* [PATCH V2 0/1] lib/atomic64 using raw_spin_lock_irq[save|resotre] for atomicity
@ 2011-09-01 3:32 Shan Hai
2011-09-01 3:32 ` [PATCH V2 1/1] " Shan Hai
0 siblings, 1 reply; 6+ messages in thread
From: Shan Hai @ 2011-09-01 3:32 UTC (permalink / raw)
To: akpm, tglx; +Cc: eric.dumazet, vapier, asharma, linux-kernel, linux-rt-users
The command 'perf top -e L1-dcache-loads' causes OOPS and hang up in the
following configuration.
Powerpc e500 core
OOPS on: 2.6.34.9 PREEMPT-RT
Whole system hangs up: 3.0.3 PREEMPT-RT
Listed the panic info. below.
Cause of the problem is that the atomic64_add_return is interrupted by the
performence counter interrupt, the interrupt handler calls atomic64_read,
failed at /build/linux/kernel/rtmutex.c:832! for the reason trying to hold the
same lock twice in the same context.
Replace the spin_lock_irq[save|restore] with raw_spin_lock_irq[save|restore]
could guarantee the atomicity of atomic64_* because the raw variant of the spin
lock disables interrupts during atomic64_* operations.
---
lib/atomic64.c | 40 ++++++++++++++++++++--------------------
1 files changed, 20 insertions(+), 20 deletions(-)
---
OOPS on 2.6.34.9+PREEMPT-RT:
------------[ cut here ]------------
kernel BUG at /build/linux/kernel/rtmutex.c:832!
Oops: Exception in kernel mode, sig: 5 [#2]
PREEMPT SMP NR_CPUS=8 LTT NESTING LEVEL : 0
P4080 DS
last sysfs file: /sys/devices/system/cpu/online
Modules linked in: ipv6(+) [last unloaded: scsi_wait_scan]
NIP: c068b218 LR: c068b1e0 CTR: 00000000
REGS: eb459ae0 TRAP: 0700 Tainted: G D (2.6.34.9-rt)
MSR: 00021002 <ME,CE> CR: 28000488 XER: 00000000
TASK = ea43d3b0[968] 'perf' THREAD: eb458000 CPU: 0
GPR00: 00000001 eb459b90 ea43d3b0 00021002 00000000 00000000 00000000 00000001
GPR08: 00000001 ea43d3b0 c068b1e0 00000000 28000482 10092c4c 7fffffff 80000000
GPR16: eb459d40 eb459c68 00000001 c2fa2098 eb459ec0 eac5a8e8 eac5a900 c0906308
GPR24: c0906334 00000000 eb459b9c c090d0ec 00021002 c09062e0 c09062e0 eb459b90
NIP [c068b218] rt_spin_lock_slowlock+0x78/0x3a8
LR [c068b1e0] rt_spin_lock_slowlock+0x40/0x3a8
Call Trace:
[eb459b90] [c068b1e0] rt_spin_lock_slowlock+0x40/0x3a8 (unreliable)
[eb459c20] [c068bdb0] rt_spin_lock+0x40/0x98
[eb459c40] [c03d2a14] atomic64_read+0x48/0x84
[eb459c60] [c001aaf4] perf_event_interrupt+0xec/0x28c
[eb459d10] [c0010138] performance_monitor_exception+0x7c/0x150
[eb459d30] [c0014170] ret_from_except_full+0x0/0x4c
--- Exception: 2060 at lock_acquire+0x94/0x130
LR = lock_acquire+0x8c/0x130
[eb459e30] [c068bdf0] rt_spin_lock+0x80/0x98
[eb459e50] [c03d2884] atomic64_add_return+0x50/0x98
[eb459e70] [c00ff888] T.902+0x150/0x4f8
[eb459eb0] [c00ffedc] sys_perf_event_open+0x2ac/0x508
[eb459f40] [c0013b6c] ret_from_syscall+0x0/0x4
--- Exception: c00 at 0xfa8abe4
LR = 0x10016034
^ permalink raw reply [flat|nested] 6+ messages in thread
* [PATCH V2 1/1] lib/atomic64 using raw_spin_lock_irq[save|resotre] for atomicity
2011-09-01 3:32 [PATCH V2 0/1] lib/atomic64 using raw_spin_lock_irq[save|resotre] for atomicity Shan Hai
@ 2011-09-01 3:32 ` Shan Hai
2011-09-01 5:27 ` Yong Zhang
2011-09-01 9:59 ` Thomas Gleixner
0 siblings, 2 replies; 6+ messages in thread
From: Shan Hai @ 2011-09-01 3:32 UTC (permalink / raw)
To: akpm, tglx
Cc: eric.dumazet, vapier, asharma, linux-kernel, linux-rt-users,
Shan Hai
The spin_lock_irq[save|restore] could break the atomicity of the
atomic64_* operations in the PREEMPT-RT configuration, because
the spin_lock_irq[save|restore] themselves are preemptable in the
PREEMPT-RT, using raw variant of the spin lock could provide the
atomicity that atomic64_* need.
