[Devel] [PATCH VZ10 v7 7/9] ve: Introduce per-VE failcount
Vladimir Riabchun
vladimir.riabchun at virtuozzo.com
Fri Aug 28 20:32:17 MSK 2026
On 8/28/26 18:52, Pavel Tikhomirov wrote:
>
>
> On 8/24/26 15:54, Vladimir Riabchun wrote:
>> It may be useful to have a history of resource limit hits for every VE,
>> this may simplify debugging and provide some information about the
>> resources usage.
>>
>> This information is provided by ve.failcount file, any write to it
>> resets all failcounts.
>>
>> To add a new failcounter we need to create a new atomic_t field
>> name_failcount in ve structure and add a new VE_FC_ENTRY in
>> ve_failcounts array.
>>
>> One change, unrelated to failcounts: aio fields are now initialized
>> in ve0.
>>
>> https://virtuozzo.atlassian.net/browse/VSTOR-135520
>>
>> Feature: per-ve failcounters
>> Signed-off-by: Vladimir Riabchun <vladimir.riabchun at virtuozzo.com>
>> ---
>> fs/aio.c | 1 +
>> fs/namespace.c | 2 ++
>> include/linux/ve.h | 6 ++++
>> kernel/bpf/syscall.c | 1 +
>> kernel/ve/ve.c | 70 ++++++++++++++++++++++++++++++++++++++++
>> net/core/dev.c | 2 ++
>> net/core/neighbour.c | 1 +
>> net/core/net_namespace.c | 4 ++-
>> 8 files changed, 86 insertions(+), 1 deletion(-)
>>
>> diff --git a/fs/aio.c b/fs/aio.c
>> index cb63416af135..3fa07cc626f8 100644
>> --- a/fs/aio.c
>> +++ b/fs/aio.c
>> @@ -814,6 +814,7 @@ static struct kioctx *ioctx_alloc(unsigned nr_events)
>> spin_lock(&ve->aio_nr_lock);
>> if (ve->aio_nr + ctx->max_reqs > ve->aio_max_nr ||
>> ve->aio_nr + ctx->max_reqs < ve->aio_nr) {
>> + atomic_inc(&ve->aio_failcount);
>> spin_unlock(&ve->aio_nr_lock);
>> err = -EAGAIN;
>> goto err_ctx;
>> diff --git a/fs/namespace.c b/fs/namespace.c
>> index e97f48204617..c30bbc370f2b 100644
>> --- a/fs/namespace.c
>> +++ b/fs/namespace.c
>> @@ -3371,6 +3371,8 @@ static inline int ve_try_reserve_mount(struct ve_struct *ve)
>>
>> if (ret)
>> get_ve(ve);
>> + else
>> + atomic_inc(&ve->mnt_failcount);
>> return ret;
>> }
>>
>> diff --git a/include/linux/ve.h b/include/linux/ve.h
>> index 5687faad46ff..9e73527e970e 100644
>> --- a/include/linux/ve.h
>> +++ b/include/linux/ve.h
>> @@ -72,12 +72,15 @@ struct ve_struct {
>> struct kmapset_key proc_perms_key;
>>
>> atomic_t netns_avail_nr;
>> + atomic_t netns_failcount;
>> int netns_max_nr;
>>
>> atomic_t netif_avail_nr;
>> + atomic_t netif_failcount;
>> int netif_max_nr;
>>
>> atomic_t bpf_prog_avail_nr;
>> + atomic_t bpf_prog_failcount;
>> int bpf_prog_max_nr;
>>
>> atomic64_t _uevent_seqnum;
>> @@ -86,6 +89,7 @@ struct ve_struct {
>>
>> atomic_t arp_neigh_nr;
>> atomic_t nd_neigh_nr;
>> + atomic_t neigh_tbl_failcount;
>> unsigned long meminfo_val;
>>
>> /*
>> @@ -94,6 +98,7 @@ struct ve_struct {
>> * other containers.
