Messages in this thread | | | Date | Mon, 16 Jul 2007 16:02:37 -0700 | From | sukadev@us ... | Subject | Re: [PATCH 1/5] Define and use task_active_pid_ns() wrapper |
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Serge E. Hallyn [serue@us.ibm.com] wrote: | Quoting sukadev@us.ibm.com (sukadev@us.ibm.com): | > | > Subject: [PATCH 1/5] Define and use task_active_pid_ns() wrapper | > | > From: Sukadev Bhattiprolu <sukadev@us.ibm.com> | > | > With multiple pid namespaces, a process is known by some pid_t in | > every ancestor pid namespace. Every time the process forks, the | > child process also gets a pid_t in every ancestor pid namespace. | > | > While a process is visible in >=1 pid namespaces, it can see pid_t's | > in only one pid namespace. We call this pid namespace it's "active | > pid namespace", and it is always the youngest pid namespace in which | > the process is known. | > | > This patch defines and uses a wrapper to find the active pid namespace | > of a process. The implementation of the wrapper will be changed in | > when support for multiple pid namespaces are added. | > | > Changelog: | > 2.6.22-rc4-mm2-pidns1: | > - [Pavel Emelianov, Alexey Dobriyan] Back out the change to use | > task_active_pid_ns() in child_reaper() since task->nsproxy | > can be NULL during task exit (so child_reaper() continues to | > use init_pid_ns). | > | > to implement child_reaper() since init_pid_ns.child_reaper to | > implement child_reaper() since tsk->nsproxy can be NULL during exit. | > | > 2.6.21-rc6-mm1: | > - Rename task_pid_ns() to task_active_pid_ns() to reflect that a | > process can have multiple pid namespaces. | > | > Signed-off-by: Sukadev Bhattiprolu <sukadev@us.ibm.com> | > Acked-by: Pavel Emelianov <xemul@openvz.org> | > | > Cc: Eric W. Biederman <ebiederm@xmission.com> | > Cc: Cedric Le Goater <clg@fr.ibm.com> | > Cc: Dave Hansen <haveblue@us.ibm.com> | > Cc: Serge Hallyn <serue@us.ibm.com> | > Cc: Herbert Poetzel <herbert@13thfloor.at> | > --- | > fs/exec.c | 2 +- | > fs/proc/proc_misc.c | 3 ++- | > include/linux/pid_namespace.h | 7 ++++++- | > kernel/exit.c | 5 +++-- | > kernel/nsproxy.c | 2 +- | > kernel/pid.c | 4 ++-- | > 6 files changed, 15 insertions(+), 8 deletions(-) | > | > Index: lx26-22-rc6-mm1/include/linux/pid_namespace.h | > =================================================================== | > --- lx26-22-rc6-mm1.orig/include/linux/pid_namespace.h 2007-07-13 13:07:01.000000000 -0700 | > +++ lx26-22-rc6-mm1/include/linux/pid_namespace.h 2007-07-13 18:22:49.000000000 -0700 | > @@ -20,7 +20,7 @@ struct pid_namespace { | > struct pidmap pidmap[PIDMAP_ENTRIES]; | > int last_pid; | > struct task_struct *child_reaper; | > - struct kmem_cache_t *pid_cachep; | > + struct kmem_cache *pid_cachep; | | This change is, of course, unrelated to the description.
Yes. It fixes a warning.
I had sent a mail earlier to this list about the warning, but I guess that mail did not make it due to our mail server being down on Fri/Sat.
| | > }; | > | > extern struct pid_namespace init_pid_ns; | > @@ -39,6 +39,11 @@ static inline void put_pid_ns(struct pid | > kref_put(&ns->kref, free_pid_ns); | > } | > | > +static inline struct pid_namespace *task_active_pid_ns(struct task_struct *tsk) | > +{ | > + return tsk->nsproxy->pid_ns; | > +} | > + | | I trust you've tested this for the NFS oops?
The NFS problem we got was when exit_task_namespaces() and exit_notify() were swapped in do_exit(). That change was in a separate patch and Pavel's has a fix for it.
And that patch is not in -mm yet I think.
