diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt
index 883901b..9344d83 100644
--- a/Documentation/kernel-parameters.txt
+++ b/Documentation/kernel-parameters.txt
@@ -1716,8 +1716,12 @@
 			7 (KERN_DEBUG)		debug-level messages
 
 	log_buf_len=n[KMG]	Sets the size of the printk ring buffer,
-			in bytes.  n must be a power of two.  The default
-			size is set in the kernel config file.
+			in bytes.  n must be a power of two and greater
+			than the minimal size. The minimal size is defined
+			by LOG_BUF_SHIFT kernel config parameter. There is
+			also CONFIG_LOG_CPU_MAX_BUF_SHIFT config parameter
+			that allows to increase the default size depending on
+			the number of CPUs. See init/Kconfig for more details.
 
 	logo.nologo	[FB] Disables display of the built-in Linux logo.
 			This may be used to provide more screen space for
diff --git a/init/Kconfig b/init/Kconfig
index 41066e4..a291b7e 100644
--- a/init/Kconfig
+++ b/init/Kconfig
@@ -807,15 +807,53 @@
 	range 12 21
 	default 17
 	help
-	  Select kernel log buffer size as a power of 2.
+	  Select the minimal kernel log buffer size as a power of 2.
+	  The final size is affected by LOG_CPU_MAX_BUF_SHIFT config
+	  parameter, see below. Any higher size also might be forced
+	  by "log_buf_len" boot parameter.
+
 	  Examples:
-	  	     17 => 128 KB
+		     17 => 128 KB
 		     16 => 64 KB
-	             15 => 32 KB
-	             14 => 16 KB
+		     15 => 32 KB
+		     14 => 16 KB
 		     13 =>  8 KB
 		     12 =>  4 KB
 
+config LOG_CPU_MAX_BUF_SHIFT
+	int "CPU kernel log buffer size contribution (13 => 8 KB, 17 => 128KB)"
+	range 0 21
+	default 12 if !BASE_SMALL
+	default 0 if BASE_SMALL
+	help
+	  This option allows to increase the default ring buffer size
+	  according to the number of CPUs. The value defines the contribution
+	  of each CPU as a power of 2. The used space is typically only few
+	  lines however it might be much more when problems are reported,
+	  e.g. backtraces.
+
+	  The increased size means that a new buffer has to be allocated and
+	  the original static one is unused. It makes sense only on systems
+	  with more CPUs. Therefore this value is used only when the sum of
+	  contributions is greater than the half of the default kernel ring
+	  buffer as defined by LOG_BUF_SHIFT. The default values are set
+	  so that more than 64 CPUs are needed to trigger the allocation.
+
+	  Also this option is ignored when "log_buf_len" kernel parameter is
+	  used as it forces an exact (power of two) size of the ring buffer.
+
+	  The number of possible CPUs is used for this computation ignoring
+	  hotplugging making the compuation optimal for the the worst case
+	  scenerio while allowing a simple algorithm to be used from bootup.
+
+	  Examples shift values and their meaning:
+		     17 => 128 KB for each CPU
+		     16 =>  64 KB for each CPU
+		     15 =>  32 KB for each CPU
+		     14 =>  16 KB for each CPU
+		     13 =>   8 KB for each CPU
+		     12 =>   4 KB for each CPU
+
 #
 # Architectures with an unreliable sched_clock() should select this:
 #
diff --git a/kernel/printk/printk.c b/kernel/printk/printk.c
index db290be..f855ec3 100644
--- a/kernel/printk/printk.c
+++ b/kernel/printk/printk.c
@@ -266,6 +266,7 @@
 #define LOG_ALIGN __alignof__(struct printk_log)
 #endif
 #define __LOG_BUF_LEN (1 << CONFIG_LOG_BUF_SHIFT)
+#define __LOG_CPU_MAX_BUF_LEN (1 << CONFIG_LOG_CPU_MAX_BUF_SHIFT)
 static char __log_buf[__LOG_BUF_LEN] __aligned(LOG_ALIGN);
 static char *log_buf = __log_buf;
 static u32 log_buf_len = __LOG_BUF_LEN;
@@ -848,12 +849,45 @@
 }
 early_param("log_buf_len", log_buf_len_setup);
 
+static void __init log_buf_add_cpu(void)
+{
+	unsigned int cpu_extra;
+
+	/*
+	 * archs should set up cpu_possible_bits properly with
+	 * set_cpu_possible() after setup_arch() but just in
+	 * case lets ensure this is valid.
+	 */
+	if (num_possible_cpus() == 1)
+		return;
+
+	cpu_extra = (num_possible_cpus() - 1) * __LOG_CPU_MAX_BUF_LEN;
+
+	/* by default this will only continue through for large > 64 CPUs */
+	if (cpu_extra <= __LOG_BUF_LEN / 2)
+		return;
+
+	pr_info("log_buf_len individual max cpu contribution: %d bytes\n",
+		__LOG_CPU_MAX_BUF_LEN);
+	pr_info("log_buf_len total cpu_extra contributions: %d bytes\n",
+		cpu_extra);
+	pr_info("log_buf_len min size: %d bytes\n", __LOG_BUF_LEN);
+
+	log_buf_len_update(cpu_extra + __LOG_BUF_LEN);
+}
+
 void __init setup_log_buf(int early)
 {
 	unsigned long flags;
 	char *new_log_buf;
 	int free;
 
+	if (log_buf != __log_buf)
+		return;
+
+	if (!early && !new_log_buf_len)
+		log_buf_add_cpu();
+
 	if (!new_log_buf_len)
 		return;