linux-kernel - [PATCH v4 001/002] mm: limit growth of 3% hardcoded other user reserve

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Date:	Tue, 5 Mar 2013 18:38:12 -0500
From:	Andrew Shewmaker <agshew@...il.com>
To:	akpm@...ux-foundation.org
Cc:	linux-mm@...ck.org, linux-kernel@...r.kernel.org,
	alan@...rguk.ukuu.org.uk, simon.jeons@...il.com,
	ric.masonn@...il.com
Subject: [PATCH v4 001/002] mm: limit growth of 3% hardcoded other user
 reserve

Limit the growth of the memory reserved for other processes
to the smaller of 3% or 8MB.

This affects only OVERCOMMIT_NEVER.

Signed-off-by: Andrew Shewmaker <agshew@...il.com>

---

Rebased onto v3.8-mmotm-2013-03-01-15-50

No longer assumes 4kb pages.
Code duplicated for nommu.

diff --git a/mm/mmap.c b/mm/mmap.c
index 49dc7d5..4eb2b1a 100644
--- a/mm/mmap.c
+++ b/mm/mmap.c
@@ -184,9 +184,11 @@ int __vm_enough_memory(struct mm_struct *mm, long pages, int cap_sys_admin)
 	allowed += total_swap_pages;
 
 	/* Don't let a single process grow too big:
-	   leave 3% of the size of this process for other processes */
+	 * leave the smaller of 3% of the size of this process 
+         * or 8MB for other processes
+         */
 	if (mm)
-		allowed -= mm->total_vm / 32;
+		allowed -= min(mm->total_vm / 32, 1 << (23 - PAGE_SHIFT));
 
 	if (percpu_counter_read_positive(&vm_committed_as) < allowed)
 		return 0;
diff --git a/mm/nommu.c b/mm/nommu.c
index f5d57a3..a93d214 100644
--- a/mm/nommu.c
+++ b/mm/nommu.c
@@ -1945,9 +1945,11 @@ int __vm_enough_memory(struct mm_struct *mm, long pages, int cap_sys_admin)
 	allowed += total_swap_pages;
 
 	/* Don't let a single process grow too big:
-	   leave 3% of the size of this process for other processes */
+	 * leave the smaller of 3% of the size of this process 
+         * or 8MB for other processes
+         */
 	if (mm)
-		allowed -= mm->total_vm / 32;
+		allowed -= min(mm->total_vm / 32, 1 << (23 - PAGE_SHIFT));
 
 	if (percpu_counter_read_positive(&vm_committed_as) < allowed)
 		return 0;
--
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