>> */
>> atomic_t mnt_avail_nr; /* number of available VE mounts */
>> + atomic_t mnt_failcount;
>> int mnt_max_nr;
>>
>> #ifdef CONFIG_COREDUMP
>> @@ -121,6 +126,7 @@ struct ve_struct {
>> spinlock_t aio_nr_lock;
>> unsigned long aio_nr;
>> unsigned long aio_max_nr;
>> + atomic_t aio_failcount;
>> #endif
>> struct vfsmount *devtmpfs_mnt;
>> };
>> diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c
>> index c94d4240e3d3..9d57e7999ae0 100644
>> --- a/kernel/bpf/syscall.c
>> +++ b/kernel/bpf/syscall.c
>> @@ -2891,6 +2891,7 @@ static int bpf_prog_load(union bpf_attr *attr, bpfptr_t uattr, u32 uattr_size)
>> 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) {
>> + atomic_inc(&load_ve->bpf_prog_failcount);
>> load_ve = NULL;
>> err = -ENOSPC;
>> goto put_token;
>> diff --git a/kernel/ve/ve.c b/kernel/ve/ve.c
>> index 0f02835765ff..826f72ad0a22 100644
>> --- a/kernel/ve/ve.c
>> +++ b/kernel/ve/ve.c
>> @@ -99,10 +99,13 @@ struct ve_struct ve0 = {
>> .features = -1,
>> .sched_lat_ve.cur = &ve0_lat_stats,
>> .netns_avail_nr = ATOMIC_INIT(INT_MAX),
>> + .netns_failcount = ATOMIC_INIT(0),
>> .netns_max_nr = INT_MAX,
>> .netif_avail_nr = ATOMIC_INIT(INT_MAX),
>> + .netif_failcount = ATOMIC_INIT(0),
>> .netif_max_nr = INT_MAX,
>> .bpf_prog_avail_nr = ATOMIC_INIT(INT_MAX),
>> + .bpf_prog_failcount = ATOMIC_INIT(0),
>> .bpf_prog_max_nr = INT_MAX,
>> .fsync_enable = FSYNC_FILTERED,
>> ._randomize_va_space =
>> @@ -114,8 +117,16 @@ struct ve_struct ve0 = {
>>
>> .arp_neigh_nr = ATOMIC_INIT(0),
>> .nd_neigh_nr = ATOMIC_INIT(0),
>> + .neigh_tbl_failcount = ATOMIC_INIT(0),
>> .mnt_avail_nr = ATOMIC_INIT(INT_MAX),
>> .mnt_max_nr = INT_MAX,
>> + .mnt_failcount = ATOMIC_INIT(0),
>> +#ifdef CONFIG_AIO
>> + .aio_nr_lock = __SPIN_LOCK_UNLOCKED(aio_nr_lock),
>> + .aio_nr = 0,
>> + .aio_max_nr = AIO_MAX_NR_DEFAULT,
>
> This feature is not intended to limit host aio, right? Should it
> be INT_MAX or something big here for ve0?
It preserves original kernel behavior. Upstream kernel has aio_max_nr
sysctl variable with the same value as AIO_MAX_NR_DEFAULT.
Commit 1f6006388601 ("ve/fs/aio: aio_nr & aio_max_nr variables virtualization")
added aio_max_nr to ve structure, but it didn't initialize it in ve0.
Here I just put the correct value in it, so no functional changes.
>
>> + .aio_failcount = ATOMIC_INIT(0),
>> +#endif
>> .meminfo_val = VE_MEMINFO_SYSTEM,
>> .umh_running_helpers = ATOMIC_INIT(0),
>> .umh_helpers_waitq = __WAIT_QUEUE_HEAD_INITIALIZER(ve0.umh_helpers_waitq),
>> @@ -780,12 +791,15 @@ static struct cgroup_subsys_state *ve_create(struct cgroup_subsys_state *parent_
>> ve->fsync_enable = FSYNC_FILTERED;
>>
>> atomic_set(&ve->netns_avail_nr, NETNS_MAX_NR_DEFAULT);
>> + atomic_set(&ve->netns_failcount, 0);
>> ve->netns_max_nr = NETNS_MAX_NR_DEFAULT;
>>
>> atomic_set(&ve->netif_avail_nr, NETIF_MAX_NR_DEFAULT);
>> + atomic_set(&ve->netif_failcount, 0);
>> ve->netif_max_nr = NETIF_MAX_NR_DEFAULT;
>>
>> atomic_set(&ve->bpf_prog_avail_nr, BPF_PROG_MAX_NR_DEFAULT);
>> + atomic_set(&ve->bpf_prog_failcount, 0);
