[PATCH] RISC-V: Fix FIXMAP_TOP to avoid overlap with VMALLOC area

Anup Patel
2019-03-22T10:04:51Z

The FIXMAP area overlaps with VMALLOC area in Linux-5.1-rc1 hence we get
below warning in Linux RISC-V 32bit kernel. This warning does not show-up
in Linux RISC-V 64bit kernel due to large VMALLOC area.

WARNING: CPU: 0 PID: 22 at mm/vmalloc.c:150 vmap_page_range_noflush+0x134/0x15c
Modules linked in:
CPU: 0 PID: 22 Comm: kworker/0:1 Not tainted 5.1.0-rc1-00005-gebc2f658040e #1
Workqueue: events pcpu_balance_workfn
Call Trace:
[<c002b950>] walk_stackframe+0x0/0xa0
[<c002baac>] show_stack+0x28/0x32
[<c0587354>] dump_stack+0x62/0x7e
[<c002fdee>] __warn+0x98/0xce
[<c002fe52>] warn_slowpath_null+0x2e/0x3c
[<c00e71ce>] vmap_page_range_noflush+0x134/0x15c
[<c00e7886>] map_kernel_range_noflush+0xc/0x14
[<c00d54b8>] pcpu_populate_chunk+0x19e/0x236
[<c00d610e>] pcpu_balance_workfn+0x448/0x464
[<c00408d6>] process_one_work+0x16c/0x2ea
[<c0040b46>] worker_thread+0xf2/0x3b2
[<c004519a>] kthread+0xce/0xdc
[<c002a974>] ret_from_exception+0x0/0xc

This patch fixes above warning by placing FIXMAP area below VMALLOC area.

Fixes: f2c17aabc917 ("RISC-V: Implement compile-time fixed mappings")
Signed-off-by: Anup Patel <anup.patel@wdc.com>
---
arch/riscv/include/asm/fixmap.h | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/riscv/include/asm/fixmap.h b/arch/riscv/include/asm/fixmap.h
index 5cf53dd882e5..9c66033c3a54 100644
--- a/arch/riscv/include/asm/fixmap.h
+++ b/arch/riscv/include/asm/fixmap.h
@@ -31,7 +31,7 @@ enum fixed_addresses {
};

#define FIXADDR_SIZE (__end_of_fixed_addresses * PAGE_SIZE)
-#define FIXADDR_TOP (PAGE_OFFSET)
+#define FIXADDR_TOP (VMALLOC_START)
#define FIXADDR_START (FIXADDR_TOP - FIXADDR_SIZE)

#define FIXMAP_PAGE_IO PAGE_KERNEL
--
2.17.1