https://github.com/torvalds/linux
Revision a98fdcef941e107eeabae622d85a1f476f25a160 authored by Oleg Nesterov on 14 January 2008, 21:02:37 UTC, committed by Linus Torvalds on 14 January 2008, 21:23:00 UTC
Commit 84427eaef1fb91704c7112bdb598c810003b99f3 (remove task_ppid_nr_ns) moved the task_tgid_nr_ns(task->real_parent) outside of lock_task_sighand(). This is wrong, ->real_parent could be freed/reused. Both ->parent/real_parent point to nothing after __exit_signal() because we remove the child from ->children list, and thus the child can't be reparented when its parent exits. rcu_read_lock() protects ->parent/real_parent, but _only_ if we know it was valid before we take rcu lock. Revert this part of the patch. Signed-off-by: Oleg Nesterov <oleg@tv-sign.ru> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
1 parent 4fd3670
Tip revision: a98fdcef941e107eeabae622d85a1f476f25a160 authored by Oleg Nesterov on 14 January 2008, 21:02:37 UTC
fix the "remove task_ppid_nr_ns" commit
fix the "remove task_ppid_nr_ns" commit
Tip revision: a98fdce
cgroup_debug.c
/*
* kernel/ccontainer_debug.c - Example cgroup subsystem that
* exposes debug info
*
* Copyright (C) Google Inc, 2007
*
* Developed by Paul Menage (menage@google.com)
*
*/
#include <linux/cgroup.h>
#include <linux/fs.h>
#include <linux/slab.h>
#include <linux/rcupdate.h>
#include <asm/atomic.h>
static struct cgroup_subsys_state *debug_create(struct cgroup_subsys *ss,
struct cgroup *cont)
{
struct cgroup_subsys_state *css = kzalloc(sizeof(*css), GFP_KERNEL);
if (!css)
return ERR_PTR(-ENOMEM);
return css;
}
static void debug_destroy(struct cgroup_subsys *ss, struct cgroup *cont)
{
kfree(cont->subsys[debug_subsys_id]);
}
static u64 cgroup_refcount_read(struct cgroup *cont, struct cftype *cft)
{
return atomic_read(&cont->count);
}
static u64 taskcount_read(struct cgroup *cont, struct cftype *cft)
{
u64 count;
cgroup_lock();
count = cgroup_task_count(cont);
cgroup_unlock();
return count;
}
static u64 current_css_set_read(struct cgroup *cont, struct cftype *cft)
{
return (u64)(long)current->cgroups;
}
static u64 current_css_set_refcount_read(struct cgroup *cont,
struct cftype *cft)
{
u64 count;
rcu_read_lock();
count = atomic_read(¤t->cgroups->ref.refcount);
rcu_read_unlock();
return count;
}
static struct cftype files[] = {
{
.name = "cgroup_refcount",
.read_uint = cgroup_refcount_read,
},
{
.name = "taskcount",
.read_uint = taskcount_read,
},
{
.name = "current_css_set",
.read_uint = current_css_set_read,
},
{
.name = "current_css_set_refcount",
.read_uint = current_css_set_refcount_read,
},
};
static int debug_populate(struct cgroup_subsys *ss, struct cgroup *cont)
{
return cgroup_add_files(cont, ss, files, ARRAY_SIZE(files));
}
struct cgroup_subsys debug_subsys = {
.name = "debug",
.create = debug_create,
.destroy = debug_destroy,
.populate = debug_populate,
.subsys_id = debug_subsys_id,
};
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