Re: [Devel] [PATCH v2 VZ10 1/2] ve/bpf: Limit number of BPF programs loadable per-VE

[Pavel Tikhomirov <ptikhomirov@virtuozzo.com>]

I thought we've decided in slack that having failcounts is enough,
so after "[PATCH VZ10 v7 7/9] ve: Introduce per-VE failcount" ads
bpf_prog_failcount, warning is not really needed to be aware about
lack of bpf programs.

On 8/26/26 18:48, Konstantin Khorenko wrote:
> a kind ping
> 
> --
> Best regards,
> 
> Konstantin Khorenko,
> Virtuozzo Linux Kernel Team
> 
> On 6/18/26 18:41, Konstantin Khorenko wrote:
>> i will apply the patch, but i would appreciate in case you add some WARN_ONCE
>> in case some CT hits the limit of available bpf programs.
>>
>> This will ease issue investigations + at some point might hints us that we need to increase the default, for example.
>>
>> --
>> Best regards,
>>
>> Konstantin Khorenko,
>> Virtuozzo Linux Kernel Team
>>
>> On 5/29/26 16:42, Pavel Tikhomirov wrote:
>>> Without a per-VE cap a single container could exhaust the system-wide
>>> bpf JIT memory budget by loading excessive numbers of CGROUP_DEVICE
>>> programs via the VE_FEATURE_BPF path.
>>>
>>> Add bpf_prog_avail_nr / bpf_prog_max_nr counters to ve_struct and
>>> enforce them in bpf_prog_load() for non-bpf-capable callers loading
>>> CGROUP_DEVICE programs.
>>>
>>> Lifetime note: A BPF program loadded in VE takes a reference to ve, when
>>> container is stopped, all open fds to the BPF programm will be closed
>>> and when container manager removes container cgroups the BPF program
>>> will be released and thus releasing the reference to VE.
>>>
>>> Default max number note: It is somehow similar to ve.netif_max_nr, there
>>> each docker container creates two veths, and I also observe that docker
>>> container loads two bpf programs (one by dockerd, one by systemd). So
>>> let's use the same number.
>>>
>>> https://virtuozzo.atlassian.net/browse/VSTOR-131947
>>> Signed-off-by: Pavel Tikhomirov <ptikhomirov@virtuozzo.com>
>>> Feature: ve: allow BPF in Containers
>>>
>>> --
>>> v2: Also put load_ve definition under CONFIG_VE.
>>> ---
>>>  include/linux/bpf.h  |  8 ++++++++
>>>  include/linux/ve.h   |  4 ++++
>>>  kernel/bpf/core.c    |  8 ++++++++
>>>  kernel/bpf/syscall.c | 37 +++++++++++++++++++++++++++++++++++++
>>>  kernel/ve/ve.c       |  5 +++++
>>>  5 files changed, 62 insertions(+)
>>>
>>> diff --git a/include/linux/bpf.h b/include/linux/bpf.h
>>> index 80175c7a21c27..0212806d5efc2 100644
>>> --- a/include/linux/bpf.h
>>> +++ b/include/linux/bpf.h
>>> @@ -56,6 +56,7 @@ struct cgroup;
>>>  struct bpf_token;
>>>  struct user_namespace;
>>>  struct super_block;
>>> +struct ve_struct;
>>>  struct inode;
>>>  
>>>  extern struct idr btf_idr;
>>> @@ -1522,6 +1523,13 @@ struct bpf_prog_aux {
>>>  	void *security;
>>>  #endif
>>>  	struct bpf_token *token;
