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authorOscar Salvador <osalvador@suse.de>2018-12-28 00:36:26 -0800
committerLinus Torvalds <torvalds@linux-foundation.org>2018-12-28 12:11:49 -0800
commit65c78784135f847e49eb98e6b976e453e71100c3 (patch)
tree0e91b39c565f269bd58b50cd5b0c9d9b9ead1846
parent2c2a5af6fed20cf74401c9d64319c76c5ff81309 (diff)
downloadlinux-65c78784135f847e49eb98e6b976e453e71100c3.tar.bz2
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@suse.de Signed-off-by: Oscar Salvador <osalvador@suse.de> Reviewed-by: David Hildenbrand <david@redhat.com> Reviewed-by: Pavel Tatashin <pasha.tatashin@soleen.com> Cc: Dan Williams <dan.j.williams@intel.com> Cc: Jerome Glisse <jglisse@redhat.com> Cc: Jonathan Cameron <Jonathan.Cameron@huawei.com> Cc: Michal Hocko <mhocko@suse.com> Cc: Oscar Salvador <osalvador@suse.com> Cc: "Rafael J. Wysocki" <rafael@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
-rw-r--r--kernel/resource.c15
1 files changed, 15 insertions, 0 deletions
diff --git a/kernel/resource.c b/kernel/resource.c
index b0fbf685c77a..915c02e8e5dd 100644
--- a/kernel/resource.c
+++ b/kernel/resource.c
@@ -1256,6 +1256,21 @@ 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;