spin_lock_irq[save|restore] would cause the following OOPS on 2.6.34.9+rt
OOPS on 2.6.34.9+PREEMPT-RT:
------------[ cut here ]------------
kernel BUG at /build/linux/kernel/rtmutex.c:832!
Oops: Exception in kernel mode, sig: 5 [#2]
PREEMPT SMP NR_CPUS=8 LTT NESTING LEVEL : 0
P4080 DS
last sysfs file: /sys/devices/system/cpu/online
Modules linked in: ipv6(+) [last unloaded: scsi_wait_scan]
NIP: c068b218 LR: c068b1e0 CTR: 00000000
REGS: eb459ae0 TRAP: 0700 Tainted: G D (2.6.34.9-rt)
MSR: 00021002 <ME,CE> CR: 28000488 XER: 00000000
TASK = ea43d3b0[968] 'perf' THREAD: eb458000 CPU: 0
GPR00: 00000001 eb459b90 ea43d3b0 00021002 00000000 00000000 00000000 00000001
GPR08: 00000001 ea43d3b0 c068b1e0 00000000 28000482 10092c4c 7fffffff 80000000
GPR16: eb459d40 eb459c68 00000001 c2fa2098 eb459ec0 eac5a8e8 eac5a900 c0906308
GPR24: c0906334 00000000 eb459b9c c090d0ec 00021002 c09062e0 c09062e0 eb459b90
NIP [c068b218] rt_spin_lock_slowlock+0x78/0x3a8
LR [c068b1e0] rt_spin_lock_slowlock+0x40/0x3a8
Call Trace:
[eb459b90] [c068b1e0] rt_spin_lock_slowlock+0x40/0x3a8 (unreliable)
[eb459c20] [c068bdb0] rt_spin_lock+0x40/0x98
[eb459c40] [c03d2a14] atomic64_read+0x48/0x84
[eb459c60] [c001aaf4] perf_event_interrupt+0xec/0x28c
[eb459d10] [c0010138] performance_monitor_exception+0x7c/0x150
[eb459d30] [c0014170] ret_from_except_full+0x0/0x4c
--- Exception: 2060 at lock_acquire+0x94/0x130
LR = lock_acquire+0x8c/0x130
[eb459e30] [c068bdf0] rt_spin_lock+0x80/0x98
[eb459e50] [c03d2884] atomic64_add_return+0x50/0x98
[eb459e70] [c00ff888] T.902+0x150/0x4f8
[eb459eb0] [c00ffedc] sys_perf_event_open+0x2ac/0x508
[eb459f40] [c0013b6c] ret_from_syscall+0x0/0x4
--- Exception: c00 at 0xfa8abe4
LR = 0x10016034
Signed-off-by: Shan Hai <haishan.bai@gmail.com>
---
lib/atomic64.c | 44 ++++++++++++++++++++++----------------------
1 files changed, 22 insertions(+), 22 deletions(-)
diff --git a/lib/atomic64.c b/lib/atomic64.c
index e12ae0d..82b3313 100644
--- a/lib/atomic64.c
+++ b/lib/atomic64.c
@@ -29,7 +29,7 @@
* Ensure each lock is in a separate cacheline.
