This is a note to let you know that I've just added the patch titled

driver core: Free DMA range map when device is released

to my driver-core git tree which can be found at git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/driver-core.git in the driver-core-linus branch.

The patch will show up in the next release of the linux-next tree (usually sometime within the next 24 hours during the week.)

The patch will hopefully also be merged in Linus's tree for the next -rc kernel release.

If you have any questions about this process, please let me know.

From d8f7a5484f2188e9af2d9e4e587587d724501b12 Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?M=C3=A5rten=20Lindahl?= marten.lindahl@axis.com Date: Wed, 16 Feb 2022 10:41:28 +0100 Subject: driver core: Free DMA range map when device is released MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit

When unbinding/binding a driver with DMA mapped memory, the DMA map is not freed before the driver is reloaded. This leads to a memory leak when the DMA map is overwritten when reprobing the driver.

This can be reproduced with a platform driver having a dma-range:

dummy { ... #address-cells = <0x2>; #size-cells = <0x2>; ranges; dma-ranges = <...>; ... };

and then unbinding/binding it:

~# echo soc:dummy >/sys/bus/platform/drivers/<driver>/unbind

DMA map object 0xffffff800b0ae540 still being held by &pdev->dev

~# echo soc:dummy >/sys/bus/platform/drivers/<driver>/bind ~# echo scan > /sys/kernel/debug/kmemleak ~# cat /sys/kernel/debug/kmemleak unreferenced object 0xffffff800b0ae540 (size 64): comm "sh", pid 833, jiffies 4295174550 (age 2535.352s) hex dump (first 32 bytes): 00 00 00 80 00 00 00 00 00 00 00 00 00 00 00 00 ................ 00 00 00 80 00 00 00 00 00 00 00 80 00 00 00 00 ................ backtrace: [<ffffffefd1694708>] create_object.isra.0+0x108/0x344 [<ffffffefd1d1a850>] kmemleak_alloc+0x8c/0xd0 [<ffffffefd167e2d0>] __kmalloc+0x440/0x6f0 [<ffffffefd1a960a4>] of_dma_get_range+0x124/0x220 [<ffffffefd1a8ce90>] of_dma_configure_id+0x40/0x2d0 [<ffffffefd198b68c>] platform_dma_configure+0x5c/0xa4 [<ffffffefd198846c>] really_probe+0x8c/0x514 [<ffffffefd1988990>] __driver_probe_device+0x9c/0x19c [<ffffffefd1988cd8>] device_driver_attach+0x54/0xbc [<ffffffefd1986634>] bind_store+0xc4/0x120 [<ffffffefd19856e0>] drv_attr_store+0x30/0x44 [<ffffffefd173c9b0>] sysfs_kf_write+0x50/0x60 [<ffffffefd173c1c4>] kernfs_fop_write_iter+0x124/0x1b4 [<ffffffefd16a013c>] new_sync_write+0xdc/0x160 [<ffffffefd16a256c>] vfs_write+0x23c/0x2a0 [<ffffffefd16a2758>] ksys_write+0x64/0xec

To prevent this we should free the dma_range_map when the device is released.

Fixes: e0d072782c73 ("dma-mapping: introduce DMA range map, supplanting dma_pfn_offset") Cc: stable stable@vger.kernel.org Suggested-by: Rob Herring robh@kernel.org Reviewed-by: Rob Herring robh@kernel.org Signed-off-by: Mårten Lindahl marten.lindahl@axis.com Link: https://lore.kernel.org/r/20220216094128.4025861-1-marten.lindahl@axis.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- drivers/base/dd.c | 5 +++++ 1 file changed, 5 insertions(+)

diff --git a/drivers/base/dd.c b/drivers/base/dd.c index 9eaaff2f556c..f47cab21430f 100644 --- a/drivers/base/dd.c +++ b/drivers/base/dd.c @@ -629,6 +629,9 @@ static int really_probe(struct device *dev, struct device_driver *drv) drv->remove(dev);

devres_release_all(dev); + arch_teardown_dma_ops(dev); + kfree(dev->dma_range_map); + dev->dma_range_map = NULL; driver_sysfs_remove(dev); dev->driver = NULL; dev_set_drvdata(dev, NULL); @@ -1209,6 +1212,8 @@ static void __device_release_driver(struct device *dev, struct device *parent)

devres_release_all(dev); arch_teardown_dma_ops(dev); + kfree(dev->dma_range_map); + dev->dma_range_map = NULL; dev->driver = NULL; dev_set_drvdata(dev, NULL); if (dev->pm_domain && dev->pm_domain->dismiss)