Messages in this thread | | | Date | Thu, 17 Aug 2023 15:49:49 +0100 | Subject | Re: [PATCH 2/2] coresight: core: fix memory leak in dict->fwnode_list | From | Suzuki K Poulose <> |
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On 17/08/2023 15:46, James Clark wrote: > > > On 17/08/2023 15:39, Suzuki K Poulose wrote: >> On 17/08/2023 09:59, Junhao He wrote: >>> There are memory leaks reported by kmemleak: >>> ... >>> unreferenced object 0xffff2020103c3200 (size 256): >>> comm "insmod", pid 4476, jiffies 4294978252 (age 50072.536s) >>> hex dump (first 32 bytes): >>> 10 60 40 06 28 20 ff ff 10 c0 59 06 20 20 ff ff .`@.( ....Y. .. >>> 10 e0 47 06 28 20 ff ff 10 00 49 06 28 20 ff ff ..G.( ....I.( .. >>> backtrace: >>> [<0000000034ec4724>] __kmem_cache_alloc_node+0x2f8/0x348 >>> [<0000000057fbc15d>] __kmalloc_node_track_caller+0x5c/0x110 >>> [<00000055d5e34b>] krealloc+0x8c/0x178 >>> [<00000000a4635beb>] coresight_alloc_device_name+0x128/0x188 >>> [coresight] >>> [<00000000a92ddfee>] funnel_cs_ops+0x10/0xfffffffffffedaa0 >>> [coresight_funnel] >>> [<00000000449e20f8>] dynamic_funnel_ids+0x80/0xfffffffffffed840 >>> [coresight_funnel] >>> ... >>> >>> when remove driver, the golab variables defined by the macro >>> DEFINE_CORESIGHT_DEVLIST will be released, dict->nr_idx and >>> dict->fwnode_list are cleared to 0. The lifetime of the golab >>> variable has ended. So the buffer pointer is lost. >>> >>> Use the callback of devm_add_action_or_reset() to free memory. >> >> Thanks for the report. But please see below: >> >>> >>> Fixes: 0f5f9b6ba9e1 ("coresight: Use platform agnostic names") >>> Signed-off-by: Junhao He <hejunhao3@huawei.com> >>> --- >>> drivers/hwtracing/coresight/coresight-core.c | 20 +++++++++++++++++++- >>> 1 file changed, 19 insertions(+), 1 deletion(-) >>> >>> diff --git a/drivers/hwtracing/coresight/coresight-core.c >>> b/drivers/hwtracing/coresight/coresight-core.c >>> index 9fabe00a40d6..6849faad697d 100644 >>> --- a/drivers/hwtracing/coresight/coresight-core.c >>> +++ b/drivers/hwtracing/coresight/coresight-core.c >>> @@ -1756,6 +1756,20 @@ bool coresight_loses_context_with_cpu(struct >>> device *dev) >>> } >>> EXPORT_SYMBOL_GPL(coresight_loses_context_with_cpu); >>> +void coresight_release_dev_list(void *data) >>> +{ >>> + struct coresight_dev_list *dict = data; >>> + >>> + mutex_lock(&coresight_mutex); >>> + >>> + if (dict->nr_idx) { >>> + kfree(dict->fwnode_list); >>> + dict->nr_idx = 0; >>> + } >>> + >>> + mutex_unlock(&coresight_mutex); >>> +} >>> + >>> /* >>> * coresight_alloc_device_name - Get an index for a given device in the >>> * device index list specific to a driver. An index is allocated for a >>> @@ -1766,12 +1780,16 @@ >>> EXPORT_SYMBOL_GPL(coresight_loses_context_with_cpu); >>> char *coresight_alloc_device_name(struct coresight_dev_list *dict, >>> struct device *dev) >>> { >>> - int idx; >>> + int idx, ret; >>> char *name = NULL; >>> struct fwnode_handle **list; >>> mutex_lock(&coresight_mutex); >>> + ret = devm_add_action_or_reset(dev, coresight_release_dev_list, >>> dict); >>> + if (ret) >>> + goto done; >> >> This looks wrong. The devlist should be only released on the "driver" >> unload, not on every device release. The list retains the fwnode to >> assign the same name for a device, if it is re-probed (e.g., due to >> -EPROBE_DEFER error). >> >> Suzuki >> > > I think in that case my suggestion to change it to devm_krealloc_array > might be wrong then. Probably worth putting an explicit comment there in > case someone tries to tidy up all the non devm allocators to devm ones. > > But how do you release a single device without releasing the whole driver?
You could unbind a device from the driver and that will make another driver probe it. I know it works for PCI/platform with VFIO.
Suzuki
> > James
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