diff mbox series

[v3,for-next,1/2] RDMA/core: Provide rdma_user_mmap_disassociate() to disassociate mmap pages

Message ID 20240828064605.887519-2-huangjunxian6@hisilicon.com (mailing list archive)
State Superseded
Headers show
Series RDMA: Provide an API for drivers to disassociate mmap pages | expand

Commit Message

Junxian Huang Aug. 28, 2024, 6:46 a.m. UTC 
From: Chengchang Tang <tangchengchang@huawei.com>

Provide a new api rdma_user_mmap_disassociate() for drivers to
disassociate mmap pages for a device.

Signed-off-by: Chengchang Tang <tangchengchang@huawei.com>
Signed-off-by: Junxian Huang <huangjunxian6@hisilicon.com>
---
 drivers/infiniband/core/uverbs.h      |  3 ++
 drivers/infiniband/core/uverbs_main.c | 45 +++++++++++++++++++++++++--
 include/rdma/ib_verbs.h               |  8 +++++
 3 files changed, 54 insertions(+), 2 deletions(-)

Comments

Leon Romanovsky Sept. 2, 2024, 6:57 a.m. UTC | #1 
On Wed, Aug 28, 2024 at 02:46:04PM +0800, Junxian Huang wrote:
> From: Chengchang Tang <tangchengchang@huawei.com>
> 
> Provide a new api rdma_user_mmap_disassociate() for drivers to
> disassociate mmap pages for a device.
> 
> Signed-off-by: Chengchang Tang <tangchengchang@huawei.com>
> Signed-off-by: Junxian Huang <huangjunxian6@hisilicon.com>
> ---
>  drivers/infiniband/core/uverbs.h      |  3 ++
>  drivers/infiniband/core/uverbs_main.c | 45 +++++++++++++++++++++++++--
>  include/rdma/ib_verbs.h               |  8 +++++
>  3 files changed, 54 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/infiniband/core/uverbs.h b/drivers/infiniband/core/uverbs.h
> index 821d93c8f712..0999d27cb1c9 100644
> --- a/drivers/infiniband/core/uverbs.h
> +++ b/drivers/infiniband/core/uverbs.h
> @@ -160,6 +160,9 @@ struct ib_uverbs_file {
>  	struct page *disassociate_page;
>  
>  	struct xarray		idr;
> +
> +	struct mutex disassociation_lock;
> +	atomic_t disassociated;
>  };
>  
>  struct ib_uverbs_event {
> diff --git a/drivers/infiniband/core/uverbs_main.c b/drivers/infiniband/core/uverbs_main.c
> index bc099287de9a..589f27c09a2e 100644
> --- a/drivers/infiniband/core/uverbs_main.c
> +++ b/drivers/infiniband/core/uverbs_main.c
> @@ -76,6 +76,7 @@ static dev_t dynamic_uverbs_dev;
>  static DEFINE_IDA(uverbs_ida);
>  static int ib_uverbs_add_one(struct ib_device *device);
>  static void ib_uverbs_remove_one(struct ib_device *device, void *client_data);
> +static struct ib_client uverbs_client;
>  
>  static char *uverbs_devnode(const struct device *dev, umode_t *mode)
>  {
> @@ -217,6 +218,7 @@ void ib_uverbs_release_file(struct kref *ref)
>  
>  	if (file->disassociate_page)
>  		__free_pages(file->disassociate_page, 0);
> +	mutex_destroy(&file->disassociation_lock);
>  	mutex_destroy(&file->umap_lock);
>  	mutex_destroy(&file->ucontext_lock);
>  	kfree(file);
> @@ -700,6 +702,12 @@ static int ib_uverbs_mmap(struct file *filp, struct vm_area_struct *vma)
>  		ret = PTR_ERR(ucontext);
>  		goto out;
>  	}
> +
> +	if (atomic_read(&file->disassociated)) {

I don't see any of the newly introduced locks here. If it is
intentional, it needs to be documented.

