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author | Hugh Dickins <hughd@google.com> | 2022-04-01 21:28:27 +0300 |
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committer | Linus Torvalds <torvalds@linux-foundation.org> | 2022-04-01 21:46:09 +0300 |
commit | ece369c7e1044a333dc002d3c3c228b8853fc5f7 (patch) | |
tree | be4173a6317ad6455505361deca0d325bdd34470 /mm/damon/dbgfs-test.h | |
parent | cdd81b313d5e09e8a248c2dbd9c6b069f82e5d71 (diff) |
mm/munlock: add lru_add_drain() to fix memcg_stat_test
Mike reports that LTP memcg_stat_test usually leads to
memcg_stat_test 3 TINFO: Test unevictable with MAP_LOCKED
memcg_stat_test 3 TINFO: Running memcg_process --mmap-lock1 -s 135168
memcg_stat_test 3 TINFO: Warming up pid: 3460
memcg_stat_test 3 TINFO: Process is still here after warm up: 3460
memcg_stat_test 3 TFAIL: unevictable is 122880, 135168 expected
but may also lead to
memcg_stat_test 4 TINFO: Test unevictable with mlock
memcg_stat_test 4 TINFO: Running memcg_process --mmap-lock2 -s 135168
memcg_stat_test 4 TINFO: Warming up pid: 4271
memcg_stat_test 4 TINFO: Process is still here after warm up: 4271
memcg_stat_test 4 TFAIL: unevictable is 122880, 135168 expected
or both. A wee bit flaky.
follow_page_pte() used to have an lru_add_drain() per each page mlocked,
and the test came to rely on accurate stats. The pagevec to be drained
is different now, but still covered by lru_add_drain(); and, never mind
the test, I believe it's in everyone's interest that a bulk faulting
interface like populate_vma_page_range() or faultin_vma_page_range()
should drain its local pagevecs at the end, to save others sometimes
needing the much more expensive lru_add_drain_all().
This does not absolutely guarantee exact stats - the mlocking task can
be migrated between CPUs as it proceeds - but it's good enough and the
tests pass.
Link: https://lkml.kernel.org/r/47f6d39c-a075-50cb-1cfb-26dd957a48af@google.com
Fixes: b67bf49ce7aa ("mm/munlock: delete FOLL_MLOCK and FOLL_POPULATE")
Signed-off-by: Hugh Dickins <hughd@google.com>
Reported-by: Mike Galbraith <efault@gmx.de>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'mm/damon/dbgfs-test.h')
0 files changed, 0 insertions, 0 deletions