• Andi Kleen's avatar
    [PATCH] i386/x86-64: Fix SMP NMI watchdog race · 2a66bc5a
    Andi Kleen authored
    Fix SMP race in NMI watchdog on i386/x86-64
    
    Fix a long standing SMP Setup race in the NMI watchdog.  The watchdog would
    tick from very early and check if all CPUs increase their timer interrupts.
    For that it would check the cpu_online_map.  Now if a CPU took too long to
    boot the watchdog would trigger prematurely because the CPU didn't increase
    its timer count yet.
    
    Fix is to check cpu_callin_map instead of cpu_online_map because the first is
    only set when a CPU started its timer interrupt.
    
    I fixed it on i386 and x86-64.
    
    Description of the problem from Manpreet Singh. Thanks.
    
    Cc: <manpreet@fabric7.com>
    Signed-off-by: default avatarAndrew Morton <akpm@osdl.org>
    Signed-off-by: default avatarLinus Torvalds <torvalds@osdl.org>
    2a66bc5a
nmi.c 11.1 KB