>> ve->bpf_prog_max_nr = BPF_PROG_MAX_NR_DEFAULT;
>>
>> err = ve_log_init(ve);
>> @@ -812,7 +826,9 @@ static struct cgroup_subsys_state *ve_create(struct cgroup_subsys_state *parent_
>>
>> atomic_set(&ve->arp_neigh_nr, 0);
>> atomic_set(&ve->nd_neigh_nr, 0);
>> + atomic_set(&ve->neigh_tbl_failcount, 0);
>> ve->mnt_max_nr = MNT_MAX_NR_DEFAULT;
>> + atomic_set(&ve->mnt_failcount, 0);
>> atomic_set(&ve->mnt_avail_nr, MNT_MAX_NR_DEFAULT);
>>
>> #ifdef CONFIG_COREDUMP
>> @@ -825,6 +841,7 @@ static struct cgroup_subsys_state *ve_create(struct cgroup_subsys_state *parent_
>> spin_lock_init(&ve->aio_nr_lock);
>> ve->aio_nr = 0;
>> ve->aio_max_nr = AIO_MAX_NR_DEFAULT;
>> + atomic_set(&ve->aio_failcount, 0);
>> #endif
>>
>> return &ve->css;
>> @@ -1065,6 +1082,53 @@ VE_RESOURCE(mnt);
>> VE_RESOURCE(netif);
>> VE_RESOURCE(bpf_prog);
>>
>> +static const struct ve_failcount_entry {
>> + const char *name;
>> + size_t offset;
>> +} ve_failcounts[] = {
>> +#define VE_FC_ENTRY(name) { #name, offsetof(struct ve_struct, name##_failcount) }
>> + VE_FC_ENTRY(netns),
>> + VE_FC_ENTRY(mnt),
>> + VE_FC_ENTRY(netif),
>> + VE_FC_ENTRY(bpf_prog),
>> + VE_FC_ENTRY(neigh_tbl),
>> +#ifdef CONFIG_AIO
>> + VE_FC_ENTRY(aio),
>> +#endif
>> + {}
>> +};
>> +
>> +static int ve_failcount_read(struct seq_file *sf, void *v)
>> +{
>> + struct ve_struct *ve = css_to_ve(seq_css(sf));
>> + const struct ve_failcount_entry *entry;
>> + atomic_t *fc;
>> +
>> + for (entry = ve_failcounts; entry->name; entry++) {
>> + fc = (void *)ve + entry->offset;
>> + seq_printf(sf, "%s: %d\n", entry->name, atomic_read(fc));
>> + }
>> + return 0;
>> +}
>> +
>> +static ssize_t ve_failcount_write(struct kernfs_open_file *of, char *buf,
>> + size_t nbytes, loff_t off)
>> +{
>> + struct ve_struct *ve = css_to_ve(of_css(of));
>> + const struct ve_failcount_entry *entry;
>> + atomic_t *fc;
>> +
>> + if (!ve_is_super(get_exec_env()) && !ve->is_pseudosuper)
>> + return -EPERM;
>> +
>> + for (entry = ve_failcounts; entry->name; entry++) {
>> + fc = (void *)ve + entry->offset;
>> + atomic_set(fc, 0);
>> + }
>> +
>> + return nbytes;
>> +}
>> +
>> static int ve_os_release_read(struct seq_file *sf, void *v)
>> {
>> struct cgroup_subsys_state *css = seq_css(sf);
>> @@ -1602,6 +1666,12 @@ static struct cftype ve_cftypes[] = {
>> .flags = CFTYPE_NOT_ON_ROOT,
>> .write_u64 = ve_rpc_kill_write,
>> },
>> + {
>> + .name = "failcount",
>> + .flags = CFTYPE_NOT_ON_ROOT,
>> + .seq_show = ve_failcount_read,
>> + .write = ve_failcount_write,
>> + },
>> { }
>> };
>>
>> diff --git a/net/core/dev.c b/net/core/dev.c
>> index c7dddb200489..05e0b9b6ba23 100644
>> --- a/net/core/dev.c
>> +++ b/net/core/dev.c
>> @@ -10997,6 +10997,7 @@ int register_netdevice(struct net_device *dev)
>>
>> ret = -ENOMEM;
>> if (atomic_dec_if_positive(&net->owner_ve->netif_avail_nr) < 0) {
>> + atomic_inc(&net->owner_ve->netif_failcount);
>> ve_pr_warn_ratelimited(VE_LOG_BOTH,
>> "CT%s: hits max number of network devices, "
>> "increase ve::netif_max_nr parameter\n",
>> @@ -12211,6 +12212,7 @@ int __dev_change_net_namespace(struct net_device *dev, struct net *net,
