[PATCH v4 36/36] mm: Align THP mappings for non-DAX

Matthew Wilcox
2020-05-15T13:17:16Z

From: William Kucharski <william.kucharski@oracle.com>

When we have the opportunity to use transparent huge pages to map a
file, we want to follow the same rules as DAX.

Signed-off-by: William Kucharski <william.kucharski@oracle.com>
[Inline __thp_get_unmapped_area() into thp_get_unmapped_area()]
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
---
mm/huge_memory.c | 40 +++++++++++++---------------------------
1 file changed, 13 insertions(+), 27 deletions(-)

diff --git a/mm/huge_memory.c b/mm/huge_memory.c
index 15a86b06befc..e78686b628ae 100644
--- a/mm/huge_memory.c
+++ b/mm/huge_memory.c
@@ -535,30 +535,30 @@ bool is_transparent_hugepage(struct page *page)
}
EXPORT_SYMBOL_GPL(is_transparent_hugepage);

-static unsigned long __thp_get_unmapped_area(struct file *filp,
- unsigned long addr, unsigned long len,
- loff_t off, unsigned long flags, unsigned long size)
+unsigned long thp_get_unmapped_area(struct file *filp, unsigned long addr,
+ unsigned long len, unsigned long pgoff, unsigned long flags)
{
+ loff_t off = (loff_t)pgoff << PAGE_SHIFT;
loff_t off_end = off + len;
- loff_t off_align = round_up(off, size);
+ loff_t off_align = round_up(off, PMD_SIZE);
unsigned long len_pad, ret;

- if (off_end <= off_align || (off_end - off_align) < size)
- return 0;
+ if (off_end <= off_align || (off_end - off_align) < PMD_SIZE)
+ goto regular;

- len_pad = len + size;
+ len_pad = len + PMD_SIZE;
if (len_pad < len || (off + len_pad) < off)
- return 0;
+ goto regular;

ret = current->mm->get_unmapped_area(filp, addr, len_pad,
off >> PAGE_SHIFT, flags);

/*
- * The failure might be due to length padding. The caller will retry
- * without the padding.
+ * The failure might be due to length padding. Retry without
+ * the padding.
*/
if (IS_ERR_VALUE(ret))
- return 0;
+ goto regular;

/*
* Do not try to align to THP boundary if allocation at the address
@@ -567,23 +567,9 @@ static unsigned long __thp_get_unmapped_area(struct file *filp,
if (ret == addr)
return addr;

- ret += (off - ret) & (size - 1);
+ ret += (off - ret) & (PMD_SIZE - 1);
return ret;
-}
-
-unsigned long thp_get_unmapped_area(struct file *filp, unsigned long addr,
- unsigned long len, unsigned long pgoff, unsigned long flags)
-{
- unsigned long ret;
- loff_t off = (loff_t)pgoff << PAGE_SHIFT;
-
- if (!IS_DAX(filp->f_mapping->host) || !IS_ENABLED(CONFIG_FS_DAX_PMD))
- goto out;
-
- ret = __thp_get_unmapped_area(filp, addr, len, off, flags, PMD_SIZE);
- if (ret)
- return ret;
-out:
+regular:
return current->mm->get_unmapped_area(filp, addr, len, pgoff, flags);
}
EXPORT_SYMBOL_GPL(thp_get_unmapped_area);
--
2.26.2