This is a note to let you know that I've just added the patch titled s390/setup: avoid reserving memory above identity mapping to the 5.15-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary The filename of the patch is: s390-setup-avoid-reserving-memory-above-identity-mapping.patch and it can be found in the queue-5.15 subdirectory. If you, or anyone else, feels it should not be added to the stable tree, please let <stable@xxxxxxxxxxxxxxx> know about it. >From 420f48f636b98fd685f44a3acc4c0a7c0840910d Mon Sep 17 00:00:00 2001 From: Vasily Gorbik <gor@xxxxxxxxxxxxx> Date: Thu, 14 Oct 2021 13:33:45 +0200 Subject: s390/setup: avoid reserving memory above identity mapping From: Vasily Gorbik <gor@xxxxxxxxxxxxx> commit 420f48f636b98fd685f44a3acc4c0a7c0840910d upstream. 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@xxxxxxxxxxxxxxx Fixes: 73045a08cf55 ("s390: unify identity mapping limits handling") Reported-by: Gerald Schaefer <gerald.schaefer@xxxxxxxxxxxxx> Reviewed-by: Heiko Carstens <hca@xxxxxxxxxxxxx> Signed-off-by: Vasily Gorbik <gor@xxxxxxxxxxxxx> Signed-off-by: Heiko Carstens <hca@xxxxxxxxxxxxx> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- 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 @@ -634,14 +634,6 @@ 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) @@ -1005,11 +997,11 @@ 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 */ Patches currently in stable-queue which might be from gor@xxxxxxxxxxxxx are queue-5.15/s390-boot-simplify-and-fix-kernel-memory-layout-setup.patch queue-5.15/s390-setup-avoid-reserving-memory-above-identity-mapping.patch