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Russell King 2be23c475a ARM: Ensure PTE modifications via dma_alloc_coherent are visible 
Dave Hylands reports:
| We've observed a problem with dma_alloc_writecombine when the system
| is under heavy load (heavy bus traffic).  We've managed to reduce the
| problem to the following snippet, which is run from a kthread in a
| continuous loop:
|
|   void *virtAddr;
|   dma_addr_t physAddr;
|   unsigned int numBytes = 256;
|
|   for (;;) {
|       virtAddr = dma_alloc_writecombine(NULL,
|             numBytes, &physAddr, GFP_KERNEL);
|       if (virtAddr == NULL) {
|          printk(KERN_ERR "Running out of memory\n");
|          break;
|       }
|
|       /* access DMA memory allocated */
|       tmp = virtAddr;
|       *tmp = 0x77;
|
|       /* free DMA memory */
|       dma_free_writecombine(NULL,
|             numBytes, virtAddr, physAddr);
|
|         ...sleep here...
|     }
|
| By itself, the code will run forever with no issues. However, as we
| increase our bus traffic (typically using DMA) then the *tmp = 0x77
| line will eventually cause a page fault. If we add a small delay (a
| few microseconds) before the *tmp = 0x77, then we don't see a page
| fault, even under heavy load.

A dsb() is required after modifying the PTE entries to ensure that they
will always be visible.  Add this dsb().

Reported-by: Dave Hylands <dhylands@gmail.com>
Tested-by: Dave Hylands <dhylands@gmail.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
 		2010-09-08 16:27:56 +01:00
..
Kconfig ARM: 6344/1: Mark CPU_32v6K as depended on CPU_V7 2010-09-02 15:32:13 +01:00
Makefile ARM: Remove DISCONTIGMEM support 2010-07-16 10:57:35 +01:00
abort-ev4.S
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abort-ev4t.S
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abort-ev5t.S
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abort-ev5tj.S
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abort-ev6.S
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abort-ev7.S arm: mm: qsd8x50: Fix incorrect permission faults 2010-05-03 11:15:05 -07:00
abort-lv4t.S
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abort-macro.S
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abort-nommu.S
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alignment.c ARM: 6268/1: ARMv6K and ARMv7 use fault statuses 3 and 6 as Access Flag fault 2010-07-27 10:48:41 +01:00
cache-fa.S
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cache-feroceon-l2.c
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cache-l2x0.c ARM: 6272/1: Convert L2x0 to use the IO relaxed operations 2010-07-29 14:04:36 +01:00
cache-tauros2.c
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cache-v3.S
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cache-v4.S
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cache-v4wb.S
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cache-v4wt.S
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cache-v6.S ARM: 6188/1: Add a config option for the ARM11MPCore DMA cache maintenance workaround 2010-07-01 10:12:31 +01:00
cache-v7.S ARM: 6139/1: ARMv7: Use the Inner Shareable I-cache on MP 2010-05-20 23:52:38 +01:00
cache-xsc3l2.c
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context.c
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copypage-fa.c ARM: Gemini: fix compiler error in copypage-fa.c 2010-04-27 12:45:10 +02:00
copypage-feroceon.c ARM: 6164/1: Add kto and kfrom to input operands list. 2010-06-08 19:42:18 +01:00
copypage-v3.c
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copypage-v4mc.c
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copypage-v4wb.c ARM: 6164/1: Add kto and kfrom to input operands list. 2010-06-08 19:42:18 +01:00
copypage-v4wt.c ARM: 6164/1: Add kto and kfrom to input operands list. 2010-06-08 19:42:18 +01:00
copypage-v6.c ARM: 6007/1: fix highmem with VIPT cache and DMA 2010-04-14 11:11:27 +01:00
copypage-xsc3.c ARM: 6164/1: Add kto and kfrom to input operands list. 2010-06-08 19:42:18 +01:00
copypage-xscale.c
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dma-mapping.c ARM: Ensure PTE modifications via dma_alloc_coherent are visible 2010-09-08 16:27:56 +01:00
extable.c
