[Devel] [PATCH rh7 1/2] bc: roll back beancounters-based numer of processes accounting

[Konstantin Khorenko]

ubc param "numproc" is handled ub in our home brew beancounters code,
while stock kernel (even RHEL7 one) now has pids cgroup which
does approximately the same.

So drop original "numproc" ubc limit code, next patch adds similar
funtionality basing on pids cgroup.

Note: the difference between approaches:
- ubc code accounts and limits processes (thus you can create a lot of
  threads in a Container with "numproc" limit)
- pids cgroup accounts and limits "pids", thus including threads

At the same time we already configure pids cgroup for a Container and
set up "pids.max" equal to ubc "numproc" value, so the semantic has been
already changed for some period.

Fixes: d821108a8a1a ("ubc: initial patch")
https://jira.sw.ru/browse/PSBM-86044

Signed-off-by: Konstantin Khorenko <khorenko at virtuozzo.com>
---
 include/bc/misc.h       |  2 --
 kernel/bc/beancounter.c |  2 --
 kernel/bc/misc.c        | 10 ----------
 kernel/exit.c           |  1 -
 kernel/fork.c           |  7 +------
 5 files changed, 1 insertion(+), 21 deletions(-)

diff --git a/include/bc/misc.h b/include/bc/misc.h
index 7bf77ef34320..b329e5fedf22 100644
--- a/include/bc/misc.h
+++ b/include/bc/misc.h
@@ -23,8 +23,6 @@ UB_DECLARE_VOID_FUNC(ub_flock_uncharge(struct file_lock *fl))
 UB_DECLARE_FUNC(int, ub_siginfo_charge(struct sigqueue *q,
 			struct user_beancounter *ub, gfp_t gfp_mask))
 UB_DECLARE_VOID_FUNC(ub_siginfo_uncharge(struct sigqueue *q))
-UB_DECLARE_FUNC(int, ub_task_charge(struct user_beancounter *ub))
-UB_DECLARE_VOID_FUNC(ub_task_uncharge(struct user_beancounter *ub))
 UB_DECLARE_VOID_FUNC(ub_task_get(struct user_beancounter *ub,
 			struct task_struct *task))
 UB_DECLARE_VOID_FUNC(ub_task_put(struct task_struct *task))
diff --git a/kernel/bc/beancounter.c b/kernel/bc/beancounter.c
index d5de31008a5e..31e5904df708 100644
--- a/kernel/bc/beancounter.c
+++ b/kernel/bc/beancounter.c
@@ -76,7 +76,6 @@ const char *ub_rnames[] = {
 /* default maximum perpcu resources precharge */
 int ub_resource_precharge[UB_RESOURCES] = {
 	[UB_PRIVVMPAGES]= 256,
-	[UB_NUMPROC]	= 4,
 	[UB_NUMSIGINFO]	= 4,
 	[UB_NUMFILE]	= 8,
 };
@@ -1089,7 +1088,6 @@ void __init ub_init_early(void)
 	memset(&current->task_bc, 0, sizeof(struct task_beancounter));
 	(void)set_exec_ub(ub);
 	current->task_bc.task_ub = get_beancounter(ub);
-	__charge_beancounter_locked(ub, UB_NUMPROC, 1, UB_FORCE);
 	init_mm.mm_ub = get_beancounter(ub);
 
 	list_add(&ub->ub_list, &ub_list_head);
diff --git a/kernel/bc/misc.c b/kernel/bc/misc.c
index 15093a719407..16e70cd220e2 100644
--- a/kernel/bc/misc.c
+++ b/kernel/bc/misc.c
@@ -22,16 +22,6 @@
  * Task staff
  */
 
-int ub_task_charge(struct user_beancounter *ub)
-{
-	return charge_beancounter_fast(ub, UB_NUMPROC, 1, UB_HARD);
-}
-
-void ub_task_uncharge(struct user_beancounter *ub)
-{
-	uncharge_beancounter_fast(ub, UB_NUMPROC, 1);
-}
-
 void ub_task_get(struct user_beancounter *ub, struct task_struct *task)
 {
 	struct task_beancounter *new_bc = &task->task_bc;
diff --git a/kernel/exit.c b/kernel/exit.c
index 1f243edca11a..bf68b87a4d60 100644
--- a/kernel/exit.c
+++ b/kernel/exit.c
@@ -214,7 +214,6 @@ void release_task(struct task_struct * p)
 	qwrite_unlock_irq(&tasklist_lock);
 	cgroup_pids_release(p);
 	release_thread(p);
-	ub_task_uncharge(get_task_ub(p));
 	call_rcu(&p->rcu, delayed_put_task_struct);
 
 	p = leader;
diff --git a/kernel/fork.c b/kernel/fork.c
index 112bef1e2695..af378117be31 100644
--- a/kernel/fork.c
+++ b/kernel/fork.c
@@ -1351,12 +1351,9 @@ static struct task_struct *copy_process(unsigned long clone_flags,
 		goto fork_out;
 
 	retval = -ENOMEM;
-	if (ub_task_charge(get_exec_ub()))
-		goto fork_out;
-
 	p = dup_task_struct(current, node);
 	if (!p)
-		goto bad_fork_uncharge;
+		goto fork_out;
 
 	ub_task_get(get_exec_ub(), p);
 
@@ -1721,8 +1718,6 @@ static struct task_struct *copy_process(unsigned long clone_flags,
 bad_fork_free:
 	ub_task_put(p);
 	free_task(p);
-bad_fork_uncharge:
-	ub_task_uncharge(get_exec_ub());
 fork_out:
 	return ERR_PTR(retval);
 }
-- 
2.15.1