-----Original Message----- From: liulongfang Sent: 21 September 2022 04:13 To: Shameerali Kolothum Thodi shameerali.kolothum.thodi@huawei.com; Jason Gunthorpe jgg@nvidia.com; Alex Williamson alex.williamson@redhat.com Cc: cohuck@redhat.com; linux-kernel@vger.kernel.org; linuxarm@openeuler.org Subject: Re: [PATCH 1/5] hisi_acc_vfio_pci: Fixes a memory leak bug
On 2022/9/21 1:03, Shameerali Kolothum Thodi wrote:
-----Original Message----- From: Jason Gunthorpe [mailto:jgg@nvidia.com] Sent: 20 September 2022 17:38 To: Alex Williamson alex.williamson@redhat.com Cc: liulongfang liulongfang@huawei.com; Shameerali Kolothum Thodi shameerali.kolothum.thodi@huawei.com; cohuck@redhat.com; linux-kernel@vger.kernel.org; linuxarm@openeuler.org Subject: Re: [PATCH 1/5] hisi_acc_vfio_pci: Fixes a memory leak bug
On Tue, Sep 20, 2022 at 10:34:43AM -0600, Alex Williamson wrote:
On Thu, 15 Sep 2022 09:31:53 +0800 Longfang Liu liulongfang@huawei.com wrote:
During the stop copy phase of live migration, the driver allocates a memory for the migrated data to save the data.
When an exception occurs when the driver reads device data, the driver will report an error to qemu and exit the current migration state. But this memory is not released, which will lead to a memory leak problem.
Why isn't it released? The fput() releases it:
static int hisi_acc_vf_release_file(struct inode *inode, struct file *filp) { struct hisi_acc_vf_migration_file *migf = filp->private_data;
hisi_acc_vf_disable_fd(migf); mutex_destroy(&migf->lock); kfree(migf); ^^^^^^^^^^
This patch looks wrong to me.
That's right. Missed that. Sorry of the oversight.
Yes, fput will call release in ops of file, here will call hisi_acc_vf_release_file to complete the release operation of migf, so this patch is unnecessary.
But there is another place that needs to be modified: hisi_acc_vf_disable_fd in hisi_acc_vf_disable_fds is not needed, because it will have an fput next. Is this correct?
I don't think that is correct either. fput() decrements ref count and will only call release() if the count is zero. We have an explicit get_file() for the hisi_acc_vf_disable_fds(). Isn't it?
Thanks, Shameer
Thanks, Shameer
.
Thanks, Longfang.