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fault-armv.c Merge branch 'devel-stable' into devel 2010-05-17 17:24:04 +01:00
fault.c ARM: 6268/1: ARMv6K and ARMv7 use fault statuses 3 and 6 as Access Flag fault 2010-07-27 10:48:41 +01:00
fault.h
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flush.c ARM: 6007/1: fix highmem with VIPT cache and DMA 2010-04-14 11:11:27 +01:00
highmem.c kmap_atomic: make kunmap_atomic() harder to misuse 2010-08-09 20:44:54 -07:00
init.c Merge branch 'devel-stable' into devel 2010-07-31 14:20:16 +01:00
iomap.c
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ioremap.c ARM: use generic ioremap_page_range() 2010-07-27 10:43:47 +01:00
mm.h ARM: Convert platform reservations to use LMB rather than bootmem 2010-07-27 08:48:23 +01:00
mmap.c [ARM] add address randomization to mmap() 2010-06-14 21:22:11 -04:00
mmu.c Merge branch 'misc' into devel 2010-07-31 14:20:02 +01:00
nommu.c ARM: Convert platform reservations to use LMB rather than bootmem 2010-07-27 08:48:23 +01:00
pabort-legacy.S
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pabort-v6.S
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pabort-v7.S
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pgd.c include cleanup: Update gfp.h and slab.h includes to prepare for breaking implicit slab.h inclusion from percpu.h 2010-03-30 22:02:32 +09:00
proc-arm6_7.S ARM: Factor out common code from cpu_proc_fin() 2010-07-27 10:48:42 +01:00
proc-arm7tdmi.S ARM: Factor out common code from cpu_proc_fin() 2010-07-27 10:48:42 +01:00
proc-arm9tdmi.S ARM: Factor out common code from cpu_proc_fin() 2010-07-27 10:48:42 +01:00
proc-arm720.S ARM: Factor out common code from cpu_proc_fin() 2010-07-27 10:48:42 +01:00
proc-arm740.S ARM: Factor out common code from cpu_proc_fin() 2010-07-27 10:48:42 +01:00
proc-arm920.S ARM: Factor out common code from cpu_proc_fin() 2010-07-27 10:48:42 +01:00
proc-arm922.S ARM: Factor out common code from cpu_proc_fin() 2010-07-27 10:48:42 +01:00
proc-arm925.S ARM: Factor out common code from cpu_proc_fin() 2010-07-27 10:48:42 +01:00
proc-arm926.S ARM: Factor out common code from cpu_proc_fin() 2010-07-27 10:48:42 +01:00
proc-arm940.S ARM: Factor out common code from cpu_proc_fin() 2010-07-27 10:48:42 +01:00
proc-arm946.S ARM: Factor out common code from cpu_proc_fin() 2010-07-27 10:48:42 +01:00
proc-arm1020.S ARM: Factor out common code from cpu_proc_fin() 2010-07-27 10:48:42 +01:00
proc-arm1020e.S ARM: Factor out common code from cpu_proc_fin() 2010-07-27 10:48:42 +01:00
proc-arm1022.S ARM: Factor out common code from cpu_proc_fin() 2010-07-27 10:48:42 +01:00
proc-arm1026.S ARM: Factor out common code from cpu_proc_fin() 2010-07-27 10:48:42 +01:00
proc-fa526.S ARM: Factor out common code from cpu_proc_fin() 2010-07-27 10:48:42 +01:00
proc-feroceon.S ARM: Factor out common code from cpu_proc_fin() 2010-07-27 10:48:42 +01:00
proc-macros.S
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proc-mohawk.S ARM: Factor out common code from cpu_proc_fin() 2010-07-27 10:48:42 +01:00
proc-sa110.S ARM: Factor out common code from cpu_proc_fin() 2010-07-27 10:48:42 +01:00
proc-sa1100.S ARM: Factor out common code from cpu_proc_fin() 2010-07-27 10:48:42 +01:00
proc-syms.c
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proc-v6.S ARM: Factor out common code from cpu_proc_fin() 2010-07-27 10:48:42 +01:00
proc-v7.S ARM: Factor out common code from cpu_proc_fin() 2010-07-27 10:48:42 +01:00
proc-xsc3.S ARM: Factor out common code from cpu_proc_fin() 2010-07-27 10:48:42 +01:00
proc-xscale.S ARM: Factor out common code from cpu_proc_fin() 2010-07-27 10:48:42 +01:00
tlb-fa.S
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tlb-v3.S
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tlb-v4.S
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tlb-v4wb.S
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tlb-v4wbi.S
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tlb-v6.S
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tlb-v7.S ARM: 6112/1: Use the Inner Shareable I-cache and BTB ops on ARMv7 SMP 2010-05-08 10:44:30 +01:00
vmregion.c ARM: DMA coherent allocator: align remapped addresses 2010-07-27 10:43:48 +01:00
vmregion.h ARM: DMA coherent allocator: align remapped addresses 2010-07-27 10:43:48 +01:00