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authorDavid Hildenbrand <david@redhat.com>2021-02-26 04:17:24 +0300
committerLinus Torvalds <torvalds@linux-foundation.org>2021-02-26 20:41:00 +0300
commite9a2e48e8704c9d20a625c6f2357147d03ea7b97 (patch)
tree5a9156a16b4947be16536f89be3038a43fa2ab2b /include/linux/memory.h
parent6c922cf75115c8b389c091a073209ca45f1af530 (diff)
downloadlinux-e9a2e48e8704c9d20a625c6f2357147d03ea7b97.tar.xz
drivers/base/memory: don't store phys_device in memory blocks
No need to store the value for each and every memory block, as we can easily query the value at runtime. Reshuffle the members to optimize the memory layout. Also, let's clarify what the interface once was used for and why it's legacy nowadays. "phys_device" was used on s390x in older versions of lsmem[2]/chmem[3], back when they were still part of s390x-tools. They were later replaced by the variants in linux-utils. For example, RHEL6 and RHEL7 contain lsmem/chmem from s390-utils. RHEL8 switched to versions from util-linux on s390x [4]. "phys_device" was added with sysfs support for memory hotplug in commit 3947be1969a9 ("[PATCH] memory hotplug: sysfs and add/remove functions") in 2005. It always returned 0. s390x started returning something != 0 on some setups (if sclp.rzm is set by HW) in 2010 via commit 57b552ba0b2f ("memory hotplug/s390: set phys_device"). For s390x, it allowed for identifying which memory block devices belong to the same storage increment (RZM). Only if all memory block devices comprising a single storage increment were offline, the memory could actually be removed in the hypervisor. Since commit e5d709bb5fb7 ("s390/memory hotplug: provide memory_block_size_bytes() function") in 2013 a memory block device spans at least one storage increment - which is why the interface isn't really helpful/used anymore (except by old lsmem/chmem tools). There were once RFC patches to make use of "phys_device" in ACPI context; however, the underlying problem could be solved using different interfaces [1]. [1] https://patchwork.kernel.org/patch/2163871/ [2] https://github.com/ibm-s390-tools/s390-tools/blob/v2.1.0/zconf/lsmem [3] https://github.com/ibm-s390-tools/s390-tools/blob/v2.1.0/zconf/chmem [4] https://bugzilla.redhat.com/show_bug.cgi?id=1504134 Link: https://lkml.kernel.org/r/20210201181347.13262-2-david@redhat.com Signed-off-by: David Hildenbrand <david@redhat.com> Acked-by: Michal Hocko <mhocko@suse.com> Reviewed-by: Oscar Salvador <osalvador@suse.de> Cc: Dave Hansen <dave.hansen@intel.com> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: Gerald Schaefer <gerald.schaefer@linux.ibm.com> Cc: Jonathan Corbet <corbet@lwn.net> Cc: "Rafael J. Wysocki" <rafael@kernel.org> Cc: Mauro Carvalho Chehab <mchehab+huawei@kernel.org> Cc: Ilya Dryomov <idryomov@gmail.com> Cc: Vaibhav Jain <vaibhav@linux.ibm.com> Cc: Tom Rix <trix@redhat.com> Cc: Geert Uytterhoeven <geert+renesas@glider.be> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'include/linux/memory.h')
-rw-r--r--include/linux/memory.h3
1 files changed, 1 insertions, 2 deletions
diff --git a/include/linux/memory.h b/include/linux/memory.h
index 439a89e758d8..4da95e684e20 100644
--- a/include/linux/memory.h
+++ b/include/linux/memory.h
@@ -27,9 +27,8 @@ struct memory_block {
unsigned long start_section_nr;
unsigned long state; /* serialized by the dev->lock */
int online_type; /* for passing data to online routine */
- int phys_device; /* to which fru does this belong? */
- struct device dev;
int nid; /* NID for this memory block */
+ struct device dev;
};
int arch_get_memory_phys_device(unsigned long start_pfn);