> +		ret = -EPERM;
> +		goto out;
> +	}
> +
>  	vma->vm_ops = &rdma_umap_ops;
>  	ret = ucontext->device->ops.mmap(ucontext, vma);
>  out:
> @@ -726,7 +734,7 @@ static void rdma_umap_open(struct vm_area_struct *vma)
>  	/*
>  	 * Disassociation already completed, the VMA should already be zapped.
>  	 */
> -	if (!ufile->ucontext)
> +	if (!ufile->ucontext || atomic_read(&ufile->disassociated))
>  		goto out_unlock;
>  
>  	priv = kzalloc(sizeof(*priv), GFP_KERNEL);
> @@ -822,6 +830,8 @@ void uverbs_user_mmap_disassociate(struct ib_uverbs_file *ufile)
>  	struct rdma_umap_priv *priv, *next_priv;
>  
>  	lockdep_assert_held(&ufile->hw_destroy_rwsem);
> +	mutex_lock(&ufile->disassociation_lock);
> +	atomic_set(&ufile->disassociated, 1);

Why do you use atomic_t and not regular bool?

>  
>  	while (1) {
>  		struct mm_struct *mm = NULL;
> @@ -847,8 +857,10 @@ void uverbs_user_mmap_disassociate(struct ib_uverbs_file *ufile)
>  			break;
>  		}
>  		mutex_unlock(&ufile->umap_lock);
> -		if (!mm)
> +		if (!mm) {
> +			mutex_unlock(&ufile->disassociation_lock);
>  			return;
> +		}
>  
>  		/*
>  		 * The umap_lock is nested under mmap_lock since it used within
> @@ -878,8 +890,34 @@ void uverbs_user_mmap_disassociate(struct ib_uverbs_file *ufile)
>  		mmap_read_unlock(mm);
>  		mmput(mm);
>  	}
> +
> +	mutex_unlock(&ufile->disassociation_lock);
>  }
>  
> +/**
> + * rdma_user_mmap_disassociate() - Revoke mmaps for a device
> + * @device: device to revoke
> + *
> + * This function should be called by drivers that need to disable mmaps for the
> + * device, for instance because it is going to be reset.
> + */
> +void rdma_user_mmap_disassociate(struct ib_device *device)
> +{
> +	struct ib_uverbs_device *uverbs_dev =
> +		ib_get_client_data(device, &uverbs_client);
> +	struct ib_uverbs_file *ufile;
> +
> +	mutex_lock(&uverbs_dev->lists_mutex);
> +	list_for_each_entry(ufile, &uverbs_dev->uverbs_file_list, list) {
> +		down_read(&ufile->hw_destroy_rwsem);

I personally don't understand this locking scheme at all. I see newly
introduced locks mixed together some old locks. 

Jason, do you agree with this proposed locking scheme?

