linux-kernel - Re: [PATCH 1/1] of: reserved_mem: fix reserve memory leak

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Date:   Mon, 4 Mar 2019 10:37:39 -0600
From:   Rob Herring <robh+dt@...nel.org>
To:     pierre Kuo <vichy.kuo@...il.com>,
        Marek Szyprowski <m.szyprowski@...sung.com>
Cc:     Frank Rowand <frowand.list@...il.com>, devicetree@...r.kernel.org,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 1/1] of: reserved_mem: fix reserve memory leak

You should Cc the author(s) of this code. I've added Marek.

On Tue, Feb 19, 2019 at 1:47 AM pierre Kuo <vichy.kuo@...il.com> wrote:
>
> The __reserved_mem_init_node will call region specific reserved memory
> init codes, but once all compatibled init codes failed, the memory region
> will left in memory.reserved and cause leakage.
>
> Take cma reserve memory DTS for example, if user declare 1MB size,
> which is not align to (PAGE_SIZE << max(MAX_ORDER - 1,
> pageblock_order)), rmem_cma_setup will return -EINVAL.
> Meanwhile, rmem_dma_setup will also return -EINVAL since "reusable"
> property is not set. If finally there is no reserved memory init pick up
> this memory, kernel will left the 1MB leak in memory.reserved.
>
> This patch will remove this kind of memory from memory.reserved, only
> when __reserved_mem_init_node return neither 0 nor -ENOENT.

I'm not sure that un-reserving memory on error is the correct
behavior. It may be fine for something like CMA, but if it is some
shared memory used by another processor in the system not reserving it
would probably never be correct.

>
> Signed-off-by: pierre Kuo <vichy.kuo@...il.com>
> ---
>  drivers/of/of_reserved_mem.c | 22 +++++++++++++++++-----
>  1 file changed, 17 insertions(+), 5 deletions(-)
>
> diff --git a/drivers/of/of_reserved_mem.c b/drivers/of/of_reserved_mem.c
> index 1977ee0adcb1..d3bde057ec46 100644
> --- a/drivers/of/of_reserved_mem.c
> +++ b/drivers/of/of_reserved_mem.c
> @@ -181,6 +181,7 @@ static int __init __reserved_mem_init_node(struct reserved_mem *rmem)
>  {
>         extern const struct of_device_id __reservedmem_of_table[];
>         const struct of_device_id *i;
> +       int ret = -ENOENT;
>
>         for (i = __reservedmem_of_table; i < &__rmem_of_table_sentinel; i++) {
>                 reservedmem_of_init_fn initfn = i->data;
> @@ -189,13 +190,14 @@ static int __init __reserved_mem_init_node(struct reserved_mem *rmem)
>                 if (!of_flat_dt_is_compatible(rmem->fdt_node, compat))
>                         continue;
>
> -               if (initfn(rmem) == 0) {
> +               ret = initfn(rmem);
> +               if (ret == 0) {
>                         pr_info("initialized node %s, compatible id %s\n",
>                                 rmem->name, compat);
> -                       return 0;
> +                       break;
>                 }
>         }
> -       return -ENOENT;
> +       return ret;
>  }
>
>  static int __init __rmem_cmp(const void *a, const void *b)
> @@ -255,7 +257,9 @@ void __init fdt_init_reserved_mem(void)
>                 int len;
>                 const __be32 *prop;
>                 int err = 0;
> +               int nomap;
>
> +               nomap = of_get_flat_dt_prop(node, "no-map", NULL) != NULL;
>                 prop = of_get_flat_dt_prop(node, "phandle", &len);
>                 if (!prop)
>                         prop = of_get_flat_dt_prop(node, "linux,phandle", &len);
> @@ -265,8 +269,16 @@ void __init fdt_init_reserved_mem(void)
>                 if (rmem->size == 0)
>                         err = __reserved_mem_alloc_size(node, rmem->name,
>                                                  &rmem->base, &rmem->size);
> -               if (err == 0)
> -                       __reserved_mem_init_node(rmem);
> +               if (err == 0) {
> +                       err = __reserved_mem_init_node(rmem);
> +                       if (err != 0 && err != -ENOENT) {
> +                               pr_info("node %s compatible matching fail\n",
> +                                       rmem->name);
> +                               memblock_free(rmem->base, rmem->size);
> +                               if (nomap)
> +                                       memblock_add(rmem->base, rmem->size);
> +                       }
> +               }
>         }
>  }
>
> --
> 2.17.1
>