The patch below does not apply to the 4.4-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 8e907ed4882714fd13cfe670681fc6cb5284c780 Mon Sep 17 00:00:00 2001

From: Lidong Chen jemmy858585@gmail.com Date: Tue, 8 May 2018 16:50:16 +0800 Subject: [PATCH] IB/umem: Use the correct mm during ib_umem_release

User-space may invoke ibv_reg_mr and ibv_dereg_mr in different threads.

If ibv_dereg_mr is called after the thread which invoked ibv_reg_mr has exited, get_pid_task will return NULL and ib_umem_release will not decrease mm->pinned_vm.

Instead of using threads to locate the mm, use the overall tgid from the ib_ucontext struct instead. This matches the behavior of ODP and disassociate in handling the mm of the process that called ibv_reg_mr.

Cc: stable@vger.kernel.org Fixes: 87773dd56d54 ("IB: ib_umem_release() should decrement mm->pinned_vm from ib_umem_get") Signed-off-by: Lidong Chen lidongchen@tencent.com Signed-off-by: Jason Gunthorpe jgg@mellanox.com

diff --git a/drivers/infiniband/core/umem.c b/drivers/infiniband/core/umem.c index 9a4e899d94b3..2b6c9b516070 100644 --- a/drivers/infiniband/core/umem.c +++ b/drivers/infiniband/core/umem.c @@ -119,7 +119,6 @@ struct ib_umem *ib_umem_get(struct ib_ucontext *context, unsigned long addr, umem->length = size; umem->address = addr; umem->page_shift = PAGE_SHIFT; - umem->pid = get_task_pid(current, PIDTYPE_PID); /* * We ask for writable memory if any of the following * access flags are set. "Local write" and "remote write" @@ -132,7 +131,6 @@ struct ib_umem *ib_umem_get(struct ib_ucontext *context, unsigned long addr, IB_ACCESS_REMOTE_ATOMIC | IB_ACCESS_MW_BIND));

if (access & IB_ACCESS_ON_DEMAND) { - put_pid(umem->pid); ret = ib_umem_odp_get(context, umem, access); if (ret) { kfree(umem); @@ -148,7 +146,6 @@ struct ib_umem *ib_umem_get(struct ib_ucontext *context, unsigned long addr,

page_list = (struct page **) __get_free_page(GFP_KERNEL); if (!page_list) { - put_pid(umem->pid); kfree(umem); return ERR_PTR(-ENOMEM); } @@ -231,7 +228,6 @@ struct ib_umem *ib_umem_get(struct ib_ucontext *context, unsigned long addr, if (ret < 0) { if (need_release) __ib_umem_release(context->device, umem, 0); - put_pid(umem->pid); kfree(umem); } else current->mm->pinned_vm = locked; @@ -274,8 +270,7 @@ void ib_umem_release(struct ib_umem *umem)

__ib_umem_release(umem->context->device, umem, 1);

- task = get_pid_task(umem->pid, PIDTYPE_PID); - put_pid(umem->pid); + task = get_pid_task(umem->context->tgid, PIDTYPE_PID); if (!task) goto out; mm = get_task_mm(task); diff --git a/include/rdma/ib_umem.h b/include/rdma/ib_umem.h index 23159dd5be18..a1fd63871d17 100644 --- a/include/rdma/ib_umem.h +++ b/include/rdma/ib_umem.h @@ -48,7 +48,6 @@ struct ib_umem { int writable; int hugetlb; struct work_struct work; - struct pid *pid; struct mm_struct *mm; unsigned long diff; struct ib_umem_odp *odp_data;