Thanks

> +		if (ufile->ucontext && !atomic_read(&ufile->disassociated))
> +			uverbs_user_mmap_disassociate(ufile);
> +		up_read(&ufile->hw_destroy_rwsem);
> +	}
> +	mutex_unlock(&uverbs_dev->lists_mutex);
> +}
> +EXPORT_SYMBOL(rdma_user_mmap_disassociate);
> +
>  /*
>   * ib_uverbs_open() does not need the BKL:
>   *
> @@ -949,6 +987,9 @@ static int ib_uverbs_open(struct inode *inode, struct file *filp)
>  	mutex_init(&file->umap_lock);
>  	INIT_LIST_HEAD(&file->umaps);
>  
> +	mutex_init(&file->disassociation_lock);
> +	atomic_set(&file->disassociated, 0);
> +
>  	filp->private_data = file;
>  	list_add_tail(&file->list, &dev->uverbs_file_list);
>  	mutex_unlock(&dev->lists_mutex);
> diff --git a/include/rdma/ib_verbs.h b/include/rdma/ib_verbs.h
> index a1dcf812d787..09b80c8253e2 100644
> --- a/include/rdma/ib_verbs.h
> +++ b/include/rdma/ib_verbs.h
> @@ -2948,6 +2948,14 @@ int rdma_user_mmap_entry_insert_range(struct ib_ucontext *ucontext,
>  				      size_t length, u32 min_pgoff,
>  				      u32 max_pgoff);
>  
> +#if IS_ENABLED(CONFIG_INFINIBAND_USER_ACCESS)
> +void rdma_user_mmap_disassociate(struct ib_device *device);
> +#else
> +static inline void rdma_user_mmap_disassociate(struct ib_device *device)
> +{
> +}
> +#endif
> +
>  static inline int
>  rdma_user_mmap_entry_insert_exact(struct ib_ucontext *ucontext,
>  				  struct rdma_user_mmap_entry *entry,
> -- 
> 2.33.0
> 
>
Junxian Huang Sept. 2, 2024, 1:32 p.m. UTC | #2 
On 2024/9/2 14:57, Leon Romanovsky wrote:
> On Wed, Aug 28, 2024 at 02:46:04PM +0800, Junxian Huang wrote:
>> From: Chengchang Tang <tangchengchang@huawei.com>
>>
>> Provide a new api rdma_user_mmap_disassociate() for drivers to
>> disassociate mmap pages for a device.
>>
>> Signed-off-by: Chengchang Tang <tangchengchang@huawei.com>
>> Signed-off-by: Junxian Huang <huangjunxian6@hisilicon.com>
>> ---
>>  drivers/infiniband/core/uverbs.h      |  3 ++
>>  drivers/infiniband/core/uverbs_main.c | 45 +++++++++++++++++++++++++--
>>  include/rdma/ib_verbs.h               |  8 +++++
>>  3 files changed, 54 insertions(+), 2 deletions(-)
>>
>> diff --git a/drivers/infiniband/core/uverbs.h b/drivers/infiniband/core/uverbs.h
>> index 821d93c8f712..0999d27cb1c9 100644
>> --- a/drivers/infiniband/core/uverbs.h
>> +++ b/drivers/infiniband/core/uverbs.h
>> @@ -160,6 +160,9 @@ struct ib_uverbs_file {
>>  	struct page *disassociate_page;
>>  
>>  	struct xarray		idr;
>> +
>> +	struct mutex disassociation_lock;
>> +	atomic_t disassociated;
>>  };
>>  
>>  struct ib_uverbs_event {
>> diff --git a/drivers/infiniband/core/uverbs_main.c b/drivers/infiniband/core/uverbs_main.c
>> index bc099287de9a..589f27c09a2e 100644
>> --- a/drivers/infiniband/core/uverbs_main.c
>> +++ b/drivers/infiniband/core/uverbs_main.c
>> @@ -76,6 +76,7 @@ static dev_t dynamic_uverbs_dev;
>>  static DEFINE_IDA(uverbs_ida);
>>  static int ib_uverbs_add_one(struct ib_device *device);
>>  static void ib_uverbs_remove_one(struct ib_device *device, void *client_data);
>> +static struct ib_client uverbs_client;
>>  
>>  static char *uverbs_devnode(const struct device *dev, umode_t *mode)
>>  {
>> @@ -217,6 +218,7 @@ void ib_uverbs_release_file(struct kref *ref)
>>  
>>  	if (file->disassociate_page)
>>  		__free_pages(file->disassociate_page, 0);
>> +	mutex_destroy(&file->disassociation_lock);
>>  	mutex_destroy(&file->umap_lock);
>>  	mutex_destroy(&file->ucontext_lock);
>>  	kfree(file);
>> @@ -700,6 +702,12 @@ static int ib_uverbs_mmap(struct file *filp, struct vm_area_struct *vma)
>>  		ret = PTR_ERR(ucontext);
>>  		goto out;
>>  	}
>> +
>> +	if (atomic_read(&file->disassociated)) {
> 
> I don't see any of the newly introduced locks here. If it is
> intentional, it needs to be documented.
> 