>>> +#ifdef CONFIG_VE
>>> +	/* VE that loaded the program via VE_FEATURE_BPF path and against whose
>>> +	 * bpf_prog_avail_nr counter the program is accounted. NULL for programs
>>> +	 * loaded through the regular (non VE-restricted) path.
>>> +	 */
>>> +	struct ve_struct *owner_ve;
>>> +#endif
>>>  	struct bpf_prog_offload *offload;
>>>  	struct btf *btf;
>>>  	struct bpf_func_info *func_info;
>>> diff --git a/include/linux/ve.h b/include/linux/ve.h
>>> index 224acf012821f..88b4d531c466e 100644
>>> --- a/include/linux/ve.h
>>> +++ b/include/linux/ve.h
>>> @@ -76,6 +76,9 @@ struct ve_struct {
>>>  	atomic_t		netif_avail_nr;
>>>  	int			netif_max_nr;
>>>  
>>> +	atomic_t		bpf_prog_avail_nr;
>>> +	int			bpf_prog_max_nr;
>>> +
>>>  	atomic64_t		_uevent_seqnum;
>>>  
>>>  	int			_randomize_va_space;
>>> @@ -149,6 +152,7 @@ extern int nr_ve;
>>>  
>>>  #define NETNS_MAX_NR_DEFAULT	256	/* number of net-namespaces per-VE */
>>>  #define NETIF_MAX_NR_DEFAULT	256	/* number of net-interfaces per-VE */
>>> +#define BPF_PROG_MAX_NR_DEFAULT	256	/* number of loaded BPF progs per-VE */
>>>  
>>>  extern unsigned int sysctl_ve_mount_nr;
>>>  
>>> diff --git a/kernel/bpf/core.c b/kernel/bpf/core.c
>>> index 4de8774458aca..7aaf73180fcdc 100644
>>> --- a/kernel/bpf/core.c
>>> +++ b/kernel/bpf/core.c
>>> @@ -38,6 +38,7 @@
>>>  #include <linux/bpf_mem_alloc.h>
>>>  #include <linux/memcontrol.h>
>>>  #include <linux/execmem.h>
>>> +#include <linux/ve.h>
>>>  
>>>  #include <asm/barrier.h>
>>>  #include <linux/unaligned.h>
>>> @@ -2828,6 +2829,13 @@ void bpf_prog_free(struct bpf_prog *fp)
>>>  	if (aux->dst_prog)
>>>  		bpf_prog_put(aux->dst_prog);
>>>  	bpf_token_put(aux->token);
>>> +#ifdef CONFIG_VE
>>> +	if (aux->owner_ve) {
>>> +		atomic_inc(&aux->owner_ve->bpf_prog_avail_nr);
>>> +		put_ve(aux->owner_ve);
>>> +		aux->owner_ve = NULL;
>>> +	}
>>> +#endif
>>>  	INIT_WORK(&aux->work, bpf_prog_free_deferred);
>>>  	schedule_work(&aux->work);
>>>  }
>>> diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c
>>> index 0475a72c93c06..481ae62429097 100644
>>> --- a/kernel/bpf/syscall.c
>>> +++ b/kernel/bpf/syscall.c
>>> @@ -2663,6 +2663,9 @@ static int bpf_prog_load(union bpf_attr *attr, bpfptr_t uattr, u32 uattr_size)
>>>  	struct bpf_prog *prog, *dst_prog = NULL;
>>>  	struct btf *attach_btf = NULL;
>>>  	struct bpf_token *token = NULL;
>>> +#ifdef CONFIG_VE
>>> +	struct ve_struct *load_ve = NULL;
>>> +#endif
>>>  	bool bpf_cap;
>>>  	int err;
>>>  	char license[128];
>>> @@ -2744,6 +2747,22 @@ static int bpf_prog_load(union bpf_attr *attr, bpfptr_t uattr, u32 uattr_size)
>>>  	if (is_perfmon_prog_type(type) && !bpf_token_capable(token, CAP_PERFMON))
>>>  		goto put_token;
>>>  
>>> +#ifdef CONFIG_VE
>>> +	/* Restrict the number of BPF programs that can be loaded via the
