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[37.188.255.121]) by smtp.gmail.com with ESMTPSA id k3sm3879311wro.59.2020.03.17.04.01.23 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 17 Mar 2020 04:01:23 -0700 (PDT) Date: Tue, 17 Mar 2020 12:01:21 +0100 From: Michal Hocko To: David Hildenbrand Cc: linux-kernel@vger.kernel.org, linux-mm@kvack.org, linuxppc-dev@lists.ozlabs.org, linux-hyperv@vger.kernel.org, Wei Yang , Greg Kroah-Hartman , Andrew Morton , Oscar Salvador , "Rafael J. Wysocki" , Baoquan He Subject: Re: [PATCH v2 8/8] mm/memory_hotplug: allow to specify a default online_type Message-ID: <20200317110121.GN26018@dhcp22.suse.cz> References: <20200317104942.11178-1-david@redhat.com> <20200317104942.11178-9-david@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20200317104942.11178-9-david@redhat.com> Sender: linux-hyperv-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-hyperv@vger.kernel.org On Tue 17-03-20 11:49:42, David Hildenbrand wrote: > 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 user space to come up with the same answer. > E.g., Hyper-V 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. This waiting > slows down adding of a bigger amount of memory. > > 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=" on the kernel cmdline > - /sys/devices/system/memory/auto_online_blocks > just like we are able to specify for a single memory block via > /sys/devices/system/memory/memoryX/state > > Reviewed-by: Wei Yang > 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 As I've said earlier and several times already, I really dislike this interface. But it is fact that this patch doesn't make it any worse. Quite contrary, so feel free to add Acked-by: Michal Hocko > --- > 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[] = { > [MMOP_ONLINE_MOVABLE] = "online_movable", > }; > > -static int memhp_online_type_from_str(const char *str) > +int memhp_online_type_from_str(const char *str) > { > int i; > > @@ -394,13 +394,12 @@ static ssize_t auto_online_blocks_store(struct device *dev, > struct device_attribute *attr, > const char *buf, size_t count) > { > - if (sysfs_streq(buf, "online")) > - memhp_default_online_type = MMOP_ONLINE; > - else if (sysfs_streq(buf, "offline")) > - memhp_default_online_type = MMOP_OFFLINE; > - else > + const int online_type = memhp_online_type_from_str(buf); > + > + if (online_type < 0) > return -EINVAL; > > + memhp_default_online_type = online_type; > return count; > } > > diff --git a/include/linux/memory_hotplug.h b/include/linux/memory_hotplug.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 size, > struct mhp_restrictions *restrictions); > extern u64 max_mem_size; > > +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 1975a2b99a2b..9916977b6ee1 100644 > --- a/mm/memory_hotplug.c > +++ b/mm/memory_hotplug.c > @@ -74,10 +74,10 @@ int memhp_default_online_type = MMOP_ONLINE; > > static int __init setup_memhp_default_state(char *str) > { > - if (!strcmp(str, "online")) > - memhp_default_online_type = MMOP_ONLINE; > - else if (!strcmp(str, "offline")) > - memhp_default_online_type = MMOP_OFFLINE; > + const int online_type = memhp_online_type_from_str(str); > + > + if (online_type >= 0) > + memhp_default_online_type = online_type; > > return 1; > } > -- > 2.24.1 -- Michal Hocko SUSE Labs