Highmem was only supported on UML/i386. And the support has been
removed by commit a98a6d864d3b ("um: Remove broken highmem support").
Remove the leftovers and stop UML from trying to setup highmem when
the sum of physmem_size and iomem_size exceeds max_physmem.

Signed-off-by: Tiwei Bie <tiwei.btw@antgroup.com>
---
 arch/um/drivers/virtio_uml.c       |  9 +--------
 arch/um/include/shared/as-layout.h |  1 -
 arch/um/include/shared/mem_user.h  |  5 ++---
 arch/um/kernel/mem.c               |  3 ---
 arch/um/kernel/physmem.c           | 28 ++++++++++------------------
 arch/um/kernel/um_arch.c           | 17 +++++++----------
 6 files changed, 20 insertions(+), 43 deletions(-)

diff --git a/arch/um/drivers/virtio_uml.c b/arch/um/drivers/virtio_uml.c
index 2b6e701776b6..e7f5556e3c96 100644
--- a/arch/um/drivers/virtio_uml.c
+++ b/arch/um/drivers/virtio_uml.c
@@ -72,7 +72,7 @@ struct virtio_uml_vq_info {
 	bool suspended;
 };
 
-extern unsigned long long physmem_size, highmem;
+extern unsigned long long physmem_size;
 
 #define vu_err(vu_dev, ...)	dev_err(&(vu_dev)->pdev->dev, ##__VA_ARGS__)
 
@@ -673,13 +673,6 @@ static int vhost_user_set_mem_table(struct virtio_uml_device *vu_dev)
 
 	if (rc < 0)
 		return rc;
-	if (highmem) {
-		msg.payload.mem_regions.num++;
-		rc = vhost_user_init_mem_region(__pa(end_iomem), highmem,
-				&fds[1], &msg.payload.mem_regions.regions[1]);
-		if (rc < 0)
-			return rc;
-	}
 
 	return vhost_user_send(vu_dev, false, &msg, fds,
 			       msg.payload.mem_regions.num);
diff --git a/arch/um/include/shared/as-layout.h b/arch/um/include/shared/as-layout.h
index 06292fca5a4d..61965a06c18a 100644
--- a/arch/um/include/shared/as-layout.h
+++ b/arch/um/include/shared/as-layout.h
@@ -41,7 +41,6 @@ extern unsigned long uml_physmem;
 extern unsigned long uml_reserved;
 extern unsigned long end_vm;
 extern unsigned long start_vm;
-extern unsigned long long highmem;
 
 extern unsigned long brk_start;
 
diff --git a/arch/um/include/shared/mem_user.h b/arch/um/include/shared/mem_user.h
index 11a723a58545..adfa08062f88 100644
--- a/arch/um/include/shared/mem_user.h
+++ b/arch/um/include/shared/mem_user.h
@@ -47,10 +47,9 @@ extern int iomem_size;
 #define ROUND_4M(n) ((((unsigned long) (n)) + (1 << 22)) & ~((1 << 22) - 1))
 
 extern unsigned long find_iomem(char *driver, unsigned long *len_out);
-extern void mem_total_pages(unsigned long physmem, unsigned long iomem,
-		     unsigned long highmem);
+extern void mem_total_pages(unsigned long physmem, unsigned long iomem);
 extern void setup_physmem(unsigned long start, unsigned long usable,
-			  unsigned long len, unsigned long long highmem);
+			  unsigned long len);
 extern void map_memory(unsigned long virt, unsigned long phys,
 		       unsigned long len, int r, int w, int x);
 
diff --git a/arch/um/kernel/mem.c b/arch/um/kernel/mem.c
index a5b4fe2ad931..5026668dc054 100644
--- a/arch/um/kernel/mem.c
+++ b/arch/um/kernel/mem.c
@@ -6,7 +6,6 @@
 #include <linux/stddef.h>
 #include <linux/module.h>
 #include <linux/memblock.h>
-#include <linux/highmem.h>
 #include <linux/mm.h>
 #include <linux/swap.h>
 #include <linux/slab.h>
@@ -51,8 +50,6 @@ EXPORT_SYMBOL(empty_zero_page);
 pgd_t swapper_pg_dir[PTRS_PER_PGD];
 
 /* Initialized at boot time, and readonly after that */
-unsigned long long highmem;
-EXPORT_SYMBOL(highmem);
 int kmalloc_ok = 0;
 
 /* Used during early boot */
diff --git a/arch/um/kernel/physmem.c b/arch/um/kernel/physmem.c
index ee693e0b2b58..94aca17993fd 100644
--- a/arch/um/kernel/physmem.c
+++ b/arch/um/kernel/physmem.c
@@ -24,17 +24,14 @@ EXPORT_SYMBOL(high_physmem);
 
 extern unsigned long long physmem_size;
 
-void __init mem_total_pages(unsigned long physmem, unsigned long iomem,
-		     unsigned long highmem)
+void __init mem_total_pages(unsigned long physmem, unsigned long iomem)
 {
-	unsigned long phys_pages, highmem_pages;
-	unsigned long iomem_pages, total_pages;
+	unsigned long phys_pages, iomem_pages, total_pages;
 
