| Message ID | 20241022083927.3592237-1-zhengyejian@huaweicloud.com (mailing list archive) |
|---|---|
| Headers | show |
| Series | mm/damon/vaddr: Fix issue in damon_va_evenly_split_region() | expand |
Hi Zheng, On Tue, 22 Oct 2024 16:39:25 +0800 Zheng Yejian <zhengyejian@huaweicloud.com> wrote: [...] > To fix it, count for each piece split and make sure no more than > 'nr_pieces'. In addition, add above case into damon_test_split_evenly(). > > And add 'nr_piece == 1' check in damon_va_evenly_split_region() > for better code readability and add a corresponding kunit testcase. > > Zheng Yejian (2): > mm/damon/vaddr: Fix issue in damon_va_evenly_split_region() > mm/damon/vaddr: Check 'nr_piece == 1' case in > damon_va_evenly_split_region() > > mm/damon/tests/vaddr-kunit.h | 2 ++ > mm/damon/vaddr.c | 7 +++++-- > 2 files changed, 7 insertions(+), 2 deletions(-) Thank you for addressing my comments and posting this new patch series. I added my Reviewed-by: tags with some trivial comments to the patches. Btw, at least on DAMON mailing list, we usually post new revisions as new threads, rather than as a reply to the previous revision. If you want to make sure involved people aware of the new series, you can send the lore link for the new series as a reply to the previous revision. Thanks, SJ
On 2024/10/23 02:05, SeongJae Park wrote: > Hi Zheng, > > On Tue, 22 Oct 2024 16:39:25 +0800 Zheng Yejian <zhengyejian@huaweicloud.com> wrote: > > [...] >> To fix it, count for each piece split and make sure no more than >> 'nr_pieces'. In addition, add above case into damon_test_split_evenly(). >> >> And add 'nr_piece == 1' check in damon_va_evenly_split_region() >> for better code readability and add a corresponding kunit testcase. >> >> Zheng Yejian (2): >> mm/damon/vaddr: Fix issue in damon_va_evenly_split_region() >> mm/damon/vaddr: Check 'nr_piece == 1' case in >> damon_va_evenly_split_region() >> >> mm/damon/tests/vaddr-kunit.h | 2 ++ >> mm/damon/vaddr.c | 7 +++++-- >> 2 files changed, 7 insertions(+), 2 deletions(-) > > Thank you for addressing my comments and posting this new patch series. I > added my Reviewed-by: tags with some trivial comments to the patches. > Thanks for your review and comments ! > Btw, at least on DAMON mailing list, we usually post new revisions as new > threads, rather than as a reply to the previous revision. If you want to make > sure involved people aware of the new series, you can send the lore link for > the new series as a reply to the previous revision. > Got it :) > > Thanks, > SJ
According to the logic of damon_va_evenly_split_region(), currently following split case would not meet the expectation: Suppose DAMON_MIN_REGION=0x1000, Case: Split [0x0, 0x3000) into 2 pieces, then the result would be acutually 3 regions: [0x0, 0x1000), [0x1000, 0x2000), [0x2000, 0x3000) but NOT the expected 2 regions: [0x0, 0x1000), [0x1000, 0x3000) !!! The root cause is that when calculating size of each split piece in damon_va_evenly_split_region(): `sz_piece = ALIGN_DOWN(sz_orig / nr_pieces, DAMON_MIN_REGION);` both the dividing and the ALIGN_DOWN may cause loss of precision, then each time split one piece of size 'sz_piece' from origin 'start' to 'end' would cause more pieces are split out than expected!!! To fix it, count for each piece split and make sure no more than 'nr_pieces'. In addition, add above case into damon_test_split_evenly(). And add 'nr_piece == 1' check in damon_va_evenly_split_region() for better code readability and add a corresponding kunit testcase. Zheng Yejian (2): mm/damon/vaddr: Fix issue in damon_va_evenly_split_region() mm/damon/vaddr: Check 'nr_piece == 1' case in damon_va_evenly_split_region() mm/damon/tests/vaddr-kunit.h | 2 ++ mm/damon/vaddr.c | 7 +++++-- 2 files changed, 7 insertions(+), 2 deletions(-)