| From be6577af0cef934ccb036445314072e8cb9217b9 Mon Sep 17 00:00:00 2001 |
| From: John David Anglin <dave.anglin@bell.net> |
| Date: Tue, 21 Jul 2020 07:36:59 -0400 |
| Subject: parisc: Add atomic64_set_release() define to avoid CPU soft lockups |
| |
| From: John David Anglin <dave.anglin@bell.net> |
| |
| commit be6577af0cef934ccb036445314072e8cb9217b9 upstream. |
| |
| Stalls are quite frequent with recent kernels. I enabled |
| CONFIG_SOFTLOCKUP_DETECTOR and I caught the following stall: |
| |
| watchdog: BUG: soft lockup - CPU#0 stuck for 22s! [cc1:22803] |
| CPU: 0 PID: 22803 Comm: cc1 Not tainted 5.6.17+ #3 |
| Hardware name: 9000/800/rp3440 |
| IAOQ[0]: d_alloc_parallel+0x384/0x688 |
| IAOQ[1]: d_alloc_parallel+0x388/0x688 |
| RP(r2): d_alloc_parallel+0x134/0x688 |
| Backtrace: |
| [<000000004036974c>] __lookup_slow+0xa4/0x200 |
| [<0000000040369fc8>] walk_component+0x288/0x458 |
| [<000000004036a9a0>] path_lookupat+0x88/0x198 |
| [<000000004036e748>] filename_lookup+0xa0/0x168 |
| [<000000004036e95c>] user_path_at_empty+0x64/0x80 |
| [<000000004035d93c>] vfs_statx+0x104/0x158 |
| [<000000004035dfcc>] __do_sys_lstat64+0x44/0x80 |
| [<000000004035e5a0>] sys_lstat64+0x20/0x38 |
| [<0000000040180054>] syscall_exit+0x0/0x14 |
| |
| The code was stuck in this loop in d_alloc_parallel: |
| |
| 4037d414: 0e 00 10 dc ldd 0(r16),ret0 |
| 4037d418: c7 fc 5f ed bb,< ret0,1f,4037d414 <d_alloc_parallel+0x384> |
| 4037d41c: 08 00 02 40 nop |
| |
| This is the inner loop of bit_spin_lock which is called by hlist_bl_unlock in |
| d_alloc_parallel: |
| |
| static inline void bit_spin_lock(int bitnum, unsigned long *addr) |
| { |
| /* |
| * Assuming the lock is uncontended, this never enters |
| * the body of the outer loop. If it is contended, then |
| * within the inner loop a non-atomic test is used to |
| * busywait with less bus contention for a good time to |
| * attempt to acquire the lock bit. |
| */ |
| preempt_disable(); |
| #if defined(CONFIG_SMP) || defined(CONFIG_DEBUG_SPINLOCK) |
| while (unlikely(test_and_set_bit_lock(bitnum, addr))) { |
| preempt_enable(); |
| do { |
| cpu_relax(); |
| } while (test_bit(bitnum, addr)); |
| preempt_disable(); |
| } |
| #endif |
| __acquire(bitlock); |
| } |
| |
| After consideration, I realized that we must be losing bit unlocks. |
| Then, I noticed that we missed defining atomic64_set_release(). |
| Adding this define fixes the stalls in bit operations. |
| |
| Signed-off-by: Dave Anglin <dave.anglin@bell.net> |
| Cc: stable@vger.kernel.org |
| Signed-off-by: Helge Deller <deller@gmx.de> |
| Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> |
| |
| --- |
| arch/parisc/include/asm/atomic.h | 2 ++ |
| 1 file changed, 2 insertions(+) |
| |
| --- a/arch/parisc/include/asm/atomic.h |
| +++ b/arch/parisc/include/asm/atomic.h |
| @@ -208,6 +208,8 @@ atomic64_set(atomic64_t *v, s64 i) |
| _atomic_spin_unlock_irqrestore(v, flags); |
| } |
| |
| +#define atomic64_set_release(v, i) atomic64_set((v), (i)) |
| + |
| static __inline__ s64 |
| atomic64_read(const atomic64_t *v) |
| { |