-	phys_pages    = physmem >> PAGE_SHIFT;
-	iomem_pages   = iomem   >> PAGE_SHIFT;
-	highmem_pages = highmem >> PAGE_SHIFT;
+	phys_pages  = physmem >> PAGE_SHIFT;
+	iomem_pages = iomem   >> PAGE_SHIFT;
 
-	total_pages   = phys_pages + iomem_pages + highmem_pages;
+	total_pages = phys_pages + iomem_pages;
 
 	max_mapnr = total_pages;
 }
@@ -64,13 +61,12 @@ void map_memory(unsigned long virt, unsigned long phys, unsigned long len,
  * @reserve_end:	end address of the physical kernel memory.
  * @len:	Length of total physical memory that should be mapped/made
  *		available, in bytes.
- * @highmem:	Number of highmem bytes that should be mapped/made available.
  *
- * Creates an unlinked temporary file of size (len + highmem) and memory maps
+ * Creates an unlinked temporary file of size (len) and memory maps
  * it on the last executable image address (uml_reserved).
  *
  * The offset is needed as the length of the total physical memory
- * (len + highmem) includes the size of the memory used be the executable image,
+ * (len) includes the size of the memory used be the executable image,
  * but the mapped-to address is the last address of the executable image
  * (uml_reserved == end address of executable image).
  *
@@ -78,7 +74,7 @@ void map_memory(unsigned long virt, unsigned long phys, unsigned long len,
  * of all user space processes/kernel tasks.
  */
 void __init setup_physmem(unsigned long start, unsigned long reserve_end,
-			  unsigned long len, unsigned long long highmem)
+			  unsigned long len)
 {
 	unsigned long reserve = reserve_end - start;
 	unsigned long map_size = len - reserve;
@@ -90,7 +86,7 @@ void __init setup_physmem(unsigned long start, unsigned long reserve_end,
 		exit(1);
 	}
 
-	physmem_fd = create_mem_file(len + highmem);
+	physmem_fd = create_mem_file(len);
 
 	err = os_map_memory((void *) reserve_end, physmem_fd, reserve,
 			    map_size, 1, 1, 1);
@@ -109,7 +105,7 @@ void __init setup_physmem(unsigned long start, unsigned long reserve_end,
 	os_write_file(physmem_fd, __syscall_stub_start, PAGE_SIZE);
 	os_fsync_file(physmem_fd);
 
-	memblock_add(__pa(start), len + highmem);
+	memblock_add(__pa(start), len);
 	memblock_reserve(__pa(start), reserve);
 
 	min_low_pfn = PFN_UP(__pa(reserve_end));
@@ -137,10 +133,6 @@ int phys_mapping(unsigned long phys, unsigned long long *offset_out)
 			region = region->next;
 		}
 	}
-	else if (phys < __pa(end_iomem) + highmem) {
-		fd = physmem_fd;
-		*offset_out = phys - iomem_size;
-	}
 
 	return fd;
 }
diff --git a/arch/um/kernel/um_arch.c b/arch/um/kernel/um_arch.c
index 8e594cda6d77..8f86aa468b50 100644
--- a/arch/um/kernel/um_arch.c
+++ b/arch/um/kernel/um_arch.c
@@ -366,18 +366,15 @@ int __init linux_main(int argc, char **argv)
 
 	setup_machinename(init_utsname()->machine);
 
-	highmem = 0;
+	physmem_size = (physmem_size + PAGE_SIZE - 1) & PAGE_MASK;
 	iomem_size = (iomem_size + PAGE_SIZE - 1) & PAGE_MASK;
+
 	max_physmem = TASK_SIZE - uml_physmem - iomem_size - MIN_VMALLOC;
 
-	/*
-	 * Zones have to begin on a 1 << MAX_PAGE_ORDER page boundary,
-	 * so this makes sure that's true for highmem
-	 */
-	max_physmem &= ~((1 << (PAGE_SHIFT + MAX_PAGE_ORDER)) - 1);
 	if (physmem_size + iomem_size > max_physmem) {
-		highmem = physmem_size + iomem_size - max_physmem;
-		physmem_size -= highmem;
+		physmem_size = max_physmem - iomem_size;
+		os_info("Physical memory size shrunk to %llu bytes\n",
+			physmem_size);
 	}
 
 	high_physmem = uml_physmem + physmem_size;
@@ -413,8 +410,8 @@ void __init setup_arch(char **cmdline_p)
 	u8 rng_seed[32];
 
 	stack_protections((unsigned long) &init_thread_info);
-	setup_physmem(uml_physmem, uml_reserved, physmem_size, highmem);
-	mem_total_pages(physmem_size, iomem_size, highmem);
+	setup_physmem(uml_physmem, uml_reserved, physmem_size);
+	mem_total_pages(physmem_size, iomem_size);
 	uml_dtb_init();
 	read_initrd();
 
-- 
2.34.1