path: root/mm
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authorNick Piggin <npiggin@suse.de>2008-08-01 03:15:21 +0200
committerIngo Molnar <mingo@elte.hu>2008-08-15 17:22:57 +0200
commit5843d9a4d0ba89719916c8f07fc9c57b7126be6d (patch)
tree3c55d6f17ce32ec3f53a324ce8fc90e291b44d79 /mm
parent466ae837424dcc538b1af2a0eaf53be32edcdbe7 (diff)
x86, pat: avoid highmem cache attribute aliasing
Highmem code can leave ptes and tlb entries around for a given page even after kunmap, and after it has been freed. >From what I can gather, the PAT code may change the cache attributes of arbitrary physical addresses (ie. including highmem pages), which would result in aliases in the case that it operates on one of these lazy tlb highmem pages. Flushing kmaps should solve the problem. I've also just added code for conditional flushing if we haven't got any dangling highmem aliases -- this should help performance if we change page attributes frequently or systems that aren't using much highmem pages (eg. if < 4G RAM). Should be turned into 2 patches, but just for RFC... Signed-off-by: Ingo Molnar <mingo@elte.hu>
Diffstat (limited to 'mm')
1 files changed, 4 insertions, 1 deletions
diff --git a/mm/highmem.c b/mm/highmem.c
index e16e1523b68..b36b83b920f 100644
--- a/mm/highmem.c
+++ b/mm/highmem.c
@@ -70,6 +70,7 @@ static DECLARE_WAIT_QUEUE_HEAD(pkmap_map_wait);
static void flush_all_zero_pkmaps(void)
int i;
+ int need_flush = 0;
@@ -101,8 +102,10 @@ static void flush_all_zero_pkmaps(void)
set_page_address(page, NULL);
+ need_flush = 1;
- flush_tlb_kernel_range(PKMAP_ADDR(0), PKMAP_ADDR(LAST_PKMAP));
+ if (need_flush)
+ flush_tlb_kernel_range(PKMAP_ADDR(0), PKMAP_ADDR(LAST_PKMAP));