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Subject: Re: [PATCH 1/3] lightnvm: use internal allocation for chunk log page
To:     hans.ml.holmberg@owltronix.com, javier@javigon.com
Cc:     igor.j.konopko@intel.com, marcin.dziegielewski@intel.com,
        linux-block@vger.kernel.org, linux-kernel@vger.kernel.org,
        javier@cnexlabs.com
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From:   =?UTF-8?Q?Matias_Bj=c3=b8rling?= <mb@lightnvm.io>
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Date:   Fri, 7 Sep 2018 17:12:40 +0200
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On 09/07/2018 02:53 PM, Hans Holmberg wrote:
> On Wed, Aug 29, 2018 at 12:10 PM Javier González <javier@javigon.com> wrote:
>>
>> The lightnvm subsystem provides helpers to retrieve chunk metadata,
>> where the target needs to provide a buffer to store the metadata. An
>> implicit assumption is that this buffer is contiguous and can be used to
>> retrieve the data from the device. If the device exposes too many
>> chunks, then kmalloc might fail, thus failing instance creation.
>>
>> This patch removes this assumption by implementing an internal buffer in
>> the lightnvm subsystem to retrieve chunk metadata. Targets can then
>> use virtual memory allocations. Since this is a target API change, adapt
>> pblk accordingly.
>>
>> Signed-off-by: Javier González <javier@cnexlabs.com>
>> ---
>>   drivers/lightnvm/pblk-core.c |  4 ++--
>>   drivers/lightnvm/pblk-init.c |  2 +-
>>   drivers/nvme/host/lightnvm.c | 23 +++++++++++++++--------
>>   3 files changed, 18 insertions(+), 11 deletions(-)
>>
>> diff --git a/drivers/lightnvm/pblk-core.c b/drivers/lightnvm/pblk-core.c
>> index fdcbeb920c9e..a311cc29afd8 100644
>> --- a/drivers/lightnvm/pblk-core.c
>> +++ b/drivers/lightnvm/pblk-core.c
>> @@ -120,7 +120,7 @@ static void pblk_end_io_erase(struct nvm_rq *rqd)
>>   /*
>>    * Get information for all chunks from the device.
>>    *
>> - * The caller is responsible for freeing the returned structure
>> + * The caller is responsible for freeing (vmalloc) the returned structure
>>    */
>>   struct nvm_chk_meta *pblk_get_chunk_meta(struct pblk *pblk)
>>   {
>> @@ -134,7 +134,7 @@ struct nvm_chk_meta *pblk_get_chunk_meta(struct pblk *pblk)
>>          ppa.ppa = 0;
>>
>>          len = geo->all_chunks * sizeof(*meta);
>> -       meta = kzalloc(len, GFP_KERNEL);
>> +       meta = vzalloc(len);
>>          if (!meta)
>>                  return ERR_PTR(-ENOMEM);
>>
>> diff --git a/drivers/lightnvm/pblk-init.c b/drivers/lightnvm/pblk-init.c
>> index e0db6de137d6..a99854439224 100644
>> --- a/drivers/lightnvm/pblk-init.c
>> +++ b/drivers/lightnvm/pblk-init.c
>> @@ -983,7 +983,7 @@ static int pblk_lines_init(struct pblk *pblk)
>>
>>          pblk_set_provision(pblk, nr_free_chks);
>>
>> -       kfree(chunk_meta);
>> +       vfree(chunk_meta);
>>          return 0;
>>
>>   fail_free_lines:
>> diff --git a/drivers/nvme/host/lightnvm.c b/drivers/nvme/host/lightnvm.c
>> index 2c96e7fcdcac..5bfa354c5dd5 100644
>> --- a/drivers/nvme/host/lightnvm.c
>> +++ b/drivers/nvme/host/lightnvm.c
>> @@ -579,7 +579,7 @@ static int nvme_nvm_get_chk_meta(struct nvm_dev *ndev,
>>          struct nvm_geo *geo = &ndev->geo;
>>          struct nvme_ns *ns = ndev->q->queuedata;
>>          struct nvme_ctrl *ctrl = ns->ctrl;
>> -       struct nvme_nvm_chk_meta *dev_meta = (struct nvme_nvm_chk_meta *)meta;
>> +       struct nvme_nvm_chk_meta *dev_meta, *dev_meta_off;
>>          struct ppa_addr ppa;
>>          size_t left = nchks * sizeof(struct nvme_nvm_chk_meta);
>>          size_t log_pos, offset, len;
>> @@ -591,6 +591,10 @@ static int nvme_nvm_get_chk_meta(struct nvm_dev *ndev,
>>           */
>>          max_len = min_t(unsigned int, ctrl->max_hw_sectors << 9, 256 * 1024);
>>
>> +       dev_meta = kmalloc(max_len, GFP_KERNEL);
>> +       if (!dev_meta)
>> +               return -ENOMEM;
> 
> We should free the memory after using it. Pardon the late review, I
> just now discovered the memory leak during testing.

Thanks Hans. No worries, I saw it just when I had ack'ed the patch. 
Would you like me to add your Reviewed-by?

> 
>> +
>>          /* Normalize lba address space to obtain log offset */
>>          ppa.ppa = slba;
>>          ppa = dev_to_generic_addr(ndev, ppa);
>> @@ -604,6 +608,9 @@ static int nvme_nvm_get_chk_meta(struct nvm_dev *ndev,
>>          while (left) {
>>                  len = min_t(unsigned int, left, max_len);
>>
>> +               memset(dev_meta, 0, max_len);
>> +               dev_meta_off = dev_meta;
>> +
>>                  ret = nvme_get_log_ext(ctrl, ns, NVME_NVM_LOG_REPORT_CHUNK,
>>                                  dev_meta, len, offset);
>>                  if (ret) {
>> @@ -612,15 +619,15 @@ static int nvme_nvm_get_chk_meta(struct nvm_dev *ndev,
>>                  }
>>
>>                  for (i = 0; i < len; i += sizeof(struct nvme_nvm_chk_meta)) {
>> -                       meta->state = dev_meta->state;
>> -                       meta->type = dev_meta->type;
>> -                       meta->wi = dev_meta->wi;
>> -                       meta->slba = le64_to_cpu(dev_meta->slba);
>> -                       meta->cnlb = le64_to_cpu(dev_meta->cnlb);
>> -                       meta->wp = le64_to_cpu(dev_meta->wp);
>> +                       meta->state = dev_meta_off->state;
>> +                       meta->type = dev_meta_off->type;
>> +                       meta->wi = dev_meta_off->wi;
>> +                       meta->slba = le64_to_cpu(dev_meta_off->slba);
>> +                       meta->cnlb = le64_to_cpu(dev_meta_off->cnlb);
>> +                       meta->wp = le64_to_cpu(dev_meta_off->wp);
>>
>>                          meta++;
>> -                       dev_meta++;
>> +                       dev_meta_off++;
>>                  }
>>
>>                  offset += len;
>> --
>> 2.7.4
>>