• Seiji Aguchi's avatar
    kmsg_dump: constrain mtdoops and ramoops to perform their actions only for KMSG_DUMP_PANIC · fc2d557c
    Seiji Aguchi authored
    This series aims to develop logging facility for enterprise use.
    It is important to save kernel messages reliably on enterprise system
    because they are helpful for diagnosing system.
    This series add kmsg_dump() to the paths loosing kernel messages.  The use
    case is the following.
    [Use case of reboot/poweroff/halt/emergency_restart]
     My company has often experienced the followings in our support service.
     - Customer's system suddenly reboots.
     - Customers ask us to investigate the reason of the reboot.
    We recognize the fact itself because boot messages remain in
    /var/log/messages.  However, we can't investigate the reason why the
    system rebooted, because the last messages don't remain.  And off course
    we can't explain the reason.
    We can solve above problem with this patch as follows.
     Case1: reboot with command
       - We can see "Restarting system with command:" or ""Restarting system.".
     Case2: halt with command
       - We can see "System halted.".
     Case3: poweroff with command
       - We can see " Power down.".
     Case4: emergency_restart with sysrq.
       - We can see "Sysrq:" outputted in __handle_sysrq().
     Case5: emergency_restart with softdog.
       - We can see "Initiating system reboot" in watchdog_fire().
    So, we can distinguish the reason of reboot, poweroff, halt and emergency_restart.
    If customer executed reboot command, you may think the customer should
    know the fact.  However, they often claim they don't execute the command
    when they rebooted system by mistake.
    No message remains on the current Linux kernel, so we can't show the proof
    to the customer.  This patch improves this situation.
    This patch:
    Alters mtdoops and ramoops to perform their actions only for
    like to log crashes only.
    Signed-off-by: default avatarSeiji Aguchi <seiji.aguchi@hds.com>
    Cc: David Woodhouse <dwmw2@infradead.org>
    Cc: Marco Stornelli <marco.stornelli@gmail.com>
    Reviewed-by: default avatarArtem Bityutskiy <Artem.Bityutskiy@nokia.com>
    Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
    Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
mtdoops.c 12.1 KB