This patch is a simple short-cut to what the mainline code is already doing.
| | Taking the pid_ns out of the nsproxy was the trigger for the original | bug, right, to which the solutions were to either take it from struct | pid, or, so long as pid namespaces couldn't yet be unshared, use | init_pid_ns? | | thanks, | -serge | | > static inline struct task_struct *child_reaper(struct task_struct *tsk) | > { | > return init_pid_ns.child_reaper; | > Index: lx26-22-rc6-mm1/fs/exec.c | > =================================================================== | > --- lx26-22-rc6-mm1.orig/fs/exec.c 2007-07-13 13:05:38.000000000 -0700 | > +++ lx26-22-rc6-mm1/fs/exec.c 2007-07-13 18:13:39.000000000 -0700 | > @@ -827,7 +827,7 @@ static int de_thread(struct task_struct | > * so it is safe to do it under read_lock. | > */ | > if (unlikely(tsk->group_leader == child_reaper(tsk))) | > - tsk->nsproxy->pid_ns->child_reaper = tsk; | > + task_active_pid_ns(tsk)->child_reaper = tsk; | > | > zap_other_threads(tsk); | > read_unlock(&tasklist_lock); | > Index: lx26-22-rc6-mm1/fs/proc/proc_misc.c | > =================================================================== | > --- lx26-22-rc6-mm1.orig/fs/proc/proc_misc.c 2007-07-13 13:05:38.000000000 -0700 | > +++ lx26-22-rc6-mm1/fs/proc/proc_misc.c 2007-07-13 13:07:48.000000000 -0700 | > @@ -94,7 +94,8 @@ static int loadavg_read_proc(char *page, | > LOAD_INT(a), LOAD_FRAC(a), | > LOAD_INT(b), LOAD_FRAC(b), | > LOAD_INT(c), LOAD_FRAC(c), | > - nr_running(), nr_threads, current->nsproxy->pid_ns->last_pid); | > + nr_running(), nr_threads, | > + task_active_pid_ns(current)->last_pid); | > return proc_calc_metrics(page, start, off, count, eof, len); | > } | > | > Index: lx26-22-rc6-mm1/kernel/exit.c | > =================================================================== | > --- lx26-22-rc6-mm1.orig/kernel/exit.c 2007-07-13 13:06:52.000000000 -0700 | > +++ lx26-22-rc6-mm1/kernel/exit.c 2007-07-13 18:13:39.000000000 -0700 | > @@ -909,8 +909,9 @@ fastcall NORET_TYPE void do_exit(long co | > if (unlikely(!tsk->pid)) | > panic("Attempted to kill the idle task!"); | > if (unlikely(tsk == child_reaper(tsk))) { | > - if (tsk->nsproxy->pid_ns != &init_pid_ns) | > - tsk->nsproxy->pid_ns->child_reaper = init_pid_ns.child_reaper; | > + if (task_active_pid_ns(tsk) != &init_pid_ns) | > + task_active_pid_ns(tsk)->child_reaper = | > + init_pid_ns.child_reaper; | > else | > panic("Attempted to kill init!"); | > } | > Index: lx26-22-rc6-mm1/kernel/pid.c | > =================================================================== | > --- lx26-22-rc6-mm1.orig/kernel/pid.c 2007-07-13 13:07:01.000000000 -0700 | > +++ lx26-22-rc6-mm1/kernel/pid.c 2007-07-13 18:13:38.000000000 -0700 | > @@ -214,7 +214,7 @@ struct pid *alloc_pid(void) | > int nr = -1; | > struct pid_namespace *ns; | > | > - ns = current->nsproxy->pid_ns; | > + ns = task_active_pid_ns(current); | > pid = kmem_cache_alloc(ns->pid_cachep, GFP_KERNEL); | > if (!pid) | > goto out; | > @@ -364,7 +364,7 @@ struct pid *find_ge_pid(int nr) | > pid = find_pid(nr); | > if (pid) | > break; | > - nr = next_pidmap(current->nsproxy->pid_ns, nr); | > + nr = next_pidmap(task_active_pid_ns(current), nr); | > } while (nr > 0); | > | > return pid; | > Index: lx26-22-rc6-mm1/kernel/nsproxy.c | > =================================================================== | > --- lx26-22-rc6-mm1.orig/kernel/nsproxy.c 2007-07-13 13:05:38.000000000 -0700 | > +++ lx26-22-rc6-mm1/kernel/nsproxy.c 2007-07-13 13:07:48.000000000 -0700 | > @@ -86,7 +86,7 @@ static struct nsproxy *create_new_namesp | > goto out_ipc; | > } | > | > - new_nsp->pid_ns = copy_pid_ns(flags, tsk->nsproxy->pid_ns); | > + new_nsp->pid_ns = copy_pid_ns(flags, task_active_pid_ns(tsk)); | > if (IS_ERR(new_nsp->pid_ns)) { | > err = PTR_ERR(new_nsp->pid_ns); | > goto out_pid; - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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