>>
>> err = -ENOMEM;
>> if (atomic_dec_if_positive(&net->owner_ve->netif_avail_nr) < 0) {
>> + atomic_inc(&net->owner_ve->netif_failcount);
>> ve_pr_warn_ratelimited(VE_LOG_BOTH,
>> "CT%s: hits max number of network devices, "
>> "increase ve::netif_max_nr parameter\n",
>> diff --git a/net/core/neighbour.c b/net/core/neighbour.c
>> index f90deb17fb25..57a49d9c98a7 100644
>> --- a/net/core/neighbour.c
>> +++ b/net/core/neighbour.c
>> @@ -520,6 +520,7 @@ static struct neighbour *neigh_alloc(struct neigh_table *tbl,
>> (glob_entries >= READ_ONCE(tbl->gc_thresh2) &&
>> time_after(now, READ_ONCE(tbl->last_flush) + 5 * HZ))) {
>> if (!neigh_forced_gc(tbl, ve) && entries >= gc_thresh3) {
>> + atomic_inc(&ve->neigh_tbl_failcount);
>> net_info_ratelimited("%s: neighbor table overflow!\n",
>> tbl->id);
>> NEIGH_CACHE_STAT_INC(tbl, table_fulls);
>> diff --git a/net/core/net_namespace.c b/net/core/net_namespace.c
>> index b3d54cad984a..9a3376d2682f 100644
>> --- a/net/core/net_namespace.c
>> +++ b/net/core/net_namespace.c
>> @@ -486,8 +486,10 @@ void net_drop_ns(void *p)
>> #ifdef CONFIG_VE
>> static int dec_netns_avail(struct ve_struct *ve)
>> {
>> - if (atomic_dec_if_positive(&ve->netns_avail_nr) < 0)
>> + if (atomic_dec_if_positive(&ve->netns_avail_nr) < 0) {
>> + atomic_inc(&ve->netns_failcount);
>
> Let's add a helper for incrementing our failcounts:
>
> #define ve_failcount_inc(ve, name) \
> do { \
> struct ve_struct *__ve = (ve); \
> \
> if (atomic_inc_return(&__ve->name##_failcount) == 1) \
> pr_warn("CT%s: hits the " #name " limit, see the '" \
> #name "' counter in ve.failcount of the " \
> "container's ve cgroup\n", ve_name(__ve)); \
> } while (0)
>
> Call sites become one-liners:
>
> --- a/fs/aio.c
> - atomic_inc(&ve->aio_failcount);
> + ve_failcount_inc(ve, aio);
> --- a/fs/namespace.c
> - atomic_inc(&ve->mnt_failcount);
> + ve_failcount_inc(ve, mnt);
> --- a/kernel/bpf/syscall.c
> - atomic_inc(&load_ve->bpf_prog_failcount);
> + ve_failcount_inc(load_ve, bpf_prog);
> --- a/net/core/dev.c (both register_netdevice() and __dev_change_net_namespace())
> - atomic_inc(&net->owner_ve->netif_failcount);
> + ve_failcount_inc(net->owner_ve, netif);
> --- a/net/core/neighbour.c
> - atomic_inc(&ve->neigh_tbl_failcount);
> + ve_failcount_inc(ve, neigh_tbl);
> --- a/net/core/net_namespace.c
> - atomic_inc(&ve->netns_failcount);
> + ve_failcount_inc(ve, netns);
>
> The idea behind it is to show in dmesg that failcount was reached, to simpify
> the detection of problematic containers for us.
>
> For reference http://lore.virtuozzo.com/kernel/ccc3cbc8-e225-41cf-b563-699254aeb57b@virtuozzo.com/T/#t
>
Fair, I'll do it in next version or as a follow-up if everything else is fine here.
Just instead of pr_warn we should use pr_warn_ratelimited, as it is easy
to trigger warning from container and flood dmesg and serial console.
>> return -ENOSPC;
>> + }
>> return 0;
>> }
>>
>
--
Best regards, Riabchun Vladimir
Linux Kernel Developer, Virtuozzo
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