*/
static union {
- spinlock_t lock;
+ raw_spinlock_t lock;
char pad[L1_CACHE_BYTES];
} atomic64_lock[NR_LOCKS] __cacheline_aligned_in_smp;
@@ -48,9 +48,9 @@ long long atomic64_read(const atomic64_t *v)
spinlock_t *lock = lock_addr(v);
long long val;
- spin_lock_irqsave(lock, flags);
+ raw_spin_lock_irqsave(lock, flags);
val = v->counter;
- spin_unlock_irqrestore(lock, flags);
+ raw_spin_unlock_irqrestore(lock, flags);
return val;
}
EXPORT_SYMBOL(atomic64_read);
@@ -60,9 +60,9 @@ void atomic64_set(atomic64_t *v, long long i)
unsigned long flags;
spinlock_t *lock = lock_addr(v);
- spin_lock_irqsave(lock, flags);
+ raw_spin_lock_irqsave(lock, flags);
v->counter = i;
- spin_unlock_irqrestore(lock, flags);
+ raw_spin_unlock_irqrestore(lock, flags);
}
EXPORT_SYMBOL(atomic64_set);
@@ -71,9 +71,9 @@ void atomic64_add(long long a, atomic64_t *v)
unsigned long flags;
spinlock_t *lock = lock_addr(v);
- spin_lock_irqsave(lock, flags);
+ raw_spin_lock_irqsave(lock, flags);
v->counter += a;
- spin_unlock_irqrestore(lock, flags);
+ raw_spin_unlock_irqrestore(lock, flags);
}
EXPORT_SYMBOL(atomic64_add);
@@ -83,9 +83,9 @@ long long atomic64_add_return(long long a, atomic64_t *v)
spinlock_t *lock = lock_addr(v);
long long val;
- spin_lock_irqsave(lock, flags);
+ raw_spin_lock_irqsave(lock, flags);
val = v->counter += a;
- spin_unlock_irqrestore(lock, flags);
+ raw_spin_unlock_irqrestore(lock, flags);
return val;
}
EXPORT_SYMBOL(atomic64_add_return);
@@ -95,9 +95,9 @@ void atomic64_sub(long long a, atomic64_t *v)
unsigned long flags;
spinlock_t *lock = lock_addr(v);
- spin_lock_irqsave(lock, flags);
+ raw_spin_lock_irqsave(lock, flags);
v->counter -= a;
- spin_unlock_irqrestore(lock, flags);
+ raw_spin_unlock_irqrestore(lock, flags);
}
EXPORT_SYMBOL(atomic64_sub);
@@ -107,9 +107,9 @@ long long atomic64_sub_return(long long a, atomic64_t *v)
spinlock_t *lock = lock_addr(v);
long long val;
- spin_lock_irqsave(lock, flags);
+ raw_spin_lock_irqsave(lock, flags);
val = v->counter -= a;
- spin_unlock_irqrestore(lock, flags);
+ raw_spin_unlock_irqrestore(lock, flags);
return val;
}
EXPORT_SYMBOL(atomic64_sub_return);
@@ -120,11 +120,11 @@ long long atomic64_dec_if_positive(atomic64_t *v)
spinlock_t *lock = lock_addr(v);
long long val;
- spin_lock_irqsave(lock, flags);
+ raw_spin_lock_irqsave(lock, flags);
val = v->counter - 1;
if (val >= 0)
v->counter = val;
- spin_unlock_irqrestore(lock, flags);
