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| author | Mahesh Salgaonkar <mahesh@linux.ibm.com> | 2024-04-10 10:00:06 +0530 |
|---|---|---|
| committer | Michael Ellerman <mpe@ellerman.id.au> | 2024-04-15 12:55:48 +1000 |
| commit | 0db880fc865ffb522141ced4bfa66c12ab1fbb70 (patch) | |
| tree | e6a277a0d7e35074d22045124b1b22e1e8d349a1 /arch/powerpc/kernel | |
| parent | 676b2f99b0f6cd11193eeae13c976565c3fc7545 (diff) | |
| download | linux-stable-0db880fc865ffb522141ced4bfa66c12ab1fbb70.tar.gz linux-stable-0db880fc865ffb522141ced4bfa66c12ab1fbb70.tar.bz2 linux-stable-0db880fc865ffb522141ced4bfa66c12ab1fbb70.zip | |
powerpc: Avoid nmi_enter/nmi_exit in real mode interrupt.
nmi_enter()/nmi_exit() touches per cpu variables which can lead to kernel
crash when invoked during real mode interrupt handling (e.g. early HMI/MCE
interrupt handler) if percpu allocation comes from vmalloc area.
Early HMI/MCE handlers are called through DEFINE_INTERRUPT_HANDLER_NMI()
wrapper which invokes nmi_enter/nmi_exit calls. We don't see any issue when
percpu allocation is from the embedded first chunk. However with
CONFIG_NEED_PER_CPU_PAGE_FIRST_CHUNK enabled there are chances where percpu
allocation can come from the vmalloc area.
With kernel command line "percpu_alloc=page" we can force percpu allocation
to come from vmalloc area and can see kernel crash in machine_check_early:
[ 1.215714] NIP [c000000000e49eb4] rcu_nmi_enter+0x24/0x110
[ 1.215717] LR [c0000000000461a0] machine_check_early+0xf0/0x2c0
[ 1.215719] --- interrupt: 200
[ 1.215720] [c000000fffd73180] [0000000000000000] 0x0 (unreliable)
[ 1.215722] [c000000fffd731b0] [0000000000000000] 0x0
[ 1.215724] [c000000fffd73210] [c000000000008364] machine_check_early_common+0x134/0x1f8
Fix this by avoiding use of nmi_enter()/nmi_exit() in real mode if percpu
first chunk is not embedded.
Reviewed-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Tested-by: Shirisha Ganta <shirisha@linux.ibm.com>
Signed-off-by: Mahesh Salgaonkar <mahesh@linux.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://msgid.link/20240410043006.81577-1-mahesh@linux.ibm.com
Diffstat (limited to 'arch/powerpc/kernel')
| -rw-r--r-- | arch/powerpc/kernel/setup_64.c | 2 |
1 files changed, 2 insertions, 0 deletions
diff --git a/arch/powerpc/kernel/setup_64.c b/arch/powerpc/kernel/setup_64.c index 2f19d5e94485..ae36a129789f 100644 --- a/arch/powerpc/kernel/setup_64.c +++ b/arch/powerpc/kernel/setup_64.c @@ -834,6 +834,7 @@ static __init int pcpu_cpu_to_node(int cpu) unsigned long __per_cpu_offset[NR_CPUS] __read_mostly; EXPORT_SYMBOL(__per_cpu_offset); +DEFINE_STATIC_KEY_FALSE(__percpu_first_chunk_is_paged); void __init setup_per_cpu_areas(void) { @@ -876,6 +877,7 @@ void __init setup_per_cpu_areas(void) if (rc < 0) panic("cannot initialize percpu area (err=%d)", rc); + static_key_enable(&__percpu_first_chunk_is_paged.key); delta = (unsigned long)pcpu_base_addr - (unsigned long)__per_cpu_start; for_each_possible_cpu(cpu) { __per_cpu_offset[cpu] = delta + pcpu_unit_offsets[cpu]; |