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Message-ID: <20190701084129.GI6376@dhcp22.suse.cz>
Date: Mon, 1 Jul 2019 10:41:29 +0200
From: Michal Hocko <mhocko@...nel.org>
To: David Hildenbrand <david@...hat.com>
Cc: linux-mm@...ck.org, linux-kernel@...r.kernel.org,
linux-ia64@...r.kernel.org, linuxppc-dev@...ts.ozlabs.org,
linux-s390@...r.kernel.org, linux-sh@...r.kernel.org,
linux-arm-kernel@...ts.infradead.org, akpm@...ux-foundation.org,
Dan Williams <dan.j.williams@...el.com>,
Wei Yang <richard.weiyang@...il.com>,
Igor Mammedov <imammedo@...hat.com>,
Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
"Rafael J. Wysocki" <rafael@...nel.org>,
"mike.travis@....com" <mike.travis@....com>,
Andrew Banman <andrew.banman@....com>,
Ingo Molnar <mingo@...nel.org>,
Alex Deucher <alexander.deucher@....com>,
"David S. Miller" <davem@...emloft.net>,
Mark Brown <broonie@...nel.org>,
Chris Wilson <chris@...is-wilson.co.uk>,
Oscar Salvador <osalvador@...e.de>,
Jonathan Cameron <Jonathan.Cameron@...wei.com>,
Pavel Tatashin <pavel.tatashin@...rosoft.com>,
Arun KS <arunks@...eaurora.org>,
Mathieu Malaterre <malat@...ian.org>
Subject: Re: [PATCH v3 09/11] mm/memory_hotplug: Remove memory block devices
before arch_remove_memory()
On Mon 27-05-19 13:11:50, David Hildenbrand wrote:
> Let's factor out removing of memory block devices, which is only
> necessary for memory added via add_memory() and friends that created
> memory block devices. Remove the devices before calling
> arch_remove_memory().
>
> This finishes factoring out memory block device handling from
> arch_add_memory() and arch_remove_memory().
OK, this makes sense again. Just a nit. Calling find_memory_block_by_id
for each memory block looks a bit suboptimal, especially when we are
removing consequent physical memblocks. I have to confess that I do not
know how expensive is the search and I also expect that there won't be
that many memblocks in the removed range anyway as large setups have
large memblocks.
> Cc: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
> Cc: "Rafael J. Wysocki" <rafael@...nel.org>
> Cc: David Hildenbrand <david@...hat.com>
> Cc: "mike.travis@....com" <mike.travis@....com>
> Cc: Andrew Morton <akpm@...ux-foundation.org>
> Cc: Andrew Banman <andrew.banman@....com>
> Cc: Ingo Molnar <mingo@...nel.org>
> Cc: Alex Deucher <alexander.deucher@....com>
> Cc: "David S. Miller" <davem@...emloft.net>
> Cc: Mark Brown <broonie@...nel.org>
> Cc: Chris Wilson <chris@...is-wilson.co.uk>
> Cc: Oscar Salvador <osalvador@...e.de>
> Cc: Jonathan Cameron <Jonathan.Cameron@...wei.com>
> Cc: Michal Hocko <mhocko@...e.com>
> Cc: Pavel Tatashin <pavel.tatashin@...rosoft.com>
> Cc: Arun KS <arunks@...eaurora.org>
> Cc: Mathieu Malaterre <malat@...ian.org>
> Reviewed-by: Dan Williams <dan.j.williams@...el.com>
> Signed-off-by: David Hildenbrand <david@...hat.com>
Other than that looks good to me.
Acked-by: Michal Hocko <mhocko@...e.com>
> ---
> drivers/base/memory.c | 37 ++++++++++++++++++-------------------
> drivers/base/node.c | 11 ++++++-----
> include/linux/memory.h | 2 +-
> include/linux/node.h | 6 ++----
> mm/memory_hotplug.c | 5 +++--
> 5 files changed, 30 insertions(+), 31 deletions(-)
>
> diff --git a/drivers/base/memory.c b/drivers/base/memory.c
> index 5a0370f0c506..f28efb0bf5c7 100644
> --- a/drivers/base/memory.c
> +++ b/drivers/base/memory.c
> @@ -763,32 +763,31 @@ int create_memory_block_devices(unsigned long start, unsigned long size)
> return ret;
> }
>
> -void unregister_memory_section(struct mem_section *section)
> +/*
> + * Remove memory block devices for the given memory area. Start and size
> + * have to be aligned to memory block granularity. Memory block devices
> + * have to be offline.
