[v3,09/11] mm/memory_hotplug: Remove memory block devices before arch_remove_memory()
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Message ID 20190527111152.16324-10-david@redhat.com
State New
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Series
  • [v3,01/11] mm/memory_hotplug: Simplify and fix check_hotplug_memory_range()
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Commit Message

David Hildenbrand May 27, 2019, 11:11 a.m. UTC
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().

Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: "Rafael J. Wysocki" <rafael@kernel.org>
Cc: David Hildenbrand <david@redhat.com>
Cc: "mike.travis@hpe.com" <mike.travis@hpe.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Andrew Banman <andrew.banman@hpe.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Alex Deucher <alexander.deucher@amd.com>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Mark Brown <broonie@kernel.org>
Cc: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Pavel Tatashin <pavel.tatashin@microsoft.com>
Cc: Arun KS <arunks@codeaurora.org>
Cc: Mathieu Malaterre <malat@debian.org>
Reviewed-by: Dan Williams <dan.j.williams@intel.com>
Signed-off-by: David Hildenbrand <david@redhat.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(-)

Comments

Wei Yang June 4, 2019, 10:07 p.m. UTC | #1
On Mon, May 27, 2019 at 01:11:50PM +0200, 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().
>
>Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
>Cc: "Rafael J. Wysocki" <rafael@kernel.org>
>Cc: David Hildenbrand <david@redhat.com>
>Cc: "mike.travis@hpe.com" <mike.travis@hpe.com>
>Cc: Andrew Morton <akpm@linux-foundation.org>
>Cc: Andrew Banman <andrew.banman@hpe.com>
>Cc: Ingo Molnar <mingo@kernel.org>
>Cc: Alex Deucher <alexander.deucher@amd.com>
>Cc: "David S. Miller" <davem@davemloft.net>
>Cc: Mark Brown <broonie@kernel.org>
>Cc: Chris Wilson <chris@chris-wilson.co.uk>
>Cc: Oscar Salvador <osalvador@suse.de>
>Cc: Jonathan Cameron <Jonathan.Cameron@huawei.com>
>Cc: Michal Hocko <mhocko@suse.com>
>Cc: Pavel Tatashin <pavel.tatashin@microsoft.com>
>Cc: Arun KS <arunks@codeaurora.org>
>Cc: Mathieu Malaterre <malat@debian.org>
>Reviewed-by: Dan Williams <dan.j.williams@intel.com>
>Signed-off-by: David Hildenbrand <david@redhat.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;

Is this step necessary?

>+		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
David Hildenbrand June 5, 2019, 9 a.m. UTC | #2
On 05.06.19 00:07, Wei Yang wrote:
> On Mon, May 27, 2019 at 01:11:50PM +0200, 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().
>>
>> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
>> Cc: "Rafael J. Wysocki" <rafael@kernel.org>
>> Cc: David Hildenbrand <david@redhat.com>
>> Cc: "mike.travis@hpe.com" <mike.travis@hpe.com>
>> Cc: Andrew Morton <akpm@linux-foundation.org>
>> Cc: Andrew Banman <andrew.banman@hpe.com>
>> Cc: Ingo Molnar <mingo@kernel.org>
>> Cc: Alex Deucher <alexander.deucher@amd.com>
>> Cc: "David S. Miller" <davem@davemloft.net>
>> Cc: Mark Brown <broonie@kernel.org>
>> Cc: Chris Wilson <chris@chris-wilson.co.uk>
>> Cc: Oscar Salvador <osalvador@suse.de>
>> Cc: Jonathan Cameron <Jonathan.Cameron@huawei.com>
>> Cc: Michal Hocko <mhocko@suse.com>
>> Cc: Pavel Tatashin <pavel.tatashin@microsoft.com>
>> Cc: Arun KS <arunks@codeaurora.org>
>> Cc: Mathieu Malaterre <malat@debian.org>
>> Reviewed-by: Dan Williams <dan.j.williams@intel.com>
>> Signed-off-by: David Hildenbrand <david@redhat.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;
> 
> Is this step necessary?

It's what the previous code does, it might not be - I'll leave it like
that for now. As mentioned in another reply, I might remove the
section_count completely, eventually.
Michal Hocko July 1, 2019, 8:41 a.m. UTC | #3
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@linuxfoundation.org>
> Cc: "Rafael J. Wysocki" <rafael@kernel.org>
> Cc: David Hildenbrand <david@redhat.com>
> Cc: "mike.travis@hpe.com" <mike.travis@hpe.com>
> Cc: Andrew Morton <akpm@linux-foundation.org>
> Cc: Andrew Banman <andrew.banman@hpe.com>
> Cc: Ingo Molnar <mingo@kernel.org>
> Cc: Alex Deucher <alexander.deucher@amd.com>
> Cc: "David S. Miller" <davem@davemloft.net>
> Cc: Mark Brown <broonie@kernel.org>
> Cc: Chris Wilson <chris@chris-wilson.co.uk>
> Cc: Oscar Salvador <osalvador@suse.de>
> Cc: Jonathan Cameron <Jonathan.Cameron@huawei.com>
> Cc: Michal Hocko <mhocko@suse.com>
> Cc: Pavel Tatashin <pavel.tatashin@microsoft.com>
> Cc: Arun KS <arunks@codeaurora.org>
> Cc: Mathieu Malaterre <malat@debian.org>
> Reviewed-by: Dan Williams <dan.j.williams@intel.com>
> Signed-off-by: David Hildenbrand <david@redhat.com>

Other than that looks good to me.
Acked-by: Michal Hocko <mhocko@suse.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
>
David Hildenbrand July 15, 2019, 10:58 a.m. UTC | #4
On 01.07.19 10:41, Michal Hocko wrote:
> 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.
> 

The devices are not allocated sequentially, so there is no easy way to
look them up.

There is a comment for find_memory_block():

"For now, we have a linear search to go find the appropriate
memory_block corresponding to a particular phys_index. If this gets to
be a real problem, we can always use a radix tree or something here."

So if this becomes a problem, we need a separate data structure to speed
up the lookup. (IOW, this was already the same in the old code)

Thanks!

Patch
diff mbox series

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);