From 65c78784135f847e49eb98e6b976e453e71100c3 Mon Sep 17 00:00:00 2001 From: Oscar Salvador Date: Fri, 28 Dec 2018 00:36:26 -0800 Subject: [PATCH] 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 Reviewed-by: David Hildenbrand Reviewed-by: Pavel Tatashin Cc: Dan Williams Cc: Jerome Glisse Cc: Jonathan Cameron Cc: Michal Hocko Cc: Oscar Salvador Cc: "Rafael J. Wysocki" Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- kernel/resource.c | 15 +++++++++++++++ 1 file changed, 15 insertions(+) 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;