pid: remove pidhash
pidhash is no longer required as all the information can be looked up from idr tree. nr_hashed represented the number of pids that had been hashed. Since, nr_hashed and PIDNS_HASH_ADDING are no longer relevant, it has been renamed to pid_allocated and PIDNS_ADDING respectively. [gs051095@gmail.com: v6] Link: http://lkml.kernel.org/r/1507760379-21662-3-git-send-email-gs051095@gmail.com Link: http://lkml.kernel.org/r/1507583624-22146-3-git-send-email-gs051095@gmail.com Signed-off-by: Gargi Sharma <gs051095@gmail.com> Reviewed-by: Rik van Riel <riel@redhat.com> Tested-by: Tony Luck <tony.luck@intel.com> [ia64] Cc: Julia Lawall <julia.lawall@lip6.fr> Cc: Ingo Molnar <mingo@kernel.org> Cc: Pavel Tatashin <pasha.tatashin@oracle.com> Cc: Kirill Tkhai <ktkhai@virtuozzo.com> Cc: Oleg Nesterov <oleg@redhat.com> Cc: Eric W. Biederman <ebiederm@xmission.com> Cc: Christoph Hellwig <hch@infradead.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
parent
95846ecf9d
commit
e8cfbc245e
8 changed files with 18 additions and 50 deletions
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@ -31,8 +31,8 @@ void foo(void)
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DEFINE(SIGFRAME_SIZE, sizeof (struct sigframe));
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DEFINE(UNW_FRAME_INFO_SIZE, sizeof (struct unw_frame_info));
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BUILD_BUG_ON(sizeof(struct upid) != 32);
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DEFINE(IA64_UPID_SHIFT, 5);
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BUILD_BUG_ON(sizeof(struct upid) != 16);
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DEFINE(IA64_UPID_SHIFT, 4);
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BLANK();
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@ -105,7 +105,6 @@ extern struct group_info init_groups;
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.numbers = { { \
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.nr = 0, \
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.ns = &init_pid_ns, \
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.pid_chain = { .next = NULL, .pprev = NULL }, \
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}, } \
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}
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@ -51,10 +51,8 @@ enum pid_type
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*/
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struct upid {
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/* Try to keep pid_chain in the same cacheline as nr for find_vpid */
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int nr;
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struct pid_namespace *ns;
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struct hlist_node pid_chain;
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};
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struct pid
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@ -25,7 +25,7 @@ struct pid_namespace {
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struct kref kref;
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struct idr idr;
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struct rcu_head rcu;
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unsigned int nr_hashed;
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unsigned int pid_allocated;
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struct task_struct *child_reaper;
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struct kmem_cache *pid_cachep;
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unsigned int level;
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@ -49,7 +49,7 @@ struct pid_namespace {
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extern struct pid_namespace init_pid_ns;
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#define PIDNS_HASH_ADDING (1U << 31)
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#define PIDNS_ADDING (1U << 31)
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#ifdef CONFIG_PID_NS
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static inline struct pid_namespace *get_pid_ns(struct pid_namespace *ns)
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@ -562,7 +562,6 @@ asmlinkage __visible void __init start_kernel(void)
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* kmem_cache_init()
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*/
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setup_log_buf(0);
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pidhash_init();
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vfs_caches_init_early();
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sort_main_extable();
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trap_init();
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@ -1871,7 +1871,7 @@ static __latent_entropy struct task_struct *copy_process(
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retval = -ERESTARTNOINTR;
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goto bad_fork_cancel_cgroup;
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}
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if (unlikely(!(ns_of_pid(pid)->nr_hashed & PIDNS_HASH_ADDING))) {
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if (unlikely(!(ns_of_pid(pid)->pid_allocated & PIDNS_ADDING))) {
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retval = -ENOMEM;
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goto bad_fork_cancel_cgroup;
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}
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48
kernel/pid.c
48
kernel/pid.c
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@ -41,10 +41,6 @@
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#include <linux/sched/task.h>
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#include <linux/idr.h>
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#define pid_hashfn(nr, ns) \
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hash_long((unsigned long)nr + (unsigned long)ns, pidhash_shift)
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static struct hlist_head *pid_hash;
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static unsigned int pidhash_shift = 4;
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struct pid init_struct_pid = INIT_STRUCT_PID;
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int pid_max = PID_MAX_DEFAULT;
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@ -54,7 +50,6 @@ int pid_max = PID_MAX_DEFAULT;
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int pid_max_min = RESERVED_PIDS + 1;
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int pid_max_max = PID_MAX_LIMIT;
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/*
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* PID-map pages start out as NULL, they get allocated upon
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* first use and are never deallocated. This way a low pid_max
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@ -64,7 +59,7 @@ int pid_max_max = PID_MAX_LIMIT;
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struct pid_namespace init_pid_ns = {
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.kref = KREF_INIT(2),
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.idr = IDR_INIT,
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.nr_hashed = PIDNS_HASH_ADDING,
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.pid_allocated = PIDNS_ADDING,
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.level = 0,
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.child_reaper = &init_task,
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.user_ns = &init_user_ns,
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@ -123,8 +118,7 @@ void free_pid(struct pid *pid)
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for (i = 0; i <= pid->level; i++) {
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struct upid *upid = pid->numbers + i;
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struct pid_namespace *ns = upid->ns;
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hlist_del_rcu(&upid->pid_chain);
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switch (--ns->nr_hashed) {
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switch (--ns->pid_allocated) {
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case 2:
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case 1:
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/* When all that is left in the pid namespace
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@ -133,10 +127,10 @@ void free_pid(struct pid *pid)
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*/