+ raw_spin_unlock_irqrestore(lock, flags);
return val;
}
EXPORT_SYMBOL(atomic64_dec_if_positive);
@@ -135,11 +135,11 @@ long long atomic64_cmpxchg(atomic64_t *v, long long o, long long n)
spinlock_t *lock = lock_addr(v);
long long val;
- spin_lock_irqsave(lock, flags);
+ raw_spin_lock_irqsave(lock, flags);
val = v->counter;
if (val == o)
v->counter = n;
- spin_unlock_irqrestore(lock, flags);
+ raw_spin_unlock_irqrestore(lock, flags);
return val;
}
EXPORT_SYMBOL(atomic64_cmpxchg);
@@ -150,10 +150,10 @@ long long atomic64_xchg(atomic64_t *v, long long new)
spinlock_t *lock = lock_addr(v);
long long val;
- spin_lock_irqsave(lock, flags);
+ raw_spin_lock_irqsave(lock, flags);
val = v->counter;
v->counter = new;
- spin_unlock_irqrestore(lock, flags);
+ raw_spin_unlock_irqrestore(lock, flags);
return val;
}
EXPORT_SYMBOL(atomic64_xchg);
@@ -164,12 +164,12 @@ int atomic64_add_unless(atomic64_t *v, long long a, long long u)
spinlock_t *lock = lock_addr(v);
int ret = 0;
- spin_lock_irqsave(lock, flags);
+ raw_spin_lock_irqsave(lock, flags);
if (v->counter != u) {
v->counter += a;
ret = 1;
}
- spin_unlock_irqrestore(lock, flags);
+ raw_spin_unlock_irqrestore(lock, flags);
return ret;
}
EXPORT_SYMBOL(atomic64_add_unless);
@@ -179,7 +179,7 @@ static int init_atomic64_lock(void)
int i;
for (i = 0; i < NR_LOCKS; ++i)
- spin_lock_init(&atomic64_lock[i].lock);
+ raw_spin_lock_init(&atomic64_lock[i].lock);
return 0;
}
--
1.7.4.1
^ permalink raw reply related [flat|nested] 6+ messages in thread
* Re: [PATCH V2 1/1] lib/atomic64 using raw_spin_lock_irq[save|resotre] for atomicity
2011-09-01 3:32 ` [PATCH V2 1/1] " Shan Hai
@ 2011-09-01 5:27 ` Yong Zhang
2011-09-01 9:59 ` Thomas Gleixner
1 sibling, 0 replies; 6+ messages in thread
From: Yong Zhang @ 2011-09-01 5:27 UTC (permalink / raw)
To: Shan Hai
Cc: akpm, tglx, eric.dumazet, vapier, asharma, linux-kernel,
linux-rt-users
On Thu, Sep 01, 2011 at 11:32:03AM +0800, Shan Hai wrote:
> The spin_lock_irq[save|restore] could break the atomicity of the
> atomic64_* operations in the PREEMPT-RT configuration, because
> the spin_lock_irq[save|restore] themselves are preemptable in the
> PREEMPT-RT, using raw variant of the spin lock could provide the
> atomicity that atomic64_* need.
>
> spin_lock_irq[save|restore] would cause the following OOPS on 2.6.34.9+rt
>
> OOPS on 2.6.34.9+PREEMPT-RT:
> ------------[ cut here ]------------
> kernel BUG at /build/linux/kernel/rtmutex.c:832!
