From: Sven Schnelle svens@linux.ibm.com
[ 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@linux.ibm.com Reviewed-by: Heiko Carstens hca@linux.ibm.com Signed-off-by: Heiko Carstens hca@linux.ibm.com Signed-off-by: Sasha Levin sashal@kernel.org --- arch/s390/mm/vmem.c | 2 ++ 1 file changed, 2 insertions(+)
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);