4 files changed, 35 insertions, 21 deletions

diff --git a/arch/mips/cavium-octeon/dma-octeon.c b/arch/mips/cavium-octeon/dma-octeon.c
index 41dd00884975..02f244475207 100644
--- a/arch/mips/cavium-octeon/dma-octeon.c
+++ b/arch/mips/cavium-octeon/dma-octeon.c
@@ -317,7 +317,8 @@ void __init plat_swiotlb_setup(void)
 
         octeon_swiotlb = alloc_bootmem_low_pages(swiotlbsize);
 
-        swiotlb_init_with_tbl(octeon_swiotlb, swiotlb_nslabs, 1);
+        if (swiotlb_init_with_tbl(octeon_swiotlb, swiotlb_nslabs, 1) == -ENOMEM)
+                panic("Cannot allocate SWIOTLB buffer");
 
         mips_dma_map_ops = &octeon_linear_dma_map_ops.dma_map_ops;
 }
diff --git a/drivers/xen/swiotlb-xen.c b/drivers/xen/swiotlb-xen.c
index af47e7594460..1d94316f0ea4 100644
--- a/drivers/xen/swiotlb-xen.c
+++ b/drivers/xen/swiotlb-xen.c
@@ -231,7 +231,9 @@ retry:
         }
         start_dma_addr = xen_virt_to_bus(xen_io_tlb_start);
         if (early) {
-                swiotlb_init_with_tbl(xen_io_tlb_start, xen_io_tlb_nslabs, verbose);
+                if (swiotlb_init_with_tbl(xen_io_tlb_start, xen_io_tlb_nslabs,
+                         verbose))
+                        panic("Cannot allocate SWIOTLB buffer");
                 rc = 0;
         } else
                 rc = swiotlb_late_init_with_tbl(xen_io_tlb_start, xen_io_tlb_nslabs);
diff --git a/include/linux/swiotlb.h b/include/linux/swiotlb.h
index 071d62c214a6..2de42f9401d2 100644
--- a/include/linux/swiotlb.h
+++ b/include/linux/swiotlb.h
@@ -23,7 +23,7 @@ extern int swiotlb_force;
 #define IO_TLB_SHIFT 11
 
 extern void swiotlb_init(int verbose);
-extern void swiotlb_init_with_tbl(char *tlb, unsigned long nslabs, int verbose);
+int swiotlb_init_with_tbl(char *tlb, unsigned long nslabs, int verbose);
 extern unsigned long swiotlb_nr_tbl(void);
 extern int swiotlb_late_init_with_tbl(char *tlb, unsigned long nslabs);
 
diff --git a/lib/swiotlb.c b/lib/swiotlb.c
index 196b06984dec..bfe02b8fc55b 100644
--- a/lib/swiotlb.c
+++ b/lib/swiotlb.c
@@ -122,11 +122,18 @@ static dma_addr_t swiotlb_virt_to_bus(struct device *hwdev,
         return phys_to_dma(hwdev, virt_to_phys(address));
 }
 
+static bool no_iotlb_memory;
+
 void swiotlb_print_info(void)
 {
         unsigned long bytes = io_tlb_nslabs << IO_TLB_SHIFT;
         unsigned char *vstart, *vend;
 
+        if (no_iotlb_memory) {
+                pr_warn("software IO TLB: No low mem\n");
+                return;
+        }
+
         vstart = phys_to_virt(io_tlb_start);
         vend = phys_to_virt(io_tlb_end);
 
@@ -136,7 +143,7 @@ void swiotlb_print_info(void)
                bytes >> 20, vstart, vend - 1);
 }
 
-void __init swiotlb_init_with_tbl(char *tlb, unsigned long nslabs, int verbose)
+int __init swiotlb_init_with_tbl(char *tlb, unsigned long nslabs, int verbose)
 {
         void *v_overflow_buffer;
         unsigned long i, bytes;
@@ -150,9 +157,10 @@ void __init swiotlb_init_with_tbl(char *tlb, unsigned long nslabs, int verbose)
         /*
          * Get the overflow emergency buffer
          */
-        v_overflow_buffer = alloc_bootmem_low_pages(PAGE_ALIGN(io_tlb_overflow));
+        v_overflow_buffer = alloc_bootmem_low_pages_nopanic(
+                                                PAGE_ALIGN(io_tlb_overflow));
         if (!v_overflow_buffer)
-                panic("Cannot allocate SWIOTLB overflow buffer!\n");
+                return -ENOMEM;
 
         io_tlb_overflow_buffer = __pa(v_overflow_buffer);
 
@@ -169,15 +177,19 @@ void __init swiotlb_init_with_tbl(char *tlb, unsigned long nslabs, int verbose)
 
         if (verbose)
                 swiotlb_print_info();
+
+        return 0;
 }
 
 /*
  * Statically reserve bounce buffer space and initialize bounce buffer data
  * structures for the software IO TLB used to implement the DMA API.
  */
-static void __init
-swiotlb_init_with_default_size(size_t default_size, int verbose)
+void  __init
+swiotlb_init(int verbose)
 {
+        /* default to 64MB */
+        size_t default_size = 64UL<<20;
         unsigned char *vstart;
         unsigned long bytes;
 
@@ -188,20 +200,16 @@ swiotlb_init_with_default_size(size_t default_size, int verbose)
 
         bytes = io_tlb_nslabs << IO_TLB_SHIFT;
 
-        /*
-         * Get IO TLB memory from the low pages
-         */
-        vstart = alloc_bootmem_low_pages(PAGE_ALIGN(bytes));
-        if (!vstart)
-                panic("Cannot allocate SWIOTLB buffer");
-
-        swiotlb_init_with_tbl(vstart, io_tlb_nslabs, verbose);
-}
+        /* Get IO TLB memory from the low pages */
+        vstart = alloc_bootmem_low_pages_nopanic(PAGE_ALIGN(bytes));
+        if (vstart && !swiotlb_init_with_tbl(vstart, io_tlb_nslabs, verbose))
+                return;
 
-void __init
-swiotlb_init(int verbose)
-{
-        swiotlb_init_with_default_size(64 * (1<<20), verbose);  /* default to 64MB */
+        if (io_tlb_start)
+                free_bootmem(io_tlb_start,
+                                 PAGE_ALIGN(io_tlb_nslabs << IO_TLB_SHIFT));
+        pr_warn("Cannot allocate SWIOTLB buffer");
+        no_iotlb_memory = true;
 }
 
 /*
@@ -405,6 +413,9 @@ phys_addr_t swiotlb_tbl_map_single(struct device *hwdev,
         unsigned long offset_slots;
         unsigned long max_slots;
 
+        if (no_iotlb_memory)
+                panic("Can not allocate SWIOTLB buffer earlier and can't now provide you with the DMA bounce buffer");
+
         mask = dma_get_seg_boundary(hwdev);
 
         tbl_dma_addr &= mask;