* Re: [PATCHv3 1/1] RDMA/rxe: Fix a dead lock problem
2022-04-13 7:42 [PATCHv3 1/1] RDMA/rxe: Fix a dead lock problem yanjun.zhu
@ 2022-04-13 0:45 ` Jason Gunthorpe
2022-04-13 14:50 ` Yanjun Zhu
0 siblings, 1 reply; 10+ messages in thread
From: Jason Gunthorpe @ 2022-04-13 0:45 UTC (permalink / raw)
To: yanjun.zhu; +Cc: leon, linux-rdma, Yi Zhang
On Wed, Apr 13, 2022 at 03:42:08AM -0400, yanjun.zhu@linux.dev wrote:
> From: Zhu Yanjun <yanjun.zhu@linux.dev>
>
> This is a dead lock problem.
> The xa_lock first is acquired in this:
>
> {SOFTIRQ-ON-W} state was registered at:
>
> lock_acquire+0x1d2/0x5a0
> _raw_spin_lock+0x33/0x80
> __rxe_add_to_pool+0x183/0x230 [rdma_rxe]
> __ib_alloc_pd+0xf9/0x550 [ib_core]
> ib_mad_init_device+0x2d9/0xd20 [ib_core]
> add_client_context+0x2fa/0x450 [ib_core]
> enable_device_and_get+0x1b7/0x350 [ib_core]
> ib_register_device+0x757/0xaf0 [ib_core]
> rxe_register_device+0x2eb/0x390 [rdma_rxe]
> rxe_net_add+0x83/0xc0 [rdma_rxe]
> rxe_newlink+0x76/0x90 [rdma_rxe]
> nldev_newlink+0x245/0x3e0 [ib_core]
> rdma_nl_rcv_msg+0x2d4/0x790 [ib_core]
> rdma_nl_rcv+0x1ca/0x3f0 [ib_core]
> netlink_unicast+0x43b/0x640
> netlink_sendmsg+0x7eb/0xc40
> sock_sendmsg+0xe0/0x110
> __sys_sendto+0x1d7/0x2b0
> __x64_sys_sendto+0xdd/0x1b0
> do_syscall_64+0x37/0x80
> entry_SYSCALL_64_after_hwframe+0x44/0xae
>
> Then xa_lock is acquired in this:
>
> {IN-SOFTIRQ-W}:
>
> Call Trace:
> <TASK>
> dump_stack_lvl+0x44/0x57
> mark_lock.part.52.cold.79+0x3c/0x46
> __lock_acquire+0x1565/0x34a0
> lock_acquire+0x1d2/0x5a0
> _raw_spin_lock_irqsave+0x42/0x90
> rxe_pool_get_index+0x72/0x1d0 [rdma_rxe]
> rxe_get_av+0x168/0x2a0 [rdma_rxe]
> rxe_requester+0x75b/0x4a90 [rdma_rxe]
> rxe_do_task+0x134/0x230 [rdma_rxe]
> tasklet_action_common.isra.12+0x1f7/0x2d0
> __do_softirq+0x1ea/0xa4c
> run_ksoftirqd+0x32/0x60
> smpboot_thread_fn+0x503/0x860
> kthread+0x29b/0x340
> ret_from_fork+0x1f/0x30
> </TASK>
>
> From the above, in the function __rxe_add_to_pool,
> xa_lock is acquired. Then the function __rxe_add_to_pool
> is interrupted by softirq. The function
> rxe_pool_get_index will also acquire xa_lock.
>
> Finally, the dead lock appears.
>
> [ 296.806097] CPU0
> [ 296.808550] ----
> [ 296.811003] lock(&xa->xa_lock#15); <----- __rxe_add_to_pool
> [ 296.814583] <Interrupt>
> [ 296.817209] lock(&xa->xa_lock#15); <---- rxe_pool_get_index
> [ 296.820961]
> *** DEADLOCK ***
>
> Fixes: 3225717f6dfa ("RDMA/rxe: Replace red-black trees by carrays")
> Reported-and-tested-by: Yi Zhang <yi.zhang@redhat.com>
> Signed-off-by: Zhu Yanjun <yanjun.zhu@linux.dev>
> ---
> V2->V3: __rxe_add_to_pool is between spin_lock and spin_unlock, so
> GFP_ATOMIC is used in __rxe_add_to_pool.
> V1->V2: Replace GFP_KERNEL with GFP_ATOMIC
> ---
> drivers/infiniband/sw/rxe/rxe_pool.c | 17 ++++++++++++-----
> 1 file changed, 12 insertions(+), 5 deletions(-)
>
> diff --git a/drivers/infiniband/sw/rxe/rxe_pool.c b/drivers/infiniband/sw/rxe/rxe_pool.c
> index 87066d04ed18..b9b147df4020 100644
> --- a/drivers/infiniband/sw/rxe/rxe_pool.c
> +++ b/drivers/infiniband/sw/rxe/rxe_pool.c
> @@ -138,8 +138,10 @@ void *rxe_alloc(struct rxe_pool *pool)
> elem->obj = obj;
> kref_init(&elem->ref_cnt);
>
> - err = xa_alloc_cyclic(&pool->xa, &elem->index, elem, pool->limit,
> - &pool->next, GFP_KERNEL);
> + xa_lock_bh(&pool->xa);
> + err = __xa_alloc_cyclic(&pool->xa, &elem->index, elem, pool->limit,
> + &pool->next, GFP_KERNEL);
> + xa_unlock_bh(&pool->xa);
> if (err)
> goto err_free;
You can't mix bh and not bh locks, either this is an irq spinlock or
it is bh spinlock, pick one and also ensure that the proper xa_init
flag is set.
