The patch titled
Subject: mm/rmap: cleanup partially-mapped handling in __folio_remove_rmap()
has been added to the -mm mm-unstable branch. Its filename is
mm-rmap-cleanup-partially-mapped-handling-in-__folio_remove_rmap.patch
This patch will shortly appear at
https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/mm-rmap-cleanup-partially-mapped-handling-in-__folio_remove_rmap.patch
This patch will later appear in the mm-unstable branch at
git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
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------------------------------------------------------
From: David Hildenbrand <david@xxxxxxxxxx>
Subject: mm/rmap: cleanup partially-mapped handling in __folio_remove_rmap()
Date: Wed, 10 Jul 2024 23:43:50 +0200
Let's simplify and reduce code indentation. In the RMAP_LEVEL_PTE case,
we already check for nr when computing partially_mapped.
For RMAP_LEVEL_PMD, it's a bit more confusing. Likely, we don't need the
"nr" check, but we could have "nr < nr_pmdmapped" also if we stumbled into
the "/* Raced ahead of another remove and an add? */" case. So let's
simply move the nr check in there.
Note that partially_mapped is always false for small folios.
No functional change intended.
Link: https://lkml.kernel.org/r/20240710214350.147864-1-david@xxxxxxxxxx
Signed-off-by: David Hildenbrand <david@xxxxxxxxxx>
Reviewed-by: Zi Yan <ziy@xxxxxxxxxx>
Reviewed-by: Yosry Ahmed <yosryahmed@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/rmap.c | 23 ++++++++++-------------
1 file changed, 10 insertions(+), 13 deletions(-)
--- a/mm/rmap.c~mm-rmap-cleanup-partially-mapped-handling-in-__folio_remove_rmap
+++ a/mm/rmap.c
@@ -1568,22 +1568,19 @@ static __always_inline void __folio_remo
}
}
- partially_mapped = nr < nr_pmdmapped;
+ partially_mapped = nr && nr < nr_pmdmapped;
break;
}
- if (nr) {
- /*
- * Queue anon large folio for deferred split if at least one
- * page of the folio is unmapped and at least one page
- * is still mapped.
- *
- * Check partially_mapped first to ensure it is a large folio.
- */
- if (folio_test_anon(folio) && partially_mapped &&
- list_empty(&folio->_deferred_list))
- deferred_split_folio(folio);
- }
+ /*
+ * Queue anon large folio for deferred split if at least one page of
+ * the folio is unmapped and at least one page is still mapped.
+ *
+ * Check partially_mapped first to ensure it is a large folio.
+ */
+ if (partially_mapped && folio_test_anon(folio) &&
+ list_empty(&folio->_deferred_list))
+ deferred_split_folio(folio);
__folio_mod_stat(folio, -nr, -nr_pmdmapped);
/*
_
Patches currently in -mm which might be from david@xxxxxxxxxx are
mm-turn-use_split_pte_ptlocks-use_split_pte_ptlocks-into-kconfig-options.patch
mm-hugetlb-enforce-that-pmd-pt-sharing-has-split-pmd-pt-locks.patch
powerpc-8xx-document-and-enforce-that-split-pt-locks-are-not-used.patch
mm-simplify-arch_make_folio_accessible.patch
mm-gup-convert-to-arch_make_folio_accessible.patch
s390-uv-drop-arch_make_page_accessible.patch
mm-hugetlb-remove-hugetlb_follow_page_mask-leftover.patch
mm-rmap-cleanup-partially-mapped-handling-in-__folio_remove_rmap.patch
