The patch below does not apply to the 4.9-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to stable@vger.kernel.org.
thanks,
greg k-h
------------------ original commit in Linus's tree ------------------
From a0ffb4c12f7fa89163e228e6f27df09b46631db1 Mon Sep 17 00:00:00 2001
From: Mark Zhang markzhang@nvidia.com Date: Thu, 3 Jun 2021 16:18:03 +0300 Subject: [PATCH] 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: e126ba97dba9 ("mlx5: Add driver for Mellanox Connect-IB adapters") Link: https://lore.kernel.org/r/feacc23fe0bc6e1088c6824d5583798745e72405.162272621... Reviewed-by: Jason Gunthorpe jgg@nvidia.com Signed-off-by: Mark Zhang markzhang@nvidia.com Signed-off-by: Leon Romanovsky leonro@nvidia.com Signed-off-by: Jason Gunthorpe jgg@nvidia.com
diff --git a/drivers/infiniband/hw/mlx5/doorbell.c b/drivers/infiniband/hw/mlx5/doorbell.c index 61475b571531..7af4df7a6823 100644 --- a/drivers/infiniband/hw/mlx5/doorbell.c +++ b/drivers/infiniband/hw/mlx5/doorbell.c @@ -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); }