> @@ -166,8 +168,10 @@ int __rxe_add_to_pool(struct rxe_pool *pool, struct rxe_pool_elem *elem)
> elem->obj = (u8 *)elem - pool->elem_offset;
> kref_init(&elem->ref_cnt);
>
> - err = xa_alloc_cyclic(&pool->xa, &elem->index, elem, pool->limit,
> - &pool->next, GFP_KERNEL);
> + xa_lock_irq(&pool->xa);
> + err = __xa_alloc_cyclic(&pool->xa, &elem->index, elem, pool->limit,
> + &pool->next, GFP_ATOMIC);
> + xa_unlock_irq(&pool->xa);
> if (err)
> goto err_cnt;
Still no, this does almost every allocation - only AH with the
non-blocking flag set should use this path.
Jason
^ permalink raw reply [flat|nested] 10+ messages in thread
* [PATCHv3 1/1] RDMA/rxe: Fix a dead lock problem
@ 2022-04-13 7:42 yanjun.zhu
2022-04-13 0:45 ` Jason Gunthorpe
0 siblings, 1 reply; 10+ messages in thread
From: yanjun.zhu @ 2022-04-13 7:42 UTC (permalink / raw)
To: jgg, leon, yanjun.zhu, linux-rdma; +Cc: Yi Zhang
From: Zhu Yanjun <yanjun.zhu@linux.dev>
This is a dead lock problem.
The xa_lock first is acquired in this:
{SOFTIRQ-ON-W} state was registered at:
lock_acquire+0x1d2/0x5a0
_raw_spin_lock+0x33/0x80
__rxe_add_to_pool+0x183/0x230 [rdma_rxe]
__ib_alloc_pd+0xf9/0x550 [ib_core]
ib_mad_init_device+0x2d9/0xd20 [ib_core]
add_client_context+0x2fa/0x450 [ib_core]
enable_device_and_get+0x1b7/0x350 [ib_core]
ib_register_device+0x757/0xaf0 [ib_core]
rxe_register_device+0x2eb/0x390 [rdma_rxe]
rxe_net_add+0x83/0xc0 [rdma_rxe]
rxe_newlink+0x76/0x90 [rdma_rxe]
nldev_newlink+0x245/0x3e0 [ib_core]
rdma_nl_rcv_msg+0x2d4/0x790 [ib_core]
rdma_nl_rcv+0x1ca/0x3f0 [ib_core]
netlink_unicast+0x43b/0x640
netlink_sendmsg+0x7eb/0xc40
sock_sendmsg+0xe0/0x110
__sys_sendto+0x1d7/0x2b0
__x64_sys_sendto+0xdd/0x1b0
do_syscall_64+0x37/0x80
entry_SYSCALL_64_after_hwframe+0x44/0xae
Then xa_lock is acquired in this:
{IN-SOFTIRQ-W}:
Call Trace:
<TASK>
dump_stack_lvl+0x44/0x57
mark_lock.part.52.cold.79+0x3c/0x46
__lock_acquire+0x1565/0x34a0
lock_acquire+0x1d2/0x5a0
_raw_spin_lock_irqsave+0x42/0x90
rxe_pool_get_index+0x72/0x1d0 [rdma_rxe]
rxe_get_av+0x168/0x2a0 [rdma_rxe]
rxe_requester+0x75b/0x4a90 [rdma_rxe]
rxe_do_task+0x134/0x230 [rdma_rxe]
tasklet_action_common.isra.12+0x1f7/0x2d0
__do_softirq+0x1ea/0xa4c
run_ksoftirqd+0x32/0x60
smpboot_thread_fn+0x503/0x860
kthread+0x29b/0x340
ret_from_fork+0x1f/0x30
</TASK>
From the above, in the function __rxe_add_to_pool,
xa_lock is acquired. Then the function __rxe_add_to_pool
is interrupted by softirq. The function
rxe_pool_get_index will also acquire xa_lock.
Finally, the dead lock appears.
[ 296.806097] CPU0
[ 296.808550] ----
[ 296.811003] lock(&xa->xa_lock#15); <----- __rxe_add_to_pool
[ 296.814583] <Interrupt>
[ 296.817209] lock(&xa->xa_lock#15); <---- rxe_pool_get_index
[ 296.820961]
*** DEADLOCK ***
Fixes: 3225717f6dfa ("RDMA/rxe: Replace red-black trees by carrays")
Reported-and-tested-by: Yi Zhang <yi.zhang@redhat.com>
Signed-off-by: Zhu Yanjun <yanjun.zhu@linux.dev>
---
V2->V3: __rxe_add_to_pool is between spin_lock and spin_unlock, so
GFP_ATOMIC is used in __rxe_add_to_pool.
