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authorPrarit Bhargava <prarit@redhat.com>2012-01-26 08:55:34 -0500
committerIngo Molnar <mingo@elte.hu>2012-01-26 21:28:45 +0100
commitb0f4c4b32c8e3aa0d44fc4dd6c40a9a9a8d66b63 (patch)
tree7387d97d5b69c587ae67a46de025468d474e0eb4
parentb64b223aed5f8aeeb6c046f1b050a8f976b87de0 (diff)
downloadlinux-b0f4c4b32c8e3aa0d44fc4dd6c40a9a9a8d66b63.tar.gz
bugs, x86: Fix printk levels for panic, softlockups and stack dumps
rsyslog will display KERN_EMERG messages on a connected terminal. However, these messages are useless/undecipherable for a general user. For example, after a softlockup we get: Message from syslogd@intel-s3e37-04 at Jan 25 14:18:06 ... kernel:Stack: Message from syslogd@intel-s3e37-04 at Jan 25 14:18:06 ... kernel:Call Trace: Message from syslogd@intel-s3e37-04 at Jan 25 14:18:06 ... kernel:Code: ff ff a8 08 75 25 31 d2 48 8d 86 38 e0 ff ff 48 89 d1 0f 01 c8 0f ae f0 48 8b 86 38 e0 ff ff a8 08 75 08 b1 01 4c 89 e0 0f 01 c9 <e8> ea 69 dd ff 4c 29 e8 48 89 c7 e8 0f bc da ff 49 89 c4 49 89 This happens because the printk levels for these messages are incorrect. Only an informational message should be displayed on a terminal. I modified the printk levels for various messages in the kernel and tested the output by using the drivers/misc/lkdtm.c kernel modules (ie, softlockups, panics, hard lockups, etc.) and confirmed that the console output was still the same and that the output to the terminals was correct. For example, in the case of a softlockup we now see the much more informative: Message from syslogd@intel-s3e37-04 at Jan 25 10:18:06 ... BUG: soft lockup - CPU4 stuck for 60s! instead of the above confusing messages. AFAICT, the messages no longer have to be KERN_EMERG. In the most important case of a panic we set console_verbose(). As for the other less severe cases the correct data is output to the console and /var/log/messages. Successfully tested by me using the drivers/misc/lkdtm.c module. Signed-off-by: Prarit Bhargava <prarit@redhat.com> Cc: dzickus@redhat.com Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Andrew Morton <akpm@linux-foundation.org> Link: http://lkml.kernel.org/r/1327586134-11926-1-git-send-email-prarit@redhat.com Signed-off-by: Ingo Molnar <mingo@elte.hu>
-rw-r--r--arch/x86/kernel/dumpstack.c3
-rw-r--r--arch/x86/kernel/dumpstack_64.c6
-rw-r--r--arch/x86/mm/fault.c4
-rw-r--r--kernel/watchdog.c2
-rw-r--r--lib/bug.c2
5 files changed, 9 insertions, 8 deletions
diff --git a/arch/x86/kernel/dumpstack.c b/arch/x86/kernel/dumpstack.c
index 1aae78f775f..4025fe4f928 100644
--- a/arch/x86/kernel/dumpstack.c
+++ b/arch/x86/kernel/dumpstack.c
@@ -252,7 +252,8 @@ int __kprobes __die(const char *str, struct pt_regs *regs, long err)
unsigned short ss;
unsigned long sp;
#endif
- printk(KERN_EMERG "%s: %04lx [#%d] ", str, err & 0xffff, ++die_counter);
+ printk(KERN_DEFAULT
+ "%s: %04lx [#%d] ", str, err & 0xffff, ++die_counter);
#ifdef CONFIG_PREEMPT
printk("PREEMPT ");
#endif
diff --git a/arch/x86/kernel/dumpstack_64.c b/arch/x86/kernel/dumpstack_64.c
index 6d728d9284b..42b2bca0b72 100644
--- a/arch/x86/kernel/dumpstack_64.c
+++ b/arch/x86/kernel/dumpstack_64.c
@@ -269,11 +269,11 @@ void show_registers(struct pt_regs *regs)
unsigned char c;
u8 *ip;
- printk(KERN_EMERG "Stack:\n");
+ printk(KERN_DEFAULT "Stack:\n");
show_stack_log_lvl(NULL, regs, (unsigned long *)sp,
- 0, KERN_EMERG);
+ 0, KERN_DEFAULT);
- printk(KERN_EMERG "Code: ");
+ printk(KERN_DEFAULT "Code: ");
ip = (u8 *)regs->ip - code_prologue;
if (ip < (u8 *)PAGE_OFFSET || probe_kernel_address(ip, c)) {
diff --git a/arch/x86/mm/fault.c b/arch/x86/mm/fault.c
index 9d74824a708..f0b4caf85c1 100644
--- a/arch/x86/mm/fault.c
+++ b/arch/x86/mm/fault.c
@@ -673,7 +673,7 @@ no_context(struct pt_regs *regs, unsigned long error_code,
stackend = end_of_stack(tsk);
if (tsk != &init_task && *stackend != STACK_END_MAGIC)
- printk(KERN_ALERT "Thread overran stack, or stack corrupted\n");
+ printk(KERN_EMERG "Thread overran stack, or stack corrupted\n");
tsk->thread.cr2 = address;
tsk->thread.trap_no = 14;
@@ -684,7 +684,7 @@ no_context(struct pt_regs *regs, unsigned long error_code,
sig = 0;
/* Executive summary in case the body of the oops scrolled away */
- printk(KERN_EMERG "CR2: %016lx\n", address);
+ printk(KERN_DEFAULT "CR2: %016lx\n", address);
oops_end(flags, regs, sig);
}
diff --git a/kernel/watchdog.c b/kernel/watchdog.c
index 1d7bca7f4f5..d117262deba 100644
--- a/kernel/watchdog.c
+++ b/kernel/watchdog.c
@@ -296,7 +296,7 @@ static enum hrtimer_restart watchdog_timer_fn(struct hrtimer *hrtimer)
if (__this_cpu_read(soft_watchdog_warn) == true)
return HRTIMER_RESTART;
- printk(KERN_ERR "BUG: soft lockup - CPU#%d stuck for %us! [%s:%d]\n",
+ printk(KERN_EMERG "BUG: soft lockup - CPU#%d stuck for %us! [%s:%d]\n",
smp_processor_id(), duration,
current->comm, task_pid_nr(current));
print_modules();
diff --git a/lib/bug.c b/lib/bug.c
index 19552096d16..a28c1415357 100644
--- a/lib/bug.c
+++ b/lib/bug.c
@@ -169,7 +169,7 @@ enum bug_trap_type report_bug(unsigned long bugaddr, struct pt_regs *regs)
return BUG_TRAP_TYPE_WARN;
}
- printk(KERN_EMERG "------------[ cut here ]------------\n");
+ printk(KERN_DEFAULT "------------[ cut here ]------------\n");
if (file)
printk(KERN_CRIT "kernel BUG at %s:%u!\n",