>>> +	 * VE-allowed path. Without this, a single container could exhaust
>>> +	 * the system-wide bpf JIT memory budget by loading excessive
>>> +	 * numbers of CGROUP_DEVICE programs.
>>> +	 */
>>> +	if (!bpf_cap && type == BPF_PROG_TYPE_CGROUP_DEVICE) {
>>> +		load_ve = get_exec_env();
>>> +		if (atomic_dec_if_positive(&load_ve->bpf_prog_avail_nr) < 0) {
>>> +			load_ve = NULL;
>>> +			err = -ENOSPC;
>>> +			goto put_token;
>>> +		}
>>> +	}
>>> +#endif
>>> +
>>>  	/* attach_prog_fd/attach_btf_obj_fd can specify fd of either bpf_prog
>>>  	 * or btf, we need to check which one it is
>>>  	 */
>>> @@ -2809,6 +2828,16 @@ static int bpf_prog_load(union bpf_attr *attr, bpfptr_t uattr, u32 uattr_size)
>>>  	prog->aux->dev_bound = !!attr->prog_ifindex;
>>>  	prog->aux->xdp_has_frags = attr->prog_flags & BPF_F_XDP_HAS_FRAGS;
>>>  
>>> +#ifdef CONFIG_VE
>>> +	/* Hand the avail_nr slot reservation over to the prog. bpf_prog_free()
>>> +	 * will release it via put_ve + counter increment.
>>> +	 */
>>> +	if (load_ve) {
>>> +		prog->aux->owner_ve = get_ve(load_ve);
>>> +		load_ve = NULL;
>>> +	}
>>> +#endif
>>> +
>>>  	/* move token into prog->aux, reuse taken refcnt */
>>>  	prog->aux->token = token;
>>>  	token = NULL;
>>> @@ -2932,6 +2961,14 @@ static int bpf_prog_load(union bpf_attr *attr, bpfptr_t uattr, u32 uattr_size)
>>>  		btf_put(prog->aux->attach_btf);
>>>  	bpf_prog_free(prog);
>>>  put_token:
>>> +#ifdef CONFIG_VE
>>> +	/* The load_ve is non-NULL only if we decremented bpf_prog_avail_nr
>>> +	 * but did not hand the reservation off to the prog yet (i.e. failure
>>> +	 * happened before bpf_prog_alloc()). Roll back the counter.
>>> +	 */
>>> +	if (load_ve)
>>> +		atomic_inc(&load_ve->bpf_prog_avail_nr);
>>> +#endif
>>>  	bpf_token_put(token);
>>>  	return err;
>>>  }
>>> diff --git a/kernel/ve/ve.c b/kernel/ve/ve.c
>>> index 198c82f010cc1..48da546117bb7 100644
>>> --- a/kernel/ve/ve.c
>>> +++ b/kernel/ve/ve.c
>>> @@ -76,6 +76,8 @@ struct ve_struct ve0 = {
>>>  	.netns_max_nr		= INT_MAX,
>>>  	.netif_avail_nr		= ATOMIC_INIT(INT_MAX),
>>>  	.netif_max_nr		= INT_MAX,
>>> +	.bpf_prog_avail_nr	= ATOMIC_INIT(INT_MAX),
>>> +	.bpf_prog_max_nr	= INT_MAX,
>>>  	.fsync_enable		= FSYNC_FILTERED,
>>>  	._randomize_va_space	=
>>>  #ifdef CONFIG_COMPAT_BRK
>>> @@ -983,6 +985,9 @@ static struct cgroup_subsys_state *ve_create(struct cgroup_subsys_state *parent_
>>>  	atomic_set(&ve->netif_avail_nr, NETIF_MAX_NR_DEFAULT);
>>>  	ve->netif_max_nr = NETIF_MAX_NR_DEFAULT;
>>>  
>>> +	atomic_set(&ve->bpf_prog_avail_nr, BPF_PROG_MAX_NR_DEFAULT);
>>> +	ve->bpf_prog_max_nr = BPF_PROG_MAX_NR_DEFAULT;
>>> +
>>>  	err = ve_log_init(ve);
>>>  	if (err)
>>>  		goto err_log;
>>
> 

-- 
Best regards, Pavel Tikhomirov
Senior Software Developer, Virtuozzo.

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