V1->V2: Replace GFP_KERNEL with GFP_ATOMIC
---
drivers/infiniband/sw/rxe/rxe_pool.c | 17 ++++++++++++-----
1 file changed, 12 insertions(+), 5 deletions(-)
diff --git a/drivers/infiniband/sw/rxe/rxe_pool.c b/drivers/infiniband/sw/rxe/rxe_pool.c
index 87066d04ed18..b9b147df4020 100644
--- a/drivers/infiniband/sw/rxe/rxe_pool.c
+++ b/drivers/infiniband/sw/rxe/rxe_pool.c
@@ -138,8 +138,10 @@ void *rxe_alloc(struct rxe_pool *pool)
elem->obj = obj;
kref_init(&elem->ref_cnt);
- err = xa_alloc_cyclic(&pool->xa, &elem->index, elem, pool->limit,
- &pool->next, GFP_KERNEL);
+ xa_lock_bh(&pool->xa);
+ err = __xa_alloc_cyclic(&pool->xa, &elem->index, elem, pool->limit,
+ &pool->next, GFP_KERNEL);
+ xa_unlock_bh(&pool->xa);
if (err)
goto err_free;
@@ -166,8 +168,10 @@ int __rxe_add_to_pool(struct rxe_pool *pool, struct rxe_pool_elem *elem)
elem->obj = (u8 *)elem - pool->elem_offset;
kref_init(&elem->ref_cnt);
- err = xa_alloc_cyclic(&pool->xa, &elem->index, elem, pool->limit,
- &pool->next, GFP_KERNEL);
+ xa_lock_irq(&pool->xa);
+ err = __xa_alloc_cyclic(&pool->xa, &elem->index, elem, pool->limit,
+ &pool->next, GFP_ATOMIC);
+ xa_unlock_irq(&pool->xa);
if (err)
goto err_cnt;
@@ -200,8 +204,11 @@ static void rxe_elem_release(struct kref *kref)
{
struct rxe_pool_elem *elem = container_of(kref, typeof(*elem), ref_cnt);
struct rxe_pool *pool = elem->pool;
+ unsigned long flags;
- xa_erase(&pool->xa, elem->index);
+ xa_lock_irqsave(&pool->xa, flags);
+ __xa_erase(&pool->xa, elem->index);
+ xa_unlock_irqrestore(&pool->xa, flags);
if (pool->cleanup)
pool->cleanup(elem);
--
2.27.0
^ permalink raw reply related [flat|nested] 10+ messages in thread
* Re: [PATCHv3 1/1] RDMA/rxe: Fix a dead lock problem
2022-04-13 0:45 ` Jason Gunthorpe
@ 2022-04-13 14:50 ` Yanjun Zhu
2022-04-14 13:01 ` Yanjun Zhu
0 siblings, 1 reply; 10+ messages in thread
From: Yanjun Zhu @ 2022-04-13 14:50 UTC (permalink / raw)
To: Jason Gunthorpe; +Cc: leon, linux-rdma, Yi Zhang
在 2022/4/13 8:45, Jason Gunthorpe 写道:
> On Wed, Apr 13, 2022 at 03:42:08AM -0400, yanjun.zhu@linux.dev wrote:
>> From: Zhu Yanjun <yanjun.zhu@linux.dev>
>>
>> This is a dead lock problem.
>> The xa_lock first is acquired in this:
>>
>> {SOFTIRQ-ON-W} state was registered at:
>>
>> lock_acquire+0x1d2/0x5a0
>> _raw_spin_lock+0x33/0x80
>> __rxe_add_to_pool+0x183/0x230 [rdma_rxe]
>> __ib_alloc_pd+0xf9/0x550 [ib_core]
>> ib_mad_init_device+0x2d9/0xd20 [ib_core]
>> add_client_context+0x2fa/0x450 [ib_core]
>> enable_device_and_get+0x1b7/0x350 [ib_core]
>> ib_register_device+0x757/0xaf0 [ib_core]
>> rxe_register_device+0x2eb/0x390 [rdma_rxe]
>> rxe_net_add+0x83/0xc0 [rdma_rxe]
>> rxe_newlink+0x76/0x90 [rdma_rxe]
>> nldev_newlink+0x245/0x3e0 [ib_core]
>> rdma_nl_rcv_msg+0x2d4/0x790 [ib_core]
>> rdma_nl_rcv+0x1ca/0x3f0 [ib_core]
>> netlink_unicast+0x43b/0x640
>> netlink_sendmsg+0x7eb/0xc40
>> sock_sendmsg+0xe0/0x110
>> __sys_sendto+0x1d7/0x2b0
>> __x64_sys_sendto+0xdd/0x1b0
>> do_syscall_64+0x37/0x80
>> entry_SYSCALL_64_after_hwframe+0x44/0xae
>>
>> Then xa_lock is acquired in this:
>>
>> {IN-SOFTIRQ-W}:
>>
>> Call Trace:
>> <TASK>
>> dump_stack_lvl+0x44/0x57
>> mark_lock.part.52.cold.79+0x3c/0x46
>> __lock_acquire+0x1565/0x34a0
>> lock_acquire+0x1d2/0x5a0
>> _raw_spin_lock_irqsave+0x42/0x90
>> rxe_pool_get_index+0x72/0x1d0 [rdma_rxe]
>> rxe_get_av+0x168/0x2a0 [rdma_rxe]
>> rxe_requester+0x75b/0x4a90 [rdma_rxe]
>> rxe_do_task+0x134/0x230 [rdma_rxe]
>> tasklet_action_common.isra.12+0x1f7/0x2d0
>> __do_softirq+0x1ea/0xa4c
>> run_ksoftirqd+0x32/0x60
>> smpboot_thread_fn+0x503/0x860
>> kthread+0x29b/0x340
>> ret_from_fork+0x1f/0x30
>> </TASK>
>>
>> From the above, in the function __rxe_add_to_pool,
>> xa_lock is acquired. Then the function __rxe_add_to_pool
>> is interrupted by softirq. The function
>> rxe_pool_get_index will also acquire xa_lock.
>>
>> Finally, the dead lock appears.
>>
>> [ 296.806097] CPU0
>> [ 296.808550] ----
>> [ 296.811003] lock(&xa->xa_lock#15); <----- __rxe_add_to_pool
>> [ 296.814583] <Interrupt>
>> [ 296.817209] lock(&xa->xa_lock#15); <---- rxe_pool_get_index
>> [ 296.820961]
>> *** DEADLOCK ***
>>
>> Fixes: 3225717f6dfa ("RDMA/rxe: Replace red-black trees by carrays")
>> Reported-and-tested-by: Yi Zhang <yi.zhang@redhat.com>
>> Signed-off-by: Zhu Yanjun <yanjun.zhu@linux.dev>
>> ---
>> V2->V3: __rxe_add_to_pool is between spin_lock and spin_unlock, so
>> GFP_ATOMIC is used in __rxe_add_to_pool.
