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Message-ID: <20170417201235.GA6511@redhat.com>
Date: Mon, 17 Apr 2017 16:12:35 -0400
From: Jerome Glisse <jglisse@...hat.com>
To: Michal Hocko <mhocko@...nel.org>
Cc: linux-mm@...ck.org, Andrew Morton <akpm@...ux-foundation.org>,
Mel Gorman <mgorman@...e.de>, Vlastimil Babka <vbabka@...e.cz>,
Andrea Arcangeli <aarcange@...hat.com>,
Reza Arbab <arbab@...ux.vnet.ibm.com>,
Yasuaki Ishimatsu <yasu.isimatu@...il.com>,
qiuxishi@...wei.com, Kani Toshimitsu <toshi.kani@....com>,
slaoub@...il.com, Joonsoo Kim <js1304@...il.com>,
Andi Kleen <ak@...ux.intel.com>,
David Rientjes <rientjes@...gle.com>,
Daniel Kiper <daniel.kiper@...cle.com>,
Igor Mammedov <imammedo@...hat.com>,
Vitaly Kuznetsov <vkuznets@...hat.com>,
LKML <linux-kernel@...r.kernel.org>,
Michal Hocko <mhocko@...e.com>,
Dan Williams <dan.j.williams@...il.com>
Subject: Re: [PATCH 4/9] mm, memory_hotplug: get rid of is_zone_device_section
On Mon, Apr 10, 2017 at 01:03:46PM +0200, Michal Hocko wrote:
> From: Michal Hocko <mhocko@...e.com>
>
> device memory hotplug hooks into regular memory hotplug only half way.
> It needs memory sections to track struct pages but there is no
> need/desire to associate those sections with memory blocks and export
> them to the userspace via sysfs because they cannot be onlined anyway.
>
> This is currently expressed by for_device argument to arch_add_memory
> which then makes sure to associate the given memory range with
> ZONE_DEVICE. register_new_memory then relies on is_zone_device_section
> to distinguish special memory hotplug from the regular one. While this
> works now, later patches in this series want to move __add_zone outside
> of arch_add_memory path so we have to come up with something else.
>
> Add want_memblock down the __add_pages path and use it to control
> whether the section->memblock association should be done. arch_add_memory
> then just trivially want memblock for everything but for_device hotplug.
>
> remove_memory_section doesn't need is_zone_device_section either. We can
> simply skip all the memblock specific cleanup if there is no memblock
> for the given section.
>
> This shouldn't introduce any functional change.
>
> Cc: Dan Williams <dan.j.williams@...il.com>
> Signed-off-by: Michal Hocko <mhocko@...e.com>
> ---
> arch/ia64/mm/init.c | 2 +-
> arch/powerpc/mm/mem.c | 2 +-
> arch/s390/mm/init.c | 2 +-
> arch/sh/mm/init.c | 2 +-
> arch/x86/mm/init_32.c | 2 +-
> arch/x86/mm/init_64.c | 2 +-
> drivers/base/memory.c | 22 ++++++++--------------
> include/linux/memory_hotplug.h | 2 +-
> mm/memory_hotplug.c | 11 +++++++----
> 9 files changed, 22 insertions(+), 25 deletions(-)
>
> diff --git a/arch/ia64/mm/init.c b/arch/ia64/mm/init.c
> index 06cdaef54b2e..62085fd902e6 100644
> --- a/arch/ia64/mm/init.c
> +++ b/arch/ia64/mm/init.c
> @@ -657,7 +657,7 @@ int arch_add_memory(int nid, u64 start, u64 size, bool for_device)
>
> zone = pgdat->node_zones +
> zone_for_memory(nid, start, size, ZONE_NORMAL, for_device);
> - ret = __add_pages(nid, zone, start_pfn, nr_pages);
> + ret = __add_pages(nid, zone, start_pfn, nr_pages, !for_device);
>
> if (ret)
> printk("%s: Problem encountered in __add_pages() as ret=%d\n",
> diff --git a/arch/powerpc/mm/mem.c b/arch/powerpc/mm/mem.c
> index 5f844337de21..ea3e09a62f38 100644
> --- a/arch/powerpc/mm/mem.c
> +++ b/arch/powerpc/mm/mem.c
> @@ -149,7 +149,7 @@ int arch_add_memory(int nid, u64 start, u64 size, bool for_device)
> zone = pgdata->node_zones +
> zone_for_memory(nid, start, size, 0, for_device);
>
> - return __add_pages(nid, zone, start_pfn, nr_pages);
> + return __add_pages(nid, zone, start_pfn, nr_pages, !for_device);
> }
>
> #ifdef CONFIG_MEMORY_HOTREMOVE
> diff --git a/arch/s390/mm/init.c b/arch/s390/mm/init.c
> index bf5b8a0c4ff7..5c84346e5211 100644
> --- a/arch/s390/mm/init.c
> +++ b/arch/s390/mm/init.c
> @@ -182,7 +182,7 @@ int arch_add_memory(int nid, u64 start, u64 size, bool for_device)
> continue;
> nr_pages = (start_pfn + size_pages > zone_end_pfn) ?
