linux-kernel - Re: [RESEND PATCH] drivers/base: kmemleak ignore a known leak

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Message-ID: <20181206175949.GR54495@arrakis.emea.arm.com>
Date:   Thu, 6 Dec 2018 17:59:49 +0000
From:   Catalin Marinas <catalin.marinas@....com>
To:     Qian Cai <cai@....us>
Cc:     akpm@...ux-foundation.org, gregkh@...uxfoundation.org,
        rafael@...nel.org, linux-kernel@...r.kernel.org
Subject: Re: [RESEND PATCH] drivers/base: kmemleak ignore a known leak

On Thu, Dec 06, 2018 at 11:07:51AM -0500, Qian Cai wrote:
> unreferenced object 0xffff808ec6dc5a80 (size 128):
>   comm "swapper/0", pid 1, jiffies 4294938063 (age 2560.530s)
>   hex dump (first 32 bytes):
>     ff ff ff ff 00 00 00 00 6b 6b 6b 6b 6b 6b 6b 6b  ........kkkkkkkk
>     6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b  kkkkkkkkkkkkkkkk
>   backtrace:
>     [<00000000476dcf8c>] kmem_cache_alloc_trace+0x430/0x500
>     [<000000004f708d37>] platform_device_register_full+0xbc/0x1e8
>     [<000000006c2a7ec7>] acpi_create_platform_device+0x370/0x450
>     [<00000000ef135642>] acpi_default_enumeration+0x34/0x78
>     [<000000003bd9a052>] acpi_bus_attach+0x2dc/0x3e0
>     [<000000003cf4f7f2>] acpi_bus_attach+0x108/0x3e0
>     [<000000003cf4f7f2>] acpi_bus_attach+0x108/0x3e0
>     [<000000002968643e>] acpi_bus_scan+0xb0/0x110
>     [<0000000010dd0bd7>] acpi_scan_init+0x1a8/0x410
>     [<00000000965b3c5a>] acpi_init+0x408/0x49c
>     [<00000000ed4b9fe2>] do_one_initcall+0x178/0x7f4
>     [<00000000a5ac5a74>] kernel_init_freeable+0x9d4/0xa9c
>     [<0000000070ea6c15>] kernel_init+0x18/0x138
>     [<00000000fb8fff06>] ret_from_fork+0x10/0x1c
>     [<0000000041273a0d>] 0xffffffffffffffff
> 
> Then, faddr2line pointed out this line,
> 
> /*
>  * This memory isn't freed when the device is put,
>  * I don't have a nice idea for that though.  Conceptually
>  * dma_mask in struct device should not be a pointer.
>  * See http://thread.gmane.org/gmane.linux.kernel.pci/9081
>  */
> pdev->dev.dma_mask =
> 	kmalloc(sizeof(*pdev->dev.dma_mask), GFP_KERNEL);
> 
> Since this leak has been existed for more than 8-year now and it does not
> reference other part of the memory, let kmemleak ignore it, so users don't
> need to waste time reporting this in the future.
> 
> Signed-off-by: Qian Cai <cai@....us>

Acked-by: Catalin Marinas <catalin.marinas@....com>