diff --git a/Documentation/sysctl/kernel.txt b/Documentation/sysctl/kernel.txt
index 9886c3d..708bb7f 100644
--- a/Documentation/sysctl/kernel.txt
+++ b/Documentation/sysctl/kernel.txt
@@ -77,6 +77,7 @@
 - shmmni
 - stop-a                      [ SPARC only ]
 - sysrq                       ==> Documentation/sysrq.txt
+- sysctl_writes_strict
 - tainted
 - threads-max
 - unknown_nmi_panic
@@ -762,6 +763,26 @@
 
 ==============================================================
 
+sysctl_writes_strict:
+
+Control how file position affects the behavior of updating sysctl values
+via the /proc/sys interface:
+
+  -1 - Legacy per-write sysctl value handling, with no printk warnings.
+       Each write syscall must fully contain the sysctl value to be
+       written, and multiple writes on the same sysctl file descriptor
+       will rewrite the sysctl value, regardless of file position.
+   0 - (default) Same behavior as above, but warn about processes that
+       perform writes to a sysctl file descriptor when the file position
+       is not 0.
+   1 - Respect file position when writing sysctl strings. Multiple writes
+       will append to the sysctl value buffer. Anything past the max length
+       of the sysctl value buffer will be ignored. Writes to numeric sysctl
+       entries must always be at file position 0 and the value must be
+       fully contained in the buffer sent in the write syscall.
+
+==============================================================
+
 tainted:
 
 Non-zero if the kernel has been tainted.  Numeric values, which
diff --git a/kernel/sysctl.c b/kernel/sysctl.c
index ac6847f..7a910b9 100644
--- a/kernel/sysctl.c
+++ b/kernel/sysctl.c
@@ -173,6 +173,13 @@
 #endif
 
 #ifdef CONFIG_PROC_SYSCTL
+
+#define SYSCTL_WRITES_LEGACY	-1
+#define SYSCTL_WRITES_WARN	 0
+#define SYSCTL_WRITES_STRICT	 1
+
+static int sysctl_writes_strict = SYSCTL_WRITES_WARN;
+
 static int proc_do_cad_pid(struct ctl_table *table, int write,
 		  void __user *buffer, size_t *lenp, loff_t *ppos);
 static int proc_taint(struct ctl_table *table, int write,
@@ -495,6 +502,15 @@
 		.mode		= 0644,
 		.proc_handler	= proc_taint,
 	},
+	{
+		.procname	= "sysctl_writes_strict",
+		.data		= &sysctl_writes_strict,
+		.maxlen		= sizeof(int),
+		.mode		= 0644,
+		.proc_handler	= proc_dointvec_minmax,
+		.extra1		= &neg_one,
+		.extra2		= &one,
+	},
 #endif
 #ifdef CONFIG_LATENCYTOP
 	{
@@ -1717,8 +1733,20 @@
 	}
 
 	if (write) {
-		/* Start writing from beginning of buffer. */
-		len = 0;
+		if (sysctl_writes_strict == SYSCTL_WRITES_STRICT) {
+			/* Only continue writes not past the end of buffer. */
+			len = strlen(data);
+			if (len > maxlen - 1)
+				len = maxlen - 1;
+
+			if (*ppos > len)
+				return 0;
+			len = *ppos;
+		} else {
+			/* Start writing from beginning of buffer. */
+			len = 0;
+		}
+
 		*ppos += *lenp;
 		p = buffer;
 		while ((p - buffer) < *lenp && len < maxlen - 1) {
@@ -1758,6 +1786,14 @@
 	return 0;
 }
 
+static void warn_sysctl_write(struct ctl_table *table)
+{
+	pr_warn_once("%s wrote to %s when file position was not 0!\n"
+		"This will not be supported in the future. To silence this\n"
+		"warning, set kernel.sysctl_writes_strict = -1\n",
+		current->comm, table->procname);
+}
+
 /**
  * proc_dostring - read a string sysctl
  * @table: the sysctl table
@@ -1778,6 +1814,9 @@
 int proc_dostring(struct ctl_table *table, int write,
 		  void __user *buffer, size_t *lenp, loff_t *ppos)
 {
+	if (write && *ppos && sysctl_writes_strict == SYSCTL_WRITES_WARN)
+		warn_sysctl_write(table);
+
 	return _proc_do_string((char *)(table->data), table->maxlen, write,
 			       (char __user *)buffer, lenp, ppos);
 }
@@ -1953,6 +1992,18 @@
 		conv = do_proc_dointvec_conv;
 
 	if (write) {
+		if (*ppos) {
+			switch (sysctl_writes_strict) {
+			case SYSCTL_WRITES_STRICT:
+				goto out;
+			case SYSCTL_WRITES_WARN:
+				warn_sysctl_write(table);
+				break;
+			default:
+				break;
+			}
+		}
+
 		if (left > PAGE_SIZE - 1)
 			left = PAGE_SIZE - 1;
 		page = __get_free_page(GFP_TEMPORARY);
@@ -2010,6 +2061,7 @@
 			return err ? : -EINVAL;
 	}
 	*lenp -= left;
+out:
 	*ppos += *lenp;
 	return err;
 }
@@ -2202,6 +2254,18 @@
 	left = *lenp;
 
 	if (write) {
+		if (*ppos) {
+			switch (sysctl_writes_strict) {
+			case SYSCTL_WRITES_STRICT:
+				goto out;
+			case SYSCTL_WRITES_WARN:
+				warn_sysctl_write(table);
+				break;
+			default:
+				break;
+			}
+		}
+
 		if (left > PAGE_SIZE - 1)
 			left = PAGE_SIZE - 1;
 		page = __get_free_page(GFP_TEMPORARY);
@@ -2257,6 +2321,7 @@
 			return err ? : -EINVAL;
 	}
 	*lenp -= left;
+out:
 	*ppos += *lenp;
 	return err;
 }