<...>

>> +		ret = -EPERM;
>> +		goto out;
>> +	}
>> +
>>  	vma->vm_ops = &rdma_umap_ops;
>>  	ret = ucontext->device->ops.mmap(ucontext, vma);
>>  out:
>> @@ -726,7 +734,7 @@ static void rdma_umap_open(struct vm_area_struct *vma)
>>  	/*
>>  	 * Disassociation already completed, the VMA should already be zapped.
>>  	 */
>> -	if (!ufile->ucontext)
>> +	if (!ufile->ucontext || atomic_read(&ufile->disassociated))
>>  		goto out_unlock;
>>  
>>  	priv = kzalloc(sizeof(*priv), GFP_KERNEL);
>> @@ -822,6 +830,8 @@ void uverbs_user_mmap_disassociate(struct ib_uverbs_file *ufile)
>>  	struct rdma_umap_priv *priv, *next_priv;
>>  
>>  	lockdep_assert_held(&ufile->hw_destroy_rwsem);
>> +	mutex_lock(&ufile->disassociation_lock);
>> +	atomic_set(&ufile->disassociated, 1);
> 
> Why do you use atomic_t and not regular bool?
> 

The original thought was that ib_uverbs_mmap() reads ufile->disassociated while
uverbs_user_mmap_disassociate() writes it, and there might be a racing. We tried
to use atomic_t to avoid racing without adding locks.

But I looked into the code again and now I think ufile->disassociated is not
sufficient to deal with the racing like this:

ib_uverbs_mmap()                                       uverbs_user_mmap_disassociate()
----------------                                       ------------------------------
atomic_read(&file->disassociated) == 0
                                                       atomic_set(&ufile->disassociated, 1)

                                                       all mmaps from the list are zapped

ucontext->device->ops.mmap(ucontext, vma)
rdma_user_mmap_io()
rdma_umap_priv_init() adds a new mmap to the list


So we may still need a lock, and ufile->disassociated can be bool now, something like:

@@ -700,9 +702,17 @@ static int ib_uverbs_mmap(struct file *filp, struct vm_area_struct *vma)
                ret = PTR_ERR(ucontext);
                goto out;
        }
+
+       mutex_lock(&file->disassociation_lock);
+       if (file->disassociated) {
+               ret = -EPERM;
+               goto out;
+       }
+
        vma->vm_ops = &rdma_umap_ops;
        ret = ucontext->device->ops.mmap(ucontext, vma);
 out:
+       mutex_unlock(&file->disassociation_lock);
        srcu_read_unlock(&file->device->disassociate_srcu, srcu_key);
        return ret;
 }

Similar changes on rdma_umap_open():

@@ -723,10 +733,12 @@ static void rdma_umap_open(struct vm_area_struct *vma)
        /* We are racing with disassociation */
        if (!down_read_trylock(&ufile->hw_destroy_rwsem))
                goto out_zap;
+
+       mutex_lock(&ufile->disassociation_lock);
        /*
         * Disassociation already completed, the VMA should already be zapped.
         */
-       if (!ufile->ucontext)
+       if (!ufile->ucontext || ufile->disassociated)
                goto out_unlock;

        priv = kzalloc(sizeof(*priv), GFP_KERNEL);
@@ -734,10 +746,12 @@ static void rdma_umap_open(struct vm_area_struct *vma)
                goto out_unlock;
        rdma_umap_priv_init(priv, vma, opriv->entry);

+       mutex_unlock(&ufile->disassociation_lock);
        up_read(&ufile->hw_destroy_rwsem);
        return;

 out_unlock:
+       mutex_unlock(&ufile->disassociation_lock);
        up_read(&ufile->hw_destroy_rwsem);
 out_zap:
        /*

