Messages in this thread | | | Date | Tue, 22 Feb 2022 08:40:42 +0100 | From | Greg Kroah-Hartman <> | Subject | Re: [PATCH] driver core: Free DMA range map when device is released |
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On Wed, Feb 16, 2022 at 09:45:09AM -0600, Rob Herring wrote: > On Wed, Feb 16, 2022 at 3:42 AM Mårten Lindahl <marten.lindahl@axis.com> wrote: > > > > 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. > > > > Signed-off-by: Mårten Lindahl <marten.lindahl@axis.com> > > Suggested-by: Rob Herring <robh@kernel.org> > Fixes: e0d072782c73 ("dma-mapping: introduce DMA range map, > supplanting dma_pfn_offset") > Reviewed-by: Rob Herring <robh@kernel.org> > > I've got a follow-up patch to refactor the 3 occurrences of this same > deinit code.
Now queued up, so feel free to send the follow-up patch too.
thanks,
greg k-h
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