kernel_optimize_test/arch/s390
Matthew Wilcox 620b4e9031 s390: use _refcount for pgtables
Patch series "Rearrange struct page", v6.

As presented at LSFMM, this patch-set rearranges struct page to give
more contiguous usable space to users who have allocated a struct page
for their own purposes.  For a graphical view of before-and-after, see
the first two tabs of

  https://docs.google.com/spreadsheets/d/1tvCszs_7FXrjei9_mtFiKV6nW1FLnYyvPvW-qNZhdog/edit?usp=sharing

Highlights:
 - deferred_list now really exists in struct page instead of just a comment.
 - hmm_data also exists in struct page instead of being a nasty hack.
 - x86's PGD pages have a real pointer to the mm_struct.
 - VMalloc pages now have all sorts of extra information stored in them
   to help with debugging and tuning.
 - rcu_head is no longer tied to slab in case anyone else wants to
   free pages by RCU.
 - slub's counters no longer share space with _refcount.
 - slub's freelist+counters are now naturally dword aligned.
 - slub loses a parameter to a lot of functions and a sysfs file.

This patch (of 17):

s390 borrows the storage used for _mapcount in struct page in order to
account whether the bottom or top half is being used for 2kB page tables.
I want to use that for something else, so use the top byte of _refcount
instead of the bottom byte of _mapcount.  _refcount may temporarily be
incremented by other CPUs that see a stale pointer to this page in the
page cache, but each CPU can only increment it by one, and there are no
systems with 2^24 CPUs today, so they will not change the upper byte of
_refcount.  We do have to be a little careful not to lose any of their
writes (as they will subsequently decrement the counter).

Link: http://lkml.kernel.org/r/20180518194519.3820-2-willy@infradead.org
Signed-off-by: Matthew Wilcox <mawilcox@microsoft.com>
Acked-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: "Kirill A . Shutemov" <kirill.shutemov@linux.intel.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: Lai Jiangshan <jiangshanlai@gmail.com>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Jérôme Glisse <jglisse@redhat.com>
Cc: Randy Dunlap <rdunlap@infradead.org>
Cc: Andrey Ryabinin <aryabinin@virtuozzo.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2018-06-07 17:34:37 -07:00
..
appldata s390: add a few more SPDX identifiers 2017-12-05 07:51:09 +01:00
boot s390/boot: remove unused COMPILE_VERSION and ccflags-y 2018-04-16 09:10:24 +02:00
configs s390: update defconfigs 2018-04-27 06:51:31 +02:00
crypto s390/archrandom: Rework arch random implementation. 2018-05-30 11:18:04 +02:00
hypfs Merge branch 'linus' into timers/2038 2018-05-19 13:55:40 +02:00
include mm: introduce ARCH_HAS_PTE_SPECIAL 2018-06-07 17:34:35 -07:00
kernel Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/s390/linux 2018-06-05 11:13:17 -07:00
kvm Merge branch 'timers-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2018-06-04 20:27:54 -07:00
lib s390: introduce compile time check for empty .bss section 2018-05-09 10:55:01 +02:00
mm s390: use _refcount for pgtables 2018-06-07 17:34:37 -07:00
net Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net-next 2018-06-06 18:39:49 -07:00
numa s390: add a few more SPDX identifiers 2017-12-05 07:51:09 +01:00
oprofile License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
pci Merge branch 'timers-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2018-06-04 20:27:54 -07:00
purgatory s390/purgatory: Fix endless interrupt loop 2018-05-18 07:24:35 +02:00
scripts s390: introduce compile time check for empty .bss section 2018-05-09 10:55:01 +02:00
tools KVM: s390: implement CPU model only facilities 2018-03-09 09:44:17 +00:00
defconfig s390: update defconfig 2018-04-16 10:29:34 +02:00
Kbuild s390/kexec_file: Add purgatory 2018-04-16 09:10:22 +02:00
Kconfig mm: introduce ARCH_HAS_PTE_SPECIAL 2018-06-07 17:34:35 -07:00
Kconfig.debug License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
Makefile kbuild: add endianness flag to CHEKCFLAGS 2018-05-29 22:05:08 +09:00