>> V1->V2: Replace GFP_KERNEL with GFP_ATOMIC
>> ---
>> drivers/infiniband/sw/rxe/rxe_pool.c | 17 ++++++++++++-----
>> 1 file changed, 12 insertions(+), 5 deletions(-)
>>
>> diff --git a/drivers/infiniband/sw/rxe/rxe_pool.c b/drivers/infiniband/sw/rxe/rxe_pool.c
>> index 87066d04ed18..b9b147df4020 100644
>> --- a/drivers/infiniband/sw/rxe/rxe_pool.c
>> +++ b/drivers/infiniband/sw/rxe/rxe_pool.c
>> @@ -138,8 +138,10 @@ void *rxe_alloc(struct rxe_pool *pool)
>> elem->obj = obj;
>> kref_init(&elem->ref_cnt);
>>
>> - err = xa_alloc_cyclic(&pool->xa, &elem->index, elem, pool->limit,
>> - &pool->next, GFP_KERNEL);
>> + xa_lock_bh(&pool->xa);
>> + err = __xa_alloc_cyclic(&pool->xa, &elem->index, elem, pool->limit,
>> + &pool->next, GFP_KERNEL);
>> + xa_unlock_bh(&pool->xa);
>> if (err)
>> goto err_free;
> You can't mix bh and not bh locks, either this is an irq spinlock or
> it is bh spinlock, pick one and also ensure that the proper xa_init
> flag is set.
Got it. I should use irq spinlock. So XA_FLAGS_LOCK_IRQ is added in
xa_init flags.
So the code should be:
@@ -106,7 +106,7 @@ void rxe_pool_init(struct rxe_dev *rxe, struct
rxe_pool *pool,
atomic_set(&pool->num_elem, 0);
- xa_init_flags(&pool->xa, XA_FLAGS_ALLOC);
+ xa_init_flags(&pool->xa, XA_FLAGS_LOCK_IRQ | XA_FLAGS_ALLOC);
pool->limit.min = info->min_index;
pool->limit.max = info->max_index;
}
@@ -138,10 +138,10 @@ void *rxe_alloc(struct rxe_pool *pool)
elem->obj = obj;
kref_init(&elem->ref_cnt);
- xa_lock_bh(&pool->xa);
+ xa_lock_irq(&pool->xa);
err = __xa_alloc_cyclic(&pool->xa, &elem->index, elem, pool->limit,
&pool->next, GFP_KERNEL);
- xa_unlock_bh(&pool->xa);
+ xa_unlock_irq(&pool->xa);
if (err)
goto err_free;
>
>> @@ -166,8 +168,10 @@ int __rxe_add_to_pool(struct rxe_pool *pool, struct rxe_pool_elem *elem)
>> elem->obj = (u8 *)elem - pool->elem_offset;
>> kref_init(&elem->ref_cnt);
>>
>> - err = xa_alloc_cyclic(&pool->xa, &elem->index, elem, pool->limit,
>> - &pool->next, GFP_KERNEL);
>> + xa_lock_irq(&pool->xa);
>> + err = __xa_alloc_cyclic(&pool->xa, &elem->index, elem, pool->limit,
>> + &pool->next, GFP_ATOMIC);
>> + xa_unlock_irq(&pool->xa);
>> if (err)
>> goto err_cnt;
> Still no, this does almost every allocation - only AH with the
> non-blocking flag set should use this path.
Yes. Got it.
In the following, xa_lock_irqsave/xa_unlock_irqrestore should be used.
int ib_send_cm_req(struct ib_cm_id *cm_id,
struct ib_cm_req_param *param)
{
...
spin_lock_irqsave(&cm_id_priv->lock, flags);
...
__rxe_add_to_pool
...
spin_unlock_irqrestore(&cm_id_priv->lock, flags);
So the diff is as below:
@@ -157,6 +157,7 @@ void *rxe_alloc(struct rxe_pool *pool)
int __rxe_add_to_pool(struct rxe_pool *pool, struct rxe_pool_elem *elem)
{
int err;
+ unsigned long flags;
if (WARN_ON(pool->flags & RXE_POOL_ALLOC))
return -EINVAL;
@@ -168,10 +169,10 @@ int __rxe_add_to_pool(struct rxe_pool *pool,
struct rxe_pool_elem *elem)
elem->obj = (u8 *)elem - pool->elem_offset;
kref_init(&elem->ref_cnt);
- xa_lock_irq(&pool->xa);
+ xa_lock_irqsave(&pool->xa, flags);
err = __xa_alloc_cyclic(&pool->xa, &elem->index, elem, pool->limit,
&pool->next, GFP_ATOMIC);
- xa_unlock_irq(&pool->xa);
+ xa_unlock_irqrestore(&pool->xa, flags);
if (err)
goto err_cnt;
Please comment. Thanks a lot.
Zhu Yanjun
>
> Jason
^ permalink raw reply [flat|nested] 10+ messages in thread
* Re: [PATCHv3 1/1] RDMA/rxe: Fix a dead lock problem
2022-04-13 14:50 ` Yanjun Zhu
@ 2022-04-14 13:01 ` Yanjun Zhu
2022-04-14 13:52 ` Jason Gunthorpe
0 siblings, 1 reply; 10+ messages in thread
From: Yanjun Zhu @ 2022-04-14 13:01 UTC (permalink / raw)
To: Jason Gunthorpe; +Cc: leon, linux-rdma, Yi Zhang
在 2022/4/13 22:50, Yanjun Zhu 写道:
>
> 在 2022/4/13 8:45, Jason Gunthorpe 写道:
>> On Wed, Apr 13, 2022 at 03:42:08AM -0400, yanjun.zhu@linux.dev wrote:
>>> From: Zhu Yanjun <yanjun.zhu@linux.dev>
>>>
>>> This is a dead lock problem.
