From: Sven Schnelle <svens@xxxxxxxxxxxxx>
commit 9e3d62d55bf455d4f9fdf2ede5c8756410c64102 upstream.
The current code doesn't clear the thread/group maps for offline
CPUs. This may cause kernel crashes like the one bewlow in common
code that assumes if a CPU has sibblings it is online.
Unable to handle kernel pointer dereference in virtual kernel address space
Call Trace:
[<000000013a4b8c3c>] blk_mq_map_swqueue+0x10c/0x388
([<000000013a4b8bcc>] blk_mq_map_swqueue+0x9c/0x388)
[<000000013a4b9300>] blk_mq_init_allocated_queue+0x448/0x478
[<000000013a4b9416>] blk_mq_init_queue+0x4e/0x90
[<000003ff8019d3e6>] loop_add+0x106/0x278 [loop]
[<000003ff801b8148>] loop_init+0x148/0x1000 [loop]
[<0000000139de4924>] do_one_initcall+0x3c/0x1e0
[<0000000139ef449a>] do_init_module+0x6a/0x2a0
[<0000000139ef61bc>] __do_sys_finit_module+0xa4/0xc0
[<0000000139de9e6e>] do_syscall+0x7e/0xd0
[<000000013a8e0aec>] __do_syscall+0xbc/0x110
[<000000013a8ee2e8>] system_call+0x78/0xa0
Fixes: 52aeda7accb6 ("s390/topology: remove offline CPUs from CPU topology masks")
Cc: <stable@xxxxxxxxxx> # 5.7+
Reported-by: Marius Hillenbrand <mhillen@xxxxxxxxxxxxx>
Signed-off-by: Sven Schnelle <svens@xxxxxxxxxxxxx>
Reviewed-by: Heiko Carstens <hca@xxxxxxxxxxxxx>
Signed-off-by: Vasily Gorbik <gor@xxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
arch/s390/kernel/topology.c | 12 +++++++++---
1 file changed, 9 insertions(+), 3 deletions(-)
diff --git a/arch/s390/kernel/topology.c b/arch/s390/kernel/topology.c
index bfcc327acc6b..26aa2614ee35 100644
--- a/arch/s390/kernel/topology.c
+++ b/arch/s390/kernel/topology.c
@@ -66,7 +66,10 @@ static void cpu_group_map(cpumask_t *dst, struct mask_info *info, unsigned int c
{
static cpumask_t mask;
- cpumask_copy(&mask, cpumask_of(cpu));
+ cpumask_clear(&mask);
+ if (!cpu_online(cpu))
+ goto out;
+ cpumask_set_cpu(cpu, &mask);
switch (topology_mode) {
case TOPOLOGY_MODE_HW:
while (info) {
@@ -83,10 +86,10 @@ static void cpu_group_map(cpumask_t *dst, struct mask_info *info, unsigned int c
default:
fallthrough;
case TOPOLOGY_MODE_SINGLE:
- cpumask_copy(&mask, cpumask_of(cpu));
break;
}
cpumask_and(&mask, &mask, cpu_online_mask);
+out:
cpumask_copy(dst, &mask);
}
@@ -95,7 +98,10 @@ static void cpu_thread_map(cpumask_t *dst, unsigned int cpu)
static cpumask_t mask;
int i;
- cpumask_copy(&mask, cpumask_of(cpu));
+ cpumask_clear(&mask);
+ if (!cpu_online(cpu))
+ goto out;
+ cpumask_set_cpu(cpu, &mask);
if (topology_mode != TOPOLOGY_MODE_HW)
goto out;
cpu -= cpu % (smp_cpu_mtid + 1);
--
2.30.2
