Re: [PATCH v5 5/7] proc: instantiate only pids that we can ptrace on 'limit_pids=1' mount option

On Fri, May 11, 2018 at 09:45:33AM -0700, Linus Torvalds wrote:

On Fri, May 11, 2018 at 2:46 AM Alexey Gladkov [off-list ref]
wrote:

quoted

+       /* Limit procfs to only ptracable tasks */
+       if (limit_pids == PROC_LIMIT_PIDS_PTRACE) {
+               cond_resched();
+               if (!has_pid_permissions(fs_info, task,

HIDEPID_NO_ACCESS))

quoted

+                       goto out_put_task;
+       }

Where did that "cond_resched()" come from? That doesn't seem to make a lot
of sense.

This call came along with has_pid_permissions from proc_pid_readdir [1]. It
seems to me that proc_pid_readdir and proc_pid_lookup should act in a
similar way in this case.

[1] https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=3ba4bceef23206349d4130ddf140819b365de7c8

-- 
Rgrds, legion