The patch titled
Subject: Documentation/vm/transhuge.rst: migration doesn't use FOLL_SPLIT anymore
has been added to the -mm tree. Its filename is
doc-mm-migration-doesnt-use-foll_split-anymore.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/doc-mm-migration-doesnt-use-foll_split-anymore.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/doc-mm-migration-doesnt-use-foll_split-anymore.patch
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------------------------------------------------------
From: Yang Shi <yang.shi@xxxxxxxxxxxxxxxxx>
Subject: Documentation/vm/transhuge.rst: migration doesn't use FOLL_SPLIT anymore
When demonstrating FOLL_SPLIT in transhuge document, migration is used as
an example. But, since commit 94723aafb9e7 ("mm: unclutter THP
migration"), the way of THP migration is totally changed. FOLL_SPLIT is
not used by migration anymore due to the change.
Remove the obsolete example to avoid confusion.
Link: http://lkml.kernel.org/r/1555618624-23957-1-git-send-email-yang.shi@xxxxxxxxxxxxxxxxx
Signed-off-by: Yang Shi <yang.shi@xxxxxxxxxxxxxxxxx>
Reviewed-by: Zi Yan <ziy@xxxxxxxxxx>
Cc: Michal Hocko <mhocko@xxxxxxxx>
Cc: Kirill A. Shutemov <kirill.shutemov@xxxxxxxxxxxxxxx>
Cc: Mike Rapoport <rppt@xxxxxxxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
Documentation/vm/transhuge.rst | 8 +-------
1 file changed, 1 insertion(+), 7 deletions(-)
--- a/Documentation/vm/transhuge.rst~doc-mm-migration-doesnt-use-foll_split-anymore
+++ a/Documentation/vm/transhuge.rst
@@ -55,13 +55,7 @@ prevent page from being split by anyone.
In case you can't handle compound pages if they're returned by
follow_page, the FOLL_SPLIT bit can be specified as parameter to
follow_page, so that it will split the hugepages before returning
-them. Migration for example passes FOLL_SPLIT as parameter to
-follow_page because it's not hugepage aware and in fact it can't work
-at all on hugetlbfs (but it instead works fine on transparent
-hugepages thanks to FOLL_SPLIT). migration simply can't deal with
-hugepages being returned (as it's not only checking the pfn of the
-page and pinning it during the copy but it pretends to migrate the
-memory in regular page sizes and with regular pte/pmd mappings).
+them.
Graceful fallback
=================
_
Patches currently in -mm which might be from yang.shi@xxxxxxxxxxxxxxxxx are
doc-mm-migration-doesnt-use-foll_split-anymore.patch