>>  
>>  	while (1) {
>>  		struct mm_struct *mm = NULL;
>> @@ -847,8 +857,10 @@ void uverbs_user_mmap_disassociate(struct ib_uverbs_file *ufile)
>>  			break;
>>  		}
>>  		mutex_unlock(&ufile->umap_lock);
>> -		if (!mm)
>> +		if (!mm) {
>> +			mutex_unlock(&ufile->disassociation_lock);
>>  			return;
>> +		}
>>  
>>  		/*
>>  		 * The umap_lock is nested under mmap_lock since it used within
>> @@ -878,8 +890,34 @@ void uverbs_user_mmap_disassociate(struct ib_uverbs_file *ufile)
>>  		mmap_read_unlock(mm);
>>  		mmput(mm);
>>  	}
>> +
>> +	mutex_unlock(&ufile->disassociation_lock);
>>  }
>>  
>> +/**
>> + * rdma_user_mmap_disassociate() - Revoke mmaps for a device
>> + * @device: device to revoke
>> + *
>> + * This function should be called by drivers that need to disable mmaps for the
>> + * device, for instance because it is going to be reset.
>> + */
>> +void rdma_user_mmap_disassociate(struct ib_device *device)
>> +{
>> +	struct ib_uverbs_device *uverbs_dev =
>> +		ib_get_client_data(device, &uverbs_client);
>> +	struct ib_uverbs_file *ufile;
>> +
>> +	mutex_lock(&uverbs_dev->lists_mutex);
>> +	list_for_each_entry(ufile, &uverbs_dev->uverbs_file_list, list) {
>> +		down_read(&ufile->hw_destroy_rwsem);
> 
> I personally don't understand this locking scheme at all. I see newly
> introduced locks mixed together some old locks. 
> 

We must hold the rwsem because of the lockdep. The newly introduced lock
is also needed to prevent the racing that one thread is calling
rdma_user_mmap_disassociate(), while the other thread is calling
ib_uverbs_mmap() or rdma_umap_open().

