linux-kernel - [PATCH v2] IB/umem: ib_ucontext already have tgid, remove pid from ib

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Message-Id: <1525769416-14596-1-git-send-email-lidongchen@tencent.com>
Date:   Tue,  8 May 2018 16:50:16 +0800
From:   Lidong Chen <jemmy858585@...il.com>
To:     dledford@...hat.com, jgg@...pe.ca, akpm@...ux-foundation.org,
        qing.huang@...cle.com, leon@...nel.org, artemyko@...lanox.com,
        dan.j.williams@...el.com
Cc:     linux-rdma@...r.kernel.org, linux-kernel@...r.kernel.org,
        adido@...lanox.com, galsha@...lanox.com, aviadye@...lanox.com,
        Lidong Chen <lidongchen@...cent.com>
Subject: [PATCH v2] IB/umem: ib_ucontext already have tgid, remove pid from ib_umem structure

The userspace may invoke ibv_reg_mr and ibv_dereg_mr by different threads.
If when ibv_dereg_mr invoke and the thread which invoked ibv_reg_mr has
exited, get_pid_task will return NULL, ib_umem_release does not decrease
mm->pinned_vm. This patch fixes it by use tgid in ib_ucontext struct.

Signed-off-by: Lidong Chen <lidongchen@...cent.com>
---
 [v2]
 - use ib_ucontext tgid instread of tgid in ib_umem structure
 
 drivers/infiniband/core/umem.c | 7 +------
 include/rdma/ib_umem.h         | 1 -
 2 files changed, 1 insertion(+), 7 deletions(-)

diff --git a/drivers/infiniband/core/umem.c b/drivers/infiniband/core/umem.c
index 9a4e899..2b6c9b5 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 23159dd..a1fd638 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;
-- 
1.8.3.1