>>> The xa_lock first is acquired in this:
>>>
>>> {SOFTIRQ-ON-W} state was registered at:
>>>
>>> lock_acquire+0x1d2/0x5a0
>>> _raw_spin_lock+0x33/0x80
>>> __rxe_add_to_pool+0x183/0x230 [rdma_rxe]
>>> __ib_alloc_pd+0xf9/0x550 [ib_core]
>>> ib_mad_init_device+0x2d9/0xd20 [ib_core]
>>> add_client_context+0x2fa/0x450 [ib_core]
>>> enable_device_and_get+0x1b7/0x350 [ib_core]
>>> ib_register_device+0x757/0xaf0 [ib_core]
>>> rxe_register_device+0x2eb/0x390 [rdma_rxe]
>>> rxe_net_add+0x83/0xc0 [rdma_rxe]
>>> rxe_newlink+0x76/0x90 [rdma_rxe]
>>> nldev_newlink+0x245/0x3e0 [ib_core]
>>> rdma_nl_rcv_msg+0x2d4/0x790 [ib_core]
>>> rdma_nl_rcv+0x1ca/0x3f0 [ib_core]
>>> netlink_unicast+0x43b/0x640
>>> netlink_sendmsg+0x7eb/0xc40
>>> sock_sendmsg+0xe0/0x110
>>> __sys_sendto+0x1d7/0x2b0
>>> __x64_sys_sendto+0xdd/0x1b0
>>> do_syscall_64+0x37/0x80
>>> entry_SYSCALL_64_after_hwframe+0x44/0xae
>>>
>>> Then xa_lock is acquired in this:
>>>
>>> {IN-SOFTIRQ-W}:
>>>
>>> Call Trace:
>>> <TASK>
>>> dump_stack_lvl+0x44/0x57
>>> mark_lock.part.52.cold.79+0x3c/0x46
>>> __lock_acquire+0x1565/0x34a0
>>> lock_acquire+0x1d2/0x5a0
>>> _raw_spin_lock_irqsave+0x42/0x90
>>> rxe_pool_get_index+0x72/0x1d0 [rdma_rxe]
>>> rxe_get_av+0x168/0x2a0 [rdma_rxe]
>>> rxe_requester+0x75b/0x4a90 [rdma_rxe]
>>> rxe_do_task+0x134/0x230 [rdma_rxe]
>>> tasklet_action_common.isra.12+0x1f7/0x2d0
>>> __do_softirq+0x1ea/0xa4c
>>> run_ksoftirqd+0x32/0x60
>>> smpboot_thread_fn+0x503/0x860
>>> kthread+0x29b/0x340
>>> ret_from_fork+0x1f/0x30
>>> </TASK>
>>>
>>> From the above, in the function __rxe_add_to_pool,
>>> xa_lock is acquired. Then the function __rxe_add_to_pool
>>> is interrupted by softirq. The function
>>> rxe_pool_get_index will also acquire xa_lock.
>>>
>>> Finally, the dead lock appears.
>>>
>>> [ 296.806097] CPU0
>>> [ 296.808550] ----
>>> [ 296.811003] lock(&xa->xa_lock#15); <----- __rxe_add_to_pool
>>> [ 296.814583] <Interrupt>
>>> [ 296.817209] lock(&xa->xa_lock#15); <---- rxe_pool_get_index
>>> [ 296.820961]
>>> *** DEADLOCK ***
>>>
>>> Fixes: 3225717f6dfa ("RDMA/rxe: Replace red-black trees by carrays")
>>> Reported-and-tested-by: Yi Zhang <yi.zhang@redhat.com>
>>> Signed-off-by: Zhu Yanjun <yanjun.zhu@linux.dev>
>>> ---
>>> V2->V3: __rxe_add_to_pool is between spin_lock and spin_unlock, so
>>> GFP_ATOMIC is used in __rxe_add_to_pool.
>>> V1->V2: Replace GFP_KERNEL with GFP_ATOMIC
>>> ---
>>> drivers/infiniband/sw/rxe/rxe_pool.c | 17 ++++++++++++-----
>>> 1 file changed, 12 insertions(+), 5 deletions(-)
>>>
>>> diff --git a/drivers/infiniband/sw/rxe/rxe_pool.c
>>> b/drivers/infiniband/sw/rxe/rxe_pool.c
>>> index 87066d04ed18..b9b147df4020 100644
>>> --- a/drivers/infiniband/sw/rxe/rxe_pool.c
>>> +++ b/drivers/infiniband/sw/rxe/rxe_pool.c
>>> @@ -138,8 +138,10 @@ void *rxe_alloc(struct rxe_pool *pool)
>>> elem->obj = obj;
>>> kref_init(&elem->ref_cnt);
>>> - err = xa_alloc_cyclic(&pool->xa, &elem->index, elem, pool->limit,
>>> - &pool->next, GFP_KERNEL);
>>> + xa_lock_bh(&pool->xa);
>>> + err = __xa_alloc_cyclic(&pool->xa, &elem->index, elem, pool->limit,
>>> + &pool->next, GFP_KERNEL);
>>> + xa_unlock_bh(&pool->xa);
>>> if (err)
>>> goto err_free;
>> You can't mix bh and not bh locks, either this is an irq spinlock or
>> it is bh spinlock, pick one and also ensure that the proper xa_init
>> flag is set.
>
> Got it. I should use irq spinlock. So XA_FLAGS_LOCK_IRQ is added in
> xa_init flags.
>
> So the code should be:
>
> @@ -106,7 +106,7 @@ void rxe_pool_init(struct rxe_dev *rxe, struct
> rxe_pool *pool,
>
> atomic_set(&pool->num_elem, 0);
>
> - xa_init_flags(&pool->xa, XA_FLAGS_ALLOC);
> + xa_init_flags(&pool->xa, XA_FLAGS_LOCK_IRQ | XA_FLAGS_ALLOC);
> pool->limit.min = info->min_index;
> pool->limit.max = info->max_index;
> }
> @@ -138,10 +138,10 @@ void *rxe_alloc(struct rxe_pool *pool)
> elem->obj = obj;
> kref_init(&elem->ref_cnt);
>
> - xa_lock_bh(&pool->xa);
> + xa_lock_irq(&pool->xa);
> err = __xa_alloc_cyclic(&pool->xa, &elem->index, elem,
> pool->limit,
> &pool->next, GFP_KERNEL);
> - xa_unlock_bh(&pool->xa);
> + xa_unlock_irq(&pool->xa);
> if (err)
> goto err_free;
>
>>
>>> @@ -166,8 +168,10 @@ int __rxe_add_to_pool(struct rxe_pool *pool,
>>> struct rxe_pool_elem *elem)
>>> elem->obj = (u8 *)elem - pool->elem_offset;
>>> kref_init(&elem->ref_cnt);
>>> - err = xa_alloc_cyclic(&pool->xa, &elem->index, elem, pool->limit,
>>> - &pool->next, GFP_KERNEL);
>>> + xa_lock_irq(&pool->xa);
>>> + err = __xa_alloc_cyclic(&pool->xa, &elem->index, elem, pool->limit,
>>> + &pool->next, GFP_ATOMIC);
>>> + xa_unlock_irq(&pool->xa);
>>> if (err)
>>> goto err_cnt;
>> Still no, this does almost every allocation - only AH with the
>> non-blocking flag set should use this path.
