The patch titled
Subject: mm: vm_insert_pages() checks if pte_index defined.
has been added to the -mm tree. Its filename is
mm-add-vm_insert_pages-2-fix.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/mm-add-vm_insert_pages-2-fix.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/mm-add-vm_insert_pages-2-fix.patch
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------------------------------------------------------
From: Arjun Roy <arjunroy@xxxxxxxxxx>
Subject: mm: vm_insert_pages() checks if pte_index defined.
pte_index() is either defined as a macro (e.g. sparc64) or as an inlined
function (e.g. x86). vm_insert_pages() depends on pte_index but it is
not defined on all platforms (e.g. m68k).
To fix compilation of vm_insert_pages() on architectures not providing
pte_index(), we perform the following fix:
0. For platforms where it is meaningful, and defined as a macro, no
change is needed.
1. For platforms where it is meaningful and defined as an inlined
function, and we want to use it with vm_insert_pages(), we define
a degenerate macro of the form: #define pte_index pte_index
2. vm_insert_pages() checks for the existence of a pte_index macro
definition. If found, it implements a batched insert. If not found,
it devolves to calling vm_insert_page() in a loop.
This patch implements step 2.
v3 of this patch fixes a compilation warning for an unused method.
v2 of this patch moved a macro definition to a more readable location.
Link: http://lkml.kernel.org/r/20200228054714.204424-2-arjunroy.kdev@xxxxxxxxx
Signed-off-by: Arjun Roy <arjunroy@xxxxxxxxxx>
Cc: Eric Dumazet <edumazet@xxxxxxxxxx>
Cc: Soheil Hassas Yeganeh <soheil@xxxxxxxxxx>
Cc: David Miller <davem@xxxxxxxxxxxxx>
Cc: Matthew Wilcox <willy@xxxxxxxxxxxxx>
Cc: Jason Gunthorpe <jgg@xxxxxxxx>
Cc: Stephen Rothwell <sfr@xxxxxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/memory.c | 41 ++++++++++++++++++++++++++++-------------
1 file changed, 28 insertions(+), 13 deletions(-)
--- a/mm/memory.c~mm-add-vm_insert_pages-2-fix
+++ a/mm/memory.c
@@ -1460,18 +1460,6 @@ static int insert_page_into_pte_locked(s
return 0;
}
-static int insert_page_in_batch_locked(struct mm_struct *mm, pmd_t *pmd,
- unsigned long addr, struct page *page, pgprot_t prot)
-{
- int err;
-
- if (!page_count(page))
- return -EINVAL;
- err = validate_page_before_insert(page);
- return err ? err : insert_page_into_pte_locked(
- mm, pte_offset_map(pmd, addr), addr, page, prot);
-}
-
/*
* This is the old fallback for page remapping.
*
@@ -1500,8 +1488,21 @@ out:
return retval;
}
+#ifdef pte_index
+static int insert_page_in_batch_locked(struct mm_struct *mm, pmd_t *pmd,
+ unsigned long addr, struct page *page, pgprot_t prot)
+{
+ int err;
+
+ if (!page_count(page))
+ return -EINVAL;
+ err = validate_page_before_insert(page);
+ return err ? err : insert_page_into_pte_locked(
+ mm, pte_offset_map(pmd, addr), addr, page, prot);
+}
+
/* insert_pages() amortizes the cost of spinlock operations
- * when inserting pages in a loop.
+ * when inserting pages in a loop. Arch *must* define pte_index.
*/
static int insert_pages(struct vm_area_struct *vma, unsigned long addr,
struct page **pages, unsigned long *num, pgprot_t prot)
@@ -1556,6 +1557,7 @@ out:
*num = remaining_pages_total;
return ret;
}
+#endif /* ifdef pte_index */
/**
* vm_insert_pages - insert multiple pages into user vma, batching the pmd lock.
@@ -1575,6 +1577,7 @@ out:
int vm_insert_pages(struct vm_area_struct *vma, unsigned long addr,
struct page **pages, unsigned long *num)
{
+#ifdef pte_index
const unsigned long end_addr = addr + (*num * PAGE_SIZE) - 1;
if (addr < vma->vm_start || end_addr >= vma->vm_end)
@@ -1586,6 +1589,18 @@ int vm_insert_pages(struct vm_area_struc
}
/* Defer page refcount checking till we're about to map that page. */
return insert_pages(vma, addr, pages, num, vma->vm_page_prot);
+#else
+ unsigned long idx = 0, pgcount = *num;
+ int err;
+
+ for (; idx < pgcount; ++idx) {
+ err = vm_insert_page(vma, addr + (PAGE_SIZE * idx), pages[idx]);
+ if (err)
+ break;
+ }
+ *num = pgcount - idx;
+ return err;
+#endif /* ifdef pte_index */
}
EXPORT_SYMBOL(vm_insert_pages);
_
Patches currently in -mm which might be from arjunroy@xxxxxxxxxx are
mm-refactor-insert_page-to-prepare-for-batched-lock-insert.patch
mm-bring-sparc-pte_index-semantics-inline-with-other-platforms.patch
mm-define-pte_index-as-macro-for-x86.patch
mm-add-vm_insert_pages.patch
mm-add-vm_insert_pages-2.patch
mm-add-vm_insert_pages-2-fix.patch
net-zerocopy-use-vm_insert_pages-for-tcp-rcv-zerocopy.patch
