[to-be-updated] oom-remove-unnecessary-code-and-cleanup.patch removed from -mm tree

[akpm@linux-foundation.org]

The patch titled
     oom: remove unnecessary code and cleanup
has been removed from the -mm tree.  Its filename was
     oom-remove-unnecessary-code-and-cleanup.patch

This patch was dropped because an updated version will be merged

The current -mm tree may be found at http://userweb.kernel.org/~akpm/mmotm/

------------------------------------------------------
Subject: oom: remove unnecessary code and cleanup
From: David Rientjes <rientjes@google.com>

Remove the redundancy in __oom_kill_task() since:

 - init can never be passed to this function: it will never be PF_EXITING
   or selectable from select_bad_process(), and

 - it will never be passed a task from oom_kill_task() without an ->mm
   and we're unconcerned about detachment from exiting tasks, there's no
   reason to protect them against SIGKILL or access to memory reserves.

Also moves the kernel log message to a higher level since the verbosity is
not always emitted here; we need not print an error message if an exiting
task is given a longer timeslice.

Signed-off-by: David Rientjes <rientjes@google.com>
Reviewed-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Reviewed-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Cc: Rik van Riel <riel@redhat.com>
Cc: Nick Piggin <npiggin@suse.de>
Cc: Balbir Singh <balbir@linux.vnet.ibm.com>
Cc: Minchan Kim <minchan.kim@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 mm/oom_kill.c |   64 ++++++++++++------------------------------------
 1 file changed, 16 insertions(+), 48 deletions(-)

diff -puN mm/oom_kill.c~oom-remove-unnecessary-code-and-cleanup mm/oom_kill.c
--- a/mm/oom_kill.c~oom-remove-unnecessary-code-and-cleanup
+++ a/mm/oom_kill.c
@@ -427,67 +427,35 @@ static void dump_header(struct task_stru
 		dump_tasks(mem);
 }
 
-#define K(x) ((x) << (PAGE_SHIFT-10))
-
 /*
- * Send SIGKILL to the selected  process irrespective of  CAP_SYS_RAW_IO
- * flag though it's unlikely that  we select a process with CAP_SYS_RAW_IO
- * set.
+ * Give the oom killed task high priority and access to memory reserves so that
+ * it may quickly exit and free its memory.
  */
-static void __oom_kill_task(struct task_struct *p, int verbose)
+static void __oom_kill_task(struct task_struct *p)
 {
-	if (is_global_init(p)) {
-		WARN_ON(1);
-		printk(KERN_WARNING "tried to kill init!\n");
-		return;
-	}
-
-	task_lock(p);
-	if (!p->mm) {
-		WARN_ON(1);
-		printk(KERN_WARNING "tried to kill an mm-less task %d (%s)!\n",
-			task_pid_nr(p), p->comm);
-		task_unlock(p);
-		return;
-	}
-
-	if (verbose)
-		printk(KERN_ERR "Killed process %d (%s) "
-		       "vsz:%lukB, anon-rss:%lukB, file-rss:%lukB\n",
-		       task_pid_nr(p), p->comm,
-		       K(p->mm->total_vm),
-		       K(get_mm_counter(p->mm, MM_ANONPAGES)),
-		       K(get_mm_counter(p->mm, MM_FILEPAGES)));
-	task_unlock(p);
-
-	/*
-	 * We give our sacrificial lamb high priority and access to
-	 * all the memory it needs. That way it should be able to
-	 * exit() and clear out its resources quickly...
-	 */
 	p->rt.time_slice = HZ;
 	set_tsk_thread_flag(p, TIF_MEMDIE);
-
 	force_sig(SIGKILL, p);
 }
 
+#define K(x) ((x) << (PAGE_SHIFT-10))
 static int oom_kill_task(struct task_struct *p)
 {
-	/* WARNING: mm may not be dereferenced since we did not obtain its
-	 * value from get_task_mm(p).  This is OK since all we need to do is
-	 * compare mm to q->mm below.
-	 *
-	 * Furthermore, even if mm contains a non-NULL value, p->mm may
-	 * change to NULL at any time since we do not hold task_lock(p).
-	 * However, this is of no concern to us.
-	 */
-	if (!p->mm || p->signal->oom_score_adj == OOM_SCORE_ADJ_MIN)
+	task_lock(p);
+	if (!p->mm || p->signal->oom_score_adj == OOM_SCORE_ADJ_MIN) {
+		task_unlock(p);
 		return 1;
+	}
+	pr_err("Killed process %d (%s) total-vm:%lukB, anon-rss:%lukB, file-rss:%lukB\n",
+		task_pid_nr(p), p->comm, K(p->mm->total_vm),
+	       K(get_mm_counter(p->mm, MM_ANONPAGES)),
+	       K(get_mm_counter(p->mm, MM_FILEPAGES)));
+	task_unlock(p);
 
