Merge tag 'dma-mapping-6.19-2026-02-06' of git://git.kernel.org/pub/scm/linux/kernel/git/mszyprowski/linux

Pull dma-mapping fixes from Marek Szyprowski:
 "Two minor fixes for the DMA-mapping subsystem:

   - check for the rare case of the allocation failure of the global CMA
     pool (Shanker Donthineni)

   - avoid perf buffer overflow when tracing large scatter-gather lists
     (Deepanshu Kartikey)"

* tag 'dma-mapping-6.19-2026-02-06' of git://git.kernel.org/pub/scm/linux/kernel/git/mszyprowski/linux:
  dma: contiguous: Check return value of dma_contiguous_reserve_area()
  tracing/dma: Cap dma_map_sg tracepoint arrays to prevent buffer overflow

Author: torvalds

include/trace/events/dma.h

@@ -275,28 +275,38 @@ TRACE_EVENT(dma_free_sgt,
 				sizeof(u64), sizeof(u64)))
 );
 
+#define DMA_TRACE_MAX_ENTRIES 128
+
 TRACE_EVENT(dma_map_sg,
 	TP_PROTO(struct device *dev, struct scatterlist *sgl, int nents,
 		 int ents, enum dma_data_direction dir, unsigned long attrs),
 	TP_ARGS(dev, sgl, nents, ents, dir, attrs),
 
 	TP_STRUCT__entry(
 		__string(device, dev_name(dev))
-		__dynamic_array(u64, phys_addrs, nents)
-		__dynamic_array(u64, dma_addrs, ents)
-		__dynamic_array(unsigned int, lengths, ents)
+		__field(int, full_nents)
+		__field(int, full_ents)
+		__field(bool, truncated)
+		__dynamic_array(u64, phys_addrs,  min(nents, DMA_TRACE_MAX_ENTRIES))
+		__dynamic_array(u64, dma_addrs, min(ents, DMA_TRACE_MAX_ENTRIES))
+		__dynamic_array(unsigned int, lengths, min(ents, DMA_TRACE_MAX_ENTRIES))
 		__field(enum dma_data_direction, dir)
 		__field(unsigned long, attrs)
 	),
 
 	TP_fast_assign(
 		struct scatterlist *sg;
 		int i;
+		int traced_nents = min_t(int, nents, DMA_TRACE_MAX_ENTRIES);
+		int traced_ents = min_t(int, ents, DMA_TRACE_MAX_ENTRIES);
 
 		__assign_str(device);
-		for_each_sg(sgl, sg, nents, i)
+		__entry->full_nents = nents;
+		__entry->full_ents = ents;
+		__entry->truncated = (nents > DMA_TRACE_MAX_ENTRIES) || (ents > DMA_TRACE_MAX_ENTRIES);
+		for_each_sg(sgl, sg, traced_nents, i)
 			((u64 *)__get_dynamic_array(phys_addrs))[i] = sg_phys(sg);
-		for_each_sg(sgl, sg, ents, i) {
+		for_each_sg(sgl, sg, traced_ents, i) {
 			((u64 *)__get_dynamic_array(dma_addrs))[i] =
 				sg_dma_address(sg);
 			((unsigned int *)__get_dynamic_array(lengths))[i] =
@@ -306,9 +316,12 @@ TRACE_EVENT(dma_map_sg,
 		__entry->attrs = attrs;
 	),
 
-	TP_printk("%s dir=%s dma_addrs=%s sizes=%s phys_addrs=%s attrs=%s",
+	TP_printk("%s dir=%s nents=%d/%d ents=%d/%d%s dma_addrs=%s sizes=%s phys_addrs=%s attrs=%s",
 		__get_str(device),
 		decode_dma_data_direction(__entry->dir),
+		min_t(int, __entry->full_nents, DMA_TRACE_MAX_ENTRIES), __entry->full_nents,
+		min_t(int, __entry->full_ents, DMA_TRACE_MAX_ENTRIES), __entry->full_ents,
+		__entry->truncated ? " [TRUNCATED]" : "",
 		__print_array(__get_dynamic_array(dma_addrs),
 			      __get_dynamic_array_len(dma_addrs) /
 				sizeof(u64), sizeof(u64)),

kernel/dma/contiguous.c

@@ -257,10 +257,12 @@ void __init dma_contiguous_reserve(phys_addr_t limit)
 		pr_debug("%s: reserving %ld MiB for global area\n", __func__,
 			 (unsigned long)selected_size / SZ_1M);
 
-		dma_contiguous_reserve_area(selected_size, selected_base,
-					    selected_limit,
-					    &dma_contiguous_default_area,
-					    fixed);
+		ret = dma_contiguous_reserve_area(selected_size, selected_base,
+						  selected_limit,
+						  &dma_contiguous_default_area,
+						  fixed);
+		if (ret)
+			return;
 
 		ret = dma_heap_cma_register_heap(dma_contiguous_default_area);
 		if (ret)