From cd0aca2d550f238d80ba58e7dcade4ea3d0a3aa7 Mon Sep 17 00:00:00 2001 From: Tejun Heo Date: Wed, 15 Apr 2009 22:10:25 +0900 Subject: [PATCH] block: fix queue bounce limit setting Impact: don't set GFP_DMA in q->bounce_gfp unnecessarily All DMA address limits are expressed in terms of the last addressable unit (byte or page) instead of one plus that. However, when determining bounce_gfp for 64bit machines in blk_queue_bounce_limit(), it compares the specified limit against 0x100000000UL to determine whether it's below 4G ending up falsely setting GFP_DMA in q->bounce_gfp. As DMA zone is very small on x86_64, this makes larger SG_IO transfers very eager to trigger OOM killer. Fix it. While at it, rename the parameter to @dma_mask for clarity and convert comment to proper winged style. Signed-off-by: Tejun Heo Signed-off-by: Jens Axboe --- block/blk-settings.c | 20 +++++++++++--------- 1 file changed, 11 insertions(+), 9 deletions(-) diff --git a/block/blk-settings.c b/block/blk-settings.c index 69c42adde52b..57af728d94bb 100644 --- a/block/blk-settings.c +++ b/block/blk-settings.c @@ -156,26 +156,28 @@ EXPORT_SYMBOL(blk_queue_make_request); /** * blk_queue_bounce_limit - set bounce buffer limit for queue - * @q: the request queue for the device - * @dma_addr: bus address limit + * @q: the request queue for the device + * @dma_mask: the maximum address the device can handle * * Description: * Different hardware can have different requirements as to what pages * it can do I/O directly to. A low level driver can call * blk_queue_bounce_limit to have lower memory pages allocated as bounce - * buffers for doing I/O to pages residing above @dma_addr. + * buffers for doing I/O to pages residing above @dma_mask. **/ -void blk_queue_bounce_limit(struct request_queue *q, u64 dma_addr) +void blk_queue_bounce_limit(struct request_queue *q, u64 dma_mask) { - unsigned long b_pfn = dma_addr >> PAGE_SHIFT; + unsigned long b_pfn = dma_mask >> PAGE_SHIFT; int dma = 0; q->bounce_gfp = GFP_NOIO; #if BITS_PER_LONG == 64 - /* 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, 0x100000000UL, BLK_BOUNCE_HIGH) >> PAGE_SHIFT)) + /* + * 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, 0xffffffffUL, BLK_BOUNCE_HIGH) >> PAGE_SHIFT)) dma = 1; q->bounce_pfn = max_low_pfn; #else -- 2.20.1