From 51b1bd2ace1595b72956224deda349efa880b693 Mon Sep 17 00:00:00 2001 From: David Rientjes Date: Mon, 9 Aug 2010 17:19:47 -0700 Subject: oom: deprecate oom_adj tunable /proc/pid/oom_adj is now deprecated so that that it may eventually be removed. The target date for removal is August 2012. A warning will be printed to the kernel log if a task attempts to use this interface. Future warning will be suppressed until the kernel is rebooted to prevent spamming the kernel log. Signed-off-by: David Rientjes Cc: Nick Piggin Cc: KAMEZAWA Hiroyuki Cc: KOSAKI Motohiro Cc: Oleg Nesterov Cc: Balbir Singh Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- Documentation/feature-removal-schedule.txt | 25 +++++++++++++++++++++++++ Documentation/filesystems/proc.txt | 3 +++ fs/proc/base.c | 8 ++++++++ include/linux/oom.h | 3 +++ 4 files changed, 39 insertions(+) diff --git a/Documentation/feature-removal-schedule.txt b/Documentation/feature-removal-schedule.txt index 71f0fea1058f..56cee4727b1a 100644 --- a/Documentation/feature-removal-schedule.txt +++ b/Documentation/feature-removal-schedule.txt @@ -151,6 +151,31 @@ Who: Eric Biederman --------------------------- +What: /proc//oom_adj +When: August 2012 +Why: /proc//oom_adj allows userspace to influence the oom killer's + badness heuristic used to determine which task to kill when the kernel + is out of memory. + + The badness heuristic has since been rewritten since the introduction of + this tunable such that its meaning is deprecated. The value was + implemented as a bitshift on a score generated by the badness() + function that did not have any precise units of measure. With the + rewrite, the score is given as a proportion of available memory to the + task allocating pages, so using a bitshift which grows the score + exponentially is, thus, impossible to tune with fine granularity. + + A much more powerful interface, /proc//oom_score_adj, was + introduced with the oom killer rewrite that allows users to increase or + decrease the badness() score linearly. This interface will replace + /proc//oom_adj. + + A warning will be emitted to the kernel log if an application uses this + deprecated interface. After it is printed once, future warnings will be + suppressed until the kernel is rebooted. + +--------------------------- + What: remove EXPORT_SYMBOL(kernel_thread) When: August 2006 Files: arch/*/kernel/*_ksyms.c diff --git a/Documentation/filesystems/proc.txt b/Documentation/filesystems/proc.txt index cf1295c2bb66..a6aca8740883 100644 --- a/Documentation/filesystems/proc.txt +++ b/Documentation/filesystems/proc.txt @@ -1285,6 +1285,9 @@ scaled linearly with /proc//oom_score_adj. Writing to /proc//oom_score_adj or /proc//oom_adj will change the other with its scaled value. +NOTICE: /proc//oom_adj is deprecated and will be removed, please see +Documentation/feature-removal-schedule.txt. + Caveat: when a parent task is selected, the oom killer will sacrifice any first generation children with seperate address spaces instead, if possible. This avoids servers and important system daemons from being killed and loses the diff --git a/fs/proc/base.c b/fs/proc/base.c index f923b728388a..69254a365ce2 100644 --- a/fs/proc/base.c +++ b/fs/proc/base.c @@ -1037,6 +1037,14 @@ static ssize_t oom_adjust_write(struct file *file, const char __user *buf, return -EACCES; } + /* + * Warn that /proc/pid/oom_adj is deprecated, see + * Documentation/feature-removal-schedule.txt. + */ + printk_once(KERN_WARNING "%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_adj = oom_adjust; /* * Scale /proc/pid/oom_score_adj appropriately ensuring that a maximum diff --git a/include/linux/oom.h b/include/linux/oom.h index 73b8d7b6dd19..f209b683e118 100644 --- a/include/linux/oom.h +++ b/include/linux/oom.h @@ -2,6 +2,9 @@ #define __INCLUDE_LINUX_OOM_H /* + * /proc//oom_adj is deprecated, see + * Documentation/feature-removal-schedule.txt. + * * /proc//oom_adj set to -17 protects from the oom-killer */ #define OOM_DISABLE (-17) -- cgit v1.2.3-59-g8ed1b