> + */
> +void remove_memory_block_devices(unsigned long start, unsigned long size)
> {
> + const int start_block_id = pfn_to_block_id(PFN_DOWN(start));
> + const int end_block_id = pfn_to_block_id(PFN_DOWN(start + size));
> struct memory_block *mem;
> + int block_id;
>
> - if (WARN_ON_ONCE(!present_section(section)))
> + if (WARN_ON_ONCE(!IS_ALIGNED(start, memory_block_size_bytes()) ||
> + !IS_ALIGNED(size, memory_block_size_bytes())))
> return;
>
> 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)
> - goto out_unlock;
> -
> - unregister_mem_sect_under_nodes(mem, __section_nr(section));
> -
> - mem->section_count--;
> - if (mem->section_count == 0)
> + for (block_id = start_block_id; block_id != end_block_id; block_id++) {
> + mem = find_memory_block_by_id(block_id, NULL);
> + if (WARN_ON_ONCE(!mem))
> + continue;
> + mem->section_count = 0;
> + unregister_memory_block_under_nodes(mem);
> unregister_memory(mem);
> - else
> - put_device(&mem->dev);
> -
> -out_unlock:
> + }
> mutex_unlock(&mem_sysfs_mutex);
> }
>
> diff --git a/drivers/base/node.c b/drivers/base/node.c
> index 8598fcbd2a17..04fdfa99b8bc 100644
> --- a/drivers/base/node.c
> +++ b/drivers/base/node.c
> @@ -801,9 +801,10 @@ int register_mem_sect_under_node(struct memory_block *mem_blk, void *arg)
> return 0;
> }
>
> -/* unregister memory section under all nodes that it spans */
> -int unregister_mem_sect_under_nodes(struct memory_block *mem_blk,
> - unsigned long phys_index)
> +/*
> + * Unregister memory block device under all nodes that it spans.
> + */
> +int unregister_memory_block_under_nodes(struct memory_block *mem_blk)
> {
> NODEMASK_ALLOC(nodemask_t, unlinked_nodes, GFP_KERNEL);
> unsigned long pfn, sect_start_pfn, sect_end_pfn;
> @@ -816,8 +817,8 @@ int unregister_mem_sect_under_nodes(struct memory_block *mem_blk,
> return -ENOMEM;
> nodes_clear(*unlinked_nodes);
>
> - sect_start_pfn = section_nr_to_pfn(phys_index);
> - sect_end_pfn = sect_start_pfn + PAGES_PER_SECTION - 1;
> + sect_start_pfn = section_nr_to_pfn(mem_blk->start_section_nr);
> + sect_end_pfn = section_nr_to_pfn(mem_blk->end_section_nr);
> for (pfn = sect_start_pfn; pfn <= sect_end_pfn; pfn++) {
> int nid;
>
> diff --git a/include/linux/memory.h b/include/linux/memory.h
> index db3e8567f900..f26a5417ec5d 100644
> --- a/include/linux/memory.h
> +++ b/include/linux/memory.h
> @@ -112,7 +112,7 @@ extern void unregister_memory_notifier(struct notifier_block *nb);
> extern int register_memory_isolate_notifier(struct notifier_block *nb);
> extern void unregister_memory_isolate_notifier(struct notifier_block *nb);
> int create_memory_block_devices(unsigned long start, unsigned long size);
> -extern void unregister_memory_section(struct mem_section *);
> +void remove_memory_block_devices(unsigned long start, unsigned long size);
> extern int memory_dev_init(void);
> extern int memory_notify(unsigned long val, void *v);
> extern int memory_isolate_notify(unsigned long val, void *v);
> diff --git a/include/linux/node.h b/include/linux/node.h
> index 1a557c589ecb..02a29e71b175 100644
> --- a/include/linux/node.h
> +++ b/include/linux/node.h
> @@ -139,8 +139,7 @@ extern int register_cpu_under_node(unsigned int cpu, unsigned int nid);
> extern int unregister_cpu_under_node(unsigned int cpu, unsigned int nid);
> extern int register_mem_sect_under_node(struct memory_block *mem_blk,
> void *arg);
> -extern int unregister_mem_sect_under_nodes(struct memory_block *mem_blk,
> - unsigned long phys_index);
> +extern int unregister_memory_block_under_nodes(struct memory_block *mem_blk);
>
> extern int register_memory_node_under_compute_node(unsigned int mem_nid,
> unsigned int cpu_nid,
> @@ -176,8 +175,7 @@ static inline int register_mem_sect_under_node(struct memory_block *mem_blk,
> {
> return 0;
> }
> -static inline int unregister_mem_sect_under_nodes(struct memory_block *mem_blk,
> - unsigned long phys_index)
> +static inline int unregister_memory_block_under_nodes(struct memory_block *mem_blk)
> {
> return 0;
> }
> diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c
> index 9a92549ef23b..82136c5b4c5f 100644
> --- a/mm/memory_hotplug.c
> +++ b/mm/memory_hotplug.c
> @@ -520,8 +520,6 @@ static void __remove_section(struct zone *zone, struct mem_section *ms,
> if (WARN_ON_ONCE(!valid_section(ms)))
> return;
>
> - unregister_memory_section(ms);
> -
> scn_nr = __section_nr(ms);
> start_pfn = section_nr_to_pfn((unsigned long)scn_nr);
> __remove_zone(zone, start_pfn);
> @@ -1845,6 +1843,9 @@ void __ref __remove_memory(int nid, u64 start, u64 size)
> memblock_free(start, size);
> memblock_remove(start, size);
>
> + /* remove memory block devices before removing memory */
> + remove_memory_block_devices(start, size);
> +
> arch_remove_memory(nid, start, size, NULL);
> __release_memory_resource(start, size);
>
> --
> 2.20.1
>
--
Michal Hocko
SUSE Labs
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