The patch titled
Subject: mm: support THPs in zero_user_segments
has been added to the -mm tree. Its filename is
mm-support-thps-in-zero_user_segments.patch
This patch should soon appear at
https://ozlabs.org/~akpm/mmots/broken-out/mm-support-thps-in-zero_user_segments.patch
and later at
https://ozlabs.org/~akpm/mmotm/broken-out/mm-support-thps-in-zero_user_segments.patch
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------------------------------------------------------
From: "Matthew Wilcox (Oracle)" <willy@xxxxxxxxxxxxx>
Subject: mm: support THPs in zero_user_segments
We can only kmap() one subpage of a THP at a time, so loop over all
relevant subpages, skipping ones which don't need to be zeroed. This is
too large to inline when THPs are enabled and we actually need highmem, so
put it in highmem.c.
Link: https://lkml.kernel.org/r/20201124041507.28996-1-willy@xxxxxxxxxxxxx
Signed-off-by: Matthew Wilcox (Oracle) <willy@xxxxxxxxxxxxx>
Cc: Yang Shi <shy828301@xxxxxxxxx>
Cc: Jan Kara <jack@xxxxxxx>
Cc: Michal Hocko <mhocko@xxxxxxxx>
Cc: Zi Yan <ziy@xxxxxxxxxx>
Cc: Song Liu <songliubraving@xxxxxx>
Cc: Mel Gorman <mgorman@xxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
include/linux/highmem.h | 19 +++++++++---
mm/highmem.c | 59 ++++++++++++++++++++++++++++++++++++++
2 files changed, 74 insertions(+), 4 deletions(-)
--- a/include/linux/highmem.h~mm-support-thps-in-zero_user_segments
+++ a/include/linux/highmem.h
@@ -284,13 +284,22 @@ static inline void clear_highpage(struct
kunmap_atomic(kaddr);
}
+/*
+ * If we pass in a base or tail page, we can zero up to PAGE_SIZE.
+ * If we pass in a head page, we can zero up to the size of the compound page.
+ */
+#if defined(CONFIG_HIGHMEM) && defined(CONFIG_TRANSPARENT_HUGEPAGE)
+void zero_user_segments(struct page *page, unsigned start1, unsigned end1,
+ unsigned start2, unsigned end2);
+#else /* !HIGHMEM || !TRANSPARENT_HUGEPAGE */
static inline void zero_user_segments(struct page *page,
- unsigned start1, unsigned end1,
- unsigned start2, unsigned end2)
+ unsigned start1, unsigned end1,
+ unsigned start2, unsigned end2)
{
void *kaddr = kmap_atomic(page);
+ unsigned int i;
- BUG_ON(end1 > PAGE_SIZE || end2 > PAGE_SIZE);
+ BUG_ON(end1 > page_size(page) || end2 > page_size(page));
if (end1 > start1)
memset(kaddr + start1, 0, end1 - start1);
@@ -299,8 +308,10 @@ static inline void zero_user_segments(st
memset(kaddr + start2, 0, end2 - start2);
kunmap_atomic(kaddr);
- flush_dcache_page(page);
+ for (i = 0; i < compound_nr(page); i++)
+ flush_dcache_page(page + i);
}
+#endif /* !HIGHMEM || !TRANSPARENT_HUGEPAGE */
static inline void zero_user_segment(struct page *page,
unsigned start, unsigned end)
--- a/mm/highmem.c~mm-support-thps-in-zero_user_segments
+++ a/mm/highmem.c
@@ -369,6 +369,65 @@ void kunmap_high(struct page *page)
}
EXPORT_SYMBOL(kunmap_high);
+
+#ifdef CONFIG_TRANSPARENT_HUGEPAGE
+void zero_user_segments(struct page *page, unsigned start1, unsigned end1,
+ unsigned start2, unsigned end2)
+{
+ unsigned int i;
+
+ BUG_ON(end1 > page_size(page) || end2 > page_size(page));
+
+ for (i = 0; i < compound_nr(page); i++) {
+ void *kaddr;
+ unsigned this_end;
+
+ if (end1 == 0 && start2 >= PAGE_SIZE) {
+ start2 -= PAGE_SIZE;
+ end2 -= PAGE_SIZE;
+ continue;
+ }
+
+ if (start1 >= PAGE_SIZE) {
+ start1 -= PAGE_SIZE;
+ end1 -= PAGE_SIZE;
+ if (start2) {
+ start2 -= PAGE_SIZE;
+ end2 -= PAGE_SIZE;
+ }
+ continue;
+ }
+
+ kaddr = kmap_atomic(page + i);
+
+ this_end = min_t(unsigned, end1, PAGE_SIZE);
+ if (end1 > start1)
+ memset(kaddr + start1, 0, this_end - start1);
+ end1 -= this_end;
+ start1 = 0;
+
+ if (start2 >= PAGE_SIZE) {
+ start2 -= PAGE_SIZE;
+ end2 -= PAGE_SIZE;
+ } else {
+ this_end = min_t(unsigned, end2, PAGE_SIZE);
+ if (end2 > start2)
+ memset(kaddr + start2, 0, this_end - start2);
+ end2 -= this_end;
+ start2 = 0;
+ }
+
+ kunmap_atomic(kaddr);
+ flush_dcache_page(page + i);
+
+ if (!end1 && !end2)
+ break;
+ }
+
+ BUG_ON((start1 | start2 | end1 | end2) != 0);
+}
+EXPORT_SYMBOL(zero_user_segments);
+#endif /* CONFIG_TRANSPARENT_HUGEPAGE */
#endif /* CONFIG_HIGHMEM */
#if defined(HASHED_PAGE_VIRTUAL)
_
Patches currently in -mm which might be from willy@xxxxxxxxxxxxx are
mm-page-flags-fix-comment.patch
mm-page_alloc-add-__free_pages-documentation.patch
mm-support-thps-in-zero_user_segments.patch
mm-make-pagecache-tagged-lookups-return-only-head-pages.patch
mm-shmem-use-pagevec_lookup-in-shmem_unlock_mapping.patch
mm-swap-optimise-get_shadow_from_swap_cache.patch
mm-add-fgp_entry.patch
mm-filemap-rename-find_get_entry-to-mapping_get_entry.patch
mm-filemap-add-helper-for-finding-pages.patch
mm-filemap-add-mapping_seek_hole_data.patch
iomap-use-mapping_seek_hole_data.patch
mm-add-and-use-find_lock_entries.patch
mm-add-an-end-parameter-to-find_get_entries.patch
mm-add-an-end-parameter-to-pagevec_lookup_entries.patch
mm-remove-nr_entries-parameter-from-pagevec_lookup_entries.patch
mm-pass-pvec-directly-to-find_get_entries.patch
mm-remove-pagevec_lookup_entries.patch
mm-truncateshmem-handle-truncates-that-split-thps.patch
mm-filemap-return-only-head-pages-from-find_get_entries.patch