>
> Yes. Got it.
>
> In the following, xa_lock_irqsave/xa_unlock_irqrestore should be used.
>
> int ib_send_cm_req(struct ib_cm_id *cm_id,
>
> struct ib_cm_req_param *param)
> {
>
> ...
>
> spin_lock_irqsave(&cm_id_priv->lock, flags);
>
> ...
>
> __rxe_add_to_pool
>
> ...
>
> spin_unlock_irqrestore(&cm_id_priv->lock, flags);
Hi,Jason
To the function ib_send_cm_req, the call chain is as below.
ib_send_cm_req --> cm_alloc_priv_msg --> cm_alloc_msg --> rdma_create_ah
--> _rdma_create_ah --> rxe_create_ah --> rxe_av_chk_attr
-->__rxe_add_to_pool
As such, xa_lock_irqsave/irqrestore is selected.
Zhu Yanjun
>
>
> So the diff is as below:
>
> @@ -157,6 +157,7 @@ void *rxe_alloc(struct rxe_pool *pool)
> int __rxe_add_to_pool(struct rxe_pool *pool, struct rxe_pool_elem *elem)
> {
> int err;
> + unsigned long flags;
>
> if (WARN_ON(pool->flags & RXE_POOL_ALLOC))
> return -EINVAL;
> @@ -168,10 +169,10 @@ int __rxe_add_to_pool(struct rxe_pool *pool,
> struct rxe_pool_elem *elem)
> elem->obj = (u8 *)elem - pool->elem_offset;
> kref_init(&elem->ref_cnt);
>
> - xa_lock_irq(&pool->xa);
> + xa_lock_irqsave(&pool->xa, flags);
> err = __xa_alloc_cyclic(&pool->xa, &elem->index, elem,
> pool->limit,
> &pool->next, GFP_ATOMIC);
> - xa_unlock_irq(&pool->xa);
> + xa_unlock_irqrestore(&pool->xa, flags);
> if (err)
> goto err_cnt;
>
> Please comment. Thanks a lot.
>
> Zhu Yanjun
>
>>
>> Jason
^ permalink raw reply [flat|nested] 10+ messages in thread
* Re: [PATCHv3 1/1] RDMA/rxe: Fix a dead lock problem
2022-04-14 13:01 ` Yanjun Zhu
@ 2022-04-14 13:52 ` Jason Gunthorpe
2022-04-14 15:13 ` Yanjun Zhu
0 siblings, 1 reply; 10+ messages in thread
From: Jason Gunthorpe @ 2022-04-14 13:52 UTC (permalink / raw)
To: Yanjun Zhu; +Cc: leon, linux-rdma, Yi Zhang
On Thu, Apr 14, 2022 at 09:01:29PM +0800, Yanjun Zhu wrote:
> > > Still no, this does almost every allocation - only AH with the
> > > non-blocking flag set should use this path.
> To the function ib_send_cm_req, the call chain is as below.
>
> ib_send_cm_req --> cm_alloc_priv_msg --> cm_alloc_msg --> rdma_create_ah -->
> _rdma_create_ah --> rxe_create_ah --> rxe_av_chk_attr -->__rxe_add_to_pool
>
> As such, xa_lock_irqsave/irqrestore is selected.
As I keep saying, only the rxe_create_ah() with the non-blocking flag
set should use the GFP_ATOMIC. All other paths must use GFP_KERNEL.
Jason
^ permalink raw reply [flat|nested] 10+ messages in thread
* Re: [PATCHv3 1/1] RDMA/rxe: Fix a dead lock problem
2022-04-14 13:52 ` Jason Gunthorpe
@ 2022-04-14 15:13 ` Yanjun Zhu
2022-04-14 16:12 ` Leon Romanovsky
2022-04-14 16:18 ` Jason Gunthorpe
0 siblings, 2 replies; 10+ messages in thread
From: Yanjun Zhu @ 2022-04-14 15:13 UTC (permalink / raw)
To: Jason Gunthorpe, Yanjun Zhu; +Cc: leon, linux-rdma, Yi Zhang
在 2022/4/14 21:52, Jason Gunthorpe 写道:
> On Thu, Apr 14, 2022 at 09:01:29PM +0800, Yanjun Zhu wrote:
>
>>>> Still no, this does almost every allocation - only AH with the
>>>> non-blocking flag set should use this path.
>
>> To the function ib_send_cm_req, the call chain is as below.
>>
>> ib_send_cm_req --> cm_alloc_priv_msg --> cm_alloc_msg --> rdma_create_ah -->
>> _rdma_create_ah --> rxe_create_ah --> rxe_av_chk_attr -->__rxe_add_to_pool
>>
>> As such, xa_lock_irqsave/irqrestore is selected.
>
> As I keep saying, only the rxe_create_ah() with the non-blocking flag
> set should use the GFP_ATOMIC. All other paths must use GFP_KERNEL.
>
Got it. The GFP_ATOMIC/GFP_KERNEL are used in different paths.
rxe_create_ah will use GFP_ATOMIC and others will use GFP_KERNEL.