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wake_up_process(ns->child_reaper);
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break;
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case PIDNS_HASH_ADDING:
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case PIDNS_ADDING:
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/* Handle a fork failure of the first process */
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WARN_ON(ns->child_reaper);
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ns->nr_hashed = 0;
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ns->pid_allocated = 0;
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/* fall through */
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case 0:
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schedule_work(&ns->proc_work);
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@ -212,14 +206,12 @@ struct pid *alloc_pid(struct pid_namespace *ns)
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upid = pid->numbers + ns->level;
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spin_lock_irq(&pidmap_lock);
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if (!(ns->nr_hashed & PIDNS_HASH_ADDING))
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if (!(ns->pid_allocated & PIDNS_ADDING))
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goto out_unlock;
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for ( ; upid >= pid->numbers; --upid) {
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hlist_add_head_rcu(&upid->pid_chain,
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&pid_hash[pid_hashfn(upid->nr, upid->ns)]);
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/* Make the PID visible to find_pid_ns. */
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idr_replace(&upid->ns->idr, pid, upid->nr);
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upid->ns->nr_hashed++;
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upid->ns->pid_allocated++;
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}
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spin_unlock_irq(&pidmap_lock);
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@ -243,21 +235,13 @@ struct pid *alloc_pid(struct pid_namespace *ns)
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void disable_pid_allocation(struct pid_namespace *ns)
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{
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spin_lock_irq(&pidmap_lock);
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ns->nr_hashed &= ~PIDNS_HASH_ADDING;
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ns->pid_allocated &= ~PIDNS_ADDING;
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spin_unlock_irq(&pidmap_lock);
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}
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struct pid *find_pid_ns(int nr, struct pid_namespace *ns)
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{
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struct upid *pnr;
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hlist_for_each_entry_rcu(pnr,
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&pid_hash[pid_hashfn(nr, ns)], pid_chain)
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if (pnr->nr == nr && pnr->ns == ns)
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return container_of(pnr, struct pid,
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numbers[ns->level]);
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return NULL;
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return idr_find(&ns->idr, nr);
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}
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EXPORT_SYMBOL_GPL(find_pid_ns);
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@ -413,6 +397,7 @@ pid_t __task_pid_nr_ns(struct task_struct *task, enum pid_type type,
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if (type != PIDTYPE_PID) {
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if (type == __PIDTYPE_TGID)
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type = PIDTYPE_PID;
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task = task->group_leader;
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}
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nr = pid_nr_ns(rcu_dereference(task->pids[type].pid), ns);
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@ -439,23 +424,10 @@ struct pid *find_ge_pid(int nr, struct pid_namespace *ns)
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return idr_get_next(&ns->idr, &nr);
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}
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/*
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* The pid hash table is scaled according to the amount of memory in the
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* machine. From a minimum of 16 slots up to 4096 slots at one gigabyte or
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* more.
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*/
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void __init pidhash_init(void)
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{
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pid_hash = alloc_large_system_hash("PID", sizeof(*pid_hash), 0, 18,
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HASH_EARLY | HASH_SMALL | HASH_ZERO,
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&pidhash_shift, NULL,
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0, 4096);
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}
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void __init pid_idr_init(void)
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{
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/* Verify no one has done anything silly: */
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BUILD_BUG_ON(PID_MAX_LIMIT >= PIDNS_HASH_ADDING);
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BUILD_BUG_ON(PID_MAX_LIMIT >= PIDNS_ADDING);
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/* bump default and minimum pid_max based on number of cpus */
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pid_max = min(pid_max_max, max_t(int, pid_max,
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@ -133,7 +133,7 @@ static struct pid_namespace *create_pid_namespace(struct user_namespace *user_ns
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ns->parent = get_pid_ns(parent_pid_ns);
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ns->user_ns = get_user_ns(user_ns);
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ns->ucounts = ucounts;
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ns->nr_hashed = PIDNS_HASH_ADDING;
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ns->pid_allocated = PIDNS_ADDING;
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INIT_WORK(&ns->proc_work, proc_cleanup_work);
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return ns;
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@ -254,7 +254,7 @@ void zap_pid_ns_processes(struct pid_namespace *pid_ns)
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* sys_wait4() above can't reap the EXIT_DEAD children but we do not
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* really care, we could reparent them to the global init. We could
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* exit and reap ->child_reaper even if it is not the last thread in
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* this pid_ns, free_pid(nr_hashed == 0) calls proc_cleanup_work(),
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* this pid_ns, free_pid(pid_allocated == 0) calls proc_cleanup_work(),
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* pid_ns can not go away until proc_kill_sb() drops the reference.
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*
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* But this ns can also have other tasks injected by setns()+fork().
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@ -268,7 +268,7 @@ void zap_pid_ns_processes(struct pid_namespace *pid_ns)
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*/
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for (;;) {
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set_current_state(TASK_INTERRUPTIBLE);
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if (pid_ns->nr_hashed == init_pids)
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if (pid_ns->pid_allocated == init_pids)
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break;
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schedule();
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}
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