From 3cc4a84e026e8d61b7ffe4a7367ed09a555f2c5b Mon Sep 17 00:00:00 2001 From: Eric Dumazet Date: Thu, 3 Dec 2015 11:12:07 -0800 Subject: [PATCH] proc: add a reschedule point in proc_readfd_common() User can pass an arbitrary large buffer to getdents(). It is typically a 32KB buffer used by libc scandir() implementation. When scanning /proc/{pid}/fd, we can hold cpu way too long, so add a cond_resched() to be kind with other tasks. We've seen latencies of more than 50ms on real workloads. Signed-off-by: Eric Dumazet Cc: Alexander Viro Signed-off-by: Al Viro --- fs/proc/fd.c | 1 + 1 file changed, 1 insertion(+) diff --git a/fs/proc/fd.c b/fs/proc/fd.c index 3c2a915c695a..56afa5ef08f2 100644 --- a/fs/proc/fd.c +++ b/fs/proc/fd.c @@ -258,6 +258,7 @@ static int proc_readfd_common(struct file *file, struct dir_context *ctx, name, len, instantiate, p, (void *)(unsigned long)fd)) goto out_fd_loop; + cond_resched(); rcu_read_lock(); } rcu_read_unlock(); -- 2.30.2