From: Zi Yan <zi.yan@xxxxxxxxxxxxxx> Hi Naoya, Here is soft-offline support for thp migration. I need comments since it has an interface change (Patch 2) of soft_offline_page() and a behavior change (Patch 3) in migrate_pages(). soft_offline_page() is used in store_soft_offline_page() from drivers/base/memory.c. The patchset is on top of mmotm-2017-08-10-15-33. The patchset is tested with: 1. simple madvise() call program (https://github.com/x-y-z/soft-offline-test) and 2. a local kernel change to intentionally fail allocating THPs for soft offline, which makes to-be-soft-offlined THPs being split by Patch 3. Patch 1: obtain the size of a offlined page before it is offlined. The size is used as the step value of the for-loop inside madvise_inject_error(). Originally, the for-loop used the size of offlined pages, which was OK. But as a THP is offlined, it is split afterwards, so the page size obtained after offlined is PAGE_SIZE instead of THP page size, which causes a THP being offlined 512 times. Patch 2: when offlining a THP, there are two situations, a) the THP is offlined as a whole, or b) the THP is split and only the raw error page is offlined. Thus, we need soft_offline_page() to tell us whether a THP is split during offlining, which leads to a new interface parameter. Patch 3: as Naoya suggested, if a THP fails to be offlined as a whole, we should retry the raw error subpage. This patch implement it. This also requires migrate_pages() not splitting a THP if migration fails for MR_MEMORY_FAILURE. Patch 4: enable thp migration support for soft offline. Any suggestions and comments are welcome. Thanks. Zi Yan (4): mm: madvise: read loop's step size beforehand in madvise_inject_error(), prepare for THP support. mm: soft-offline: Change soft_offline_page() interface to tell if the page is split or not. mm: soft-offline: retry to split and soft-offline the raw error if the original THP offlining fails. mm: hwpoison: soft offline supports thp migration drivers/base/memory.c | 2 +- include/linux/mm.h | 2 +- mm/madvise.c | 24 ++++++++++-- mm/memory-failure.c | 103 +++++++++++++++++++++++++++++--------------------- mm/migrate.c | 16 ++++++++ 5 files changed, 97 insertions(+), 50 deletions(-) -- 2.13.2 -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>
