This is a note to let you know that I've just added the patch titled
s390/vmem: split pages when debug pagealloc is enabled
to the 6.4-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-vmem-split-pages-when-debug-pagealloc-is-enable.patch
and it can be found in the queue-6.4 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
commit 80f6a4e001711ee634ac53beabb5f3d10de1c561
Author: Sven Schnelle <svens@xxxxxxxxxxxxx>
Date: Wed Jul 26 11:10:19 2023 +0200
s390/vmem: split pages when debug pagealloc is enabled
[ Upstream commit edc1e4b6e26536868ef819a735e04a5b32c10589 ]
Since commit bb1520d581a3 ("s390/mm: start kernel with DAT enabled")
the kernel crashes early during boot when debug pagealloc is enabled:
mem auto-init: stack:off, heap alloc:off, heap free:off
addressing exception: 0005 ilc:2 [#1] SMP DEBUG_PAGEALLOC
Modules linked in:
CPU: 0 PID: 0 Comm: swapper Not tainted 6.5.0-rc3-09759-gc5666c912155 #630
[..]
Krnl Code: 00000000001325f6: ec5600248064 cgrj %r5,%r6,8,000000000013263e
00000000001325fc: eb880002000c srlg %r8,%r8,2
#0000000000132602: b2210051 ipte %r5,%r1,%r0,0
>0000000000132606: b90400d1 lgr %r13,%r1
000000000013260a: 41605008 la %r6,8(%r5)
000000000013260e: a7db1000 aghi %r13,4096
0000000000132612: b221006d ipte %r6,%r13,%r0,0
0000000000132616: e3d0d0000171 lay %r13,4096(%r13)
Call Trace:
__kernel_map_pages+0x14e/0x320
__free_pages_ok+0x23a/0x5a8)
free_low_memory_core_early+0x214/0x2c8
memblock_free_all+0x28/0x58
mem_init+0xb6/0x228
mm_core_init+0xb6/0x3b0
start_kernel+0x1d2/0x5a8
startup_continue+0x36/0x40
Kernel panic - not syncing: Fatal exception: panic_on_oops
This is caused by using large mappings on machines with EDAT1/EDAT2. Add
the code to split the mappings into 4k pages if debug pagealloc is enabled
by CONFIG_DEBUG_PAGEALLOC_ENABLE_DEFAULT or the debug_pagealloc kernel
command line option.
Fixes: bb1520d581a3 ("s390/mm: start kernel with DAT enabled")
Signed-off-by: Sven Schnelle <svens@xxxxxxxxxxxxx>
Reviewed-by: Heiko Carstens <hca@xxxxxxxxxxxxx>
Signed-off-by: Heiko Carstens <hca@xxxxxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
diff --git a/arch/s390/mm/vmem.c b/arch/s390/mm/vmem.c
index b9dcb4ae6c59a..05f4912380fac 100644
--- a/arch/s390/mm/vmem.c
+++ b/arch/s390/mm/vmem.c
@@ -761,6 +761,8 @@ void __init vmem_map_init(void)
if (static_key_enabled(&cpu_has_bear))
set_memory_nx(0, 1);
set_memory_nx(PAGE_SIZE, 1);
+ if (debug_pagealloc_enabled())
+ set_memory_4k(0, ident_map_size >> PAGE_SHIFT);
pr_info("Write protected kernel read-only data: %luk\n",
(unsigned long)(__end_rodata - _stext) >> 10);
