Received-SPF: pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) client-ip=209.132.180.67;
From:   Ajay Kaher <akaher@vmware.com>
To:     <aarcange@redhat.com>, <jannh@google.com>, <oleg@redhat.com>,
        <peterx@redhat.com>, <rppt@linux.ibm.com>, <jgg@mellanox.com>,
        <mhocko@suse.com>
CC:     <jglisse@redhat.com>, <akpm@linux-foundation.org>,
        <mike.kravetz@oracle.com>, <viro@zeniv.linux.org.uk>,
        <riandrews@android.com>, <arve@android.com>,
        <yishaih@mellanox.com>, <dledford@redhat.com>,
        <sean.hefty@intel.com>, <hal.rosenstock@gmail.com>,
        <matanb@mellanox.com>, <leonro@mellanox.com>,
        <linux-fsdevel@vger.kernel.org>, <linux-mm@kvack.org>,
        <devel@driverdev.osuosl.org>, <linux-rdma@vger.kernel.org>,
        <linux-kernel@vger.kernel.org>, <stable@vger.kernel.org>,
        <akaher@vmware.com>, <srivatsab@vmware.com>, <amakhalov@vmware.com>
Subject: [PATCH v4 2/3][v4.9.y] coredump: fix race condition between mmget_not_zero()/get_task_mm() and core dumping
Date:   Tue, 25 Jun 2019 02:33:04 +0530
Message-ID: <1561410186-3919-2-git-send-email-akaher@vmware.com>
In-Reply-To: <1561410186-3919-1-git-send-email-akaher@vmware.com>
References: <1561410186-3919-1-git-send-email-akaher@vmware.com>
MIME-Version: 1.0
Content-Type: text/plain
Received-SPF: None (EX13-EDG-OU-002.vmware.com: akaher@vmware.com does not
 designate permitted sender hosts)
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

This patch is the extension of following upstream commit to fix
the race condition between get_task_mm() and core dumping
for IB->mlx4 and IB->mlx5 drivers:

commit 04f5866e41fb ("coredump: fix race condition between
mmget_not_zero()/get_task_mm() and core dumping")'

Thanks to Jason for pointing this.

Signed-off-by: Ajay Kaher <akaher@vmware.com>
---
 drivers/infiniband/hw/mlx4/main.c | 4 +++-
 drivers/infiniband/hw/mlx5/main.c | 3 +++
 2 files changed, 6 insertions(+), 1 deletion(-)

diff --git a/drivers/infiniband/hw/mlx4/main.c b/drivers/infiniband/hw/mlx4/main.c
index 8d59a59..7ccf722 100644
--- a/drivers/infiniband/hw/mlx4/main.c
+++ b/drivers/infiniband/hw/mlx4/main.c
@@ -1172,6 +1172,8 @@ static void mlx4_ib_disassociate_ucontext(struct ib_ucontext *ibcontext)
 	 * mlx4_ib_vma_close().
 	 */
 	down_write(&owning_mm->mmap_sem);
+	if (!mmget_still_valid(owning_mm))
+		goto skip_mm;
 	for (i = 0; i < HW_BAR_COUNT; i++) {
 		vma = context->hw_bar_info[i].vma;
 		if (!vma)
@@ -1190,7 +1192,7 @@ static void mlx4_ib_disassociate_ucontext(struct ib_ucontext *ibcontext)
 		/* context going to be destroyed, should not access ops any more */
 		context->hw_bar_info[i].vma->vm_ops = NULL;
 	}
-
+skip_mm:
 	up_write(&owning_mm->mmap_sem);
 	mmput(owning_mm);
 	put_task_struct(owning_process);
diff --git a/drivers/infiniband/hw/mlx5/main.c b/drivers/infiniband/hw/mlx5/main.c
index b1daf5c..f94df0e 100644
--- a/drivers/infiniband/hw/mlx5/main.c
+++ b/drivers/infiniband/hw/mlx5/main.c
@@ -1307,6 +1307,8 @@ static void mlx5_ib_disassociate_ucontext(struct ib_ucontext *ibcontext)
 	 * mlx5_ib_vma_close.
 	 */
 	down_write(&owning_mm->mmap_sem);
+	if (!mmget_still_valid(owning_mm))
+		goto skip_mm;
 	list_for_each_entry_safe(vma_private, n, &context->vma_private_list,
 				 list) {
 		vma = vma_private->vma;
@@ -1321,6 +1323,7 @@ static void mlx5_ib_disassociate_ucontext(struct ib_ucontext *ibcontext)
 		list_del(&vma_private->list);
 		kfree(vma_private);
 	}
+skip_mm:
 	up_write(&owning_mm->mmap_sem);
 	mmput(owning_mm);
 	put_task_struct(owning_process);
-- 
2.7.4