Messages in this thread | | | Date | Fri, 21 Oct 2022 11:41:49 -0700 | From | Andrew Morton <> | Subject | Re: [PATCH v2 1/2] mm: migrate: Fix return value if all subpages of THPs are migrated successfully |
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On Fri, 21 Oct 2022 18:16:23 +0800 Baolin Wang <baolin.wang@linux.alibaba.com> wrote:
> When THP migration, if THPs are split and all subpages are migrated successfully > , the migrate_pages() will still return the number of THP that were not migrated. > That will confuse the callers of migrate_pages(), for example, which will make > the longterm pinning failed though all pages are migrated successfully. > > Thus we should return 0 to indicate all pages are migrated in this case. >
This had me puzzled for a while. I think this wording is clearer?
: During THP migration, if THPs are not migrated but they are split and all : subpages are migrated successfully, migrate_pages() will still return the : number of THP pages that were not migrated. This will confuse the callers : of migrate_pages(). For example, the longterm pinning will failed though : all pages are migrated successfully. : : Thus we should return 0 to indicate that all pages are migrated in this : case.
This is a fairly longstanding problem? No Fixes: we can identify?
Did you consider the desirability of a -stable backport?
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