There's a concern that removing /proc/sys/vm/oom_kill_allocating_task
will unnecessarily break the userspace API as the result of the oom
killer rewrite.
This patch reintroduces the sysctl and deprecates it by adding an entry
to Documentation/feature-removal-schedule.txt with a suggested removal
date of December 2011 and emitting a warning the first time it is written
including the writing task's name and pid.
/proc/sys/vm/oom_kill_allocating task mirrors the value of
/proc/sys/vm/oom_kill_quick.
Signed-off-by: David Rientjes <rientjes@xxxxxxxxxx>
---
Documentation/feature-removal-schedule.txt | 19 +++++++++++++++++++
include/linux/oom.h | 2 ++
kernel/sysctl.c | 7 +++++++
mm/oom_kill.c | 14 ++++++++++++++
4 files changed, 42 insertions(+), 0 deletions(-)
diff --git a/Documentation/feature-removal-schedule.txt b/Documentation/feature-removal-schedule.txt
--- a/Documentation/feature-removal-schedule.txt
+++ b/Documentation/feature-removal-schedule.txt
@@ -204,6 +204,25 @@ Who: David Rientjes <rientjes@xxxxxxxxxx>
---------------------------
+What: /proc/sys/vm/oom_kill_allocating_task
+When: December 2011
+Why: /proc/sys/vm/oom_kill_allocating_task is equivalent to
+ /proc/sys/vm/oom_kill_quick. The two sysctls will mirror each other's
+ value when set.
+
+ Existing users of /proc/sys/vm/oom_kill_allocating_task should simply
+ write a non-zero value to /proc/sys/vm/oom_kill_quick. This will also
+ suppress a costly tasklist scan when dumping VM information for all
+ oom kill candidates.
+
+ A warning will be emitted to the kernel log if an application uses this
+ deprecated interface. After it is printed once, future warning will be
+ suppressed until the kernel is rebooted.
+
+Who: David Rientjes <rientjes@xxxxxxxxxx>
+
+---------------------------
+
What: remove EXPORT_SYMBOL(kernel_thread)
When: August 2006
Files: arch/*/kernel/*_ksyms.c
diff --git a/include/linux/oom.h b/include/linux/oom.h
--- a/include/linux/oom.h
+++ b/include/linux/oom.h
@@ -67,5 +67,7 @@ extern int sysctl_panic_on_oom;
extern int sysctl_oom_forkbomb_thres;
extern int sysctl_oom_kill_quick;
+extern int oom_kill_allocating_task_handler(struct ctl_table *table, int write,
+ void __user *buffer, size_t *lenp, loff_t *ppos);
#endif /* __KERNEL__*/
#endif /* _INCLUDE_LINUX_OOM_H */
diff --git a/kernel/sysctl.c b/kernel/sysctl.c
--- a/kernel/sysctl.c
+++ b/kernel/sysctl.c
@@ -983,6 +983,13 @@ static struct ctl_table vm_table[] = {
.proc_handler = proc_dointvec,
},
{
+ .procname = "oom_kill_allocating_task",
+ .data = &sysctl_oom_kill_quick,
+ .maxlen = sizeof(sysctl_oom_kill_quick),
+ .mode = 0644,
+ .proc_handler = oom_kill_allocating_task_handler,
+ },
+ {
.procname = "oom_forkbomb_thres",
.data = &sysctl_oom_forkbomb_thres,
.maxlen = sizeof(sysctl_oom_forkbomb_thres),
diff --git a/mm/oom_kill.c b/mm/oom_kill.c
--- a/mm/oom_kill.c
+++ b/mm/oom_kill.c
@@ -37,6 +37,20 @@ int sysctl_oom_forkbomb_thres = DEFAULT_OOM_FORKBOMB_THRES;
int sysctl_oom_kill_quick;
static DEFINE_SPINLOCK(zone_scan_lock);
+int oom_kill_allocating_task_handler(struct ctl_table *table, int write,
+ void __user *buffer, size_t *lenp, loff_t *ppos)
+{
+ int ret;
+
+ ret = proc_dointvec(table, write, buffer, lenp, ppos);
+ if (!ret && write)
+ printk_once(KERN_WARNING "%s (%d): "
+ "/proc/sys/vm/oom_kill_allocating_task is deprecated, "
+ "please use /proc/sys/vm/oom_kill_quick instead.\n",
+ current->comm, task_pid_nr(current));
+ return ret;
+}
+
/*
* Do all threads of the target process overlap our allowed nodes?
* @tsk: task struct of which task to consider
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