Re: [PATCH] IPC initialize shmmax and shmall from the current value not the default

[Serge Hallyn]

Quoting Manfred Spraul (manfred@xxxxxxxxxxxxxxxx):
> Hi Marian,
> 
> On 05/22/2014 03:01 PM, Marian Marinov wrote:
> >-----BEGIN PGP SIGNED MESSAGE-----
> >Hash: SHA1
> >
> >On 05/05/2014 10:59 PM, Marian Marinov wrote:
> >>
> >>In my tests it worked exactly as expected. Here is an example:
> >>
> >>[root@sp2 ~]# sysctl -a|grep shmmax kernel.shmmax = 68719476736 [root@sp2 ~]# lxc-attach -n cent_plain
> >>[root@localhost ~]# sysctl -a|grep shmmax kernel.shmmax = 68719476736 [root@localhost ~]# halt [root@sp2 ~]# sysctl
> >>-a|grep shmmax kernel.shmmax = 68719476736 [root@sp2 ~]# sysctl kernel.shmmax=34359738368 kernel.shmmax =
> >>34359738368 [root@sp2 ~]# lxc-start -n cent_plain -d [root@sp2 ~]# lxc-attach -n cent_plain [root@localhost ~]#
> >>sysctl -a|grep shmmax kernel.shmmax = 34359738368 [root@localhost ~]#
> >>
> >>So it seams to work as expected :)
> >>
> >>It works because wen you setup a new shmmax limit it is actually the limit in the init_ipc_ns. So when we are
> >>creating a new ipc_ns its ok to copy the values from init_ipc_ns.
> >>
> >>-Marian
> >>
> >Ping?
> >
> >So will there be any more comments on that?
> >
> >
> Attached is an untested idea:
> - each new namespace copies from it's parent, i.e. nested namespaces
> should work.
> - msg, sem and shm updated

Agreed, I prefer this.