-	__oom_kill_task(p, 1);
-
+	__oom_kill_task(p);
 	return 0;
 }
+#undef K
 
 static int oom_kill_process(struct task_struct *p, gfp_t gfp_mask, int order,
 			    unsigned int points, unsigned long totalpages,
@@ -506,7 +474,7 @@ static int oom_kill_process(struct task_
 	 * its children or threads, just set TIF_MEMDIE so it can die quickly
 	 */
 	if (p->flags & PF_EXITING) {
-		__oom_kill_task(p, 0);
+		__oom_kill_task(p);
 		return 0;
 	}
 
_

Patches currently in -mm which might be from rientjes@google.com are

origin.patch
linux-next.patch
mempolicy-remove-redundant-code.patch
oom-remove-unnecessary-code-and-cleanup.patch
oom-default-to-killing-current-for-pagefault-ooms.patch
oom-avoid-race-for-oom-killed-tasks-detaching-mm-prior-to-exit.patch
oom-select_bad_process-check-pf_kthread-instead-of-mm-to-skip-kthreads.patch
oom-select_bad_process-pf_exiting-check-should-take-mm-into-account.patch
oom-introduce-find_lock_task_mm-to-fix-mm-false-positives.patch
oom-oom_forkbomb_penalty-move-thread_group_cputime-out-of-task_lock.patch
oom-hold-tasklist_lock-when-dumping-tasks.patch
oom-give-current-access-to-memory-reserves-if-it-has-been-killed.patch
oom-avoid-sending-exiting-tasks-a-sigkill.patch
oom-clean-up-oom_kill_task.patch
oom-clean-up-oom_badness.patch
oom-select_bad_process-never-choose-tasks-with-badness-==-0.patch
oom-avoid-divide-by-zero.patch
mempolicy-remove-case-mpol_interleave-from-policy_zonelist.patch
mempolicy-remove-redundant-check.patch
mempolicy-dont-call-mpol_set_nodemask-when-no_context.patch
mempolicy-lose-unnecessary-loop-variable-in-mpol_parse_str.patch
mempolicy-rename-policy_types-and-cleanup-initialization.patch
mempolicy-factor-mpol_shared_policy_init-return-paths.patch
mempolicy-document-cpuset-interaction-with-tmpfs-mpol-mount-option.patch
mempolicy-restructure-rebinding-mempolicy-functions.patch
cpusetmm-fix-no-node-to-alloc-memory-when-changing-cpusets-mems.patch
cpusetmm-fix-no-node-to-alloc-memory-when-changing-cpusets-mems-fix2.patch
mm-default-to-node-zonelist-ordering-when-nodes-have-only-lowmem.patch
mmcompaction-memory-compaction-core-do-not-schedule-work-on-other-cpus-for-compaction.patch
memcg-oom-wakeup-filter.patch
memcg-oom-wakeup-filter-update.patch
memcg-oom-notifier.patch
memcg-oom-notifier-update.patch
memcg-oom-kill-disable-and-oom-status.patch
memcg-oom-kill-disable-and-oom-status-update.patch
memcg-make-oom-killer-a-no-op-when-no-killable-task-can-be-found.patch
numa-add-generic-percpu-var-numa_node_id-implementation.patch
numa-add-generic-percpu-var-numa_node_id-implementation-fix1.patch
numa-add-generic-percpu-var-numa_node_id-implementation-fix2.patch
numa-x86_64-use-generic-percpu-var-numa_node_id-implementation.patch
numa-x86_64-use-generic-percpu-var-numa_node_id-implementation-fix1.patch
numa-x86_64-use-generic-percpu-var-numa_node_id-implementation-fix2.patch
numa-ia64-use-generic-percpu-var-numa_node_id-implementation.patch
numa-introduce-numa_mem_id-effective-local-memory-node-id.patch
numa-introduce-numa_mem_id-effective-local-memory-node-id-fix2.patch
numa-introduce-numa_mem_id-effective-local-memory-node-id-fix3.patch
numa-ia64-support-numa_mem_id-for-memoryless-nodes.patch
numa-slab-use-numa_mem_id-for-slab-local-memory-node.patch
numa-in-kernel-profiling-use-cpu_to_mem-for-per-cpu-allocations.patch
numa-update-documentation-vm-numa-add-memoryless-node-info.patch
numa-update-documentation-vm-numa-add-memoryless-node-info-fix1.patch