oom: add sysctl to enable task memory dump

Adds a new sysctl, 'oom_dump_tasks', that enables the kernel to produce a
dump of all system tasks (excluding kernel threads) when performing an
OOM-killing.  Information includes pid, uid, tgid, vm size, rss, cpu,
oom_adj score, and name.

This is helpful for determining why there was an OOM condition and which
rogue task caused it.

It is configurable so that large systems, such as those with several
thousand tasks, do not incur a performance penalty associated with dumping
data they may not desire.

If an OOM was triggered as a result of a memory controller, the tasklist
shall be filtered to exclude tasks that are not a member of the same
cgroup.

Cc: Andrea Arcangeli <andrea@suse.de>
Cc: Christoph Lameter <clameter@sgi.com>
Cc: Balbir Singh <balbir@linux.vnet.ibm.com>
Signed-off-by: David Rientjes <rientjes@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/Documentation/sysctl/vm.txt b/Documentation/sysctl/vm.txt
index 24eac1b..8a4863c 100644 (file)
--- a/Documentation/sysctl/vm.txt
+++ b/Documentation/sysctl/vm.txt
@@ -32,6 +32,7 @@ Currently, these files are in /proc/sys/vm:
 - min_unmapped_ratio
 - min_slab_ratio
 - panic_on_oom
+- oom_dump_tasks
 - oom_kill_allocating_task
 - mmap_min_address
 - numa_zonelist_order
@@ -232,6 +233,27 @@ according to your policy of failover.
 
 =============================================================
 
+oom_dump_tasks
+
+Enables a system-wide task dump (excluding kernel threads) to be
+produced when the kernel performs an OOM-killing and includes such
+information as pid, uid, tgid, vm size, rss, cpu, oom_adj score, and
+name.  This is helpful to determine why the OOM killer was invoked
+and to identify the rogue task that caused it.
+
+If this is set to zero, this information is suppressed.  On very
+large systems with thousands of tasks it may not be feasible to dump
+the memory state information for each one.  Such systems should not
+be forced to incur a performance penalty in OOM conditions when the
+information may not be desired.
+
+If this is set to non-zero, this information is shown whenever the
+OOM killer actually kills a memory-hogging task.
+
+The default value is 0.
+
+=============================================================
+
 oom_kill_allocating_task
 
 This enables or disables killing the OOM-triggering task in

diff --git a/kernel/sysctl.c b/kernel/sysctl.c
index 86daaa2..8c98d81 100644 (file)
--- a/kernel/sysctl.c
+++ b/kernel/sysctl.c
@@ -67,6 +67,7 @@ extern int sysctl_overcommit_memory;
 extern int sysctl_overcommit_ratio;
 extern int sysctl_panic_on_oom;
 extern int sysctl_oom_kill_allocating_task;
+extern int sysctl_oom_dump_tasks;
 extern int max_threads;
 extern int core_uses_pid;
 extern int suid_dumpable;
@@ -870,6 +871,14 @@ static struct ctl_table vm_table[] = {
                .mode           = 0644,
                .proc_handler   = &proc_dointvec,
        },
+       {
+               .ctl_name       = CTL_UNNUMBERED,
+               .procname       = "oom_dump_tasks",
+               .data           = &sysctl_oom_dump_tasks,
+               .maxlen         = sizeof(sysctl_oom_dump_tasks),
+               .mode           = 0644,
+               .proc_handler   = &proc_dointvec,
+       },
        {
                .ctl_name       = VM_OVERCOMMIT_RATIO,
                .procname       = "overcommit_ratio",

diff --cc mm/oom_kill.c
Simple merge