The patch titled
block: fix the setting of the bounce limit
has been removed from the -mm tree. Its filename was
block-fix-the-setting-of-the-bounce-limit.patch
This patch was dropped because it was merged into mainline or a subsystem tree
The current -mm tree may be found at http://userweb.kernel.org/~akpm/mmotm/
------------------------------------------------------
Subject: block: fix the setting of the bounce limit
From: Andrea Arcangeli <andrea@xxxxxxxxxxxx>
Fix a post-2.624 regression introduced by
commit 419c434c35614609fd0c79d335c134bf4b88b30b
Author: Yang Shi <yang.shi@xxxxxxxxxxxxx>
Date: Tue Mar 4 11:20:51 2008 +0100
Fix DMA access of block device in 64-bit kernel on some non-x86 systems with 4GB or upper 4GB memory
For some non-x86 systems with 4GB or upper 4GB memory,
we need increase the range of addresses that can be
used for direct DMA in 64-bit kernel.
This is crashing at boot my lowmem reserved RAM patch. This is causing
GFP_DMA allocations at boot for no good reason. It crashes in my case because
there's no ram below 16M available to linux.
Looking a bit closer into this regression the reason this can't be right is
that dma_addr common default is BLK_BOUNCE_HIGH and most machines have less
than 4G. So if you do:
if (b_pfn <= (min_t(u64, 0xffffffff, BLK_BOUNCE_HIGH) >> PAGE_SHIFT))
dma = 1
that will translate to:
if (BLK_BOUNCE_HIGH <= BLK_BOUNCE_HIGH)
dma = 1
So for 99% of hardware this will trigger unnecessary GFP_DMA
allocations and isa pooling operations.
Also note how the 32bit code still does b_pfn < blk_max_low_pfn.
I guess this is what you were looking after. As I can tell, this will stop
the regression with isa dma operations at boot for 99% of blkdev/memory
combinations out there and I guess this fixes the setups with >4G of ram and
32bit pci cards as well (this also retains symmetry with the 32bit code).
Signed-off-by: Andrea Arcangeli <andrea@xxxxxxxxxxxx>
Tested-by: Yang Shi <yang.shi@xxxxxxxxxxxxx>
Cc: Jens Axboe <jens.axboe@xxxxxxxxxx>
Cc: "Rafael J. Wysocki" <rjw@xxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
block/blk-settings.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff -puN block/blk-settings.c~block-fix-the-setting-of-the-bounce-limit block/blk-settings.c
--- a/block/blk-settings.c~block-fix-the-setting-of-the-bounce-limit
+++ a/block/blk-settings.c
@@ -140,7 +140,7 @@ void blk_queue_bounce_limit(struct reque
/* Assume anything <= 4GB can be handled by IOMMU.
Actually some IOMMUs can handle everything, but I don't
know of a way to test this here. */
- if (b_pfn <= (min_t(u64, 0xffffffff, BLK_BOUNCE_HIGH) >> PAGE_SHIFT))
+ if (b_pfn < (min_t(u64, 0x100000000UL, BLK_BOUNCE_HIGH) >> PAGE_SHIFT))
dma = 1;
q->bounce_pfn = max_low_pfn;
#else
_
Patches currently in -mm which might be from andrea@xxxxxxxxxxxx are
origin.patch
git-kvm.patch
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