Re: [Devel] [PATCH VZ10 v6 7/9] ve: Introduce per-VE failcount

[Vasileios Almpanis <vasileios.almpanis@virtuozzo.com>]

> 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@virtuozzo.com>
>
> 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 c9e2ab9b3b57..eeeb2f780e46 100644
> --- a/fs/namespace.c
> +++ b/fs/namespace.c
> @@ -3369,6 +3369,8 @@ 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..55a83b0b5981 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,
> +	.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 +1082,50 @@ 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;
Should we allow the container itself to reset the failcount? All other
resource write handlers have a check that return EPERM when we are not
super ve. Here we will allow the container to reset its failcount so it
will no longer be trustworthy information.

-- 
Vasileios Almpanis <vasileios.almpanis@virtuozzo.com>