tree: https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git master head: 8225f4e85cb03daea14661380745886ce01fd83a commit: 0dd08f12cafd7868be55bc10ebcd4ea13880860b [5266/5426] UBSAN: run-time undefined behavior sanity checker config: x86_64-randconfig-s5-12102221 (attached as .config) reproduce: git checkout 0dd08f12cafd7868be55bc10ebcd4ea13880860b # save the attached .config to linux build tree make ARCH=x86_64 Note: it may well be a FALSE warning. FWIW you are at least aware of it now. http://gcc.gnu.org/wiki/Better_Uninitialized_Warnings All warnings (new ones prefixed by >>): arch/x86/kernel/cpu/mcheck/mce.c: In function 'do_machine_check': >> arch/x86/kernel/cpu/mcheck/mce.c:884:5: warning: 'order' may be used uninitialized in this function [-Wmaybe-uninitialized] if (order == 1) { ^ arch/x86/kernel/cpu/mcheck/mce.c:984:6: note: 'order' was declared here int order; ^ vim +/order +884 arch/x86/kernel/cpu/mcheck/mce.c 3c079792 Andi Kleen 2009-05-27 868 */ 3c079792 Andi Kleen 2009-05-27 869 static int mce_end(int order) 3c079792 Andi Kleen 2009-05-27 870 { 3c079792 Andi Kleen 2009-05-27 871 int ret = -1; 84c2559d Borislav Petkov 2012-10-15 872 u64 timeout = (u64)mca_cfg.monarch_timeout * NSEC_PER_USEC; 3c079792 Andi Kleen 2009-05-27 873 3c079792 Andi Kleen 2009-05-27 874 if (!timeout) 3c079792 Andi Kleen 2009-05-27 875 goto reset; 3c079792 Andi Kleen 2009-05-27 876 if (order < 0) 3c079792 Andi Kleen 2009-05-27 877 goto reset; 3c079792 Andi Kleen 2009-05-27 878 3c079792 Andi Kleen 2009-05-27 879 /* 3c079792 Andi Kleen 2009-05-27 880 * Allow others to run. 3c079792 Andi Kleen 2009-05-27 881 */ 3c079792 Andi Kleen 2009-05-27 882 atomic_inc(&mce_executing); 3c079792 Andi Kleen 2009-05-27 883 3c079792 Andi Kleen 2009-05-27 @884 if (order == 1) { 3c079792 Andi Kleen 2009-05-27 885 /* CHECKME: Can this race with a parallel hotplug? */ 3c079792 Andi Kleen 2009-05-27 886 int cpus = num_online_cpus(); 3c079792 Andi Kleen 2009-05-27 887 3c079792 Andi Kleen 2009-05-27 888 /* 3c079792 Andi Kleen 2009-05-27 889 * Monarch: Wait for everyone to go through their scanning 3c079792 Andi Kleen 2009-05-27 890 * loops. 3c079792 Andi Kleen 2009-05-27 891 */ 3c079792 Andi Kleen 2009-05-27 892 while (atomic_read(&mce_executing) <= cpus) { :::::: The code at line 884 was first introduced by commit :::::: 3c0797925f4ef9d55a32059d2af61a9c262e639d x86, mce: switch x86 machine check handler to Monarch election. :::::: TO: Andi Kleen <andi@xxxxxxxxxxxxxx> :::::: CC: H. Peter Anvin <hpa@xxxxxxxxx> --- 0-DAY kernel test infrastructure Open Source Technology Center https://lists.01.org/pipermail/kbuild-all Intel Corporation
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