From: Vasily Gorbik <gor@linux.ibm.com>
Date: Thu, 14 Oct 2021 13:33:45 +0200
Subject: s390/setup: avoid reserving memory above identity mapping
Git-commit: 420f48f636b98fd685f44a3acc4c0a7c0840910d
Patch-mainline: v5.16-rc2
References: git-fixes

Such reserved memory region, if not cleaned up later causes problems when
memblock_free_all() is called to release free pages to the buddy allocator
and those reserved regions are carried over to reserve_bootmem_region()
which marks the pages as PageReserved.

Instead use memblock_set_current_limit() to make sure memblock allocations
do not go over identity mapping (which could happen when "mem=" option
is used or during kdump).

Cc: stable@vger.kernel.org
Fixes: 73045a08cf55 ("s390: unify identity mapping limits handling")
Reported-by: Gerald Schaefer <gerald.schaefer@linux.ibm.com>
Reviewed-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
Acked-by: Petr Tesarik <ptesarik@suse.com>
---
 arch/s390/kernel/setup.c |   10 +---------
 1 file changed, 1 insertion(+), 9 deletions(-)

--- a/arch/s390/kernel/setup.c
+++ b/arch/s390/kernel/setup.c
@@ -590,14 +590,6 @@ static struct notifier_block kdump_mem_n
 #endif
 
 /*
- * Make sure that the area above identity mapping is protected
- */
-static void __init reserve_above_ident_map(void)
-{
-	memblock_reserve(ident_map_size, ULONG_MAX);
-}
-
-/*
  * Reserve memory for kdump kernel to be loaded with kexec
  */
 static void __init reserve_crashkernel(void)
@@ -1064,11 +1056,11 @@ void __init setup_arch(char **cmdline_p)
 	setup_control_program_code();
 
 	/* Do some memory reservations *before* memory is added to memblock */
-	reserve_above_ident_map();
 	reserve_kernel();
 	reserve_initrd();
 	reserve_certificate_list();
 	reserve_mem_detect_info();
+	memblock_set_current_limit(ident_map_size);
 	memblock_allow_resize();
 
 	/* Get information about *all* installed memory */