Gerald Schaefer 4db28111b2 s390/gmap: improve THP splitting ...

commit ba925fa35057a062ac98c3e8138b013ce4ce351c upstream.

During s390_enable_sie(), we need to take care of splitting all qemu user
process THP mappings. This is currently done with follow_page(FOLL_SPLIT),
by simply iterating over all vma ranges, with PAGE_SIZE increment.

This logic is sub-optimal and can result in a lot of unnecessary overhead,
especially when using qemu and ASAN with large shadow map. Ilya reported
significant system slow-down with one CPU busy for a long time and overall
unresponsiveness.

Fix this by using walk_page_vma() and directly calling split_huge_pmd()
only for present pmds, which greatly reduces overhead.

Cc: <stable@vger.kernel.org> # v5.4+
Reported-by: Ilya Leoshkevich <iii@linux.ibm.com>
Tested-by: Ilya Leoshkevich <iii@linux.ibm.com>
Acked-by: Christian Borntraeger <borntraeger@de.ibm.com>
Signed-off-by: Gerald Schaefer <gerald.schaefer@linux.ibm.com>
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

2020-08-19 08:16:29 +02:00

..

cmm.c

s390/cmm: fix information leak in cmm_timeout_handler()

2019-10-31 17:26:48 +01:00

dump_pagetables.c

s390/mm: fix dump_pagetables top level page table walking

2019-08-06 13:58:34 +02:00

extmem.c

s390/extmem: use refcount_t for refcount

2019-08-21 12:41:43 +02:00

fault.c

s390/mm: add fallthrough annotations

2019-07-29 18:05:03 +02:00

gmap.c

s390/gmap: improve THP splitting

2020-08-19 08:16:29 +02:00

hugetlbpage.c

s390/mm: fix huge pte soft dirty copying

2020-07-16 08:16:47 +02:00

init.c

mm/memory_hotplug: shrink zones when offlining memory

2020-01-09 10:19:56 +01:00

kasan_init.c

s390/kasan: add kdump support

2019-08-29 15:34:58 +02:00

maccess.c

s390/maccess: add no DAT mode to kernel_write

2020-07-16 08:16:48 +02:00

Makefile

s390/mm: convert to the generic get_user_pages_fast code

2019-04-23 16:30:04 +02:00

mmap.c

s390/mm: mmap base does not depend on ADDR_NO_RANDOMIZE personality

2019-06-04 15:03:53 +02:00

page-states.c

s390/cmma: reuse kstrtobool for option value parsing

2019-08-26 12:51:18 +02:00

pageattr.c

s390/mm: Clear huge page storage keys on enable_skey

2018-07-30 11:20:18 +01:00

pgalloc.c

s390/mm: fix page table upgrade vs 2ndary address mode accesses

2020-04-29 16:33:25 +02:00

pgtable.c

s390/mm: silence compiler warning when compiling without CONFIG_PGSTE

2019-04-10 17:48:28 +02:00

vmem.c

s390: prevent leaking kernel address in BEAR

2020-04-13 10:48:06 +02:00