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Commit 162a7e75 authored by Mike Travis's avatar Mike Travis Committed by Linus Torvalds
Browse files

printk: allocate kernel log buffer earlier 



On larger systems, because of the numerous ACPI, Bootmem and EFI messages,
the static log buffer overflows before the larger one specified by the
log_buf_len param is allocated.  Minimize the overflow by allocating the
new log buffer as soon as possible.

On kernels without memblock, a later call to setup_log_buf from
kernel/init.c is the fallback.

[akpm@linux-foundation.org: coding-style fixes]
[akpm@linux-foundation.org: fix CONFIG_PRINTK=n build]
Signed-off-by: default avatarMike Travis <travis@sgi.com>
Cc: Yinghai Lu <yhlu.kernel@gmail.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Jack Steiner <steiner@sgi.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 95dde501

arch/x86/kernel/setup.c

+2 −0
Original line number Diff line number Diff line
@@ -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();

include/linux/printk.h

+7 −0
Original line number Diff line number Diff line 
#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;

init/main.c

+1 −0
Original line number Diff line number Diff line
@@ -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();

kernel/printk.c

+58 −29
Original line number Diff line number Diff line
@@ -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>
@@ -167,31 +168,62 @@ 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) {

	if (size > log_buf_len)

		new_log_buf_len = size;



	return 0;

}

early_param("log_buf_len", log_buf_len_setup);



void __init setup_log_buf(int early)

{

	unsigned long flags;

	unsigned start, dest_idx, offset;

	char *new_log_buf;

	int free;



		new_log_buf = alloc_bootmem(size);

		if (!new_log_buf) {

			printk(KERN_WARNING "log_buf_len: allocation failed\n");

			goto out;

	if (!new_log_buf_len)

		return;



	if (early) {

		unsigned long mem;



		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);

	}



	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 = size;

	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) {

			log_buf[dest_idx] = __log_buf[start & (__LOG_BUF_LEN - 1)];

		unsigned log_idx_mask = start & (__LOG_BUF_LEN - 1);



		log_buf[dest_idx] = __log_buf[log_idx_mask];

		start++;

		dest_idx++;

	}
@@ -200,13 +232,10 @@ static int __init log_buf_len_setup(char *str) 
	log_end -= offset;

	spin_unlock_irqrestore(&logbuf_lock, flags);



		printk(KERN_NOTICE "log_buf_len: %d\n", log_buf_len);

	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);

}

out:

	return 1;

}



__setup("log_buf_len=", log_buf_len_setup);



#ifdef CONFIG_BOOT_PRINTK_DELAY