Thanks,
Junxian

> Jason, do you agree with this proposed locking scheme?
> 
> Thanks
> 
>> +		if (ufile->ucontext && !atomic_read(&ufile->disassociated))
>> +			uverbs_user_mmap_disassociate(ufile);
>> +		up_read(&ufile->hw_destroy_rwsem);
>> +	}
>> +	mutex_unlock(&uverbs_dev->lists_mutex);
>> +}
>> +EXPORT_SYMBOL(rdma_user_mmap_disassociate);
>> +
>>  /*
>>   * ib_uverbs_open() does not need the BKL:
>>   *
>> @@ -949,6 +987,9 @@ static int ib_uverbs_open(struct inode *inode, struct file *filp)
>>  	mutex_init(&file->umap_lock);
>>  	INIT_LIST_HEAD(&file->umaps);
>>  
>> +	mutex_init(&file->disassociation_lock);
>> +	atomic_set(&file->disassociated, 0);
>> +
>>  	filp->private_data = file;
>>  	list_add_tail(&file->list, &dev->uverbs_file_list);
>>  	mutex_unlock(&dev->lists_mutex);
>> diff --git a/include/rdma/ib_verbs.h b/include/rdma/ib_verbs.h
>> index a1dcf812d787..09b80c8253e2 100644
>> --- a/include/rdma/ib_verbs.h
>> +++ b/include/rdma/ib_verbs.h
>> @@ -2948,6 +2948,14 @@ int rdma_user_mmap_entry_insert_range(struct ib_ucontext *ucontext,
>>  				      size_t length, u32 min_pgoff,
>>  				      u32 max_pgoff);
>>  
>> +#if IS_ENABLED(CONFIG_INFINIBAND_USER_ACCESS)
>> +void rdma_user_mmap_disassociate(struct ib_device *device);
>> +#else
>> +static inline void rdma_user_mmap_disassociate(struct ib_device *device)
>> +{
>> +}
>> +#endif
>> +
>>  static inline int
>>  rdma_user_mmap_entry_insert_exact(struct ib_ucontext *ucontext,
>>  				  struct rdma_user_mmap_entry *entry,
>> -- 
>> 2.33.0
>>
>>
Leon Romanovsky Sept. 3, 2024, 7:09 a.m. UTC | #3 
On Mon, Sep 02, 2024 at 09:32:10PM +0800, Junxian Huang wrote:
> 
> 
> On 2024/9/2 14:57, Leon Romanovsky wrote:
> > On Wed, Aug 28, 2024 at 02:46:04PM +0800, Junxian Huang wrote:
> >> From: Chengchang Tang <tangchengchang@huawei.com>
> >>
> >> Provide a new api rdma_user_mmap_disassociate() for drivers to
> >> disassociate mmap pages for a device.
> >>
> >> Signed-off-by: Chengchang Tang <tangchengchang@huawei.com>
> >> Signed-off-by: Junxian Huang <huangjunxian6@hisilicon.com>
> >> ---
> >>  drivers/infiniband/core/uverbs.h      |  3 ++
> >>  drivers/infiniband/core/uverbs_main.c | 45 +++++++++++++++++++++++++--
> >>  include/rdma/ib_verbs.h               |  8 +++++
> >>  3 files changed, 54 insertions(+), 2 deletions(-)
> >>
> >> diff --git a/drivers/infiniband/core/uverbs.h b/drivers/infiniband/core/uverbs.h
> >> index 821d93c8f712..0999d27cb1c9 100644
> >> --- a/drivers/infiniband/core/uverbs.h
> >> +++ b/drivers/infiniband/core/uverbs.h
> >> @@ -160,6 +160,9 @@ struct ib_uverbs_file {
> >>  	struct page *disassociate_page;
> >>  
> >>  	struct xarray		idr;
> >> +
> >> +	struct mutex disassociation_lock;
> >> +	atomic_t disassociated;
> >>  };
> >>  
> >>  struct ib_uverbs_event {
> >> diff --git a/drivers/infiniband/core/uverbs_main.c b/drivers/infiniband/core/uverbs_main.c
> >> index bc099287de9a..589f27c09a2e 100644
> >> --- a/drivers/infiniband/core/uverbs_main.c
> >> +++ b/drivers/infiniband/core/uverbs_main.c
> >> @@ -76,6 +76,7 @@ static dev_t dynamic_uverbs_dev;
> >>  static DEFINE_IDA(uverbs_ida);
> >>  static int ib_uverbs_add_one(struct ib_device *device);
> >>  static void ib_uverbs_remove_one(struct ib_device *device, void *client_data);
> >> +static struct ib_client uverbs_client;
> >>  
> >>  static char *uverbs_devnode(const struct device *dev, umode_t *mode)
> >>  {
> >> @@ -217,6 +218,7 @@ void ib_uverbs_release_file(struct kref *ref)
> >>  
> >>  	if (file->disassociate_page)
> >>  		__free_pages(file->disassociate_page, 0);
> >> +	mutex_destroy(&file->disassociation_lock);
> >>  	mutex_destroy(&file->umap_lock);
> >>  	mutex_destroy(&file->ucontext_lock);
> >>  	kfree(file);
> >> @@ -700,6 +702,12 @@ static int ib_uverbs_mmap(struct file *filp, struct vm_area_struct *vma)
> >>  		ret = PTR_ERR(ucontext);
> >>  		goto out;
> >>  	}
> >> +
> >> +	if (atomic_read(&file->disassociated)) {
> > 
> > I don't see any of the newly introduced locks here. If it is
> > intentional, it needs to be documented.
> > 
> 
> <...>
> 
> >> +		ret = -EPERM;
> >> +		goto out;
> >> +	}
> >> +
> >>  	vma->vm_ops = &rdma_umap_ops;
> >>  	ret = ucontext->device->ops.mmap(ucontext, vma);
> >>  out:
> >> @@ -726,7 +734,7 @@ static void rdma_umap_open(struct vm_area_struct *vma)
> >>  	/*
> >>  	 * Disassociation already completed, the VMA should already be zapped.
> >>  	 */
> >> -	if (!ufile->ucontext)
> >> +	if (!ufile->ucontext || atomic_read(&ufile->disassociated))
> >>  		goto out_unlock;
> >>  
> >>  	priv = kzalloc(sizeof(*priv), GFP_KERNEL);
> >> @@ -822,6 +830,8 @@ void uverbs_user_mmap_disassociate(struct ib_uverbs_file *ufile)
> >>  	struct rdma_umap_priv *priv, *next_priv;
> >>  
> >>  	lockdep_assert_held(&ufile->hw_destroy_rwsem);
> >> +	mutex_lock(&ufile->disassociation_lock);
> >> +	atomic_set(&ufile->disassociated, 1);
> > 
> > Why do you use atomic_t and not regular bool?
> > 
> 
> The original thought was that ib_uverbs_mmap() reads ufile->disassociated while
> uverbs_user_mmap_disassociate() writes it, and there might be a racing. We tried
> to use atomic_t to avoid racing without adding locks.

