diff options
author | Oscar Salvador <osalvador@suse.de> | 2018-12-28 00:36:26 -0800 |
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committer | Linus Torvalds <torvalds@linux-foundation.org> | 2018-12-28 12:11:49 -0800 |
commit | 65c78784135f847e49eb98e6b976e453e71100c3 (patch) | |
tree | 0e91b39c565f269bd58b50cd5b0c9d9b9ead1846 /kernel/resource.c | |
parent | 2c2a5af6fed20cf74401c9d64319c76c5ff81309 (diff) | |
download | lwn-65c78784135f847e49eb98e6b976e453e71100c3.tar.gz lwn-65c78784135f847e49eb98e6b976e453e71100c3.zip |
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>
Diffstat (limited to 'kernel/resource.c')
-rw-r--r-- | kernel/resource.c | 15 |
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; |