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Date: Sat, 12 Jul 2014 10:44:17 +0200
From: Nikolay Aleksandrov <nikolay@...hat.com>
To: Mahesh Bandewar <maheshb@...gle.com>,
Jay Vosburgh <j.vosburgh@...il.com>,
Veaceslav Falico <vfalico@...hat.com>,
Andy Gospodarek <andy@...yhouse.net>,
David Miller <davem@...emloft.net>
CC: netdev <netdev@...r.kernel.org>,
Eric Dumazet <edumazet@...gle.com>,
Maciej Zenczykowski <maze@...gle.com>
Subject: Re: [PATCHv2] bonding: Do not try to send packets over dead link
in TLB mode.
On 07/11/2014 11:15 PM, Mahesh Bandewar wrote:
> In my tests with added instrumentation (similar to __might_sleep()) in
> the update_arr function; the calls were never in the automic context
> so did not change the GFP flag to GFP_ATOMIC.
>
> On Fri, Jul 11, 2014 at 2:10 PM, Mahesh Bandewar <maheshb@...gle.com> wrote:
>> In TLB mode if tlb_dynamic_lb is NOT set, slaves from the bond
>> group are selected based on the hash distribution. This does not
>> exclude dead links which are part of the bond. Also if there is a
>> temporary link event which brings down the interface, packets
>> hashed on that interface would be dropped too.
>>
>> This patch fixes these issues and distributes flows across the
>> UP links only. Also the array construction of links which are
>> capable of sending packets happen in the control path leaving
>> only link-selection during the data-path.
>>
>> One possible side effect of this is - at a link event; all
>> flows will be shuffled to get good distribution. But impact of
>> this should be minimum with the assumption that a member or
>> members of the bond group are not available is a very temporary
>> situation.
>>
>> Signed-off-by: Mahesh Bandewar <maheshb@...gle.com>
>> ---
>> drivers/net/bonding/bond_alb.c | 44 +++++++++++++++++++++++++++++++++++++-----
>> drivers/net/bonding/bond_alb.h | 8 ++++++++
>> drivers/net/bonding/bonding.h | 6 ++++++
>> 3 files changed, 53 insertions(+), 5 deletions(-)
>>
>> [v1]
>> * Initial patch
>> [v2]
>> * Removed spinlock protection
>> * Removed explicit rcu_read_(un)lock() calls since Xmit fn run in RCU
>> * Updated condition during bond-dismantle to check for only arrays' existance.
>>
>> diff --git a/drivers/net/bonding/bond_alb.c b/drivers/net/bonding/bond_alb.c
>> index 76c0dade233f..7fb2066432b1 100644
>> --- a/drivers/net/bonding/bond_alb.c
>> +++ b/drivers/net/bonding/bond_alb.c
>> @@ -209,6 +209,9 @@ static void tlb_deinitialize(struct bonding *bond)
>> bond_info->tx_hashtbl = NULL;
>>
>> _unlock_tx_hashtbl_bh(bond);
>> +
>> + if (bond_info->slave_arr)
>> + kfree_rcu(bond_info->slave_arr, rcu);
>> }
>>
>> static long long compute_gap(struct slave *slave)
>> @@ -1406,9 +1409,35 @@ out:
>> return NETDEV_TX_OK;
>> }
>>
>> +static int bond_tlb_update_slave_arr(struct bonding *bond)
>> +{
>> + struct alb_bond_info *bond_info = &(BOND_ALB_INFO(bond));
>> + struct slave *tx_slave;
>> + struct list_head *iter;
>> + struct tlb_up_slave *new_arr, *old_arr;
>> +
>> + new_arr = kzalloc(offsetof(struct tlb_up_slave, arr[bond->slave_cnt]),
>> + GFP_KERNEL);
>> + if (!new_arr)
>> + return -ENOMEM;
>> +
>> + bond_for_each_slave(bond, tx_slave, iter) {
>> + if (bond_slave_can_tx(tx_slave))
>> + new_arr->arr[new_arr->count++] = tx_slave;
>> + }
>> +
>> + old_arr = bond_info->slave_arr;
>> + rcu_assign_pointer(bond_info->slave_arr, new_arr);
>> + if (old_arr)
>> + kfree_rcu(old_arr, rcu);
>> +
>> + return 0;
>> +}
>> +
>> int bond_tlb_xmit(struct sk_buff *skb, struct net_device *bond_dev)
>> {
>> struct bonding *bond = netdev_priv(bond_dev);
>> + struct alb_bond_info *bond_info = &(BOND_ALB_INFO(bond));
>> struct ethhdr *eth_data;
>> struct slave *tx_slave = NULL;
>> u32 hash_index;
>> @@ -1429,12 +1458,12 @@ int bond_tlb_xmit(struct sk_buff *skb, struct net_device *bond_dev)
>> hash_index & 0xFF,
>> skb->len);
>> } else {
>> - struct list_head *iter;
>> - int idx = hash_index % bond->slave_cnt;
>> + struct tlb_up_slave *slaves;
>>
>> - bond_for_each_slave_rcu(bond, tx_slave, iter)
