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Subject[PATCH 4.14 020/496] IB/umem: Use the correct mm during ib_umem_release
Date
4.14-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Lidong Chen <jemmy858585@gmail.com>

commit 8e907ed4882714fd13cfe670681fc6cb5284c780 upstream.

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>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
drivers/infiniband/core/umem.c | 7 +------
include/rdma/ib_umem.h | 1 -
2 files changed, 1 insertion(+), 7 deletions(-)

--- a/drivers/infiniband/core/umem.c
+++ b/drivers/infiniband/core/umem.c
@@ -119,7 +119,6 @@ struct ib_umem *ib_umem_get(struct ib_uc
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_uc
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_uc

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 @@ out:
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 *ume

__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);
--- 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;

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