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Wysocki" , Baoquan He , Wei Yang Subject: [PATCH v1 5/5] mm/memory_hotplug: allow to specify a default online_type Date: Wed, 11 Mar 2020 13:30:26 +0100 Message-Id: <20200311123026.16071-6-david@redhat.com> In-Reply-To: <20200311123026.16071-1-david@redhat.com> References: <20200311123026.16071-1-david@redhat.com> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.79 on 10.5.11.16 Content-Transfer-Encoding: quoted-printable Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org For now, distributions implement advanced udev rules to essentially - Don't online any hotplugged memory (s390x) - Online all memory to ZONE_NORMAL (e.g., most virt environments like hyperv) - Online all memory to ZONE_MOVABLE in case the zone imbalance is taken care of (e.g., bare metal, special virt environments) In summary: All memory is usually onlined the same way, however, the kernel always has to ask userspace to come up with the same answer. E.g., HyperV always waits for a memory block to get onlined before continuing, otherwise it might end up adding memory faster than hotplugging it, which can result in strange OOM situations. Let's allow to specify a default online_type, not just "online" and "offline". This allows distributions to configure the default online_type when booting up and be done with it. We can now specify "offline", "online", "online_movable" and "online_kernel" via - "memhp_default_state=3D" on the kernel cmdline - /sys/devices/systemn/memory/auto_online_blocks just like we are able to specify for a single memory block via /sys/devices/systemn/memory/memoryX/state Cc: Greg Kroah-Hartman Cc: Andrew Morton Cc: Michal Hocko Cc: Oscar Salvador Cc: "Rafael J. Wysocki" Cc: Baoquan He Cc: Wei Yang Signed-off-by: David Hildenbrand --- drivers/base/memory.c | 11 +++++------ include/linux/memory_hotplug.h | 2 ++ mm/memory_hotplug.c | 8 ++++---- 3 files changed, 11 insertions(+), 10 deletions(-) diff --git a/drivers/base/memory.c b/drivers/base/memory.c index 8d3e16dab69f..2b09b68b9f78 100644 --- a/drivers/base/memory.c +++ b/drivers/base/memory.c @@ -35,7 +35,7 @@ static const char *const online_type_to_str[] =3D { [MMOP_ONLINE_MOVABLE] =3D "online_movable", }; =20 -static int memhp_online_type_from_str(const char *str) +int memhp_online_type_from_str(const char *str) { int i; =20 @@ -394,13 +394,12 @@ static ssize_t auto_online_blocks_store(struct devi= ce *dev, struct device_attribute *attr, const char *buf, size_t count) { - if (sysfs_streq(buf, "online")) - memhp_default_online_type =3D MMOP_ONLINE; - else if (sysfs_streq(buf, "offline")) - memhp_default_online_type =3D MMOP_OFFLINE; - else + const int online_type =3D memhp_online_type_from_str(buf); + + if (online_type < 0) return -EINVAL; =20 + memhp_default_online_type =3D online_type; return count; } =20 diff --git a/include/linux/memory_hotplug.h b/include/linux/memory_hotplu= g.h index c6e090b34c4b..ef55115320fb 100644 --- a/include/linux/memory_hotplug.h +++ b/include/linux/memory_hotplug.h @@ -117,6 +117,8 @@ extern int arch_add_memory(int nid, u64 start, u64 si= ze, struct mhp_restrictions *restrictions); extern u64 max_mem_size; =20 +extern int memhp_online_type_from_str(const char *str); + /* Default online_type (MMOP_*) when new memory blocks are added. */ extern int memhp_default_online_type; /* If movable_node boot option specified */ diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c index 01443c70aa27..4a96273eafa7 100644 --- a/mm/memory_hotplug.c +++ b/mm/memory_hotplug.c @@ -75,10 +75,10 @@ EXPORT_SYMBOL_GPL(memhp_default_online_type); =20 static int __init setup_memhp_default_state(char *str) { - if (!strcmp(str, "online")) - memhp_default_online_type =3D MMOP_ONLINE; - else if (!strcmp(str, "offline")) - memhp_default_online_type =3D MMOP_OFFLINE; + const int online_type =3D memhp_online_type_from_str(str); + + if (online_type >=3D 0) + memhp_default_online_type =3D online_type; =20 return 1; } --=20 2.24.1