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
potential for overflow by allocating the new log buffer as soon
as possible.
We do this by changing the log_buf_len from an early_param to a
_setup param. But _setup params are processed before the
alloc_bootmem is available, so this function will now just save
the requested log buf len. The real work routine (setup_log_buf)
is called after bootmem is available.
Signed-off-by: Mike Travis <travis@xxxxxxx>
Reviewed-by: Jack Steiner <steiner@xxxxxxx>
Reviewed-by: Robin Holt <holt@xxxxxxx>
---
arch/x86/kernel/setup.c | 5 +++
include/linux/printk.h | 4 ++
init/main.c | 1
kernel/printk.c | 75 ++++++++++++++++++++++++++++--------------------
4 files changed, 54 insertions(+), 31 deletions(-)
--- linux.orig/arch/x86/kernel/setup.c
+++ linux/arch/x86/kernel/setup.c
@@ -1007,6 +1007,11 @@ void __init setup_arch(char **cmdline_p)
memblock_find_dma_reserve();
dma32_reserve_bootmem();
+ /*
+ * Allocate bigger log buffer as early as possible
+ */
+ setup_log_buf();
+
#ifdef CONFIG_KVM_CLOCK
kvmclock_init();
#endif
--- linux.orig/include/linux/printk.h
+++ linux/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[];
@@ -89,6 +91,8 @@ int no_printk(const char *fmt, ...)
extern asmlinkage __attribute__ ((format (printf, 1, 2)))
void early_printk(const char *fmt, ...);
+void __init setup_log_buf(void);
+
extern int printk_needs_cpu(int cpu);
extern void printk_tick(void);
--- linux.orig/init/main.c
+++ linux/init/main.c
@@ -592,6 +592,7 @@ asmlinkage void __init start_kernel(void
* These use large bootmem allocations and must precede
* kmem_cache_init()
*/
+ setup_log_buf();
pidhash_init();
vfs_caches_init_early();
sort_main_extable();
--- linux.orig/kernel/printk.c
+++ linux/kernel/printk.c
@@ -162,46 +162,59 @@ 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;
-
- new_log_buf = alloc_bootmem(size);
- if (!new_log_buf) {
- printk(KERN_WARNING "log_buf_len: allocation failed\n");
- goto out;
- }
-
- 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);
+ if (size > log_buf_len)
+ new_log_buf_len = size;
- printk(KERN_NOTICE "log_buf_len: %d\n", log_buf_len);
- }
-out:
- return 1;
+ return 0;
}
+early_param("log_buf_len", log_buf_len_setup);
-__setup("log_buf_len=", log_buf_len_setup);
+void __init setup_log_buf(void)
+{
+ unsigned long flags;
+ unsigned start, dest_idx, offset;
+ char *new_log_buf;
+ int free;
+
+ if (!new_log_buf_len)
+ return;
+
+ new_log_buf = alloc_bootmem(new_log_buf_len);
+
+ 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
--
--
To unsubscribe from this list: send the line "unsubscribe linux-acpi" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
