Commit a0ffb4c1 authored by Mark Zhang's avatar Mark Zhang Committed by Jason Gunthorpe
Browse files

RDMA/mlx5: Use different doorbell memory for different processes 

In a fork scenario, the parent and child can have same virtual address and
also share the uverbs fd.  That causes to the list_for_each_entry search
return same doorbell physical page for all processes, even though that
page has been COW' or copied.

This patch takes the mm_struct into consideration during search, to make
sure that VA's belonging to different processes are not intermixed.

Resolves the malfunction of uverbs after fork in some specific cases.

Fixes: e126ba97 ("mlx5: Add driver for Mellanox Connect-IB adapters")
Link: https://lore.kernel.org/r/feacc23fe0bc6e1088c6824d5583798745e72405.1622726212.git.leonro@nvidia.com


Reviewed-by: default avatarJason Gunthorpe <jgg@nvidia.com>
Signed-off-by: default avatarMark Zhang <markzhang@nvidia.com>
Signed-off-by: default avatarLeon Romanovsky <leonro@nvidia.com>
Signed-off-by: default avatarJason Gunthorpe <jgg@nvidia.com>
parent a3e74fb9

drivers/infiniband/hw/mlx5/doorbell.c

+6 −1
Original line number Diff line number Diff line
@@ -41,6 +41,7 @@ struct mlx5_ib_user_db_page { 
	struct ib_umem	       *umem;

	unsigned long		user_virt;

	int			refcnt;

	struct mm_struct	*mm;

};



int mlx5_ib_db_map_user(struct mlx5_ib_ucontext *context,
@@ -53,7 +54,8 @@ int mlx5_ib_db_map_user(struct mlx5_ib_ucontext *context, 
	mutex_lock(&context->db_page_mutex);



	list_for_each_entry(page, &context->db_page_list, list)

		if (page->user_virt == (virt & PAGE_MASK))

		if ((current->mm == page->mm) &&

		    (page->user_virt == (virt & PAGE_MASK)))

			goto found;



	page = kmalloc(sizeof(*page), GFP_KERNEL);
@@ -71,6 +73,8 @@ int mlx5_ib_db_map_user(struct mlx5_ib_ucontext *context, 
		kfree(page);

		goto out;

	}

	mmgrab(current->mm);

	page->mm = current->mm;



	list_add(&page->list, &context->db_page_list);
@@ -91,6 +95,7 @@ void mlx5_ib_db_unmap_user(struct mlx5_ib_ucontext *context, struct mlx5_db *db) 


	if (!--db->u.user_page->refcnt) {

		list_del(&db->u.user_page->list);

		mmdrop(db->u.user_page->mm);

		ib_umem_release(db->u.user_page->umem);

		kfree(db->u.user_page);

	}