atomic_t is never a replacement for locks. It is a way to provide
coherent view of the data between CPUs and makes sure that write/read is
not interrupted.

Thanks
Jason Gunthorpe Sept. 4, 2024, 4:04 p.m. UTC | #4 
On Tue, Sep 03, 2024 at 10:09:22AM +0300, Leon Romanovsky wrote:

> > The original thought was that ib_uverbs_mmap() reads ufile->disassociated while
> > uverbs_user_mmap_disassociate() writes it, and there might be a racing. We tried
> > to use atomic_t to avoid racing without adding locks.
> 
> atomic_t is never a replacement for locks. It is a way to provide
> coherent view of the data between CPUs and makes sure that write/read is
> not interrupted.

Yes, add a lock, like I said

Jason
diff mbox series

Patch

diff --git a/drivers/infiniband/core/uverbs.h b/drivers/infiniband/core/uverbs.h
index 821d93c8f712..0999d27cb1c9 100644
--- a/drivers/infiniband/core/uverbs.h
+++ b/drivers/infiniband/core/uverbs.h
@@ -160,6 +160,9 @@  struct ib_uverbs_file {
 	struct page *disassociate_page;
 
 	struct xarray		idr;
+
+	struct mutex disassociation_lock;
+	atomic_t disassociated;
 };
 
 struct ib_uverbs_event {
diff --git a/drivers/infiniband/core/uverbs_main.c b/drivers/infiniband/core/uverbs_main.c
index bc099287de9a..589f27c09a2e 100644
--- a/drivers/infiniband/core/uverbs_main.c
+++ b/drivers/infiniband/core/uverbs_main.c
@@ -76,6 +76,7 @@  static dev_t dynamic_uverbs_dev;
 static DEFINE_IDA(uverbs_ida);
 static int ib_uverbs_add_one(struct ib_device *device);
 static void ib_uverbs_remove_one(struct ib_device *device, void *client_data);
+static struct ib_client uverbs_client;
 
 static char *uverbs_devnode(const struct device *dev, umode_t *mode)
 {
@@ -217,6 +218,7 @@  void ib_uverbs_release_file(struct kref *ref)
 
 	if (file->disassociate_page)
 		__free_pages(file->disassociate_page, 0);
+	mutex_destroy(&file->disassociation_lock);
 	mutex_destroy(&file->umap_lock);
 	mutex_destroy(&file->ucontext_lock);
 	kfree(file);
@@ -700,6 +702,12 @@  static int ib_uverbs_mmap(struct file *filp, struct vm_area_struct *vma)
 		ret = PTR_ERR(ucontext);
 		goto out;
 	}
+
+	if (atomic_read(&file->disassociated)) {
+		ret = -EPERM;
+		goto out;
+	}
+
 	vma->vm_ops = &rdma_umap_ops;
 	ret = ucontext->device->ops.mmap(ucontext, vma);
 out:
@@ -726,7 +734,7 @@  static void rdma_umap_open(struct vm_area_struct *vma)
 	/*
 	 * Disassociation already completed, the VMA should already be zapped.
 	 */
-	if (!ufile->ucontext)
+	if (!ufile->ucontext || atomic_read(&ufile->disassociated))
 		goto out_unlock;
 
