On Tue, 27 Apr 2010 15:58:41 -0700 (PDT)
David Rientjes <rientjes@xxxxxxxxxx> wrote:
> 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>
Reviewed-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@xxxxxxxxxxxxxx>
> ---
> 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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