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| author | Gerald Schaefer <gerald.schaefer@linux.ibm.com> | 2020-07-29 23:22:34 +0300 |
|---|---|---|
| committer | Heiko Carstens <hca@linux.ibm.com> | 2020-08-11 19:16:13 +0300 |
| commit | ba925fa35057a062ac98c3e8138b013ce4ce351c (patch) | |
| tree | 90e90da496783eecb3ae5ae33d65773d174bd5dd /arch/s390/lib/test_unwind.c | |
| parent | f0cbd3b83ed47803df941865f720934c69abb803 (diff) | |
| download | linux-ba925fa35057a062ac98c3e8138b013ce4ce351c.tar.xz | |
s390/gmap: improve THP splitting
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>
Diffstat (limited to 'arch/s390/lib/test_unwind.c')
0 files changed, 0 insertions, 0 deletions