commit 22a33c7e4ed6aae8c47de72461162021dad87473
author Vasily Gorbik <gor@linux.ibm.com> Fri Aug 16 10:43:55 2019 +0200
committer Vasily Gorbik <gor@linux.ibm.com> Wed Aug 21 12:58:53 2019 +0200
tree 2d63962fbdb65ce30a2bd0c41cbe8e9652d72489
parent 80ef517b018257220f14410004ede094c577c276

s390/startup: round down "mem" option to page boundary

Make a usable value out of "mem" option once and for all. Kasan memory
allocator just takes memory_end or online memory size as allocation
base. If memory_end is not aligned paging structures allocated in kasan
end up unaligned as well. So this change fixes potential kasan crash
as well.

Fixes: 78333d1f908a ("s390/kasan: add support for mem= kernel parameter")
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>

arch/s390/boot/ipl_parm.c

diff --git a/arch/s390/boot/ipl_parm.c b/arch/s390/boot/ipl_parm.c
index 449d26a..4a052a8 100644
--- a/arch/s390/boot/ipl_parm.c
+++ b/arch/s390/boot/ipl_parm.c
@@ -224,7 +224,7 @@ void parse_boot_command_line(void)
 		args = next_arg(args, &param, &val);
 
 		if (!strcmp(param, "mem")) {
-			memory_end = memparse(val, NULL);
+			memory_end = round_down(memparse(val, NULL), PAGE_SIZE);
 			memory_end_set = 1;
 		}