From: Michal Schmidt The avenrun[] values are supposed to be protected by xtime_lock. loadavg_read_proc does not use it. Theoretically this may result in an occasional glitch when the value read from /proc/loadavg would be as much as 1<<11 times higher than it should be. Signed-off-by: Michal Schmidt Cc: Thomas Gleixner Signed-off-by: Andrew Morton --- fs/proc/proc_misc.c | 11 ++++++++--- 1 file changed, 8 insertions(+), 3 deletions(-) diff -puN fs/proc/proc_misc.c~proc-loadavg-reading-race fs/proc/proc_misc.c --- a/fs/proc/proc_misc.c~proc-loadavg-reading-race +++ a/fs/proc/proc_misc.c @@ -84,10 +84,15 @@ static int loadavg_read_proc(char *page, { int a, b, c; int len; + unsigned long seq; + + do { + seq = read_seqbegin(&xtime_lock); + a = avenrun[0] + (FIXED_1/200); + b = avenrun[1] + (FIXED_1/200); + c = avenrun[2] + (FIXED_1/200); + } while (read_seqretry(&xtime_lock, seq)); - a = avenrun[0] + (FIXED_1/200); - b = avenrun[1] + (FIXED_1/200); - c = avenrun[2] + (FIXED_1/200); len = sprintf(page,"%d.%02d %d.%02d %d.%02d %ld/%d %d\n", LOAD_INT(a), LOAD_FRAC(a), LOAD_INT(b), LOAD_FRAC(b), _