Hi,

On Wed, Nov 29, 2023 at 05:57:44PM +0900, Hyesoo Yu wrote:

On Sun, Nov 19, 2023 at 04:57:09PM +0000, Alexandru Elisei wrote:

quoted

alloc_contig_range() requires that the requested pages are in the same
zone. Check that this is indeed the case before initializing the tag
storage blocks.

Signed-off-by: Alexandru Elisei <redacted>
---
 arch/arm64/kernel/mte_tag_storage.c | 33 +++++++++++++++++++++++++++++
 1 file changed, 33 insertions(+)

diff --git a/arch/arm64/kernel/mte_tag_storage.c b/arch/arm64/kernel/mte_tag_storage.c
index 8b9bedf7575d..fd63430d4dc0 100644
--- a/arch/arm64/kernel/mte_tag_storage.c
+++ b/arch/arm64/kernel/mte_tag_storage.c

@@ -265,6 +265,35 @@ void __init mte_tag_storage_init(void)
 	}
 }
 
+/* alloc_contig_range() requires all pages to be in the same zone. */
+static int __init mte_tag_storage_check_zone(void)
+{
+	struct range *tag_range;
+	struct zone *zone;
+	unsigned long pfn;
+	u32 block_size;
+	int i, j;
+
+	for (i = 0; i < num_tag_regions; i++) {
+		block_size = tag_regions[i].block_size;
+		if (block_size == 1)
+			continue;
+
+		tag_range = &tag_regions[i].tag_range;
+		for (pfn = tag_range->start; pfn <= tag_range->end; pfn += block_size) {
+			zone = page_zone(pfn_to_page(pfn));

Hello.

Since the blocks within the tag_range must all be in the same zone, can we move the "page_zone"
out of the loop ?

Hmm.. why do you say that the pages in a tag_range must be in the same
zone? I am not very familiar with how the memory management code puts pages
into zones, but I would imagine that pages in a tag range straddling the
4GB limit (so, let's say, from 3GB to 5GB) will end up in both ZONE_DMA and
ZONE_NORMAL.

Thanks,
Alex

Thanks,
Regards.

quoted

+			for (j = 1; j < block_size; j++) {
+				if (page_zone(pfn_to_page(pfn + j)) != zone) {
+					pr_err("Tag storage block pages in different zones");
+					return -EINVAL;
+				}
+			}
+		}
+	}
+
+	 return 0;
+}
+
 static int __init mte_tag_storage_activate_regions(void)
 {
 	phys_addr_t dram_start, dram_end;

@@ -321,6 +350,10 @@ static int __init mte_tag_storage_activate_regions(void)
 		goto out_disabled;
 	}
 
+	ret = mte_tag_storage_check_zone();
+	if (ret)
+		goto out_disabled;
+
 	for (i = 0; i < num_tag_regions; i++) {
 		tag_range = &tag_regions[i].tag_range;
 		for (pfn = tag_range->start; pfn <= tag_range->end; pfn += pageblock_nr_pages)

-- 
2.42.1

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