On 26/07/2024 21:37, Ira Weiny wrote:
> Li Zhijian wrote:
>> The leakage would happend when create_namespace_pmem() meets an invalid
>> label which gets failure in validating isetcookie.
>>
>> Try to resuse the devs that may have already been allocated with size
>> (2 * sizeof(dev)) previously.
>>
>> A kmemleak reports:
>> unreferenced object 0xffff88800dda1980 (size 16):
>> comm "kworker/u10:5", pid 69, jiffies 4294671781
>> hex dump (first 16 bytes):
>> 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................
>> backtrace (crc 0):
>> [<00000000c5dea560>] __kmalloc+0x32c/0x470
>> [<000000009ed43c83>] nd_region_register_namespaces+0x6fb/0x1120
>> [libnvdimm]
>> [<000000000e07a65c>] nd_region_probe+0xfe/0x210 [libnvdimm]
>> [<000000007b79ce5f>] nvdimm_bus_probe+0x7a/0x1e0 [libnvdimm]
>> [<00000000a5f3da2e>] really_probe+0xc6/0x390
>> [<00000000129e2a69>] __driver_probe_device+0x78/0x150
>> [<000000002dfed28b>] driver_probe_device+0x1e/0x90
>> [<00000000e7048de2>] __device_attach_driver+0x85/0x110
>> [<0000000032dca295>] bus_for_each_drv+0x85/0xe0
>> [<00000000391c5a7d>] __device_attach+0xbe/0x1e0
>> [<0000000026dabec0>] bus_probe_device+0x94/0xb0
>> [<00000000c590d936>] device_add+0x656/0x870
>> [<000000003d69bfaa>] nd_async_device_register+0xe/0x50 [libnvdimm]
>> [<000000003f4c52a4>] async_run_entry_fn+0x2e/0x110
>> [<00000000e201f4b0>] process_one_work+0x1ee/0x600
>> [<000000006d90d5a9>] worker_thread+0x183/0x350
>>
>> Cc: Dave Jiang <dave.ji...@intel.com>
>> Cc: Ira Weiny <ira.we...@intel.com>
>> Fixes: 1b40e09a1232 ("libnvdimm: blk labels and namespace instantiation")
>
> What is the bigger effect the user will see?
*Users* cannot use this pmem until they zero-label the device.
In my understanding, once the leakage occurs, there is no way to reclaim the
memory until reboot
>
> Does this cause a long term user effect? For example, if a users system
> has a bad label I think this is going to be a pretty minor memory leak
> which just hangs around until reboot, correct?
>
>> Signed-off-by: Li Zhijian <lizhij...@fujitsu.com>
>> ---
>>
>> Cc: Ira Weiny <ira.we...@intel.com>
>>> From what I can tell create_namespace_pmem() must be returning EAGAIN
>>> which leaves devs allocated but fails to increment count. Thus there are
>>> no valid labels but devs was not free'ed.
>>
>>> Can you trace the error you are seeing a bit more to see if this is the
>>> case?
>> Hi Ira, Sorry for the late reply. I have reproduced it these days.
>> Yeah, the LSA is containing a label in which the isetcookie is invalid.
>
> NP, sometimes it takes a while to really debug something.
>
>>
>> V2:
>> update description and comment
>> ---
>> drivers/nvdimm/namespace_devs.c | 8 +++++++-
>> 1 file changed, 7 insertions(+), 1 deletion(-)
>>
>> diff --git a/drivers/nvdimm/namespace_devs.c
>> b/drivers/nvdimm/namespace_devs.c
>> index d6d558f94d6b..28c9afc01dca 100644
>> --- a/drivers/nvdimm/namespace_devs.c
>> +++ b/drivers/nvdimm/namespace_devs.c
>> @@ -1994,7 +1994,13 @@ static struct device **scan_labels(struct nd_region
>> *nd_region)
>> /* Publish a zero-sized namespace for userspace to configure. */
>> nd_mapping_free_labels(nd_mapping);
>>
>> - devs = kcalloc(2, sizeof(dev), GFP_KERNEL);
>> + /*
>> + * Try to use the devs that may have already been allocated
>> + * above first. This would happend when create_namespace_pmem()
>> + * meets an invalid label.
>> + */
>> + if (!devs)
>> + devs = kcalloc(2, sizeof(dev), GFP_KERNEL);
>
> I'm still tempted to try and fix the count but I think this will work.
I cannot get your *fix the count* ?
Does "fix the count*" means to free the devs in the case of error cases:
$ git diff
diff --git a/drivers/nvdimm/namespace_devs.c b/drivers/nvdimm/namespace_devs.c
index 28c9afc01dca..3fae00a05ad7 100644
--- a/drivers/nvdimm/namespace_devs.c
+++ b/drivers/nvdimm/namespace_devs.c
@@ -1970,6 +1970,10 @@ static struct device **scan_labels(struct nd_region
*nd_region)
dev = create_namespace_pmem(nd_region, nd_mapping, nd_label);
if (IS_ERR(dev)) {
+ if (!count) {
+ kfree(devs);
+ devs = NULL;
+ }
> Let me know about the severity of the issue.
>
> Ira
>
>> if (!devs)
>> goto err;
>>
>> --
>> 2.29.2
>>
>
>
>
