On 10/13/26 14:11, Lizhi Hou wrote:
>
> On 10/12/26 21:38, Matthew Brost wrote:
>> On Mon, Oct 12, 2026 at 09:10:15PM -0700, Max Zhen wrote:
>>>
>>> On 10/12/2026 Mon 13:31, Lizhi Hou wrote:
>>>> Two hardware contexts can submit jobs that use the same GEM object while
>>>> a user mapping is invalid. aie2_cmd_submit() drops the reservation and
>>>> notifier_lock before aie2_populate_range(), and that function takes a
>>>> reference on the first invalid umap without clearing invalid until the
>>>> fault returns. Both submissions then call
>>>> hmm_range_fault_unlocked_timeout() on the same struct hmm_range. That
>>>> structure is not safe for concurrent callers. The calls write
>>>> notifier_seq and hmm_pfns[] at the same time, so mmu_interval_read_retry()
>>>> can see the other call's sequence, miss an invalidation, and clear
>>>> invalid. The job is then pushed while the pages may already be gone.
>>>> Give each umap its own mutex and hold it from the fault through the retry
>>>> check and the store that clears invalid. notifier_lock is dropped before
>>>> this mutex is taken, and the fault drops mmap_lock before notifier_lock
>>>> is taken again.
>>>>
>>>> Fixes: aac243092b70 ("accel/amdxdna: Add command execution")
>>>> Signed-off-by: Lizhi Hou <[email protected]>
>>> Reviewed-by: Max Zhen <[email protected]>
>> I was browsing dri-devel and this hmm interaction annoyed me enough to
>> ask my AI to fix this and converge properly on a DRM framework:
>>
>> https://gitlab.freedesktop.org/mbrost/xe-kernel-driver-svn-perf-6-15-2025/-/commits/local_dev/amd_hmm_cleanup
>
> The patch looks clean. I pull it on top of latest drm-misc-next and run some
> regression tests. It works fine too. :)
>
Sure, I will wait for this fix merged then rebase my next patch on top of this
fix.
/David
> Lizhi
>
>>
>> Improper HMM or abuse affects the entire kernel, hence we should
>> converge.
>>
>> Please consider the AI suggestions (last 3 patches) instead of open
>> coding this.
>>
>> Matt
>>
>>>> ---
>>>> drivers/accel/amdxdna/aie2_ctx.c | 7 ++++++-
>>>> drivers/accel/amdxdna/amdxdna_gem.c | 2 ++
>>>> drivers/accel/amdxdna/amdxdna_gem.h | 1 +
>>>> 3 files changed, 9 insertions(+), 1 deletion(-)
>>>>
>>>> diff --git a/drivers/accel/amdxdna/aie2_ctx.c
>>>> b/drivers/accel/amdxdna/aie2_ctx.c
>>>> index d927c8c9d557..4db67a789c34 100644
>>>> --- a/drivers/accel/amdxdna/aie2_ctx.c
>>>> +++ b/drivers/accel/amdxdna/aie2_ctx.c
>>>> @@ -1155,19 +1155,24 @@ static int aie2_populate_range(struct
>>>> amdxdna_gem_obj *abo)
>>>> return -EFAULT;
>>>> }
>>>> + mutex_lock(&mapp->lock);
>>>> ret = hmm_range_fault_unlocked_timeout(&mapp->range, timeout);
>>>> - if (ret)
>>>> + if (ret) {
>>>> + mutex_unlock(&mapp->lock);
>>>> goto put_mm;
>>>> + }
>>>> down_write(&xdna->notifier_lock);
>>>> if (mmu_interval_read_retry(&mapp->notifier,
>>>> mapp->range.notifier_seq)) {
>>>> up_write(&xdna->notifier_lock);
>>>> + mutex_unlock(&mapp->lock);
>>>> amdxdna_umap_put(mapp);
>>>> mmput(mm);
>>>> goto again;
>>>> }
>>>> mapp->invalid = false;
>>>> up_write(&xdna->notifier_lock);
>>>> + mutex_unlock(&mapp->lock);
>>>> amdxdna_umap_put(mapp);
>>>> mmput(mm);
>>>> goto again;
>>>> diff --git a/drivers/accel/amdxdna/amdxdna_gem.c
>>>> b/drivers/accel/amdxdna/amdxdna_gem.c
>>>> index f14484bc31ec..37bfa5058095 100644
>>>> --- a/drivers/accel/amdxdna/amdxdna_gem.c
>>>> +++ b/drivers/accel/amdxdna/amdxdna_gem.c
>>>> @@ -318,6 +318,7 @@ static void amdxdna_umap_release(struct kref *ref)
>>>> struct amdxdna_umap *mapp = container_of(ref, struct amdxdna_umap,
>>>> refcnt);
>>>> mmu_interval_notifier_remove(&mapp->notifier);
>>>> + mutex_destroy(&mapp->lock);
>>>> kvfree(mapp->range.hmm_pfns);
>>>> kfree(mapp);
>>>> }
>>>> @@ -402,6 +403,7 @@ static int amdxdna_hmm_register(struct amdxdna_gem_obj
>>>> *abo,
>>>> goto free_pfns;
>>>> }
>>>> + mutex_init(&mapp->lock);
>>>> down_write(&xdna->notifier_lock);
>>>> if (list_empty(&abo->mem.umap_list))
>>>> abo->mem.uva = addr;
>>>> diff --git a/drivers/accel/amdxdna/amdxdna_gem.h
>>>> b/drivers/accel/amdxdna/amdxdna_gem.h
>>>> index 9b4aa21a37c9..456a537eb68c 100644
>>>> --- a/drivers/accel/amdxdna/amdxdna_gem.h
>>>> +++ b/drivers/accel/amdxdna/amdxdna_gem.h
>>>> @@ -19,6 +19,7 @@ struct amdxdna_umap {
>>>> struct kref refcnt;
>>>> bool invalid;
>>>> bool unmapped;
>>>> + struct mutex lock; /* protect range */
>>>> };
>>>> struct amdxdna_mem {
