locks: Filter /proc/locks output on proc pid ns (d67fd44f) · Commits · 戴 / test

On busy container servers reading /proc/locks shows all the locks created by all clients. This can cause large latency spikes. In my case I observed lsof taking up to 5-10 seconds while processing around 50k locks. Fix this by limiting the locks shown only to those created in the same pidns as the one the proc fs was mounted in. When reading /proc/locks from the init_pid_ns proc instance then perform no filtering [ jlayton: reformat comments for 80 columns ] Signed-off-by:

Nikolay Borisov <kernel@kyup.com> Suggested-by:

Eric W. Biederman <ebiederm@xmission.com> Signed-off-by:

Jeff Layton <jlayton@redhat.com>

fs/locks.c

+18 −3

Original line number	Diff line number	Diff line
		@@ -2574,9 +2574,20 @@ static void lock_get_status(struct seq_file f, struct file_lock fl,
		struct inode *inode = NULL;
		unsigned int fl_pid;

		if (fl->fl_nspid)
		fl_pid = pid_vnr(fl->fl_nspid);
		else
		if (fl->fl_nspid) {
		struct pid_namespace *proc_pidns = file_inode(f->file)->i_sb->s_fs_info;

		/* Don't let fl_pid change based on who is reading the file */
		fl_pid = pid_nr_ns(fl->fl_nspid, proc_pidns);

		/*
		* If there isn't a fl_pid don't display who is waiting on
		* the lock if we are called from locks_show, or if we are
		* called from __show_fd_info - skip lock entirely
		*/
		if (fl_pid == 0)
		return;
		} else
		fl_pid = fl->fl_pid;

		if (fl->fl_file != NULL)
		@@ -2648,9 +2659,13 @@ static int locks_show(struct seq_file f, void v)
		{
		struct locks_iterator *iter = f->private;
		struct file_lock fl, bfl;
		struct pid_namespace *proc_pidns = file_inode(f->file)->i_sb->s_fs_info;

		fl = hlist_entry(v, struct file_lock, fl_link);

		if (fl->fl_nspid && !pid_nr_ns(fl->fl_nspid, proc_pidns))
		return 0;

		lock_get_status(f, fl, iter->li_pos, "");

		list_for_each_entry(bfl, &fl->fl_block, fl_block)

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