Sorry, resend patch, the one in previous email missed couple of lines
duo to copy/paste.
On 2019-11-01 3:45 p.m., Yang, Philip wrote:
>
>
> On 2019-11-01 1:42 p.m., Jason Gunthorpe wrote:
>> On Fri, Nov 01, 2019 at 03:59:26PM +0000, Yang, Philip wrote:
>>>> This test for range_blockable should be before mutex_lock, I can move
>>>> it up
>>>>
>>> yes, thanks.
>>
>> Okay, I wrote it like this:
>>
>> if (mmu_notifier_range_blockable(range))
>> mutex_lock(&adev->notifier_lock);
>> else if (!mutex_trylock(&adev->notifier_lock))
>> return false;
>>
>>>> Also, do you know if notifier_lock is held while calling
>>>> amdgpu_ttm_tt_get_user_pages_done()? Can we add a 'lock assert held'
>>>> to amdgpu_ttm_tt_get_user_pages_done()?
>>>
>>> gpu side hold notifier_lock but kfd side doesn't. kfd side doesn't check
>>> amdgpu_ttm_tt_get_user_pages_done/mmu_range_read_retry return value but
>>> check mem->invalid flag which is updated from invalidate callback. It
>>> takes more time to change, I will come to another patch to fix it later.
>>
>> Ah.. confusing, OK, I'll let you sort that
>>
>>>> However, this is all pre-existing bugs, so I'm OK go ahead with this
>>>> patch as modified. I advise AMD to make a followup patch ..
>>>>
>>> yes, I will.
>>
>> While you are here, this is also wrong:
>>
>> int amdgpu_ttm_tt_get_user_pages(struct amdgpu_bo *bo, struct page **pages)
>> {
>> down_read(&mm->mmap_sem);
>> r = hmm_range_fault(range, 0);
>> up_read(&mm->mmap_sem);
>> if (unlikely(r <= 0)) {
>> if ((r == 0 || r == -EBUSY) && !time_after(jiffies, timeout))
>> goto retry;
>> goto out_free_pfns;
>> }
>>
>> for (i = 0; i < ttm->num_pages; i++) {
>> pages[i] = hmm_device_entry_to_page(range, range->pfns[i]);
>>
>> It is not allowed to read the results of hmm_range_fault() outside
>> locking, and in particular, we can't convert to a struct page.
>>
>> This must be done inside the notifier_lock, after checking
>> mmu_range_read_retry(), all handling of the struct page must be
>> structured like that.
>>
> Below change will fix this, then driver will call mmu_range_read_retry
> second time using same range->notifier_seq to check if range is
> invalidated inside amdgpu_cs_submit, this looks ok for me.
>
@@ -797,6 +797,7 @@ static const uint64_t
hmm_range_values[HMM_PFN_VALUE_MAX] = {
*/
int amdgpu_ttm_tt_get_user_pages(struct amdgpu_bo *bo, struct page
**pages)
{
+ struct amdgpu_device *adev = amdgpu_ttm_adev(bo->tbo.bdev);
struct ttm_tt *ttm = bo->tbo.ttm;
struct amdgpu_ttm_tt *gtt = (void *)ttm;
unsigned long start = gtt->userptr;
@@ -868,6 +869,13 @@ int amdgpu_ttm_tt_get_user_pages(struct amdgpu_bo
*bo, struct page **pages)
goto out_free_pfns;
}
+ mutex_lock(&adev->notifier_lock);
+
+ if (mmu_range_read_retry(&bo->notifier, range->notifier_seq)) {
+ mutex_unlock(&adev->notifier_lock);
+ goto retry;
+ }
+
for (i = 0; i < ttm->num_pages; i++) {
pages[i] = hmm_device_entry_to_page(range, range->pfns[i]);
if (unlikely(!pages[i])) {
@@ -875,10 +883,12 @@ int amdgpu_ttm_tt_get_user_pages(struct amdgpu_bo
*bo, struct page **pages)
i, range->pfns[i]);
r = -ENOMEM;
+ mutex_unlock(&adev->notifier_lock);
goto out_free_pfns;
}
}
+ mutex_unlock(&adev->notifier_lock);
gtt->range = range;
mmput(mm);
>
> Philip
>
>>>>> @@ -997,10 +1004,18 @@ static void amdgpu_ttm_tt_unpin_userptr(struct ttm_tt *ttm)
>>>>> sg_free_table(ttm->sg);
>>>>>
>>>>> #if IS_ENABLED(CONFIG_DRM_AMDGPU_USERPTR)
>>>>> - if (gtt->range &&
>>>>> - ttm->pages[0] == hmm_device_entry_to_page(gtt->range,
>>>>> - gtt->range->pfns[0]))
>>>>> - WARN_ONCE(1, "Missing get_user_page_done\n");
>>>>> + if (gtt->range) {
>>>>> + unsigned long i;
>>>>> +
>>>>> + for (i = 0; i < ttm->num_pages; i++) {
>>>>> + if (ttm->pages[i] !=
>>>>> + hmm_device_entry_to_page(gtt->range,
>>>>> + gtt->range->pfns[i]))
>>>>> + break;
>>>>> + }
>>>>> +
>>>>> + WARN((i == ttm->num_pages), "Missing get_user_page_done\n");
>>>>> + }
>>>>
>>>> Is this related/necessary? I can put it in another patch if it is just
>>>> debugging improvement? Please advise
>>>>
>>> I see this WARN backtrace now, but I didn't see it before. This is
>>> somehow related.
>>
>> Hm, might be instructive to learn what is going on..
>>
>> Thanks,
>> Jason
>>
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