Lockdep warns that the use of the hpte_lock in native_hpte_remove() is
not safe against an IRQ coming in:
================================
WARNING: inconsistent lock state
6.4.0-rc2-g0c54f4d30ecc #1 Not tainted
--------------------------------
inconsistent {IN-SOFTIRQ-W} -> {SOFTIRQ-ON-W} usage.
qemu-system-ppc/93865 [HC0[0]:SC0[0]:HE1:SE1] takes:
c0000000021f5180 (hpte_lock){+.?.}-{0:0}, at: native_lock_hpte+0x8/0xd0
{IN-SOFTIRQ-W} state was registered at:
lock_acquire+0x134/0x3f0
native_lock_hpte+0x44/0xd0
native_hpte_insert+0xd4/0x2a0
__hash_page_64K+0x218/0x4f0
hash_page_mm+0x464/0x840
do_hash_fault+0x11c/0x260
data_access_common_virt+0x210/0x220
__ip_select_ident+0x140/0x150
...
net_rx_action+0x3bc/0x440
__do_softirq+0x180/0x534
...
sys_sendmmsg+0x34/0x50
system_call_exception+0x128/0x320
system_call_common+0x160/0x2e4
...
Possible unsafe locking scenario:
CPU0
----
lock(hpte_lock);
<Interrupt>
lock(hpte_lock);
*** DEADLOCK ***
...
Call Trace:
dump_stack_lvl+0x98/0xe0 (unreliable)
print_usage_bug.part.0+0x250/0x278
mark_lock+0xc9c/0xd30
__lock_acquire+0x440/0x1ca0
lock_acquire+0x134/0x3f0
native_lock_hpte+0x44/0xd0
native_hpte_remove+0xb0/0x190
kvmppc_mmu_map_page+0x650/0x698 [kvm_pr]
kvmppc_handle_pagefault+0x534/0x6e8 [kvm_pr]
kvmppc_handle_exit_pr+0x6d8/0xe90 [kvm_pr]
after_sprg3_load+0x80/0x90 [kvm_pr]
kvmppc_vcpu_run_pr+0x108/0x270 [kvm_pr]
kvmppc_vcpu_run+0x34/0x48 [kvm]
kvm_arch_vcpu_ioctl_run+0x340/0x470 [kvm]
kvm_vcpu_ioctl+0x338/0x8b8 [kvm]
sys_ioctl+0x7c4/0x13e0
system_call_exception+0x128/0x320
system_call_common+0x160/0x2e4
I suspect kvm_pr is the only caller that doesn't already have IRQs
disabled, which is why this hasn't been reported previously.
Fix it by disabling IRQs in native_hpte_remove().
Fixes: 35159b5717fa ("powerpc/64s: make HPTE lock and native_tlbie_lock
irq-safe")
Cc: sta...@vger.kernel.org # v6.1+
Signed-off-by: Michael Ellerman <m...@ellerman.id.au>
---
arch/powerpc/mm/book3s64/hash_native.c | 13 +++++++++----
1 file changed, 9 insertions(+), 4 deletions(-)
diff --git a/arch/powerpc/mm/book3s64/hash_native.c
b/arch/powerpc/mm/book3s64/hash_native.c
index 9342e79870df..430d1d935a7c 100644
--- a/arch/powerpc/mm/book3s64/hash_native.c
+++ b/arch/powerpc/mm/book3s64/hash_native.c
@@ -328,10 +328,12 @@ static long native_hpte_insert(unsigned long hpte_group,
unsigned long vpn,
static long native_hpte_remove(unsigned long hpte_group)
{
+ unsigned long hpte_v, flags;
struct hash_pte *hptep;
int i;
int slot_offset;
- unsigned long hpte_v;
+
+ local_irq_save(flags);
DBG_LOW(" remove(group=%lx)\n", hpte_group);
@@ -356,13 +358,16 @@ static long native_hpte_remove(unsigned long hpte_group)
slot_offset &= 0x7;
}
- if (i == HPTES_PER_GROUP)
- return -1;
+ if (i == HPTES_PER_GROUP) {
+ i = -1;
+ goto out;
+ }
/* Invalidate the hpte. NOTE: this also unlocks it */
release_hpte_lock();
hptep->v = 0;
-
+out:
+ local_irq_restore(flags);
return i;
}
--
2.40.1
