From: Baoquan He <bhe@redhat.com>
To: linux-kernel@vger.kernel.org
Cc: linux-mm@kvack.org, mhocko@kernel.org, david@redhat.com,
jgross@suse.com, akpm@linux-foundation.org, bhe@redhat.com
Subject: [Patch v2] mm/hotplug: Only respect mem= parameter during boot stage
Date: Tue, 10 Dec 2019 16:44:13 +0800 [thread overview]
Message-ID: <20191210084413.21957-1-bhe@redhat.com> (raw)
In commit 357b4da50a62 ("x86: respect memory size limiting via mem=
parameter") a global varialbe global max_mem_size is added to store
the value parsed from 'mem= ', then checked when memory region is
added. This truly stops those DIMM from being added into system memory
during boot-time.
However, it also limits the later memory hotplug functionality. Any
memory board can't be hot added any more if its region is beyond the
max_mem_size. System will print error like below:
[ 216.387164] acpi PNP0C80:02: add_memory failed
[ 216.389301] acpi PNP0C80:02: acpi_memory_enable_device() error
[ 216.392187] acpi PNP0C80:02: Enumeration failure
From document of 'mem= ' parameter, it should be a restriction during
boot, but not impact the system memory adding/removing after booting.
mem=nn[KMG] [KNL,BOOT] Force usage of a specific amount of memory
...
So fix it by also checking if it's during boot-time when restrict memory
adding. Otherwise, skip the restriction.
Fixes: 357b4da50a62 ("x86: respect memory size limiting via mem= parameter")
Signed-off-by: Baoquan He <bhe@redhat.com>
---
mm/memory_hotplug.c | 6 +++++-
1 file changed, 5 insertions(+), 1 deletion(-)
diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c
index 55ac23ef11c1..989707295d15 100644
--- a/mm/memory_hotplug.c
+++ b/mm/memory_hotplug.c
@@ -105,7 +105,11 @@ static struct resource *register_memory_resource(u64 start, u64 size)
unsigned long flags = IORESOURCE_SYSTEM_RAM | IORESOURCE_BUSY;
char *resource_name = "System RAM";
- if (start + size > max_mem_size)
+ /*
+ * Make sure value parsed from 'mem=' only restricts memory adding
+ * during boot-time, so that memory hotplug won't be impacted.
+ */
+ if (start + size > max_mem_size && system_state < SYSTEM_RUNNING)
return ERR_PTR(-E2BIG);
/*
--
2.17.2
next reply other threads:[~2019-12-10 8:44 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-12-10 8:44 Baoquan He [this message]
2019-12-10 9:07 ` [Patch v2] mm/hotplug: Only respect mem= parameter during boot stage Jürgen Groß
2019-12-10 9:24 ` Balbir Singh
2019-12-10 9:34 ` Baoquan He
2019-12-10 9:36 ` David Hildenbrand
2019-12-10 9:37 ` David Hildenbrand
2019-12-10 9:41 ` Balbir Singh
2019-12-10 9:50 ` Michal Hocko
2019-12-10 10:11 ` Baoquan He
2019-12-10 10:21 ` Michal Hocko
2019-12-10 9:32 ` David Hildenbrand
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