From: Alexey Dobriyan Eternal quest to make while true; do cat /proc/fs/xfs/stat >/dev/null 2>/dev/null; done while true; do find /proc -type f 2>/dev/null | xargs cat >/dev/null 2>/dev/null; done while true; do modprobe xfs; rmmod xfs; done work reliably continues and now kernel oopses in the following way: BUG: unable to handle ... at virtual address 6b6b6b6b EIP is at badness process: cat proc_oom_score proc_info_read sys_fstat64 vfs_read proc_info_read sys_read Failing code is prefetch hidden in list_for_each_entry() in badness(). badness() is reachable from two points. One is proc_oom_score, another is out_of_memory() => select_bad_process() => badness(). Second path grabs tasklist_lock, while first doesn't. Signed-off-by: Alexey Dobriyan Signed-off-by: Andrew Morton --- fs/proc/base.c | 2 ++ 1 file changed, 2 insertions(+) diff -puN fs/proc/base.c~proc-oom_score-oops-re-badness fs/proc/base.c --- a/fs/proc/base.c~proc-oom_score-oops-re-badness +++ a/fs/proc/base.c @@ -314,7 +314,9 @@ static int proc_oom_score(struct task_st struct timespec uptime; do_posix_clock_monotonic_gettime(&uptime); + read_lock(&tasklist_lock); points = badness(task, uptime.tv_sec); + read_unlock(&tasklist_lock); return sprintf(buffer, "%lu\n", points); } _