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Commit 704a7624 authored by Lance Yang's avatar Lance Yang Committed by Treehugger Robot
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UPSTREAM: mm/vmscan: avoid split lazyfree THP during shrink_folio_list()

When the user no longer requires the pages, they would use
madvise(MADV_FREE) to mark the pages as lazy free.  Subsequently, they
typically would not re-write to that memory again.

During memory reclaim, if we detect that the large folio and its PMD are
both still marked as clean and there are no unexpected references (such as
GUP), so we can just discard the memory lazily, improving the efficiency
of memory reclamation in this case.

On an Intel i5 CPU, reclaiming 1GiB of lazyfree THPs using
mem_cgroup_force_empty() results in the following runtimes in seconds
(shorter is better):

--------------------------------------------
|     Old       |      New       |  Change  |
--------------------------------------------
|   0.683426    |    0.049197    |  -92.80% |
--------------------------------------------

[ioworker0@gmail.com: minor changes per David]
  Link: https://lkml.kernel.org/r/20240622100057.3352-1-ioworker0@gmail.com
Link: https://lkml.kernel.org/r/20240614015138.31461-4-ioworker0@gmail.com


Change-Id: I716b3f00627134eb58fbaa44a8cc81fd11f52f8c
Signed-off-by: default avatarLance Yang <ioworker0@gmail.com>
Suggested-by: default avatarZi Yan <ziy@nvidia.com>
Suggested-by: default avatarDavid Hildenbrand <david@redhat.com>
Cc: Bang Li <libang.li@antgroup.com>
Cc: Baolin Wang <baolin.wang@linux.alibaba.com>
Cc: Barry Song <baohua@kernel.org>
Cc: Fangrui Song <maskray@google.com>
Cc: Jeff Xie <xiehuan09@gmail.com>
Cc: Kefeng Wang <wangkefeng.wang@huawei.com>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Muchun Song <songmuchun@bytedance.com>
Cc: Peter Xu <peterx@redhat.com>
Cc: Ryan Roberts <ryan.roberts@arm.com>
Cc: SeongJae Park <sj@kernel.org>
Cc: Yang Shi <shy828301@gmail.com>
Cc: Yin Fengwei <fengwei.yin@intel.com>
Cc: Zach O'Keefe <zokeefe@google.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
(cherry picked from commit 735ecdfa)
Bug: 313807618
Signed-off-by: default avatarKalesh Singh <kaleshsingh@google.com>
parent 11d1e09d
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