4 files changed, 68 insertions, 29 deletions

diff --git a/arch/x86/kernel/setup.c b/arch/x86/kernel/setup.c
index 605e5ae19c7f..a3e5948670c2 100644
--- a/arch/x86/kernel/setup.c
+++ b/arch/x86/kernel/setup.c
@@ -946,6 +946,8 @@ void __init setup_arch(char **cmdline_p)
         if (init_ohci1394_dma_early)
                 init_ohci1394_dma_on_all_controllers();
 #endif
+        /* Allocate bigger log buffer */
+        setup_log_buf(1);
 
         reserve_initrd();
 
diff --git a/include/linux/printk.h b/include/linux/printk.h
index ee048e77e1ae..0101d55d9651 100644
--- a/include/linux/printk.h
+++ b/include/linux/printk.h
@@ -1,6 +1,8 @@
 #ifndef __KERNEL_PRINTK__
 #define __KERNEL_PRINTK__
 
+#include <linux/init.h>
+
 extern const char linux_banner[];
 extern const char linux_proc_banner[];
 
@@ -113,6 +115,7 @@ extern int dmesg_restrict;
 extern int kptr_restrict;
 
 void log_buf_kexec_setup(void);
+void __init setup_log_buf(int early);
 #else
 static inline __attribute__ ((format (printf, 1, 0)))
 int vprintk(const char *s, va_list args)
@@ -137,6 +140,10 @@ static inline bool printk_timed_ratelimit(unsigned long *caller_jiffies,
 static inline void log_buf_kexec_setup(void)
 {
 }
+
+static inline void setup_log_buf(int early)
+{
+}
 #endif
 
 extern void dump_stack(void) __cold;
diff --git a/init/main.c b/init/main.c
index 22da33918aef..d2f1e086bf33 100644
--- a/init/main.c
+++ b/init/main.c
@@ -504,6 +504,7 @@ asmlinkage void __init start_kernel(void)
          * These use large bootmem allocations and must precede
          * kmem_cache_init()
          */
+        setup_log_buf(0);
         pidhash_init();
         vfs_caches_init_early();
         sort_main_extable();
diff --git a/kernel/printk.c b/kernel/printk.c
index da8ca817eae3..35185392173f 100644
--- a/kernel/printk.c
+++ b/kernel/printk.c
@@ -31,6 +31,7 @@
 #include <linux/smp.h>
 #include <linux/security.h>
 #include <linux/bootmem.h>
+#include <linux/memblock.h>
 #include <linux/syscalls.h>
 #include <linux/kexec.h>
 #include <linux/kdb.h>
@@ -167,46 +168,74 @@ void log_buf_kexec_setup(void)
 }
 #endif
 
+/* requested log_buf_len from kernel cmdline */
+static unsigned long __initdata new_log_buf_len;
+
+/* save requested log_buf_len since it's too early to process it */
 static int __init log_buf_len_setup(char *str)
 {
         unsigned size = memparse(str, &str);
-        unsigned long flags;
 
         if (size)
                 size = roundup_pow_of_two(size);
-        if (size > log_buf_len) {
-                unsigned start, dest_idx, offset;
-                char *new_log_buf;
+        if (size > log_buf_len)
+                new_log_buf_len = size;
 
-                new_log_buf = alloc_bootmem(size);
-                if (!new_log_buf) {
-                        printk(KERN_WARNING "log_buf_len: allocation failed\n");
-                        goto out;
-                }
+        return 0;
+}
+early_param("log_buf_len", log_buf_len_setup);
 
-                spin_lock_irqsave(&logbuf_lock, flags);
-                log_buf_len = size;
-                log_buf = new_log_buf;
-
-                offset = start = min(con_start, log_start);
-                dest_idx = 0;
-                while (start != log_end) {
-                        log_buf[dest_idx] = __log_buf[start & (__LOG_BUF_LEN - 1)];
-                        start++;
-                        dest_idx++;
-                }
-                log_start -= offset;
-                con_start -= offset;
-                log_end -= offset;
-                spin_unlock_irqrestore(&logbuf_lock, flags);
+void __init setup_log_buf(int early)
+{
+        unsigned long flags;
+        unsigned start, dest_idx, offset;
+        char *new_log_buf;
+        int free;
+
+        if (!new_log_buf_len)
+                return;
+
+        if (early) {
+                unsigned long mem;
 
-                printk(KERN_NOTICE "log_buf_len: %d\n", log_buf_len);
+                mem = memblock_alloc(new_log_buf_len, PAGE_SIZE);
+                if (mem == MEMBLOCK_ERROR)
+                        return;
+                new_log_buf = __va(mem);
+        } else {
+                new_log_buf = alloc_bootmem_nopanic(new_log_buf_len);
         }
-out:
-        return 1;
-}
 
-__setup("log_buf_len=", log_buf_len_setup);
+        if (unlikely(!new_log_buf)) {
+                pr_err("log_buf_len: %ld bytes not available\n",
+                        new_log_buf_len);
+                return;
+        }
+
+        spin_lock_irqsave(&logbuf_lock, flags);
+        log_buf_len = new_log_buf_len;
+        log_buf = new_log_buf;
+        new_log_buf_len = 0;
+        free = __LOG_BUF_LEN - log_end;
+
+        offset = start = min(con_start, log_start);
+        dest_idx = 0;
+        while (start != log_end) {
+                unsigned log_idx_mask = start & (__LOG_BUF_LEN - 1);
+
+                log_buf[dest_idx] = __log_buf[log_idx_mask];
+                start++;
+                dest_idx++;
+        }
+        log_start -= offset;
+        con_start -= offset;
+        log_end -= offset;
+        spin_unlock_irqrestore(&logbuf_lock, flags);
+
+        pr_info("log_buf_len: %d\n", log_buf_len);
+        pr_info("early log buf free: %d(%d%%)\n",
+                free, (free * 100) / __LOG_BUF_LEN);
+}
 
 #ifdef CONFIG_BOOT_PRINTK_DELAY