[PATCH v2] drm/amdkfd: reserve the BO before validating it
Felix Kuehling
felix.kuehling at amd.com
Fri Jan 26 19:21:48 UTC 2024
On 2024-01-25 20:59, Yu, Lang wrote:
> [AMD Official Use Only - General]
>
>> -----Original Message-----
>> From: Kuehling, Felix <Felix.Kuehling at amd.com>
>> Sent: Thursday, January 25, 2024 5:41 AM
>> To: Yu, Lang <Lang.Yu at amd.com>; amd-gfx at lists.freedesktop.org
>> Cc: Francis, David <David.Francis at amd.com>
>> Subject: Re: [PATCH v2] drm/amdkfd: reserve the BO before validating it
>>
>> On 2024-01-22 4:08, Lang Yu wrote:
>>> Fixes: 410f08516e0f ("drm/amdkfd: Move dma unmapping after TLB flush")
>>>
>>> v2:
>>> Avoid unmapping attachment twice when ERESTARTSYS.
>>>
>>> [ 41.708711] WARNING: CPU: 0 PID: 1463 at
>> drivers/gpu/drm/ttm/ttm_bo.c:846 ttm_bo_validate+0x146/0x1b0 [ttm]
>>> [ 41.708989] Call Trace:
>>> [ 41.708992] <TASK>
>>> [ 41.708996] ? show_regs+0x6c/0x80
>>> [ 41.709000] ? ttm_bo_validate+0x146/0x1b0 [ttm]
>>> [ 41.709008] ? __warn+0x93/0x190
>>> [ 41.709014] ? ttm_bo_validate+0x146/0x1b0 [ttm]
>>> [ 41.709024] ? report_bug+0x1f9/0x210
>>> [ 41.709035] ? handle_bug+0x46/0x80
>>> [ 41.709041] ? exc_invalid_op+0x1d/0x80
>>> [ 41.709048] ? asm_exc_invalid_op+0x1f/0x30
>>> [ 41.709057] ? amdgpu_amdkfd_gpuvm_dmaunmap_mem+0x2c/0x80
>> [amdgpu]
>>> [ 41.709185] ? ttm_bo_validate+0x146/0x1b0 [ttm]
>>> [ 41.709197] ? amdgpu_amdkfd_gpuvm_dmaunmap_mem+0x2c/0x80
>> [amdgpu]
>>> [ 41.709337] ? srso_alias_return_thunk+0x5/0x7f
>>> [ 41.709346] kfd_mem_dmaunmap_attachment+0x9e/0x1e0 [amdgpu]
>>> [ 41.709467] amdgpu_amdkfd_gpuvm_dmaunmap_mem+0x56/0x80
>> [amdgpu]
>>> [ 41.709586] kfd_ioctl_unmap_memory_from_gpu+0x1b7/0x300 [amdgpu]
>>> [ 41.709710] kfd_ioctl+0x1ec/0x650 [amdgpu]
>>> [ 41.709822] ? __pfx_kfd_ioctl_unmap_memory_from_gpu+0x10/0x10
>> [amdgpu]
>>> [ 41.709945] ? srso_alias_return_thunk+0x5/0x7f
>>> [ 41.709949] ? tomoyo_file_ioctl+0x20/0x30
>>> [ 41.709959] __x64_sys_ioctl+0x9c/0xd0
>>> [ 41.709967] do_syscall_64+0x3f/0x90
>>> [ 41.709973] entry_SYSCALL_64_after_hwframe+0x6e/0xd8
>>>
>>> Signed-off-by: Lang Yu <Lang.Yu at amd.com>
>>> ---
>>> drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd.h | 2 +-
>>> .../gpu/drm/amd/amdgpu/amdgpu_amdkfd_gpuvm.c | 28
>> +++++++++++++++++--
>>> drivers/gpu/drm/amd/amdkfd/kfd_chardev.c | 4 ++-
>>> 3 files changed, 29 insertions(+), 5 deletions(-)
>>>
>>> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd.h
>>> b/drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd.h
>>> index 584a0cea5572..41854417e487 100644
>>> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd.h
>>> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd.h
>>> @@ -311,7 +311,7 @@ int
>> amdgpu_amdkfd_gpuvm_map_memory_to_gpu(struct amdgpu_device *adev,
>>> struct kgd_mem *mem, void
>> *drm_priv);
>>> int amdgpu_amdkfd_gpuvm_unmap_memory_from_gpu(
>>> struct amdgpu_device *adev, struct kgd_mem *mem, void
>> *drm_priv);
>>> -void amdgpu_amdkfd_gpuvm_dmaunmap_mem(struct kgd_mem *mem, void
>>> *drm_priv);
>>> +int amdgpu_amdkfd_gpuvm_dmaunmap_mem(struct kgd_mem *mem, void
>>> +*drm_priv);
>>> int amdgpu_amdkfd_gpuvm_sync_memory(
>>> struct amdgpu_device *adev, struct kgd_mem *mem, bool intr);
>>> int amdgpu_amdkfd_gpuvm_map_gtt_bo_to_kernel(struct kgd_mem *mem,
>>> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd_gpuvm.c
>>> b/drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd_gpuvm.c
