From: Will Deacon <will.deacon@xxxxxxx>
[ Upstream commit 3fcbb8260a87efb691d837e8cd24e81f65b3eb70 ]
In 4.19-rc1, Eugeniy reported weird boot and IO errors on ARC HSDK
| INFO: task syslogd:77 blocked for more than 10 seconds.
| Not tainted 4.19.0-rc1-00007-gf213acea4e88 #40
| "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this
| message.
| syslogd D 0 77 76 0x00000000
|
| Stack Trace:
| __switch_to+0x0/0xac
| __schedule+0x1b2/0x730
| io_schedule+0x5c/0xc0
| __lock_page+0x98/0xdc
| find_lock_entry+0x38/0x100
| shmem_getpage_gfp.isra.3+0x82/0xbfc
| shmem_fault+0x46/0x138
| handle_mm_fault+0x5bc/0x924
| do_page_fault+0x100/0x2b8
| ret_from_exception+0x0/0x8
He bisected to 84c6591103db ("locking/atomics,
asm-generic/bitops/lock.h: Rewrite using atomic_fetch_*()")
This commit however only unmasked the real issue introduced by commit
4aef66c8ae9 ("locking/atomic, arch/arc: Fix build") which missed the
retry-if-scond-failed branch in atomic_fetch_##op() macros.
The bisected commit started using atomic_fetch_##op() macros for building
the rest of atomics.
Fixes: 4aef66c8ae9 ("locking/atomic, arch/arc: Fix build")
Reported-by: Eugeniy Paltsev <paltsev@xxxxxxxxxxxx>
Acked-by: Peter Zijlstra (Intel) <peterz@xxxxxxxxxxxxx>
Signed-off-by: Will Deacon <will.deacon@xxxxxxx>
Signed-off-by: Vineet Gupta <vgupta@xxxxxxxxxxxx>
[vgupta: wrote changelog]
Signed-off-by: Sasha Levin <alexander.levin@xxxxxxxxxxxxx>
---
arch/arc/include/asm/atomic.h | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/arch/arc/include/asm/atomic.h b/arch/arc/include/asm/atomic.h
index 54b54da6384c..49112f76710c 100644
--- a/arch/arc/include/asm/atomic.h
+++ b/arch/arc/include/asm/atomic.h
@@ -84,7 +84,7 @@ static inline int atomic_fetch_##op(int i, atomic_t *v) \
"1: llock %[orig], [%[ctr]] \n" \
" " #asm_op " %[val], %[orig], %[i] \n" \
" scond %[val], [%[ctr]] \n" \
- " \n" \
+ " bnz 1b \n" \
: [val] "=&r" (val), \
[orig] "=&r" (orig) \
: [ctr] "r" (&v->counter), \
--
2.17.1
