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Message-ID: <CA+CK2bBu7DnG73SaBDwf9cBceNvKnZDEqA-gBJmKC9K_rqgO+A@mail.gmail.com>
Date: Thu, 18 Jul 2019 08:19:46 -0400
From: Pavel Tatashin <pasha.tatashin@...een.com>
To: Leonardo Bras <leonardo@...ux.ibm.com>
Cc: LKML <linux-kernel@...r.kernel.org>, linux-mm <linux-mm@...ck.org>,
Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
"Rafael J. Wysocki" <rafael@...nel.org>,
Andrew Morton <akpm@...ux-foundation.org>,
Mike Rapoport <rppt@...ux.ibm.com>,
Michal Hocko <mhocko@...e.com>,
Pavel Tatashin <pasha.tatashin@...cle.com>,
Jérôme Glisse <jglisse@...hat.com>,
Thomas Gleixner <tglx@...utronix.de>,
Pasha Tatashin <Pavel.Tatashin@...rosoft.com>,
Bartlomiej Zolnierkiewicz <b.zolnierkie@...sung.com>
Subject: Re: [PATCH 1/1] mm/memory_hotplug: Adds option to hot-add memory in ZONE_MOVABLE
On Wed, Jul 17, 2019 at 10:42 PM Leonardo Bras <leonardo@...ux.ibm.com> wrote:
>
> Adds an option on kernel config to make hot-added memory online in
> ZONE_MOVABLE by default.
>
> This would be great in systems with MEMORY_HOTPLUG_DEFAULT_ONLINE=y by
> allowing to choose which zone it will be auto-onlined
This is a desired feature. From reading the code it looks to me that
auto-selection of online method type should be done in
memory_subsys_online().
When it is called from device online, mem->online_type should be -1:
if (mem->online_type < 0)
mem->online_type = MMOP_ONLINE_KEEP;
Change it to:
if (mem->online_type < 0)
mem->online_type = MMOP_DEFAULT_ONLINE_TYPE;
And in "linux/memory_hotplug.h"
#ifdef CONFIG_MEMORY_HOTPLUG_MOVABLE
#define MMOP_DEFAULT_ONLINE_TYPE MMOP_ONLINE_MOVABLE
#else
#define MMOP_DEFAULT_ONLINE_TYPE MMOP_ONLINE_KEEP
#endif
Could be expanded to support MMOP_ONLINE_KERNEL as well.
Pasha
>
> Signed-off-by: Leonardo Bras <leonardo@...ux.ibm.com>
> ---
> drivers/base/memory.c | 3 +++
> mm/Kconfig | 14 ++++++++++++++
> 2 files changed, 17 insertions(+)
>
> diff --git a/drivers/base/memory.c b/drivers/base/memory.c
> index f180427e48f4..378b585785c1 100644
> --- a/drivers/base/memory.c
> +++ b/drivers/base/memory.c
> @@ -670,6 +670,9 @@ static int init_memory_block(struct memory_block **memory,
> mem->state = state;
> start_pfn = section_nr_to_pfn(mem->start_section_nr);
> mem->phys_device = arch_get_memory_phys_device(start_pfn);
> +#ifdef CONFIG_MEMORY_HOTPLUG_MOVABLE
> + mem->online_type = MMOP_ONLINE_MOVABLE;
> +#endif
>
> ret = register_memory(mem);
>
> diff --git a/mm/Kconfig b/mm/Kconfig
> index f0c76ba47695..74e793720f43 100644
> --- a/mm/Kconfig
> +++ b/mm/Kconfig
> @@ -180,6 +180,20 @@ config MEMORY_HOTREMOVE
> depends on MEMORY_HOTPLUG && ARCH_ENABLE_MEMORY_HOTREMOVE
> depends on MIGRATION
>
> +config MEMORY_HOTPLUG_MOVABLE
> + bool "Enhance the likelihood of hot-remove"
> + depends on MEMORY_HOTREMOVE
> + help
> + This option sets the hot-added memory zone to MOVABLE which
> + drastically reduces the chance of a hot-remove to fail due to
> + unmovable memory segments. Kernel memory can't be allocated in
> + this zone.
> +
> + Say Y here if you want to have better chance to hot-remove memory
> + that have been previously hot-added.
> + Say N here if you want to make all hot-added memory available to
> + kernel space.
> +
> # Heavily threaded applications may benefit from splitting the mm-wide
> # page_table_lock, so that faults on different parts of the user address
> # space can be handled with less contention: split it at this NR_CPUS.
> --
> 2.20.1
>
On Wed, Jul 17, 2019 at 10:42 PM Leonardo Bras <leonardo@...ux.ibm.com> wrote:
>
> Adds an option on kernel config to make hot-added memory online in
> ZONE_MOVABLE by default.
>
> This would be great in systems with MEMORY_HOTPLUG_DEFAULT_ONLINE=y by
> allowing to choose which zone it will be auto-onlined
>
> Signed-off-by: Leonardo Bras <leonardo@...ux.ibm.com>
> ---
> drivers/base/memory.c | 3 +++
> mm/Kconfig | 14 ++++++++++++++
> 2 files changed, 17 insertions(+)
>
> diff --git a/drivers/base/memory.c b/drivers/base/memory.c
> index f180427e48f4..378b585785c1 100644
> --- a/drivers/base/memory.c
> +++ b/drivers/base/memory.c
> @@ -670,6 +670,9 @@ static int init_memory_block(struct memory_block **memory,
> mem->state = state;
> start_pfn = section_nr_to_pfn(mem->start_section_nr);
> mem->phys_device = arch_get_memory_phys_device(start_pfn);
> +#ifdef CONFIG_MEMORY_HOTPLUG_MOVABLE
> + mem->online_type = MMOP_ONLINE_MOVABLE;
> +#endif
>
> ret = register_memory(mem);
>
> diff --git a/mm/Kconfig b/mm/Kconfig
> index f0c76ba47695..74e793720f43 100644
> --- a/mm/Kconfig
> +++ b/mm/Kconfig
> @@ -180,6 +180,20 @@ config MEMORY_HOTREMOVE
> depends on MEMORY_HOTPLUG && ARCH_ENABLE_MEMORY_HOTREMOVE
> depends on MIGRATION
>
> +config MEMORY_HOTPLUG_MOVABLE
> + bool "Enhance the likelihood of hot-remove"
> + depends on MEMORY_HOTREMOVE
> + help
> + This option sets the hot-added memory zone to MOVABLE which
> + drastically reduces the chance of a hot-remove to fail due to
> + unmovable memory segments. Kernel memory can't be allocated in
> + this zone.
> +
> + Say Y here if you want to have better chance to hot-remove memory
> + that have been previously hot-added.
> + Say N here if you want to make all hot-added memory available to
> + kernel space.
> +
> # Heavily threaded applications may benefit from splitting the mm-wide
> # page_table_lock, so that faults on different parts of the user address
> # space can be handled with less contention: split it at this NR_CPUS.
> --
> 2.20.1
>
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