> --
>     Manfred

> From ed73ce838fc3f55e34041591a72b3135ccaa460b Mon Sep 17 00:00:00 2001
> From: Manfred Spraul <manfred@xxxxxxxxxxxxxxxx>
> Date: Sun, 25 May 2014 21:04:42 +0200
> Subject: [PATCH] ipc namespace: copy settings from parent namespace
> 
> Right now, each IPC namespace starts with the kernel boot standard
> settings.
> This patch changes that:
> Now each new namespace starts with the settings from the parent
> namespace.
> 
> The patch updates msg, sem and shm.
> 
> Marian: Would that patch help you?
> 
> It's just a proposal - not yet tested.
> 
> Open issues:
> - auto_msgmni is not yet taken from parent.
> 
> --
> 	Manfred
> ---
>  ipc/msg.c       | 13 +++++++++----
>  ipc/namespace.c |  6 +++---
>  ipc/sem.c       | 19 +++++++++++++------
>  ipc/shm.c       | 19 +++++++++++++------
>  ipc/util.h      | 12 ++++++------
>  5 files changed, 44 insertions(+), 25 deletions(-)
> 
> diff --git a/ipc/msg.c b/ipc/msg.c
> index 6498531..6c72d43 100644
> --- a/ipc/msg.c
> +++ b/ipc/msg.c
> @@ -107,10 +107,15 @@ void recompute_msgmni(struct ipc_namespace *ns)
>  	ns->msg_ctlmni = allowed;
>  }
>  
> -void msg_init_ns(struct ipc_namespace *ns)
> +void msg_init_ns(struct ipc_namespace *ns, struct ipc_namespace *old_ns)
>  {
> -	ns->msg_ctlmax = MSGMAX;
> -	ns->msg_ctlmnb = MSGMNB;
> +	if (old_ns != NULL) {
> +		ns->msg_ctlmax = old_ns->msg_ctlmax;
> +		ns->msg_ctlmnb = old_ns->msg_ctlmnb;
> +	} else {
> +		ns->msg_ctlmax = MSGMAX;
> +		ns->msg_ctlmnb = MSGMNB;
> +	}
>  
>  	recompute_msgmni(ns);
>  
> @@ -129,7 +134,7 @@ void msg_exit_ns(struct ipc_namespace *ns)
>  
>  void __init msg_init(void)
>  {
> -	msg_init_ns(&init_ipc_ns);
> +	msg_init_ns(&init_ipc_ns, NULL);
>  
>  	printk(KERN_INFO "msgmni has been set to %d\n",
>  		init_ipc_ns.msg_ctlmni);
> diff --git a/ipc/namespace.c b/ipc/namespace.c
> index 59451c1..57b65fa 100644
> --- a/ipc/namespace.c
> +++ b/ipc/namespace.c
> @@ -41,9 +41,9 @@ static struct ipc_namespace *create_ipc_ns(struct user_namespace *user_ns,
>  	}
>  	atomic_inc(&nr_ipc_ns);
>  
> -	sem_init_ns(ns);
> -	msg_init_ns(ns);
> -	shm_init_ns(ns);
> +	sem_init_ns(ns, old_ns);
> +	msg_init_ns(ns, old_ns);
> +	shm_init_ns(ns, old_ns);
>  
>  	/*
>  	 * msgmni has already been computed for the new ipc ns.
> diff --git a/ipc/sem.c b/ipc/sem.c
> index bee5554..0e232e6 100644
> --- a/ipc/sem.c
> +++ b/ipc/sem.c
> @@ -170,12 +170,19 @@ static int sysvipc_sem_proc_show(struct seq_file *s, void *it);
>  #define sc_semopm	sem_ctls[2]
>  #define sc_semmni	sem_ctls[3]
>  
> -void sem_init_ns(struct ipc_namespace *ns)
> +void sem_init_ns(struct ipc_namespace *ns, struct ipc_namespace *old_ns)
>  {
> -	ns->sc_semmsl = SEMMSL;
> -	ns->sc_semmns = SEMMNS;
> -	ns->sc_semopm = SEMOPM;
> -	ns->sc_semmni = SEMMNI;
> +	if (old_ns != NULL) {
> +		ns->sc_semmsl = old_ns->sc_semmsl;
> +		ns->sc_semmns = old_ns->sc_semmns;
> +		ns->sc_semopm = old_ns->sc_semopm;
> +		ns->sc_semmni = old_ns->sc_semmni;
> +	} else {
> +		ns->sc_semmsl = SEMMSL;
> +		ns->sc_semmns = SEMMNS;
> +		ns->sc_semopm = SEMOPM;
> +		ns->sc_semmni = SEMMNI;
> +	}
>  	ns->used_sems = 0;
>  	ipc_init_ids(&ns->ids[IPC_SEM_IDS]);
>  }
> @@ -190,7 +197,7 @@ void sem_exit_ns(struct ipc_namespace *ns)
>  
>  void __init sem_init(void)
>  {
> -	sem_init_ns(&init_ipc_ns);
> +	sem_init_ns(&init_ipc_ns, NULL);
>  	ipc_init_proc_interface("sysvipc/sem",
>  				"       key      semid perms      nsems   uid   gid  cuid  cgid      otime      ctime\n",
>  				IPC_SEM_IDS, sysvipc_sem_proc_show);
> diff --git a/ipc/shm.c b/ipc/shm.c
> index 7645961..5c54b25 100644
> --- a/ipc/shm.c
> +++ b/ipc/shm.c
> @@ -72,12 +72,19 @@ static void shm_destroy(struct ipc_namespace *ns, struct shmid_kernel *shp);
>  static int sysvipc_shm_proc_show(struct seq_file *s, void *it);
>  #endif
>  
> -void shm_init_ns(struct ipc_namespace *ns)
> +void shm_init_ns(struct ipc_namespace *ns, struct ipc_namespace *old_ns)
>  {
> -	ns->shm_ctlmax = SHMMAX;
> -	ns->shm_ctlall = SHMALL;
> -	ns->shm_ctlmni = SHMMNI;
> -	ns->shm_rmid_forced = 0;
> +	if (old_ns != NULL) {
> +		ns->shm_ctlmax = old_ns->shm_ctlmax;
> +		ns->shm_ctlall = old_ns->shm_ctlall;
> +		ns->shm_ctlmni = old_ns->shm_ctlmni;
> +		ns->shm_rmid_forced = old_ns->shm_rmid_forced;
> +	} else {
> +		ns->shm_ctlmax = SHMMAX;
> +		ns->shm_ctlall = SHMALL;
> +		ns->shm_ctlmni = SHMMNI;
> +		ns->shm_rmid_forced = 0;
> +	}
>  	ns->shm_tot = 0;
>  	ipc_init_ids(&shm_ids(ns));
>  }
> @@ -110,7 +117,7 @@ void shm_exit_ns(struct ipc_namespace *ns)
>  
>  static int __init ipc_ns_init(void)
>  {
> -	shm_init_ns(&init_ipc_ns);
> +	shm_init_ns(&init_ipc_ns, NULL);
>  	return 0;
>  }
>  
> diff --git a/ipc/util.h b/ipc/util.h
> index 9c47d6f..bb62b44 100644
> --- a/ipc/util.h
> +++ b/ipc/util.h
> @@ -30,17 +30,17 @@ static inline void mq_put_mnt(struct ipc_namespace *ns) { }
>  #endif
>  
>  #ifdef CONFIG_SYSVIPC
> -void sem_init_ns(struct ipc_namespace *ns);
> -void msg_init_ns(struct ipc_namespace *ns);
> -void shm_init_ns(struct ipc_namespace *ns);
> +void sem_init_ns(struct ipc_namespace *ns, struct ipc_namespace *old_ns);
> +void msg_init_ns(struct ipc_namespace *ns, struct ipc_namespace *old_ns);
> +void shm_init_ns(struct ipc_namespace *ns, struct ipc_namespace *old_ns);
>  
>  void sem_exit_ns(struct ipc_namespace *ns);
>  void msg_exit_ns(struct ipc_namespace *ns);
>  void shm_exit_ns(struct ipc_namespace *ns);
>  #else
> -static inline void sem_init_ns(struct ipc_namespace *ns) { }
> -static inline void msg_init_ns(struct ipc_namespace *ns) { }
> -static inline void shm_init_ns(struct ipc_namespace *ns) { }
> +static inline void sem_init_ns(struct ipc_namespace *ns, struct ipc_namespace *old_ns) { }
> +static inline void msg_init_ns(struct ipc_namespace *ns, struct ipc_namespace *old_ns) { }
> +static inline void shm_init_ns(struct ipc_namespace *ns, struct ipc_namespace *old_ns) { }
>  
>  static inline void sem_exit_ns(struct ipc_namespace *ns) { }
>  static inline void msg_exit_ns(struct ipc_namespace *ns) { }
> -- 
> 1.9.0
> 
> 

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