mces_seen is a Per-CPU variable which should only be accessed by Per-CPU as possible. So the clear operation of mces_seen should also be lcoal to Per-CPU rather than monarch CPU.
Meanwhile, there is also a potential risk that mces_seen will not be be cleared if a timeout occors in mce_end for monarch CPU. As a reuslt, the stale value of mces_seen will reappear on the next mce. Based on the above reasons, this patch distirbute the clear operation of mces_seen to Per-CPU rather than only monarch CPU. * From v1 * Add Reviewed-by: Andi Kleen * Put the clear operation of mces_seen before the MCG_STATUS write. Reviewed-by: Andi Kleen <a...@linux.intel.com> Signed-off-by: Chen Yucong <sla...@gmail.com> --- arch/x86/kernel/cpu/mcheck/mce.c | 18 +++++++----------- 1 file changed, 7 insertions(+), 11 deletions(-) diff --git a/arch/x86/kernel/cpu/mcheck/mce.c b/arch/x86/kernel/cpu/mcheck/mce.c index 68317c8..966a5f5 100644 --- a/arch/x86/kernel/cpu/mcheck/mce.c +++ b/arch/x86/kernel/cpu/mcheck/mce.c @@ -785,13 +785,6 @@ static void mce_reign(void) */ if (global_worst <= MCE_KEEP_SEVERITY && mca_cfg.tolerant < 3) mce_panic("Machine check from unknown source", NULL, NULL); - - /* - * Now clear all the mces_seen so that they don't reappear on - * the next mce. - */ - for_each_possible_cpu(cpu) - memset(&per_cpu(mces_seen, cpu), 0, sizeof(struct mce)); } static atomic_t global_nwo; @@ -1137,9 +1130,6 @@ void do_machine_check(struct pt_regs *regs, long error_code) } } - /* mce_clear_state will clear *final, save locally for use later */ - m = *final; - if (!no_way_out) mce_clear_state(toclear); @@ -1161,7 +1151,7 @@ void do_machine_check(struct pt_regs *regs, long error_code) mce_panic("Fatal machine check on current CPU", &m, msg); if (worst == MCE_AR_SEVERITY) { /* schedule action before return to userland */ - mce_save_info(m.addr, m.mcgstatus & MCG_STATUS_RIPV); + mce_save_info(final->addr, final->mcgstatus & MCG_STATUS_RIPV); set_thread_flag(TIF_MCE_NOTIFY); } else if (kill_it) { force_sig(SIGBUS, current); @@ -1170,6 +1160,12 @@ void do_machine_check(struct pt_regs *regs, long error_code) if (worst > 0) mce_report_event(regs); + + /* + * Now clear the mces_seen of current CPU -*final - so that it does not + * reappear on the next mce. + */ + memset(final, 0, sizeof(struct mce)); mce_wrmsrl(MSR_IA32_MCG_STATUS, 0); out: atomic_dec(&mce_entry); -- 1.7.10.4 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/