>>> index 6f3a4cb2a9ef..7a050d46fa4d 100644
>>> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd_gpuvm.c
>>> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd_gpuvm.c
>>> @@ -2088,21 +2088,43 @@ int
>> amdgpu_amdkfd_gpuvm_map_memory_to_gpu(
>>> return ret;
>>> }
>>>
>>> -void amdgpu_amdkfd_gpuvm_dmaunmap_mem(struct kgd_mem *mem, void
>>> *drm_priv)
>>> +int amdgpu_amdkfd_gpuvm_dmaunmap_mem(struct kgd_mem *mem, void
>>> +*drm_priv)
>>> {
>>> struct kfd_mem_attachment *entry;
>>> struct amdgpu_vm *vm;
>>> + bool reserved = false;
>>> + int ret = 0;
>>>
>>> vm = drm_priv_to_vm(drm_priv);
>>>
>>> mutex_lock(&mem->lock);
>>>
>>> list_for_each_entry(entry, &mem->attachments, list) {
>>> - if (entry->bo_va->base.vm == vm)
>>> - kfd_mem_dmaunmap_attachment(mem, entry);
>>> + if (entry->bo_va->base.vm != vm)
>>> + continue;
>>> + if (entry->type == KFD_MEM_ATT_SHARED ||
>>> + entry->type == KFD_MEM_ATT_DMABUF)
>>> + continue;
>>> + if (!entry->bo_va->base.bo->tbo.ttm->sg)
>>> + continue;
>> You're going to great lengths to avoid the reservation when it's not needed by
>> kfd_mem_dmaunmap_attachment. However, this feels a bit fragile. Any changes
>> in the kfd_mem_dmaunmap_* functions could break this.
>>
>>> +
>>> + if (!reserved) {
>>> + ret = amdgpu_bo_reserve(mem->bo, true);
>>> + if (ret)
>>> + goto out;
>>> + reserved = true;
>>> + }
>>> +
>>> + kfd_mem_dmaunmap_attachment(mem, entry);
>>> }
>>>
>>> + if (reserved)
>>> + amdgpu_bo_unreserve(mem->bo);
>>> +
>>> +out:
>>> mutex_unlock(&mem->lock);
>>> +
>>> + return ret;
>>> }
>>>
>>> int amdgpu_amdkfd_gpuvm_unmap_memory_from_gpu(
>>> diff --git a/drivers/gpu/drm/amd/amdkfd/kfd_chardev.c
>>> b/drivers/gpu/drm/amd/amdkfd/kfd_chardev.c
>>> index ce4c52ec34d8..80e90fdef291 100644
>>> --- a/drivers/gpu/drm/amd/amdkfd/kfd_chardev.c
>>> +++ b/drivers/gpu/drm/amd/amdkfd/kfd_chardev.c
>>> @@ -1442,7 +1442,9 @@ static int kfd_ioctl_unmap_memory_from_gpu(struct
>> file *filep,
>>> kfd_flush_tlb(peer_pdd, TLB_FLUSH_HEAVYWEIGHT);
>>>
>>> /* Remove dma mapping after tlb flush to avoid IO_PAGE_FAULT
>> */
>>> - amdgpu_amdkfd_gpuvm_dmaunmap_mem(mem, peer_pdd-
>>> drm_priv);
>>> + err = amdgpu_amdkfd_gpuvm_dmaunmap_mem(mem,
>> peer_pdd->drm_priv);
>>> + if (err)
>>> + goto sync_memory_failed;
>> This handles the case that the system call got interrupted. But you're not handling
>> the restart correctly. When the ioctl is restarted, you don't know how many
>> dmaunmaps are already done. So you'd need to make sure that repeating the
>> dmaunmap is safe in all cases. Or what David tried earlier, find a way to track the
>> unmapping so you only try to dmaunmap on GPUs where it's actually dmamapped.
> From previous discussion, no one likes add another variable to track the unmappings. So I'm avoiding adding another variable.
>
> Actually, all memory attachments use sg_table, ttm->sg is NULL? can be used as an indicator to see whether an attachment is already unmapped.
> That already unmapped will not be repeated.
I think that should work. I'd add the checks in kfd_mem_dmaunmap_userptr
and kfd_mem_dmaunmap_sg_bo, where we also set ttm->sg to NULL. In fact,
both those functions already have that check. So looks like it should
handle the the restart correctly with your patch.
Regards,
Felix
>
> Regards,
> Lang
>
>> Regards,
>> Felix
>>
>>
>>> }
>>>
>>> mutex_unlock(&p->mutex);
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