dma-mapping fixes for Linux 6.6

- move a dma-debug call that prints a message out from a lock that's
    causing problems with the lock order in serial drivers (Sergey Senozhatsky)
  - fix the CONFIG_DMA_NUMA_CMA Kconfig entry to have the right dependency
    on not default to y (Christoph Hellwig)
  - move an ifdef a bit to remove a __maybe_unused that seems to trip up
    some sensitivities (Christoph Hellwig)
  - revert a bogus check in the CMA allocator (Zhenhua Huang)
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Merge tag 'dma-mapping-6.6-2023-09-09' of git://git.infradead.org/users/hch/dma-mapping

Pull dma-mapping fixes from Christoph Hellwig:

 - move a dma-debug call that prints a message out from a lock that's
   causing problems with the lock order in serial drivers (Sergey
   Senozhatsky)

 - fix the CONFIG_DMA_NUMA_CMA Kconfig entry to have the right
   dependency and not default to y (Christoph Hellwig)

 - move an ifdef a bit to remove a __maybe_unused that seems to trip up
   some sensitivities (Christoph Hellwig)

 - revert a bogus check in the CMA allocator (Zhenhua Huang)

* tag 'dma-mapping-6.6-2023-09-09' of git://git.infradead.org/users/hch/dma-mapping:
  Revert "dma-contiguous: check for memory region overlap"
  dma-pool: remove a __maybe_unused label in atomic_pool_expand
  dma-contiguous: fix the Kconfig entry for CONFIG_DMA_NUMA_CMA
  dma-debug: don't call __dma_entry_alloc_check_leak() under free_entries_lock

kernel/dma/Kconfig

@@ -160,7 +160,7 @@ if  DMA_CMA
 
 config DMA_NUMA_CMA
 	bool "Enable separate DMA Contiguous Memory Area for NUMA Node"
-	default NUMA
+	depends on NUMA
 	help
 	  Enable this option to get numa CMA areas so that NUMA devices
 	  can get local memory by DMA coherent APIs.

kernel/dma/contiguous.c

@@ -473,11 +473,6 @@ static int __init rmem_cma_setup(struct reserved_mem *rmem)
 		return -EBUSY;
 	}
 
-	if (memblock_is_region_reserved(rmem->base, rmem->size)) {
-		pr_info("Reserved memory: overlap with other memblock reserved region\n");
-		return -EBUSY;
-	}
-
 	if (!of_get_flat_dt_prop(node, "reusable", NULL) ||
 	    of_get_flat_dt_prop(node, "no-map", NULL))
 		return -EINVAL;

kernel/dma/debug.c

@@ -637,15 +637,19 @@ static struct dma_debug_entry *__dma_entry_alloc(void)
 	return entry;
 }
 
-static void __dma_entry_alloc_check_leak(void)
+/*
+ * This should be called outside of free_entries_lock scope to avoid potential
+ * deadlocks with serial consoles that use DMA.
+ */
+static void __dma_entry_alloc_check_leak(u32 nr_entries)
 {
-	u32 tmp = nr_total_entries % nr_prealloc_entries;
+	u32 tmp = nr_entries % nr_prealloc_entries;
 
 	/* Shout each time we tick over some multiple of the initial pool */
 	if (tmp < DMA_DEBUG_DYNAMIC_ENTRIES) {
 		pr_info("dma_debug_entry pool grown to %u (%u00%%)\n",
-			nr_total_entries,
-			(nr_total_entries / nr_prealloc_entries));
+			nr_entries,
+			(nr_entries / nr_prealloc_entries));
 	}
 }
 
@@ -656,8 +660,10 @@ static void __dma_entry_alloc_check_leak(void)
  */
 static struct dma_debug_entry *dma_entry_alloc(void)
 {
+	bool alloc_check_leak = false;
 	struct dma_debug_entry *entry;
 	unsigned long flags;
+	u32 nr_entries;
 
 	spin_lock_irqsave(&free_entries_lock, flags);
 	if (num_free_entries == 0) {
@@ -667,13 +673,17 @@ static struct dma_debug_entry *dma_entry_alloc(void)
 			pr_err("debugging out of memory - disabling\n");
 			return NULL;
 		}
-		__dma_entry_alloc_check_leak();
+		alloc_check_leak = true;
+		nr_entries = nr_total_entries;
 	}
 
 	entry = __dma_entry_alloc();
 
 	spin_unlock_irqrestore(&free_entries_lock, flags);
 
+	if (alloc_check_leak)
+		__dma_entry_alloc_check_leak(nr_entries);
+
 #ifdef CONFIG_STACKTRACE
 	entry->stack_len = stack_trace_save(entry->stack_entries,
 					    ARRAY_SIZE(entry->stack_entries),

kernel/dma/pool.c

@@ -135,9 +135,9 @@ encrypt_mapping:
 remove_mapping:
 #ifdef CONFIG_DMA_DIRECT_REMAP
 	dma_common_free_remap(addr, pool_size);
-#endif
-free_page: __maybe_unused
+free_page:
 	__free_pages(page, order);
+#endif
 out:
 	return ret;
 }