So the codes should be as below:
-int __rxe_add_to_pool(struct rxe_pool *pool, struct rxe_pool_elem *elem)
+int __rxe_add_to_pool(struct rxe_pool *pool, struct rxe_pool_elem
*elem, gfp_t gfp)
{
int err;
+ unsigned long flags;
if (WARN_ON(pool->flags & RXE_POOL_ALLOC))
return -EINVAL;
@@ -168,10 +170,17 @@ int __rxe_add_to_pool(struct rxe_pool *pool,
struct rxe_pool_elem *elem)
elem->obj = (u8 *)elem - pool->elem_offset;
kref_init(&elem->ref_cnt);
- xa_lock_irq(&pool->xa);
- err = __xa_alloc_cyclic(&pool->xa, &elem->index, elem, pool->limit,
- &pool->next, GFP_ATOMIC);
- xa_unlock_irq(&pool->xa);
+ if (gfp == GFP_ATOMIC) { /* for rxe_create_ah */
+ xa_lock_irqsave(&pool->xa, flags);
+ err = __xa_alloc_cyclic(&pool->xa, &elem->index, elem,
pool->limit,
+ &pool->next, GFP_ATOMIC);
+ xa_unlock_irqrestore(&pool->xa, flags);
+ } else if (gfp == GFP_KERNEL) {
+ xa_lock_irq(&pool->xa);
+ err = __xa_alloc_cyclic(&pool->xa, &elem->index, elem,
pool->limit,
+ &pool->next, GFP_KERNEL);
+ xa_unlock_irq(&pool->xa);
+ }
if (err)
goto err_cnt;
Please commnet.
Zhu Yanjun
> Jason
^ permalink raw reply [flat|nested] 10+ messages in thread
* Re: [PATCHv3 1/1] RDMA/rxe: Fix a dead lock problem
2022-04-14 15:13 ` Yanjun Zhu
@ 2022-04-14 16:12 ` Leon Romanovsky
2022-04-15 2:35 ` Yanjun Zhu
2022-04-14 16:18 ` Jason Gunthorpe
1 sibling, 1 reply; 10+ messages in thread
From: Leon Romanovsky @ 2022-04-14 16:12 UTC (permalink / raw)
To: Yanjun Zhu; +Cc: Jason Gunthorpe, linux-rdma, Yi Zhang
On Thu, Apr 14, 2022 at 11:13:57PM +0800, Yanjun Zhu wrote:
> 在 2022/4/14 21:52, Jason Gunthorpe 写道:
> > On Thu, Apr 14, 2022 at 09:01:29PM +0800, Yanjun Zhu wrote:
> >
> > > > > Still no, this does almost every allocation - only AH with the
> > > > > non-blocking flag set should use this path.
> >
> > > To the function ib_send_cm_req, the call chain is as below.
> > >
> > > ib_send_cm_req --> cm_alloc_priv_msg --> cm_alloc_msg --> rdma_create_ah -->
> > > _rdma_create_ah --> rxe_create_ah --> rxe_av_chk_attr -->__rxe_add_to_pool
> > >
> > > As such, xa_lock_irqsave/irqrestore is selected.
> >
> > As I keep saying, only the rxe_create_ah() with the non-blocking flag
> > set should use the GFP_ATOMIC. All other paths must use GFP_KERNEL.
> >
>
> Got it. The GFP_ATOMIC/GFP_KERNEL are used in different paths.
> rxe_create_ah will use GFP_ATOMIC and others will use GFP_KERNEL.
> So the codes should be as below:
>
> -int __rxe_add_to_pool(struct rxe_pool *pool, struct rxe_pool_elem *elem)
> +int __rxe_add_to_pool(struct rxe_pool *pool, struct rxe_pool_elem *elem,
> gfp_t gfp)
> {
> int err;
> + unsigned long flags;
>
> if (WARN_ON(pool->flags & RXE_POOL_ALLOC))
> return -EINVAL;
> @@ -168,10 +170,17 @@ int __rxe_add_to_pool(struct rxe_pool *pool, struct
> rxe_pool_elem *elem)
> elem->obj = (u8 *)elem - pool->elem_offset;
> kref_init(&elem->ref_cnt);
>
> - xa_lock_irq(&pool->xa);
> - err = __xa_alloc_cyclic(&pool->xa, &elem->index, elem, pool->limit,
> - &pool->next, GFP_ATOMIC);
> - xa_unlock_irq(&pool->xa);
> + if (gfp == GFP_ATOMIC) { /* for rxe_create_ah */
gfp is bitfield.
"gfp == GFP_ATOMIC" -> "gfp & GFP_ATOMIC"
Thanks
^ permalink raw reply [flat|nested] 10+ messages in thread
* Re: [PATCHv3 1/1] RDMA/rxe: Fix a dead lock problem
2022-04-14 15:13 ` Yanjun Zhu
2022-04-14 16:12 ` Leon Romanovsky
@ 2022-04-14 16:18 ` Jason Gunthorpe
2022-04-15 2:36 ` Yanjun Zhu
1 sibling, 1 reply; 10+ messages in thread
From: Jason Gunthorpe @ 2022-04-14 16:18 UTC (permalink / raw)
To: Yanjun Zhu; +Cc: leon, linux-rdma, Yi Zhang
On Thu, Apr 14, 2022 at 11:13:57PM +0800, Yanjun Zhu wrote:
> 在 2022/4/14 21:52, Jason Gunthorpe 写道:
> > On Thu, Apr 14, 2022 at 09:01:29PM +0800, Yanjun Zhu wrote:
> >
> > > > > Still no, this does almost every allocation - only AH with the
> > > > > non-blocking flag set should use this path.
> >
> > > To the function ib_send_cm_req, the call chain is as below.
> > >
> > > ib_send_cm_req --> cm_alloc_priv_msg --> cm_alloc_msg --> rdma_create_ah -->
> > > _rdma_create_ah --> rxe_create_ah --> rxe_av_chk_attr -->__rxe_add_to_pool
> > >
> > > As such, xa_lock_irqsave/irqrestore is selected.
> >
> > As I keep saying, only the rxe_create_ah() with the non-blocking flag
> > set should use the GFP_ATOMIC. All other paths must use GFP_KERNEL.
> >
>
> Got it. The GFP_ATOMIC/GFP_KERNEL are used in different paths.
> rxe_create_ah will use GFP_ATOMIC and others will use GFP_KERNEL.
