linux-kernel - Re: [PATCH 1/3] lightnvm: use internal allocation for chunk log page

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Message-ID: <CANr-nt0DBCSux=acwkOohFy4BsG7KgzHKH_KA+OG3Y_h7ee1Qw@mail.gmail.com>
Date:   Fri, 7 Sep 2018 14:53:25 +0200
From:   Hans Holmberg <hans.ml.holmberg@...tronix.com>
To:     Javier González <javier@...igon.com>
Cc:     Matias Bjorling <mb@...htnvm.io>, igor.j.konopko@...el.com,
        marcin.dziegielewski@...el.com, linux-block@...r.kernel.org,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        Javier Gonzalez <javier@...xlabs.com>
Subject: Re: [PATCH 1/3] lightnvm: use internal allocation for chunk log page

On Wed, Aug 29, 2018 at 12:10 PM Javier González <javier@...igon.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@...xlabs.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.

> +
>         /* 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
>