Merge tag 'dma-mapping-6.2-2022-12-13' of git://git.infradead.org/users/hch/dma-mapping

Pull dma-mapping updates from Christoph Hellwig:

 - reduce the swiotlb buffer size on allocation failure (Alexey
   Kardashevskiy)

 - clean up passing of bogus GFP flags to the dma-coherent allocator
   (Christoph Hellwig)

* tag 'dma-mapping-6.2-2022-12-13' of git://git.infradead.org/users/hch/dma-mapping:
  dma-mapping: reject __GFP_COMP in dma_alloc_attrs
  ALSA: memalloc: don't pass bogus GFP_ flags to dma_alloc_*
  s390/ism: don't pass bogus GFP_ flags to dma_alloc_coherent
  cnic: don't pass bogus GFP_ flags to dma_alloc_coherent
  RDMA/qib: don't pass bogus GFP_ flags to dma_alloc_coherent
  RDMA/hfi1: don't pass bogus GFP_ flags to dma_alloc_coherent
  media: videobuf-dma-contig: use dma_mmap_coherent
  swiotlb: reduce the swiotlb buffer size on allocation failure

2 files changed, 47 insertions, 24 deletions

diff --git a/kernel/dma/mapping.c b/kernel/dma/mapping.c
index 33437d620644..c026a5a5e046 100644
--- a/kernel/dma/mapping.c
+++ b/kernel/dma/mapping.c
@@ -498,6 +498,14 @@ void *dma_alloc_attrs(struct device *dev, size_t size, dma_addr_t *dma_handle,
 
 	WARN_ON_ONCE(!dev->coherent_dma_mask);
 
+	/*
+	 * DMA allocations can never be turned back into a page pointer, so
+	 * requesting compound pages doesn't make sense (and can't even be
+	 * supported at all by various backends).
+	 */
+	if (WARN_ON_ONCE(flag & __GFP_COMP))
+		return NULL;
+
 	if (dma_alloc_from_dev_coherent(dev, size, dma_handle, &cpu_addr))
 		return cpu_addr;
 
diff --git a/kernel/dma/swiotlb.c b/kernel/dma/swiotlb.c
index 339a990554e7..a34c38bbe28f 100644
--- a/kernel/dma/swiotlb.c
+++ b/kernel/dma/swiotlb.c
@@ -300,6 +300,37 @@ static void swiotlb_init_io_tlb_mem(struct io_tlb_mem *mem, phys_addr_t start,
 	return;
 }
 
+static void *swiotlb_memblock_alloc(unsigned long nslabs, unsigned int flags,
+		int (*remap)(void *tlb, unsigned long nslabs))
+{
+	size_t bytes = PAGE_ALIGN(nslabs << IO_TLB_SHIFT);
+	void *tlb;
+
+	/*
+	 * By default allocate the bounce buffer memory from low memory, but
+	 * allow to pick a location everywhere for hypervisors with guest
+	 * memory encryption.
+	 */
+	if (flags & SWIOTLB_ANY)
+		tlb = memblock_alloc(bytes, PAGE_SIZE);
+	else
+		tlb = memblock_alloc_low(bytes, PAGE_SIZE);
+
+	if (!tlb) {
+		pr_warn("%s: Failed to allocate %zu bytes tlb structure\n",
+			__func__, bytes);
+		return NULL;
+	}
+
+	if (remap && remap(tlb, nslabs) < 0) {
+		memblock_free(tlb, PAGE_ALIGN(bytes));
+		pr_warn("%s: Failed to remap %zu bytes\n", __func__, bytes);
+		return NULL;
+	}
+
+	return tlb;
+}
+
 /*
  * Statically reserve bounce buffer space and initialize bounce buffer data
  * structures for the software IO TLB used to implement the DMA API.
@@ -310,7 +341,6 @@ void __init swiotlb_init_remap(bool addressing_limit, unsigned int flags,
 	struct io_tlb_mem *mem = &io_tlb_default_mem;
 	unsigned long nslabs;
 	size_t alloc_size;
-	size_t bytes;
 	void *tlb;
 
 	if (!addressing_limit && !swiotlb_force_bounce)
@@ -326,31 +356,16 @@ void __init swiotlb_init_remap(bool addressing_limit, unsigned int flags,
 		swiotlb_adjust_nareas(num_possible_cpus());
 
 	nslabs = default_nslabs;
-	/*
-	 * By default allocate the bounce buffer memory from low memory, but
-	 * allow to pick a location everywhere for hypervisors with guest
-	 * memory encryption.
-	 */
-retry:
-	bytes = PAGE_ALIGN(nslabs << IO_TLB_SHIFT);
-	if (flags & SWIOTLB_ANY)
-		tlb = memblock_alloc(bytes, PAGE_SIZE);
-	else
-		tlb = memblock_alloc_low(bytes, PAGE_SIZE);
-	if (!tlb) {
-		pr_warn("%s: failed to allocate tlb structure\n", __func__);
-		return;
-	}
-
-	if (remap && remap(tlb, nslabs) < 0) {
-		memblock_free(tlb, PAGE_ALIGN(bytes));
-
+	while ((tlb = swiotlb_memblock_alloc(nslabs, flags, remap)) == NULL) {
+		if (nslabs <= IO_TLB_MIN_SLABS)
+			return;
 		nslabs = ALIGN(nslabs >> 1, IO_TLB_SEGSIZE);
-		if (nslabs >= IO_TLB_MIN_SLABS)
-			goto retry;
+	}
 
-		pr_warn("%s: Failed to remap %zu bytes\n", __func__, bytes);
-		return;
+	if (default_nslabs != nslabs) {
+		pr_info("SWIOTLB bounce buffer size adjusted %lu -> %lu slabs",
+			default_nslabs, nslabs);
+		default_nslabs = nslabs;
 	}
 
 	alloc_size = PAGE_ALIGN(array_size(sizeof(*mem->slots), nslabs));