Re: [PATCH 2/6] dmaengine: idxd: fix duplicate memory frees on initialization error path

[Frank Li <Frank.li@oss.nxp.com>]

On Mon, Oct 12, 2026 at 02:38:05PM -0700, Vinicius Costa Gomes wrote:
> From: Steve Wahl <steve.wahl@hpe.com>
>
> Error paths within idxd_pci_probe_alloc and related functions end

idxd_pci_probe_alloc(), check other commit message.

Frank

> attempting to free memory already freed from idxd_conf_device_release
> via put_device.
>
> This was encountered running in a kexec'd kdump kernel with reduced
> resources, causing the "Device is HALTED!" branch in
> idxd_device_init_reset to be taken.
>
> [   18.628791] idxd 0000:00:01.0: Device is HALTED!
> [   18.631447] idxd 0000:00:01.0: Intel(R) IDXD DMA Engine init failed
> [   18.631450] ------------[ cut here ]------------
> [   18.631451] ida_free called for id=0 which is not allocated.
> [   18.631462] WARNING: CPU: 0 PID: 11 at lib/idr.c:525 ida_free+0xd3/0x130
> [   18.631474] CPU: 0 UID: 0 PID: 11 Comm: kworker/0:1 Not tainted 6.12.0-1-rt-amd64 #1
> [   18.631477] Hardware name: Dell Inc. PowerEdge XR8720t/0J91KV, BIOS 1.1.3 02/03/2026
> [   18.631478] Workqueue: events work_for_cpu_fn
> [   18.631480] RIP: 0010:ida_free+0xd3/0x130
> [   18.631492] Call Trace:
> [   18.631494]  <TASK>
> [   18.631495]  idxd_pci_probe+0x1b0/0x1860 [idxd]
> [   18.631506]  local_pci_probe+0x43/0xa0
> [   18.631508]  work_for_cpu_fn+0x13/0x20
> [   18.631510]  process_one_work+0x179/0x390
> [   18.631512]  worker_thread+0x237/0x340
> [   18.631517]  kthread+0xc6/0x100
> [   18.631520]  ret_from_fork+0x2d/0x50
> [   18.631524]  ret_from_fork_asm+0x1a/0x30
> [   18.631526]  </TASK>
>
> In idxd_free and idxd_alloc, do not attempt to free allocations that
> will already have been freed.
>
> Fixes: 90022b3a6981 ("dmaengine: idxd: fix memory leak in error handling path of idxd_pci_probe")
> Fixes: 46a5cca76c76 ("dmaengine: idxd: fix memory leak in error handling path of idxd_alloc")
> Reported-by: Bogdan Codres <bogdan.codres@windriver.com>
> Link: https://lore.kernel.org/all/akLBL7b2h73pK0AC@ilogsc-qemu.local/
> Signed-off-by: Steve Wahl <steve.wahl@hpe.com>
> ---
>  drivers/dma/idxd/init.c | 10 ++++++----
>  1 file changed, 6 insertions(+), 4 deletions(-)
>
> diff --git a/drivers/dma/idxd/init.c b/drivers/dma/idxd/init.c
> index 4b827a329756..4adb3f3bcd01 100644
> --- a/drivers/dma/idxd/init.c
> +++ b/drivers/dma/idxd/init.c
> @@ -581,9 +581,6 @@ static void idxd_free(struct idxd_device *idxd)
>  		return;
>
>  	put_device(idxd_confdev(idxd));
> -	bitmap_free(idxd->opcap_bmap);
> -	ida_free(&idxd_ida, idxd->id);
> -	kfree(idxd);
>  }
>
>  static struct idxd_device *idxd_alloc(struct pci_dev *pdev, struct idxd_driver_data *data)
> @@ -623,8 +620,13 @@ static struct idxd_device *idxd_alloc(struct pci_dev *pdev, struct idxd_driver_d
>  	return idxd;
>
>  err_name:
> +	/*
> +	 * once device_initialize(conf_dev) is called,
> +	 * put_device(conf_dev) will end up calling
> +	 * idxd_conf_device_release() which will free the rest.
> +	 */
>  	put_device(conf_dev);
> -	bitmap_free(idxd->opcap_bmap);
> +	return NULL;
>  err_opcap:
>  	ida_free(&idxd_ida, idxd->id);
>  err_ida:
>
> --
> 2.56.0
>