From b0f4c4b32c8e3aa0d44fc4dd6c40a9a9a8d66b63 Mon Sep 17 00:00:00 2001 From: Prarit Bhargava Date: Thu, 26 Jan 2012 08:55:34 -0500 Subject: [PATCH] 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 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 Cc: dzickus@redhat.com Cc: Linus Torvalds Cc: Andrew Morton Link: http://lkml.kernel.org/r/1327586134-11926-1-git-send-email-prarit@redhat.com Signed-off-by: Ingo Molnar --- arch/x86/kernel/dumpstack.c | 3 ++- arch/x86/kernel/dumpstack_64.c | 6 +++--- arch/x86/mm/fault.c | 4 ++-- kernel/watchdog.c | 2 +- lib/bug.c | 2 +- 5 files changed, 9 insertions(+), 8 deletions(-) diff --git a/arch/x86/kernel/dumpstack.c b/arch/x86/kernel/dumpstack.c index 1aae78f775fc..4025fe4f928f 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 6d728d9284bd..42b2bca0b72c 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 9d74824a708d..f0b4caf85c1a 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 1d7bca7f4f52..d117262deba3 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 19552096d16b..a28c1415357c 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",