The patch titled
Subject: mm, highmem: makes flush_all_zero_pkmaps() return index of last flushed entry
has been added to the -mm tree. Its filename is
mm-highmem-makes-flush_all_zero_pkmaps-return-index-of-last-flushed-entry.patch
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From: Joonsoo Kim <js1304@xxxxxxxxx>
Subject: mm, highmem: makes flush_all_zero_pkmaps() return index of last flushed entry
In current code, after flush_all_zero_pkmaps() is invoked we re-iterate
all pkmaps. This can be optimized if flush_all_zero_pkmaps() returns an
index of flushed entry. With this index, we can immediately map highmem
page to virtual address represented by index. So change return type of
flush_all_zero_pkmaps() and return index of last flushed entry.
Signed-off-by: Joonsoo Kim <js1304@xxxxxxxxx>
Cc: Mel Gorman <mel@xxxxxxxxx>
Cc: Minchan Kim <minchan@xxxxxxxxxx>
Cc: Peter Zijlstra <a.p.zijlstra@xxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
include/linux/highmem.h | 1
mm/highmem.c | 68 +++++++++++++++++++++-----------------
2 files changed, 39 insertions(+), 30 deletions(-)
diff -puN include/linux/highmem.h~mm-highmem-makes-flush_all_zero_pkmaps-return-index-of-last-flushed-entry include/linux/highmem.h
--- a/include/linux/highmem.h~mm-highmem-makes-flush_all_zero_pkmaps-return-index-of-last-flushed-entry
+++ a/include/linux/highmem.h
@@ -32,6 +32,7 @@ static inline void invalidate_kernel_vma
#ifdef CONFIG_HIGHMEM
#include <asm/highmem.h>
+#define PKMAP_INDEX_INVAL (-1)
/* declarations for linux/mm/highmem.c */
unsigned int nr_free_highpages(void);
diff -puN mm/highmem.c~mm-highmem-makes-flush_all_zero_pkmaps-return-index-of-last-flushed-entry mm/highmem.c
--- a/mm/highmem.c~mm-highmem-makes-flush_all_zero_pkmaps-return-index-of-last-flushed-entry
+++ a/mm/highmem.c
@@ -107,10 +107,10 @@ struct page *kmap_to_page(void *vaddr)
}
EXPORT_SYMBOL(kmap_to_page);
-static void flush_all_zero_pkmaps(void)
+static int flush_all_zero_pkmaps(void)
{
int i;
- int need_flush = 0;
+ int index = PKMAP_INDEX_INVAL;
flush_cache_kmaps();
@@ -142,10 +142,12 @@ static void flush_all_zero_pkmaps(void)
&pkmap_page_table[i]);
set_page_address(page, NULL);
- need_flush = 1;
+ index = i;
}
- if (need_flush)
+ if (index != PKMAP_INDEX_INVAL)
flush_tlb_kernel_range(PKMAP_ADDR(0), PKMAP_ADDR(LAST_PKMAP));
+
+ return index;
}
/**
@@ -161,6 +163,7 @@ void kmap_flush_unused(void)
static inline unsigned long map_new_virtual(struct page *page)
{
unsigned long vaddr;
+ int index = PKMAP_INDEX_INVAL;
int count;
start:
@@ -169,40 +172,45 @@ start:
for (;;) {
last_pkmap_nr = (last_pkmap_nr + 1) & LAST_PKMAP_MASK;
if (!last_pkmap_nr) {
- flush_all_zero_pkmaps();
- count = LAST_PKMAP;
+ index = flush_all_zero_pkmaps();
+ if (index != PKMAP_INDEX_INVAL)
+ break; /* Found a usable entry */
}
- if (!pkmap_count[last_pkmap_nr])
+ if (!pkmap_count[last_pkmap_nr]) {
+ index = last_pkmap_nr;
break; /* Found a usable entry */
- if (--count)
- continue;
+ }
+ if (--count == 0)
+ break;
+ }
- /*
- * Sleep for somebody else to unmap their entries
- */
- {
- DECLARE_WAITQUEUE(wait, current);
+ /*
+ * Sleep for somebody else to unmap their entries
+ */
+ if (index == PKMAP_INDEX_INVAL) {
+ DECLARE_WAITQUEUE(wait, current);
- __set_current_state(TASK_UNINTERRUPTIBLE);
- add_wait_queue(&pkmap_map_wait, &wait);
- unlock_kmap();
- schedule();
- remove_wait_queue(&pkmap_map_wait, &wait);
- lock_kmap();
-
- /* Somebody else might have mapped it while we slept */
- if (page_address(page))
- return (unsigned long)page_address(page);
+ __set_current_state(TASK_UNINTERRUPTIBLE);
+ add_wait_queue(&pkmap_map_wait, &wait);
+ unlock_kmap();
+ schedule();
+ remove_wait_queue(&pkmap_map_wait, &wait);
+ lock_kmap();
+
+ /* Somebody else might have mapped it while we slept */
+ vaddr = (unsigned long)page_address(page);
+ if (vaddr)
+ return vaddr;
- /* Re-start */
- goto start;
- }
+ /* Re-start */
+ goto start;
}
- vaddr = PKMAP_ADDR(last_pkmap_nr);
+
+ vaddr = PKMAP_ADDR(index);
set_pte_at(&init_mm, vaddr,
- &(pkmap_page_table[last_pkmap_nr]), mk_pte(page, kmap_prot));
+ &(pkmap_page_table[index]), mk_pte(page, kmap_prot));
- pkmap_count[last_pkmap_nr] = 1;
+ pkmap_count[index] = 1;
set_page_address(page, (void *)vaddr);
return vaddr;
_
Patches currently in -mm which might be from js1304@xxxxxxxxx are
linux-next.patch
mm-highmem-use-pkmap_nr-to-calculate-an-index-of-pkmap.patch
mm-highmem-remove-useless-pool_lock.patch
mm-highmem-remove-page_address_pool-list.patch
mm-highmem-makes-flush_all_zero_pkmaps-return-index-of-last-flushed-entry.patch
mm-highmem-get-virtual-address-of-the-page-using-pkmap_addr.patch
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