linux-kernel - Re: [PATCH v2 1/8] coresight: Fix memory leak in coresight_alloc_device

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Message-ID: <062c51c2-082d-4771-83df-3e5bfa90927d@arm.com>
Date: Mon, 26 Jan 2026 15:48:28 +0000
From: Suzuki K Poulose <suzuki.poulose@....com>
To: Leo Yan <leo.yan@....com>, Mike Leach <mike.leach@...aro.org>,
 James Clark <james.clark@...aro.org>,
 Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
 Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
 Mathieu Poirier <mathieu.poirier@...aro.org>,
 Mao Jinlong <quic_jinlmao@...cinc.com>
Cc: coresight@...ts.linaro.org, linux-arm-kernel@...ts.infradead.org,
 linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2 1/8] coresight: Fix memory leak in
 coresight_alloc_device_name()

Hi Leo

On 26/01/2026 13:52, Leo Yan wrote:
> The memory leak detector reports:
> 
>    echo clear > /sys/kernel/debug/kmemleak
>    modprobe coresight_funnel
>    rmmod coresight_funnel
> 
>    # Scan memory leak and report it
>    echo scan > /sys/kernel/debug/kmemleak
>    cat /sys/kernel/debug/kmemleak
>    unreferenced object 0xffff0008020c7200 (size 64):
>      comm "modprobe", pid 410, jiffies 4295333721
>      hex dump (first 32 bytes):
>        d8 da fe 7e 09 00 ff ff e8 2e ff 7e 09 00 ff ff  ...~.......~....
>        b0 6c ff 7e 09 00 ff ff 30 83 00 7f 09 00 ff ff  .l.~....0.......
>      backtrace (crc 4116a690):
>        kmemleak_alloc+0xd8/0xf8
>        __kmalloc_node_track_caller_noprof+0x2c8/0x6f0
>        krealloc_node_align_noprof+0x13c/0x2c8
>        coresight_alloc_device_name+0xe4/0x158 [coresight]
>        0xffffd327ecef8394
>        0xffffd327ecef85ec
>        amba_probe+0x118/0x1c8
>        really_probe+0xc8/0x3f0
>        __driver_probe_device+0x88/0x190
>        driver_probe_device+0x44/0x120
>        __driver_attach+0x100/0x238
>        bus_for_each_dev+0x84/0xf0
>        driver_attach+0x2c/0x40
>        bus_add_driver+0x128/0x258
>        driver_register+0x64/0x138
>        __amba_driver_register+0x2c/0x48
> 
> Change to use devm_krealloc_array() for allocation fwnode_list so that
> the device model can automatically release the memory when the module
> is unloaded.
> 
> Fixes: 0f5f9b6ba9e1 ("coresight: Use platform agnostic names")
> Signed-off-by: Leo Yan <leo.yan@....com>
> ---
>   drivers/hwtracing/coresight/coresight-core.c | 2 +-
>   1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/hwtracing/coresight/coresight-core.c b/drivers/hwtracing/coresight/coresight-core.c
> index c660cf8adb1c7cafff8f85e501f056e4e151e372..ed304f292b7b02e89c59053d43f88fbf663cc993 100644
> --- a/drivers/hwtracing/coresight/coresight-core.c
> +++ b/drivers/hwtracing/coresight/coresight-core.c
> @@ -1546,7 +1546,7 @@ char *coresight_alloc_device_name(struct coresight_dev_list *dict,
>   	if (idx < 0) {
>   		/* Make space for the new entry */
>   		idx = dict->nr_idx;
> -		list = krealloc_array(dict->fwnode_list,
> +		list = devm_krealloc_array(dev, dict->fwnode_list,
>   				      idx + 1, sizeof(*dict->fwnode_list),

This is wrong. This would mean, the array gets released when the "dev" 
goes away and thats not good. This is a per-driver list, not a 
per-device list. Also, please remember that, we need to keep that node alive
when the device goes away, to make sure to allocate the same device name
when if/it comes back.  May be, you could release the  list and array, 
when the "driver" goes away.


Kind regards
Suzuki

>   				      GFP_KERNEL);
>   		if (ZERO_OR_NULL_PTR(list)) {
>