> So the codes should be as below:
This seems better
Jason
^ permalink raw reply [flat|nested] 10+ messages in thread
* Re: [PATCHv3 1/1] RDMA/rxe: Fix a dead lock problem
2022-04-14 16:12 ` Leon Romanovsky
@ 2022-04-15 2:35 ` Yanjun Zhu
0 siblings, 0 replies; 10+ messages in thread
From: Yanjun Zhu @ 2022-04-15 2:35 UTC (permalink / raw)
To: Leon Romanovsky, Yanjun Zhu; +Cc: Jason Gunthorpe, linux-rdma, Yi Zhang
在 2022/4/15 0:12, Leon Romanovsky 写道:
> On Thu, Apr 14, 2022 at 11:13:57PM +0800, Yanjun Zhu wrote:
>> 在 2022/4/14 21:52, Jason Gunthorpe 写道:
>>> On Thu, Apr 14, 2022 at 09:01:29PM +0800, Yanjun Zhu wrote:
>>>
>>>>>> Still no, this does almost every allocation - only AH with the
>>>>>> non-blocking flag set should use this path.
>>>
>>>> To the function ib_send_cm_req, the call chain is as below.
>>>>
>>>> ib_send_cm_req --> cm_alloc_priv_msg --> cm_alloc_msg --> rdma_create_ah -->
>>>> _rdma_create_ah --> rxe_create_ah --> rxe_av_chk_attr -->__rxe_add_to_pool
>>>>
>>>> As such, xa_lock_irqsave/irqrestore is selected.
>>>
>>> As I keep saying, only the rxe_create_ah() with the non-blocking flag
>>> set should use the GFP_ATOMIC. All other paths must use GFP_KERNEL.
>>>
>>
>> Got it. The GFP_ATOMIC/GFP_KERNEL are used in different paths.
>> rxe_create_ah will use GFP_ATOMIC and others will use GFP_KERNEL.
>> So the codes should be as below:
>>
>> -int __rxe_add_to_pool(struct rxe_pool *pool, struct rxe_pool_elem *elem)
>> +int __rxe_add_to_pool(struct rxe_pool *pool, struct rxe_pool_elem *elem,
>> gfp_t gfp)
>> {
>> int err;
>> + unsigned long flags;
>>
>> if (WARN_ON(pool->flags & RXE_POOL_ALLOC))
>> return -EINVAL;
>> @@ -168,10 +170,17 @@ int __rxe_add_to_pool(struct rxe_pool *pool, struct
>> rxe_pool_elem *elem)
>> elem->obj = (u8 *)elem - pool->elem_offset;
>> kref_init(&elem->ref_cnt);
>>
>> - xa_lock_irq(&pool->xa);
>> - err = __xa_alloc_cyclic(&pool->xa, &elem->index, elem, pool->limit,
>> - &pool->next, GFP_ATOMIC);
>> - xa_unlock_irq(&pool->xa);
>> + if (gfp == GFP_ATOMIC) { /* for rxe_create_ah */
>
> gfp is bitfield.
> "gfp == GFP_ATOMIC" -> "gfp & GFP_ATOMIC"
Got it. Thanks
Zhu Yanjun
>
> Thanks
^ permalink raw reply [flat|nested] 10+ messages in thread
* Re: [PATCHv3 1/1] RDMA/rxe: Fix a dead lock problem
2022-04-14 16:18 ` Jason Gunthorpe
@ 2022-04-15 2:36 ` Yanjun Zhu
0 siblings, 0 replies; 10+ messages in thread
From: Yanjun Zhu @ 2022-04-15 2:36 UTC (permalink / raw)
To: Jason Gunthorpe, Yanjun Zhu; +Cc: leon, linux-rdma, Yi Zhang
在 2022/4/15 0:18, Jason Gunthorpe 写道:
> On Thu, Apr 14, 2022 at 11:13:57PM +0800, Yanjun Zhu wrote:
>> 在 2022/4/14 21:52, Jason Gunthorpe 写道:
>>> On Thu, Apr 14, 2022 at 09:01:29PM +0800, Yanjun Zhu wrote:
>>>
>>>>>> Still no, this does almost every allocation - only AH with the
>>>>>> non-blocking flag set should use this path.
>>>
>>>> To the function ib_send_cm_req, the call chain is as below.
>>>>
>>>> ib_send_cm_req --> cm_alloc_priv_msg --> cm_alloc_msg --> rdma_create_ah -->
>>>> _rdma_create_ah --> rxe_create_ah --> rxe_av_chk_attr -->__rxe_add_to_pool
>>>>
>>>> As such, xa_lock_irqsave/irqrestore is selected.
>>>
>>> As I keep saying, only the rxe_create_ah() with the non-blocking flag
>>> set should use the GFP_ATOMIC. All other paths must use GFP_KERNEL.
>>>
>>
>> Got it. The GFP_ATOMIC/GFP_KERNEL are used in different paths.
>> rxe_create_ah will use GFP_ATOMIC and others will use GFP_KERNEL.
>> So the codes should be as below:
>
> This seems better
Thanks. I will send the latest patch very soon.
Zhu Yanjun
>
> Jason
^ permalink raw reply [flat|nested] 10+ messages in thread
end of thread, other threads:[~2022-04-15 2:36 UTC | newest]
Thread overview: 10+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2022-04-13 7:42 [PATCHv3 1/1] RDMA/rxe: Fix a dead lock problem yanjun.zhu
2022-04-13 0:45 ` Jason Gunthorpe
2022-04-13 14:50 ` Yanjun Zhu
2022-04-14 13:01 ` Yanjun Zhu
2022-04-14 13:52 ` Jason Gunthorpe
2022-04-14 15:13 ` Yanjun Zhu
2022-04-14 16:12 ` Leon Romanovsky
2022-04-15 2:35 ` Yanjun Zhu
2022-04-14 16:18 ` Jason Gunthorpe
2022-04-15 2:36 ` Yanjun Zhu
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.