>> - if (--idx < 0)
>> - break;
>> + slaves = rcu_dereference(bond_info->slave_arr);
>> + if (slaves && slaves->count)
>> + tx_slave = slaves->arr[hash_index %
>> + slaves->count];
>> }
>> break;
>> }
>> @@ -1721,6 +1750,11 @@ void bond_alb_handle_link_change(struct bonding *bond, struct slave *slave, char
>> */
>> }
>> }
>> +
>> + if (bond_is_nondyn_tlb(bond)) {
>> + if (bond_tlb_update_slave_arr(bond))
>> + pr_err("Failed to build slave-array for TLB mode.\n");
>> + }
>> }
>>
>> /**
>> diff --git a/drivers/net/bonding/bond_alb.h b/drivers/net/bonding/bond_alb.h
>> index 5fc76c01636c..aaeac61d03cf 100644
>> --- a/drivers/net/bonding/bond_alb.h
>> +++ b/drivers/net/bonding/bond_alb.h
>> @@ -139,12 +139,20 @@ struct tlb_slave_info {
>> */
>> };
>>
>> +struct tlb_up_slave {
>> + unsigned int count;
>> + struct rcu_head rcu;
>> + struct slave *arr[0];
>> +};
>> +
>> struct alb_bond_info {
>> struct tlb_client_info *tx_hashtbl; /* Dynamically allocated */
>> spinlock_t tx_hashtbl_lock;
>> u32 unbalanced_load;
>> int tx_rebalance_counter;
>> int lp_counter;
>> + /* -------- non-dynamic tlb mode only ---------*/
>> + struct tlb_up_slave __rcu *slave_arr; /* Up slaves */
>> /* -------- rlb parameters -------- */
>> int rlb_enabled;
>> struct rlb_client_info *rx_hashtbl; /* Receive hash table */
>> diff --git a/drivers/net/bonding/bonding.h b/drivers/net/bonding/bonding.h
>> index 0b4d9cde0b05..ad9b3dce07d8 100644
>> --- a/drivers/net/bonding/bonding.h
>> +++ b/drivers/net/bonding/bonding.h
>> @@ -265,6 +265,12 @@ static inline bool bond_is_lb(const struct bonding *bond)
>> BOND_MODE(bond) == BOND_MODE_ALB;
>> }
>>
>> +static inline bool bond_is_nondyn_tlb(const struct bonding *bond)
>> +{
>> + return (BOND_MODE(bond) == BOND_MODE_TLB) &&
>> + (bond->params.tlb_dynamic_lb == 0);
>> +}
>> +
>> static inline bool bond_mode_uses_arp(int mode)
>> {
>> return mode != BOND_MODE_8023AD && mode != BOND_MODE_TLB &&
>> --
>> 2.0.0.526.g5318336
>>
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Did you have CONFIG_DEBUG_ATOMIC_SLEEP in your kernel config ?
[ 556.669144] BUG: sleeping function called from invalid context at
mm/slub.c:965
[ 556.670262] in_atomic(): 1, irqs_disabled(): 0, pid: 3316, name: bash
[ 556.670939] CPU: 1 PID: 3316 Comm: bash Tainted: G OE
3.16.0-rc2+ #3
[ 556.670941] Hardware name: Bochs Bochs, BIOS Bochs 01/01/2011
[ 556.670943] 0000000000000000 ffff88005b60fc70 ffffffff816af012
ffff8800490cb900
[ 556.670957] ffff88005b60fc80 ffffffff8109c30a ffff88005b60fcc0
ffffffff811b2283
[ 556.670961] ffffffffa01f45ae ffff8800490cb900 0000000000000000
ffff880049d9ac00
[ 556.670965] Call Trace:
[ 556.670975] [<ffffffff816af012>] dump_stack+0x4d/0x66
[ 556.670981] [<ffffffff8109c30a>] __might_sleep+0xca/0x100
[ 556.670987] [<ffffffff811b2283>] __kmalloc+0x63/0x270
[ 556.670996] [<ffffffffa01f45ae>] ?
bond_alb_handle_link_change+0x7e/0x180 [bonding]
[ 556.671010] [<ffffffffa01f45ae>] bond_alb_handle_link_change+0x7e/0x180
[bonding]
[ 556.671068] [<ffffffffa01eac62>] bond_change_active_slave+0x3b2/0x620
[bonding]
[ 556.671076] [<ffffffffa01eaf94>] bond_select_active_slave+0xc4/0x1a0
[bonding]
[ 556.671082] [<ffffffffa01ec00d>] bond_enslave+0xf9d/0xfc0 [bonding]
[ 556.671089] [<ffffffffa01f70df>] bond_option_slaves_set+0xff/0x130
[bonding]
[ 556.671095] [<ffffffffa01f83ff>] __bond_opt_set+0xdf/0x330 [bonding]
[ 556.671100] [<ffffffffa01f8697>] bond_opt_tryset_rtnl+0x47/0x80 [bonding]
[ 556.671106] [<ffffffffa01f52e5>] bonding_sysfs_store_option+0x35/0x60
[bonding]
[ 556.671113] [<ffffffff8141e6f8>] dev_attr_store+0x18/0x30
[ 556.671118] [<ffffffff812435ad>] sysfs_kf_write+0x3d/0x50
[ 556.671121] [<ffffffff812430a4>] kernfs_fop_write+0xe4/0x160
[ 556.671126] [<ffffffff811cc367>] vfs_write+0xb7/0x1f0
[ 556.671129] [<ffffffff811ccf19>] SyS_write+0x49/0xb0
[ 556.671134] [<ffffffff81106f36>] ? __audit_syscall_exit+0x1f6/0x2a0
[ 556.671139] [<ffffffff816b69d2>] system_call_fastpath+0x16/0x1b
Cheers,
Nik
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