> Oops: Exception in kernel mode, sig: 5 [#2]
> PREEMPT SMP NR_CPUS=8 LTT NESTING LEVEL : 0
> P4080 DS
> last sysfs file: /sys/devices/system/cpu/online
> Modules linked in: ipv6(+) [last unloaded: scsi_wait_scan]
> NIP: c068b218 LR: c068b1e0 CTR: 00000000
> REGS: eb459ae0 TRAP: 0700 Tainted: G D (2.6.34.9-rt)
> MSR: 00021002 <ME,CE> CR: 28000488 XER: 00000000
> TASK = ea43d3b0[968] 'perf' THREAD: eb458000 CPU: 0
> GPR00: 00000001 eb459b90 ea43d3b0 00021002 00000000 00000000 00000000 00000001
> GPR08: 00000001 ea43d3b0 c068b1e0 00000000 28000482 10092c4c 7fffffff 80000000
> GPR16: eb459d40 eb459c68 00000001 c2fa2098 eb459ec0 eac5a8e8 eac5a900 c0906308
> GPR24: c0906334 00000000 eb459b9c c090d0ec 00021002 c09062e0 c09062e0 eb459b90
> NIP [c068b218] rt_spin_lock_slowlock+0x78/0x3a8
> LR [c068b1e0] rt_spin_lock_slowlock+0x40/0x3a8
> Call Trace:
> [eb459b90] [c068b1e0] rt_spin_lock_slowlock+0x40/0x3a8 (unreliable)
> [eb459c20] [c068bdb0] rt_spin_lock+0x40/0x98
> [eb459c40] [c03d2a14] atomic64_read+0x48/0x84
> [eb459c60] [c001aaf4] perf_event_interrupt+0xec/0x28c
> [eb459d10] [c0010138] performance_monitor_exception+0x7c/0x150
> [eb459d30] [c0014170] ret_from_except_full+0x0/0x4c
> --- Exception: 2060 at lock_acquire+0x94/0x130
> LR = lock_acquire+0x8c/0x130
> [eb459e30] [c068bdf0] rt_spin_lock+0x80/0x98
> [eb459e50] [c03d2884] atomic64_add_return+0x50/0x98
> [eb459e70] [c00ff888] T.902+0x150/0x4f8
> [eb459eb0] [c00ffedc] sys_perf_event_open+0x2ac/0x508
> [eb459f40] [c0013b6c] ret_from_syscall+0x0/0x4
> --- Exception: c00 at 0xfa8abe4
> LR = 0x10016034
>
> Signed-off-by: Shan Hai <haishan.bai@gmail.com>
Reviewed-by: Yong Zhang <yong.zhang0@gmail.com>
> ---
> lib/atomic64.c | 44 ++++++++++++++++++++++----------------------
> 1 files changed, 22 insertions(+), 22 deletions(-)
>
> diff --git a/lib/atomic64.c b/lib/atomic64.c
> index e12ae0d..82b3313 100644
> --- a/lib/atomic64.c
> +++ b/lib/atomic64.c
> @@ -29,7 +29,7 @@
> * Ensure each lock is in a separate cacheline.
> */
> static union {
> - spinlock_t lock;
> + raw_spinlock_t lock;
> char pad[L1_CACHE_BYTES];
> } atomic64_lock[NR_LOCKS] __cacheline_aligned_in_smp;
>
> @@ -48,9 +48,9 @@ long long atomic64_read(const atomic64_t *v)
> spinlock_t *lock = lock_addr(v);
> long long val;
>
> - spin_lock_irqsave(lock, flags);
> + raw_spin_lock_irqsave(lock, flags);
> val = v->counter;
> - spin_unlock_irqrestore(lock, flags);
> + raw_spin_unlock_irqrestore(lock, flags);
> return val;
> }
> EXPORT_SYMBOL(atomic64_read);
> @@ -60,9 +60,9 @@ void atomic64_set(atomic64_t *v, long long i)
> unsigned long flags;
> spinlock_t *lock = lock_addr(v);
>
> - spin_lock_irqsave(lock, flags);
> + raw_spin_lock_irqsave(lock, flags);
> v->counter = i;
> - spin_unlock_irqrestore(lock, flags);
> + raw_spin_unlock_irqrestore(lock, flags);
> }
> EXPORT_SYMBOL(atomic64_set);
>
> @@ -71,9 +71,9 @@ void atomic64_add(long long a, atomic64_t *v)
> unsigned long flags;
> spinlock_t *lock = lock_addr(v);
>
> - spin_lock_irqsave(lock, flags);
> + raw_spin_lock_irqsave(lock, flags);
> v->counter += a;
> - spin_unlock_irqrestore(lock, flags);
> + raw_spin_unlock_irqrestore(lock, flags);
> }
> EXPORT_SYMBOL(atomic64_add);
>
> @@ -83,9 +83,9 @@ long long atomic64_add_return(long long a, atomic64_t *v)
> spinlock_t *lock = lock_addr(v);
> long long val;
>
> - spin_lock_irqsave(lock, flags);
> + raw_spin_lock_irqsave(lock, flags);
> val = v->counter += a;
> - spin_unlock_irqrestore(lock, flags);
> + raw_spin_unlock_irqrestore(lock, flags);