> zone_end_pfn - start_pfn : size_pages;
> - rc = __add_pages(nid, zone, start_pfn, nr_pages);
> + rc = __add_pages(nid, zone, start_pfn, nr_pages, !for_device);
> if (rc)
> break;
> start_pfn += nr_pages;
> diff --git a/arch/sh/mm/init.c b/arch/sh/mm/init.c
> index 75491862d900..a9d57f75ae8c 100644
> --- a/arch/sh/mm/init.c
> +++ b/arch/sh/mm/init.c
> @@ -498,7 +498,7 @@ int arch_add_memory(int nid, u64 start, u64 size, bool for_device)
> ret = __add_pages(nid, pgdat->node_zones +
> zone_for_memory(nid, start, size, ZONE_NORMAL,
> for_device),
> - start_pfn, nr_pages);
> + start_pfn, nr_pages, !for_device);
> if (unlikely(ret))
> printk("%s: Failed, __add_pages() == %d\n", __func__, ret);
>
> diff --git a/arch/x86/mm/init_32.c b/arch/x86/mm/init_32.c
> index c68078fd06fd..4b0f05328af0 100644
> --- a/arch/x86/mm/init_32.c
> +++ b/arch/x86/mm/init_32.c
> @@ -834,7 +834,7 @@ int arch_add_memory(int nid, u64 start, u64 size, bool for_device)
> unsigned long start_pfn = start >> PAGE_SHIFT;
> unsigned long nr_pages = size >> PAGE_SHIFT;
>
> - return __add_pages(nid, zone, start_pfn, nr_pages);
> + return __add_pages(nid, zone, start_pfn, nr_pages, !for_device);
> }
>
> #ifdef CONFIG_MEMORY_HOTREMOVE
> diff --git a/arch/x86/mm/init_64.c b/arch/x86/mm/init_64.c
> index 7eef17239378..39cfaee93975 100644
> --- a/arch/x86/mm/init_64.c
> +++ b/arch/x86/mm/init_64.c
> @@ -652,7 +652,7 @@ int arch_add_memory(int nid, u64 start, u64 size, bool for_device)
>
> init_memory_mapping(start, start + size);
>
> - ret = __add_pages(nid, zone, start_pfn, nr_pages);
> + ret = __add_pages(nid, zone, start_pfn, nr_pages, !for_device);
> WARN_ON_ONCE(ret);
>
> /* update max_pfn, max_low_pfn and high_memory */
> diff --git a/drivers/base/memory.c b/drivers/base/memory.c
> index cc4f1d0cbffe..89c15e942852 100644
> --- a/drivers/base/memory.c
> +++ b/drivers/base/memory.c
> @@ -685,14 +685,6 @@ static int add_memory_block(int base_section_nr)
> return 0;
> }
>
> -static bool is_zone_device_section(struct mem_section *ms)
> -{
> - struct page *page;
> -
> - page = sparse_decode_mem_map(ms->section_mem_map, __section_nr(ms));
> - return is_zone_device_page(page);
> -}
> -
> /*
> * need an interface for the VM to add new memory regions,
> * but without onlining it.
> @@ -702,9 +694,6 @@ int register_new_memory(int nid, struct mem_section *section)
> int ret = 0;
> struct memory_block *mem;
>
> - if (is_zone_device_section(section))
> - return 0;
> -
> mutex_lock(&mem_sysfs_mutex);
>
> mem = find_memory_block(section);
> @@ -741,11 +730,16 @@ static int remove_memory_section(unsigned long node_id,
> {
> struct memory_block *mem;
>
> - if (is_zone_device_section(section))
> - return 0;
> -
> mutex_lock(&mem_sysfs_mutex);
> +
> + /*
> + * Some users of the memory hotplug do not want/need memblock to
> + * track all sections. Skip over those.
> + */
> mem = find_memory_block(section);
> + if (!mem)
> + return 0;
> +
Another bug above spoted by Evgeny Baskakov from NVidia, mutex unlock
is missing ie something like:
if (!mem) {
mutex_unlock(&mem_sysfs_mutex);
return 0;
}
Between when are you planning on reposting ? I was hoping sometime soon
so i can repost HMM on top. I know with springtime celebration eveyrone
is out collecting chocolate eggs :)
Cheers,
Jérôme
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