WRITE_ONCE(task->memcg_over_high_signal, signal);
+ WRITE_ONCE(task->memcg_over_high_flags, flags);
+ WRITE_ONCE(task->memcg_over_high_climit, vals[1]);
+ WRITE_ONCE(task->memcg_over_high_plimit, vals[2]);
+out:
+ put_task_struct(task);
+ return err < 0 ? err : count;
+}
+
+const struct file_operations proc_memctl_operations = {
+ .read = proc_memctl_read,
+ .write = proc_memctl_write,
+ .llseek = generic_file_llseek,
+};
+#endif /* CONFIG_MEMCG */
+
/*
* Thread groups
*/
@@ -3258,6 +3361,9 @@ static const struct pid_entry tgid_base_stuff[] = {
#ifdef CONFIG_PROC_PID_ARCH_STATUS
ONE("arch_status", S_IRUGO, proc_pid_arch_status),
#endif
+#ifdef CONFIG_MEMCG
+ REG("memctl", 0644, proc_memctl_operations),
+#endif
};
static int proc_tgid_base_readdir(struct file *file, struct dir_context *ctx)
@@ -3587,6 +3693,9 @@ static const struct pid_entry tid_base_stuff[] = {
#ifdef CONFIG_PROC_PID_ARCH_STATUS
ONE("arch_status", S_IRUGO, proc_pid_arch_status),
#endif
+#ifdef CONFIG_MEMCG
+ REG("memctl", 0644, proc_memctl_operations),
+#endif
};
static int proc_tid_base_readdir(struct file *file, struct dir_context *ctx)
--
2.18.1
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