From: Oscar Salvador <osalvador@suse.de>
To: akpm@linux-foundation.org
Cc: mhocko@suse.com, dan.j.williams@intel.com,
pavel.tatashin@microsoft.com, jglisse@redhat.com,
Jonathan.Cameron@huawei.com, rafael@kernel.org, david@redhat.com,
linux-mm@kvack.org, Oscar Salvador <osalvador@suse.de>
Subject: [PATCH v2 2/5] kernel, resource: Check for IORESOURCE_SYSRAM in release_mem_region_adjustable
Date: Tue, 27 Nov 2018 17:20:02 +0100 [thread overview]
Message-ID: <20181127162005.15833-3-osalvador@suse.de> (raw)
In-Reply-To: <20181127162005.15833-1-osalvador@suse.de>
This is a preparation for the next patch.
Currently, we only call release_mem_region_adjustable() in __remove_pages
if the zone is not ZONE_DEVICE, because resources that belong to
HMM/devm are being released by themselves with devm_release_mem_region.
Since we do not want to touch any zone/page stuff during the removing
of the memory (but during the offlining), we do not want to check for
the zone here.
So we need another way to tell release_mem_region_adjustable() to not
realease the resource in case it belongs to HMM/devm.
HMM/devm acquires/releases a resource through
devm_request_mem_region/devm_release_mem_region.
These resources have the flag IORESOURCE_MEM, while resources acquired by
hot-add memory path (register_memory_resource()) contain
IORESOURCE_SYSTEM_RAM.
So, we can check for this flag in release_mem_region_adjustable, and if
the resource does not contain such flag, we know that we are dealing with
a HMM/devm resource, so we can back off.
Signed-off-by: Oscar Salvador <osalvador@suse.de>
Reviewed-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Pavel Tatashin <pasha.tatashin@soleen.com>
---
kernel/resource.c | 15 +++++++++++++++
1 file changed, 15 insertions(+)
diff --git a/kernel/resource.c b/kernel/resource.c
index 0aaa95005a2e..e20cea416f1f 100644
--- a/kernel/resource.c
+++ b/kernel/resource.c
@@ -1266,6 +1266,21 @@ int release_mem_region_adjustable(struct resource *parent,
continue;
}
+ /*
+ * All memory regions added from memory-hotplug path have the
+ * flag IORESOURCE_SYSTEM_RAM. If the resource does not have
+ * this flag, we know that we are dealing with a resource coming
+ * from HMM/devm. HMM/devm use another mechanism to add/release
+ * a resource. This goes via devm_request_mem_region and
+ * devm_release_mem_region.
+ * HMM/devm take care to release their resources when they want,
+ * so if we are dealing with them, let us just back off here.
+ */
+ if (!(res->flags & IORESOURCE_SYSRAM)) {
+ ret = 0;
+ break;
+ }
+
if (!(res->flags & IORESOURCE_MEM))
break;
--
2.13.6
next prev parent reply other threads:[~2018-11-27 16:20 UTC|newest]
Thread overview: 26+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-11-27 16:20 [PATCH v2 0/5] Do not touch pages in hot-remove path Oscar Salvador
2018-11-27 16:20 ` [PATCH v2 1/5] mm, memory_hotplug: Add nid parameter to arch_remove_memory Oscar Salvador
2018-11-27 16:20 ` Oscar Salvador [this message]
2018-11-27 16:20 ` [PATCH v2 3/5] mm, memory_hotplug: Move zone/pages handling to offline stage Oscar Salvador
2018-11-28 7:52 ` Mike Rapoport
2018-11-28 14:25 ` osalvador
2018-11-28 14:15 ` osalvador
2018-11-27 16:20 ` [PATCH v2 4/5] mm, memory-hotplug: Rework unregister_mem_sect_under_nodes Oscar Salvador
2019-03-24 6:48 ` Anshuman Khandual
2019-03-25 7:40 ` Oscar Salvador
2019-03-25 8:04 ` Michal Hocko
2019-03-25 8:14 ` Oscar Salvador
2018-11-27 16:20 ` [PATCH v2 5/5] mm, memory_hotplug: Refactor shrink_zone/pgdat_span Oscar Salvador
2018-11-28 6:50 ` Michal Hocko
2018-11-28 7:07 ` Oscar Salvador
2018-11-28 10:03 ` David Hildenbrand
2018-11-28 10:14 ` Michal Hocko
2018-11-28 11:00 ` osalvador
2018-11-28 12:31 ` Michal Hocko
2018-11-28 12:51 ` osalvador
2018-11-28 13:08 ` Michal Hocko
2018-11-28 13:18 ` osalvador
2018-11-28 15:50 ` Michal Hocko
2018-11-28 16:02 ` osalvador
2018-11-29 9:29 ` osalvador
2018-11-28 13:09 ` osalvador
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