I am working on v2 while you are point out this. Thanks.
On 2017-07-19 10:33 PM, zhoucm1 wrote:
>
>
> On 2017å¹´07æ??20æ?¥ 10:27, Alex Xie wrote:
>> In RCU read-side critical sections, blocking or sleeping is prohibited.
>>
>> Reported by: Dave Airlie
>>
>> [ 141.965723] =============================
>> [ 141.965724] WARNING: suspicious RCU usage
>> [ 141.965726] 4.12.0-rc7 #221 Not tainted
>> [ 141.965727] -----------------------------
>> [ 141.965728]
>> /home/airlied/devel/kernel/linux-2.6/include/linux/rcupdate.h:531
>> Illegal context switch in RCU read-side critical section!
>> [ 141.965730]
>> other info that might help us debug this:
>>
>> [ 141.965731]
>> rcu_scheduler_active = 2, debug_locks = 0
>> [ 141.965732] 1 lock held by amdgpu_cs:0/1332:
>> [ 141.965733] #0: (rcu_read_lock){......}, at: [<ffffffffa01a0d07>]
>> amdgpu_bo_list_get+0x0/0x109 [amdgpu]
>> [ 141.965774]
>> stack backtrace:
>> [ 141.965776] CPU: 6 PID: 1332 Comm: amdgpu_cs:0 Not tainted
>> 4.12.0-rc7 #221
>> [ 141.965777] Hardware name: To be filled by O.E.M. To be filled by
>> O.E.M./M5A97 R2.0, BIOS 2603 06/26/2015
>> [ 141.965778] Call Trace:
>> [ 141.965782] dump_stack+0x68/0x92
>> [ 141.965785] lockdep_rcu_suspicious+0xf7/0x100
>> [ 141.965788] ___might_sleep+0x56/0x1fc
>> [ 141.965790] __might_sleep+0x68/0x6f
>> [ 141.965793] __mutex_lock+0x4e/0x7b5
>> [ 141.965817] ? amdgpu_bo_list_get+0xa4/0x109 [amdgpu]
>> [ 141.965820] ? lock_acquire+0x125/0x1b9
>> [ 141.965844] ? amdgpu_bo_list_set+0x464/0x464 [amdgpu]
>> [ 141.965846] mutex_lock_nested+0x16/0x18
>> [ 141.965848] ? mutex_lock_nested+0x16/0x18
>> [ 141.965872] amdgpu_bo_list_get+0xa4/0x109 [amdgpu]
>> [ 141.965895] amdgpu_cs_ioctl+0x4a0/0x17dd [amdgpu]
>> [ 141.965898] ? radix_tree_node_alloc.constprop.11+0x77/0xab
>> [ 141.965916] drm_ioctl+0x264/0x393 [drm]
>> [ 141.965939] ? amdgpu_cs_find_mapping+0x83/0x83 [amdgpu]
>> [ 141.965942] ? trace_hardirqs_on_caller+0x16a/0x186
>>
>> Signed-off-by: Alex Xie <AlexBin.Xie at amd.com>
>> ---
>> drivers/gpu/drm/amd/amdgpu/amdgpu_bo_list.c | 9 ++++++---
>> 1 file changed, 6 insertions(+), 3 deletions(-)
>>
>> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_bo_list.c
>> b/drivers/gpu/drm/amd/amdgpu/amdgpu_bo_list.c
>> index dc87962..565ca90 100644
>> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_bo_list.c
>> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_bo_list.c
>> @@ -198,12 +198,15 @@ amdgpu_bo_list_get(struct amdgpu_fpriv *fpriv,
>> int id)
>> result = idr_find(&fpriv->bo_list_handles, id);
>> if (result) {
>> - if (kref_get_unless_zero(&result->refcount))
>> + if (kref_get_unless_zero(&result->refcount)) {
>> + rcu_read_unlock();
>> mutex_lock(&result->lock);
>> - else
>> + }
>> + else {
>> + rcu_read_unlock();
>> result = NULL;
>> + }
>> }
>> - rcu_read_unlock();
> how about result==NULL case? will lost rcu unlock, right?
>
> David Zhou
>> return result;
>> }
>
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