linux-kernel - Re: [PATCH] kernel/resource: make iomem_resource implicit in release_mem_region

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Date:   Thu, 17 Sep 2020 10:38:09 +0200
From:   Pankaj Gupta <pankaj.gupta.linux@...il.com>
To:     David Hildenbrand <david@...hat.com>
Cc:     LKML <linux-kernel@...r.kernel.org>,
        virtualization@...ts.linux-foundation.org,
        Linux MM <linux-mm@...ck.org>, linux-hyperv@...r.kernel.org,
        xen-devel@...ts.xenproject.org, linux-acpi@...r.kernel.org,
        linux-nvdimm <linux-nvdimm@...ts.01.org>,
        linux-s390@...r.kernel.org,
        Andrew Morton <akpm@...ux-foundation.org>,
        Wei Yang <richard.weiyang@...ux.alibaba.com>,
        Michal Hocko <mhocko@...e.com>,
        Dan Williams <dan.j.williams@...el.com>,
        Jason Gunthorpe <jgg@...pe.ca>,
        Kees Cook <keescook@...omium.org>,
        Ard Biesheuvel <ardb@...nel.org>, Baoquan He <bhe@...hat.com>
Subject: Re: [PATCH] kernel/resource: make iomem_resource implicit in release_mem_region_adjustable()

> "mem" in the name already indicates the root, similar to
> release_mem_region() and devm_request_mem_region(). Make it implicit.
> The only single caller always passes iomem_resource, other parents are
> not applicable.
>
> Suggested-by: Wei Yang <richard.weiyang@...ux.alibaba.com>
> Cc: Andrew Morton <akpm@...ux-foundation.org>
> Cc: Michal Hocko <mhocko@...e.com>
> Cc: Dan Williams <dan.j.williams@...el.com>
> Cc: Jason Gunthorpe <jgg@...pe.ca>
> Cc: Kees Cook <keescook@...omium.org>
> Cc: Ard Biesheuvel <ardb@...nel.org>
> Cc: Pankaj Gupta <pankaj.gupta.linux@...il.com>
> Cc: Baoquan He <bhe@...hat.com>
> Cc: Wei Yang <richard.weiyang@...ux.alibaba.com>
> Signed-off-by: David Hildenbrand <david@...hat.com>
> ---
>
> Based on next-20200915. Follow up on
>         "[PATCH v4 0/8] selective merging of system ram resources" [1]
> That's in next-20200915. As noted during review of v2 by Wei [2].
>
> [1] https://lkml.kernel.org/r/20200911103459.10306-1-david@redhat.com
> [2] https://lkml.kernel.org/r/20200915021012.GC2007@L-31X9LVDL-1304.local
>
> ---
>  include/linux/ioport.h | 3 +--
>  kernel/resource.c      | 5 ++---
>  mm/memory_hotplug.c    | 2 +-
>  3 files changed, 4 insertions(+), 6 deletions(-)
>
> diff --git a/include/linux/ioport.h b/include/linux/ioport.h
> index 7e61389dcb01..5135d4b86cd6 100644
> --- a/include/linux/ioport.h
> +++ b/include/linux/ioport.h
> @@ -251,8 +251,7 @@ extern struct resource * __request_region(struct resource *,
>  extern void __release_region(struct resource *, resource_size_t,
>                                 resource_size_t);
>  #ifdef CONFIG_MEMORY_HOTREMOVE
> -extern void release_mem_region_adjustable(struct resource *, resource_size_t,
> -                                         resource_size_t);
> +extern void release_mem_region_adjustable(resource_size_t, resource_size_t);
>  #endif
>  #ifdef CONFIG_MEMORY_HOTPLUG
>  extern void merge_system_ram_resource(struct resource *res);
> diff --git a/kernel/resource.c b/kernel/resource.c
> index 7a91b935f4c2..ca2a666e4317 100644
> --- a/kernel/resource.c
> +++ b/kernel/resource.c
> @@ -1240,7 +1240,6 @@ EXPORT_SYMBOL(__release_region);
>  #ifdef CONFIG_MEMORY_HOTREMOVE
>  /**
>   * release_mem_region_adjustable - release a previously reserved memory region
> - * @parent: parent resource descriptor
>   * @start: resource start address
>   * @size: resource region size
>   *
> @@ -1258,9 +1257,9 @@ EXPORT_SYMBOL(__release_region);
>   *   assumes that all children remain in the lower address entry for
>   *   simplicity.  Enhance this logic when necessary.
>   */
> -void release_mem_region_adjustable(struct resource *parent,
> -                                  resource_size_t start, resource_size_t size)
> +void release_mem_region_adjustable(resource_size_t start, resource_size_t size)
>  {
> +       struct resource *parent = &iomem_resource;
>         struct resource *new_res = NULL;
>         bool alloc_nofail = false;
>         struct resource **p;
> diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c
> index 553c718226b3..7c5e4744ac51 100644
> --- a/mm/memory_hotplug.c
> +++ b/mm/memory_hotplug.c
> @@ -1764,7 +1764,7 @@ static int __ref try_remove_memory(int nid, u64 start, u64 size)
>                 memblock_remove(start, size);
>         }
>
> -       release_mem_region_adjustable(&iomem_resource, start, size);
> +       release_mem_region_adjustable(start, size);
>
>         try_offline_node(nid);
>

Reviewed-by: Pankaj Gupta <pankaj.gupta.linux@...il.com>