From: Marek Bykowski <marekx.bykow...@intel.com>
__install_bp_hardening_cb() is called with the spinlock taken to allow each
CPU to take its turn when allocating slots. With the RT patches applied,
the spinlock becomes a mutex, and we get warnings about sleeping in
the cpu stop callback executing in the atomic context from the migration
thread. Changing to a raw spinlock resolves it.
BUG: scheduling while atomic: migration/<cpu_no>/84/0x00000002
Modules linked in:
[<ffffff800819af6c>] cpu_stopper_thread+0x9c/0x128
CPU: <cpu_no> PID: 76 Comm: migration/8 Tainted: G W 4.19.19-rt3
#1
Hardware name: AXM56xx Victoria (DT)
Call trace:
dump_backtrace+0x0/0x168
show_stack+0x24/0x30
dump_stack+0x9c/0xd4
__schedule_bug+0x74/0xc0
__schedule+0x500/0x558
schedule+0x44/0xf0
rt_spin_lock_slowlock_locked+0x100/0x298
rt_spin_lock_slowlock+0x68/0x98
rt_spin_lock+0x60/0x70
enable_smccc_arch_workaround_1+0x154/0x270
__enable_cpu_capability+0x24/0x38
multi_cpu_stop+0x100/0x148
cpu_stopper_thread+0xa4/0x128
smpboot_thread_fn+0x1f8/0x2c0
kthread+0x104/0x130
ret_from_fork+0x10/0x1c
Signed-off-by: James Morse <james.mo...@arm.com>
Signed-off-by: Will Deacon <will.dea...@arm.com>
Signed-off-by: Marek Bykowski <marekx.bykow...@intel.com>
Signed-off-by: John Jacques <john.jacq...@intel.com>
---
arch/arm64/kernel/cpu_errata.c | 6 +++---
1 file changed, 3 insertions(+), 3 deletions(-)
diff --git a/arch/arm64/kernel/cpu_errata.c b/arch/arm64/kernel/cpu_errata.c
index d191ce8..589f0b3 100644
--- a/arch/arm64/kernel/cpu_errata.c
+++ b/arch/arm64/kernel/cpu_errata.c
@@ -114,10 +114,10 @@ static void install_bp_hardening_cb(bp_hardening_cb_t fn,
const char *hyp_vecs_start,
const char *hyp_vecs_end)
{
- static DEFINE_SPINLOCK(bp_lock);
+ static DEFINE_RAW_SPINLOCK(bp_lock);
int cpu, slot = -1;
- spin_lock(&bp_lock);
+ raw_spin_lock(&bp_lock);
for_each_possible_cpu(cpu) {
if (per_cpu(bp_hardening_data.fn, cpu) == fn) {
slot = per_cpu(bp_hardening_data.hyp_vectors_slot, cpu);
@@ -133,7 +133,7 @@ static void install_bp_hardening_cb(bp_hardening_cb_t fn,
__this_cpu_write(bp_hardening_data.hyp_vectors_slot, slot);
__this_cpu_write(bp_hardening_data.fn, fn);
- spin_unlock(&bp_lock);
+ raw_spin_unlock(&bp_lock);
}
#else
#define __smccc_workaround_1_smc_start NULL
--
2.7.4
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