Messages in this thread Patch in this message | | | Date | Tue, 14 Jun 2011 11:53:25 +0900 | From | Hidetoshi Seto <> | Subject | [PATCH 2/2] x86, mce: rework use of TIF_MCE_NOTIFY |
| |
The basic flow of MCE handler is summarized as follows: 1) from NMI context: check hardware error registers, determine error severity, and then panic or request non-NMI context by irq_work() to continue the system. 2) from (irq) context: call non-NMI safe functions, wake up loggers and schedule work if required 3) from worker thread: process some time-consuming works like memory poisoning.
TIF_MCE_NOTIFY flag is relatively legacy and have used to do tasks of 2) and 3) on the thread context that interrupted by MCE. However now use of irq_work() and work-queue is enough for these tasks, so this patch removes duplicated tasks in mce_notify_process().
As the result there is no task to be done in the interrupted context, but soon if SRAR is supported there would be some thread-specific thing for action required. So keep the flag for such possible future use, until better mechanism is introduced.
Signed-off-by: Hidetoshi Seto <seto.hidetoshi@jp.fujitsu.com> --- arch/x86/kernel/cpu/mcheck/mce.c | 28 ++++++++++++---------------- 1 files changed, 12 insertions(+), 16 deletions(-)
diff --git a/arch/x86/kernel/cpu/mcheck/mce.c b/arch/x86/kernel/cpu/mcheck/mce.c index 26d7994..b1c2f1f 100644 --- a/arch/x86/kernel/cpu/mcheck/mce.c +++ b/arch/x86/kernel/cpu/mcheck/mce.c @@ -1053,8 +1053,9 @@ void do_machine_check(struct pt_regs *regs, long error_code) if (kill_it && tolerant < 3) force_sig(SIGBUS, current); - /* notify userspace ASAP */ - set_thread_flag(TIF_MCE_NOTIFY); + /* Trap this thread before returning to user, for action required */ + if (worst == MCE_AR_SEVERITY) + set_thread_flag(TIF_MCE_NOTIFY); if (worst > 0) mce_report_event(regs); @@ -1066,25 +1067,22 @@ out: EXPORT_SYMBOL_GPL(do_machine_check); /* - * Called after mce notification in process context. This code - * is allowed to sleep. Call the high level VM handler to process - * any corrupted pages. - * Assume that the work queue code only calls this one at a time - * per CPU. - * Note we don't disable preemption, so this code might run on the wrong - * CPU. In this case the event is picked up by the scheduled work queue. - * This is merely a fast path to expedite processing in some common - * cases. + * Called in process context that interrupted by MCE and marked with + * TIF_MCE_NOTFY, just before returning to errorneous userland. + * This code is allowed to sleep. + * Attempt possible recovery such as calling the high level VM handler to + * process any corrupted pages, and kill/signal current process if required. */ void mce_notify_process(void) { - mce_notify_irq(); - mce_memory_failure_process(); + clear_thread_flag(TIF_MCE_NOTIFY); + + /* TBD: do recovery for action required event */ } static void mce_process_work(struct work_struct *dummy) { - mce_notify_process(); + mce_memory_failure_process(); } #ifdef CONFIG_X86_MCE_INTEL @@ -1165,8 +1163,6 @@ int mce_notify_irq(void) /* Not more than two messages every minute */ static DEFINE_RATELIMIT_STATE(ratelimit, 60*HZ, 2); - clear_thread_flag(TIF_MCE_NOTIFY); - if (test_and_clear_bit(0, &mce_need_notify)) { /* wake processes polling /dev/mcelog */ wake_up_interruptible(&mce_chrdev_wait); -- 1.7.1
| |