mm, oom: keep oom_adj under or at upper limit when printing

For oom_score_adj values in the range [942,999], the current
calculations will print 16 for oom_adj.  This patch simply limits the
output so output is inline with docs.
Signed-off-by: NCharles Haithcock <chaithco@redhat.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Acked-by: NMichal Hocko <mhocko@suse.com>
Cc: Alexey Dobriyan <adobriyan@gmail.com>
Link: https://lkml.kernel.org/r/20201020165130.33927-1-chaithco@redhat.comSigned-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

fs/proc/base.c

@@ -1049,6 +1049,8 @@ static ssize_t oom_adj_read(struct file *file, char __user *buf, size_t count,
 		oom_adj = (task->signal->oom_score_adj * -OOM_DISABLE) /
 			  OOM_SCORE_ADJ_MAX;
 	put_task_struct(task);
+	if (oom_adj > OOM_ADJUST_MAX)
+		oom_adj = OOM_ADJUST_MAX;
 	len = snprintf(buffer, sizeof(buffer), "%d\n", oom_adj);
 	return simple_read_from_buffer(buf, count, ppos, buffer, len);
 }