trying to analyze struct vm_area_struct

src/lib/iov_iter.c

@@ -1238,12 +1238,15 @@ ssize_t iov_iter_get_pages_elphel(struct iov_iter *i,
 	const struct page * circbuf0_page0 = phys_to_page(circbuf_pa[0]);
 	size_t len;
 	const struct iovec *iov = i->iov; // only use first in array - supposed to be a single-element
-	unsigned long addr = (unsigned long) iov->iov_base;
+	unsigned long addr;
+	unsigned long faddr = (unsigned long) iov->iov_base;
+	struct vm_area_struct *vm_area;
 
 // *** Putting temporary address here
 	struct page * cur_page = (struct page * ) circbuf0_page0;
+	pr_debug("circbuf0_page0 = 0x%08x, circbuf0_page0->compound_head=0x%08lx, faddr=0x%08lx, mapcount=%u", \
+			(int) circbuf0_page0, circbuf0_page0->compound_head, faddr ,page_mapcount((struct page *) circbuf0_page0));
 	addr = 0;
-	pr_debug("circbuf0_page0 = 0x%08x, circbuf0_page0->compound_head=0x%08lx", (int) circbuf0_page0, circbuf0_page0->compound_head );
 	len = iov->iov_len + (*start = addr & (PAGE_SIZE - 1)); // to inlude beginning of the page - for now 0;
 	if (maxsize > i->count)
 		maxsize = i->count;
@@ -1259,7 +1262,15 @@ ssize_t iov_iter_get_pages_elphel(struct iov_iter *i,
 		pages[indx] = cur_page++;
 	}
 	len -= *start;
-	pr_debug("iov_iter_get_pages_elphel()->0x%08x, n=%u, current->mm->map_count=%u", len, n, current->mm->map_count);
+	pr_debug("iov_iter_get_pages_elphel()->0x%08x, n=%u, current->mm->map_count=%u",\
+			len, n, current->mm->map_count);
+	pr_debug("sizeof(struct vm_area_struct)=%d", sizeof(struct vm_area_struct));
+	for (vm_area = current->mm->mmap; vm_area;  vm_area = vm_area-> vm_next) {
+		if ((faddr >= vm_area->vm_start) && (faddr < vm_area->vm_end)) {
+			print_hex_dump_bytes("", DUMP_PREFIX_OFFSET, vm_area, sizeof(struct vm_area_struct));
+		}
+
+	}
 	return len;
 }
 EXPORT_SYMBOL(iov_iter_get_pages_elphel);