Re: [PATCH v4] coredump: Add /proc/<pid>/coredump_pre_exit for pre-exit before dumping

[Al Viro <viro@zeniv.linux.org.uk>]

On Wed, Jun 24, 2026 at 10:55:52PM +0800, Xin Zhao wrote:
> +void exit_files_pre_exit(struct task_struct *tsk, bool checkflock)
> +{
> +	struct files_struct *files = tsk->files;
> +	struct fdtable *fdt;
> +	struct file *file;
> +	unsigned int i, j = 0;
> +
> +	if (!files)
> +		return;
> +
> +	fdt = rcu_dereference_raw(files->fdt);
> +	for (;;) {
> +		unsigned long set;
> +
> +		i = j * BITS_PER_LONG;
> +		if (i >= fdt->max_fds)
> +			break;
> +		set = fdt->open_fds[j++];
> +		while (set) {
> +			if (!(set & 1))
> +				goto next_fd;
> +			file = fdt->fd[i];
> +			if (!file)
> +				goto next_fd;
> +			if (file->f_flags & O_TMPCLOS) {
> +				file->f_flags &= ~O_TMPCLOS;
> +				goto close_fd;
> +			}

*blink*

	How could that possibly make sense?  Many descriptors
may refer to the same file; what's more, many descriptor tables
may contain such descriptors, so... just what is that code
trying to do?