> return val;
> }
> EXPORT_SYMBOL(atomic64_add_return);
> @@ -95,9 +95,9 @@ void atomic64_sub(long long a, atomic64_t *v)
> unsigned long flags;
> spinlock_t *lock = lock_addr(v);
>
> - spin_lock_irqsave(lock, flags);
> + raw_spin_lock_irqsave(lock, flags);
> v->counter -= a;
> - spin_unlock_irqrestore(lock, flags);
> + raw_spin_unlock_irqrestore(lock, flags);
> }
> EXPORT_SYMBOL(atomic64_sub);
>
> @@ -107,9 +107,9 @@ long long atomic64_sub_return(long long a, atomic64_t *v)
> spinlock_t *lock = lock_addr(v);
> long long val;
>
> - spin_lock_irqsave(lock, flags);
> + raw_spin_lock_irqsave(lock, flags);
> val = v->counter -= a;
> - spin_unlock_irqrestore(lock, flags);
> + raw_spin_unlock_irqrestore(lock, flags);
> return val;
> }
> EXPORT_SYMBOL(atomic64_sub_return);
> @@ -120,11 +120,11 @@ long long atomic64_dec_if_positive(atomic64_t *v)
> spinlock_t *lock = lock_addr(v);
> long long val;
>
> - spin_lock_irqsave(lock, flags);
> + raw_spin_lock_irqsave(lock, flags);
> val = v->counter - 1;
> if (val >= 0)
> v->counter = val;
> - spin_unlock_irqrestore(lock, flags);
> + raw_spin_unlock_irqrestore(lock, flags);
> return val;
> }
> EXPORT_SYMBOL(atomic64_dec_if_positive);
> @@ -135,11 +135,11 @@ long long atomic64_cmpxchg(atomic64_t *v, long long o, long long n)
> spinlock_t *lock = lock_addr(v);
> long long val;
>
> - spin_lock_irqsave(lock, flags);
> + raw_spin_lock_irqsave(lock, flags);
> val = v->counter;
> if (val == o)
> v->counter = n;
> - spin_unlock_irqrestore(lock, flags);
> + raw_spin_unlock_irqrestore(lock, flags);
> return val;
> }
> EXPORT_SYMBOL(atomic64_cmpxchg);
> @@ -150,10 +150,10 @@ long long atomic64_xchg(atomic64_t *v, long long new)
> spinlock_t *lock = lock_addr(v);
> long long val;
>
> - spin_lock_irqsave(lock, flags);
> + raw_spin_lock_irqsave(lock, flags);
> val = v->counter;
> v->counter = new;
> - spin_unlock_irqrestore(lock, flags);
> + raw_spin_unlock_irqrestore(lock, flags);
> return val;
> }
> EXPORT_SYMBOL(atomic64_xchg);
> @@ -164,12 +164,12 @@ int atomic64_add_unless(atomic64_t *v, long long a, long long u)
> spinlock_t *lock = lock_addr(v);
> int ret = 0;
>
> - spin_lock_irqsave(lock, flags);
> + raw_spin_lock_irqsave(lock, flags);
> if (v->counter != u) {
> v->counter += a;
> ret = 1;
> }
> - spin_unlock_irqrestore(lock, flags);
> + raw_spin_unlock_irqrestore(lock, flags);
> return ret;
> }
> EXPORT_SYMBOL(atomic64_add_unless);
> @@ -179,7 +179,7 @@ static int init_atomic64_lock(void)
> int i;
>
> for (i = 0; i < NR_LOCKS; ++i)
> - spin_lock_init(&atomic64_lock[i].lock);
> + raw_spin_lock_init(&atomic64_lock[i].lock);
> return 0;
> }
>
> --
> 1.7.4.1
>
> --
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--
Only stand for myself
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [PATCH V2 1/1] lib/atomic64 using raw_spin_lock_irq[save|resotre] for atomicity
2011-09-01 3:32 ` [PATCH V2 1/1] " Shan Hai
2011-09-01 5:27 ` Yong Zhang
@ 2011-09-01 9:59 ` Thomas Gleixner
2011-09-01 10:11 ` Thomas Gleixner
1 sibling, 1 reply; 6+ messages in thread
From: Thomas Gleixner @ 2011-09-01 9:59 UTC (permalink / raw)
To: Shan Hai
Cc: akpm, eric.dumazet, vapier, asharma, linux-kernel, linux-rt-users
On Thu, 1 Sep 2011, Shan Hai wrote:
> The spin_lock_irq[save|restore] could break the atomicity of the
> atomic64_* operations in the PREEMPT-RT configuration, because
> the spin_lock_irq[save|restore] themselves are preemptable in the
> PREEMPT-RT, using raw variant of the spin lock could provide the
> atomicity that atomic64_* need.