 	priv = kzalloc(sizeof(*priv), GFP_KERNEL);
@@ -822,6 +830,8 @@  void uverbs_user_mmap_disassociate(struct ib_uverbs_file *ufile)
 	struct rdma_umap_priv *priv, *next_priv;
 
 	lockdep_assert_held(&ufile->hw_destroy_rwsem);
+	mutex_lock(&ufile->disassociation_lock);
+	atomic_set(&ufile->disassociated, 1);
 
 	while (1) {
 		struct mm_struct *mm = NULL;
@@ -847,8 +857,10 @@  void uverbs_user_mmap_disassociate(struct ib_uverbs_file *ufile)
 			break;
 		}
 		mutex_unlock(&ufile->umap_lock);
-		if (!mm)
+		if (!mm) {
+			mutex_unlock(&ufile->disassociation_lock);
 			return;
+		}
 
 		/*
 		 * The umap_lock is nested under mmap_lock since it used within
@@ -878,8 +890,34 @@  void uverbs_user_mmap_disassociate(struct ib_uverbs_file *ufile)
 		mmap_read_unlock(mm);
 		mmput(mm);
 	}
+
+	mutex_unlock(&ufile->disassociation_lock);
 }
 
+/**
+ * rdma_user_mmap_disassociate() - Revoke mmaps for a device
+ * @device: device to revoke
+ *
+ * This function should be called by drivers that need to disable mmaps for the
+ * device, for instance because it is going to be reset.
+ */
+void rdma_user_mmap_disassociate(struct ib_device *device)
+{
+	struct ib_uverbs_device *uverbs_dev =
+		ib_get_client_data(device, &uverbs_client);
+	struct ib_uverbs_file *ufile;
+
+	mutex_lock(&uverbs_dev->lists_mutex);
+	list_for_each_entry(ufile, &uverbs_dev->uverbs_file_list, list) {
+		down_read(&ufile->hw_destroy_rwsem);
+		if (ufile->ucontext && !atomic_read(&ufile->disassociated))
+			uverbs_user_mmap_disassociate(ufile);
+		up_read(&ufile->hw_destroy_rwsem);
+	}
+	mutex_unlock(&uverbs_dev->lists_mutex);
+}
+EXPORT_SYMBOL(rdma_user_mmap_disassociate);
+
 /*
  * ib_uverbs_open() does not need the BKL:
  *
@@ -949,6 +987,9 @@  static int ib_uverbs_open(struct inode *inode, struct file *filp)
 	mutex_init(&file->umap_lock);
 	INIT_LIST_HEAD(&file->umaps);
 
+	mutex_init(&file->disassociation_lock);
+	atomic_set(&file->disassociated, 0);
+
 	filp->private_data = file;
 	list_add_tail(&file->list, &dev->uverbs_file_list);
 	mutex_unlock(&dev->lists_mutex);
diff --git a/include/rdma/ib_verbs.h b/include/rdma/ib_verbs.h
index a1dcf812d787..09b80c8253e2 100644
--- a/include/rdma/ib_verbs.h
+++ b/include/rdma/ib_verbs.h
@@ -2948,6 +2948,14 @@  int rdma_user_mmap_entry_insert_range(struct ib_ucontext *ucontext,
 				      size_t length, u32 min_pgoff,
 				      u32 max_pgoff);
 
+#if IS_ENABLED(CONFIG_INFINIBAND_USER_ACCESS)
+void rdma_user_mmap_disassociate(struct ib_device *device);
+#else
+static inline void rdma_user_mmap_disassociate(struct ib_device *device)
+{
+}
+#endif
+
 static inline int
 rdma_user_mmap_entry_insert_exact(struct ib_ucontext *ucontext,
 				  struct rdma_user_mmap_entry *entry,