On 07/22/2014 12:01 PM, Max Filippov wrote:
From: Leonid Yegoshin <Leonid.Yegoshin@xxxxxxxxxx>
Provide hooks that allow architectures with aliasing cache to align
mapping address of high pages according to their color. Such architectures
may enforce similar coloring of low- and high-memory page mappings and
reuse existing cache management functions to support highmem.
Cc: linux-mm@xxxxxxxxx
Cc: linux-arch@xxxxxxxxxxxxxxx
Cc: linux-mips@xxxxxxxxxxxxxx
Cc: David Rientjes <rientjes@xxxxxxxxxx>
Signed-off-by: Leonid Yegoshin <Leonid.Yegoshin@xxxxxxxxxx>
[ Max: extract architecture-independent part of the original patch, clean
up checkpatch and build warnings. ]
Signed-off-by: Max Filippov <jcmvbkbc@xxxxxxxxx>
---
Changes since the initial version:
- define set_pkmap_color(pg, cl) as do { } while (0) instead of /* */;
- rename is_no_more_pkmaps to no_more_pkmaps;
- change 'if (count > 0)' to 'if (count)' to better match the original
code behavior;
mm/highmem.c | 19 ++++++++++++++++---
1 file changed, 16 insertions(+), 3 deletions(-)
diff --git a/mm/highmem.c b/mm/highmem.c
index b32b70c..88fb62e 100644
--- a/mm/highmem.c
+++ b/mm/highmem.c
@@ -44,6 +44,14 @@ DEFINE_PER_CPU(int, __kmap_atomic_idx);
*/
#ifdef CONFIG_HIGHMEM
+#ifndef ARCH_PKMAP_COLORING
+#define set_pkmap_color(pg, cl) do { } while (0)
+#define get_last_pkmap_nr(p, cl) (p)
+#define get_next_pkmap_nr(p, cl) (((p) + 1) & LAST_PKMAP_MASK)
+#define no_more_pkmaps(p, cl) (!(p))
+#define get_next_pkmap_counter(c, cl) ((c) - 1)
+#endif
+
unsigned long totalhigh_pages __read_mostly;
EXPORT_SYMBOL(totalhigh_pages);
@@ -161,19 +169,24 @@ static inline unsigned long map_new_virtual(struct page *page)
{
unsigned long vaddr;
int count;
+ int color __maybe_unused;
+
+ set_pkmap_color(page, color);
+ last_pkmap_nr = get_last_pkmap_nr(last_pkmap_nr, color);
start:
count = LAST_PKMAP;
/* Find an empty entry */
for (;;) {
- last_pkmap_nr = (last_pkmap_nr + 1) & LAST_PKMAP_MASK;
- if (!last_pkmap_nr) {
+ last_pkmap_nr = get_next_pkmap_nr(last_pkmap_nr, color);
+ if (no_more_pkmaps(last_pkmap_nr, color)) {
flush_all_zero_pkmaps();
count = LAST_PKMAP;
}
if (!pkmap_count[last_pkmap_nr])
break; /* Found a usable entry */
- if (--count)
+ count = get_next_pkmap_counter(count, color);
+ if (count)
continue;
/*
I would like to return back to "if (count >0)".
The reason is in easy way to jump through the same coloured pages - next
element is calculated via decrementing by non "1" value of colours and
it can easy become negative on last page available:
#define get_next_pkmap_counter(c,cl) (c - FIX_N_COLOURS)
where FIX_N_COLOURS is a max number of page colours.
Besides that it is a good practice in stopping cycle.
- Leonid.