Good catch. Queued for the next release.
Thanks,
tglx
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [PATCH V2 1/1] lib/atomic64 using raw_spin_lock_irq[save|resotre] for atomicity
2011-09-01 9:59 ` Thomas Gleixner
@ 2011-09-01 10:11 ` Thomas Gleixner
2011-09-02 0:48 ` Shan Hai
0 siblings, 1 reply; 6+ messages in thread
From: Thomas Gleixner @ 2011-09-01 10:11 UTC (permalink / raw)
To: Shan Hai
Cc: akpm, eric.dumazet, vapier, asharma, linux-kernel, linux-rt-users
On Thu, 1 Sep 2011, Thomas Gleixner wrote:
> On Thu, 1 Sep 2011, Shan Hai wrote:
>
> > The spin_lock_irq[save|restore] could break the atomicity of the
> > atomic64_* operations in the PREEMPT-RT configuration, because
> > the spin_lock_irq[save|restore] themselves are preemptable in the
> > PREEMPT-RT, using raw variant of the spin lock could provide the
> > atomicity that atomic64_* need.
>
> Good catch. Queued for the next release.
Though the changelog is misleading. The reason is not that they are
preemtible.
The reason for your OOPs is that the sleeping locks are not IRQ
safe. And your system simply deadlocked due to that.
Thanks,
tglx
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [PATCH V2 1/1] lib/atomic64 using raw_spin_lock_irq[save|resotre] for atomicity
2011-09-01 10:11 ` Thomas Gleixner
@ 2011-09-02 0:48 ` Shan Hai
0 siblings, 0 replies; 6+ messages in thread
From: Shan Hai @ 2011-09-02 0:48 UTC (permalink / raw)
To: Thomas Gleixner
Cc: akpm, eric.dumazet, vapier, asharma, linux-kernel, linux-rt-users
On 09/01/2011 06:11 PM, Thomas Gleixner wrote:
> On Thu, 1 Sep 2011, Thomas Gleixner wrote:
>
>> On Thu, 1 Sep 2011, Shan Hai wrote:
>>
>>> The spin_lock_irq[save|restore] could break the atomicity of the
>>> atomic64_* operations in the PREEMPT-RT configuration, because
>>> the spin_lock_irq[save|restore] themselves are preemptable in the
>>> PREEMPT-RT, using raw variant of the spin lock could provide the
>>> atomicity that atomic64_* need.
>> Good catch. Queued for the next release.
> Though the changelog is misleading. The reason is not that they are
> preemtible.
>
> The reason for your OOPs is that the sleeping locks are not IRQ
> safe. And your system simply deadlocked due to that.
>
Will correct it in the V3 patch, thanks for the advice.
Cheers
Shan Hai
> Thanks,
>
> tglx
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^ permalink raw reply [flat|nested] 6+ messages in thread
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-- links below jump to the message on this page --
2011-09-01 3:32 [PATCH V2 0/1] lib/atomic64 using raw_spin_lock_irq[save|resotre] for atomicity Shan Hai
2011-09-01 3:32 ` [PATCH V2 1/1] " Shan Hai
2011-09-01 5:27 ` Yong Zhang
2011-09-01 9:59 ` Thomas Gleixner
2011-09-01 10:11 ` Thomas Gleixner
2011-09-02 0:48 ` Shan Hai
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