The patch titled
Subject: kernel, resource: check for IORESOURCE_SYSRAM in release_mem_region_adjustable
has been added to the -mm tree. Its filename is
kernel-resource-check-for-ioresource_sysram-in-release_mem_region_adjustable.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/kernel-resource-check-for-ioresource_sysram-in-release_mem_region_adjustable.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/kernel-resource-check-for-ioresource_sysram-in-release_mem_region_adjustable.patch
Before you just go and hit "reply", please:
a) Consider who else should be cc'ed
b) Prefer to cc a suitable mailing list as well
c) Ideally: find the original patch on the mailing list and do a
reply-to-all to that, adding suitable additional cc's
*** Remember to use Documentation/process/submit-checklist.rst when testing your code ***
The -mm tree is included into linux-next and is updated
there every 3-4 working days
------------------------------------------------------
From: Oscar Salvador <osalvador@xxxxxxx>
Subject: kernel, resource: check for IORESOURCE_SYSRAM in release_mem_region_adjustable
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.
Link: http://lkml.kernel.org/r/20181127162005.15833-3-osalvador@xxxxxxx
Signed-off-by: Oscar Salvador <osalvador@xxxxxxx>
Reviewed-by: David Hildenbrand <david@xxxxxxxxxx>
Reviewed-by: Pavel Tatashin <pasha.tatashin@xxxxxxxxxx>
Cc: Dan Williams <dan.j.williams@xxxxxxxxx>
Cc: Jerome Glisse <jglisse@xxxxxxxxxx>
Cc: Jonathan Cameron <Jonathan.Cameron@xxxxxxxxxx>
Cc: Michal Hocko <mhocko@xxxxxxxx>
Cc: Oscar Salvador <osalvador@xxxxxxxx>
Cc: "Rafael J. Wysocki" <rafael@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
--- a/kernel/resource.c~kernel-resource-check-for-ioresource_sysram-in-release_mem_region_adjustable
+++ a/kernel/resource.c
@@ -1256,6 +1256,21 @@ int release_mem_region_adjustable(struct
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;
_
Patches currently in -mm which might be from osalvador@xxxxxxx are
kernel-resource-check-for-ioresource_sysram-in-release_mem_region_adjustable.patch
