From 19c5d45a09312ca20cd1f9df3fd1a87fe0cb8aac Mon Sep 17 00:00:00 2001 From: Alexey Dobriyan Date: Tue, 8 May 2007 00:26:46 -0700 Subject: [PATCH] /proc/*/oom_score oops re badness 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 Signed-off-by: Linus Torvalds --- fs/proc/base.c | 2 ++ 1 file changed, 2 insertions(+) diff --git a/fs/proc/base.c b/fs/proc/base.c index 0697fd089de8..ab1b439923e6 100644 --- a/fs/proc/base.c +++ b/fs/proc/base.c @@ -314,7 +314,9 @@ static int proc_oom_score(struct task_struct *task, char *buffer) 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); } -- 2.39.2