| Message ID | 1444080771-22468-1-git-send-email-yang.shi@linaro.org (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On Mon, Oct 05, 2015 at 02:32:51PM -0700, Yang Shi wrote: > BUG: sleeping function called from invalid context at kernel/locking/rtmutex.c:917 > in_atomic(): 0, irqs_disabled(): 128, pid: 342, name: perf > 1 lock held by perf/342: > #0: (break_hook_lock){+.+...}, at: [<ffffffc0000851ac>] call_break_hook+0x34/0xd0 > irq event stamp: 62224 > hardirqs last enabled at (62223): [<ffffffc00010b7bc>] __call_rcu.constprop.59+0x104/0x270 > hardirqs last disabled at (62224): [<ffffffc0000fbe20>] vprintk_emit+0x68/0x640 > softirqs last enabled at (0): [<ffffffc000097928>] copy_process.part.8+0x428/0x17f8 > softirqs last disabled at (0): [< (null)>] (null) > CPU: 0 PID: 342 Comm: perf Not tainted 4.1.6-rt5 #4 > Hardware name: linux,dummy-virt (DT) > Call trace: > [<ffffffc000089968>] dump_backtrace+0x0/0x128 > [<ffffffc000089ab0>] show_stack+0x20/0x30 > [<ffffffc0007030d0>] dump_stack+0x7c/0xa0 > [<ffffffc0000c878c>] ___might_sleep+0x174/0x260 > [<ffffffc000708ac8>] __rt_spin_lock+0x28/0x40 > [<ffffffc000708db0>] rt_read_lock+0x60/0x80 > [<ffffffc0000851a8>] call_break_hook+0x30/0xd0 > [<ffffffc000085a70>] brk_handler+0x30/0x98 > [<ffffffc000082248>] do_debug_exception+0x50/0xb8 > Exception stack(0xffffffc00514fe30 to 0xffffffc00514ff50) > fe20: 00000000 00000000 c1594680 0000007f > fe40: ffffffff ffffffff 92063940 0000007f 0550dcd8 ffffffc0 00000000 00000000 > fe60: 0514fe70 ffffffc0 000be1f8 ffffffc0 0514feb0 ffffffc0 0008948c ffffffc0 > fe80: 00000004 00000000 0514fed0 ffffffc0 ffffffff ffffffff 9282a948 0000007f > fea0: 00000000 00000000 9282b708 0000007f c1592820 0000007f 00083914 ffffffc0 > fec0: 00000000 00000000 00000010 00000000 00000064 00000000 00000001 00000000 > fee0: 005101e0 00000000 c1594680 0000007f c1594740 0000007f ffffffd8 ffffff80 > ff00: 00000000 00000000 00000000 00000000 c1594770 0000007f c1594770 0000007f > ff20: 00665e10 00000000 7f7f7f7f 7f7f7f7f 01010101 01010101 00000000 00000000 > ff40: 928e4cc0 0000007f 91ff11e8 0000007f > > call_break_hook is called in atomic context (hard irq disabled), so replace > the sleepable lock to rcu lock, replace relevant list operations to rcu > version and call synchronize_rcu() in unregister_break_hook(). > > And, replace write lock to spinlock in {un}register_break_hook. > > Signed-off-by: Yang Shi <yang.shi@linaro.org> Looks more plausible to me. Does it look OK to you, Steven? Thanx, Paul > --- > v2 -> v3 > Add synchronize_rcu() in ungister_break_hook() > Replace write lock to spinlock > > v1 -> v2 > Replace list operations to rcu version. > > arch/arm64/kernel/debug-monitors.c | 21 +++++++++++---------- > 1 file changed, 11 insertions(+), 10 deletions(-) > > diff --git a/arch/arm64/kernel/debug-monitors.c b/arch/arm64/kernel/debug-monitors.c > index cebf786..13ca9cd 100644 > --- a/arch/arm64/kernel/debug-monitors.c > +++ b/arch/arm64/kernel/debug-monitors.c > @@ -271,20 +271,21 @@ static int single_step_handler(unsigned long addr, unsigned int esr, > * Use reader/writer locks instead of plain spinlock. > */ > static LIST_HEAD(break_hook); > -static DEFINE_RWLOCK(break_hook_lock); > +static DEFINE_SPINLOCK(break_hook_lock); > > void register_break_hook(struct break_hook *hook) > { > - write_lock(&break_hook_lock); > - list_add(&hook->node, &break_hook); > - write_unlock(&break_hook_lock); > + spin_lock(&break_hook_lock); > + list_add_rcu(&hook->node, &break_hook); > + spin_unlock(&break_hook_lock); > } > > void unregister_break_hook(struct break_hook *hook) > { > - write_lock(&break_hook_lock); > - list_del(&hook->node); > - write_unlock(&break_hook_lock); > + spin_lock(&break_hook_lock); > + list_del_rcu(&hook->node); > + spin_unlock(&break_hook_lock); > + synchronize_rcu(); > } > > static int call_break_hook(struct pt_regs *regs, unsigned int esr) > @@ -292,11 +293,11 @@ static int call_break_hook(struct pt_regs *regs, unsigned int esr) > struct break_hook *hook; > int (*fn)(struct pt_regs *regs, unsigned int esr) = NULL; > > - read_lock(&break_hook_lock); > - list_for_each_entry(hook, &break_hook, node) > + rcu_read_lock(); > + list_for_each_entry_rcu(hook, &break_hook, node) > if ((esr & hook->esr_mask) == hook->esr_val) > fn = hook->fn; > - read_unlock(&break_hook_lock); > + rcu_read_unlock(); > > return fn ? fn(regs, esr) : DBG_HOOK_ERROR; > } > -- > 2.0.2 >
On Thu, Oct 08, 2015 at 04:55:38PM -0700, Paul E. McKenney wrote: > On Mon, Oct 05, 2015 at 02:32:51PM -0700, Yang Shi wrote: > > BUG: sleeping function called from invalid context at kernel/locking/rtmutex.c:917 > > in_atomic(): 0, irqs_disabled(): 128, pid: 342, name: perf > > 1 lock held by perf/342: > > #0: (break_hook_lock){+.+...}, at: [<ffffffc0000851ac>] call_break_hook+0x34/0xd0 > > irq event stamp: 62224 > > hardirqs last enabled at (62223): [<ffffffc00010b7bc>] __call_rcu.constprop.59+0x104/0x270 > > hardirqs last disabled at (62224): [<ffffffc0000fbe20>] vprintk_emit+0x68/0x640 > > softirqs last enabled at (0): [<ffffffc000097928>] copy_process.part.8+0x428/0x17f8 > > softirqs last disabled at (0): [< (null)>] (null) > > CPU: 0 PID: 342 Comm: perf Not tainted 4.1.6-rt5 #4 > > Hardware name: linux,dummy-virt (DT) > > Call trace: > > [<ffffffc000089968>] dump_backtrace+0x0/0x128 > > [<ffffffc000089ab0>] show_stack+0x20/0x30 > > [<ffffffc0007030d0>] dump_stack+0x7c/0xa0 > > [<ffffffc0000c878c>] ___might_sleep+0x174/0x260 > > [<ffffffc000708ac8>] __rt_spin_lock+0x28/0x40 > > [<ffffffc000708db0>] rt_read_lock+0x60/0x80 > > [<ffffffc0000851a8>] call_break_hook+0x30/0xd0 > > [<ffffffc000085a70>] brk_handler+0x30/0x98 > > [<ffffffc000082248>] do_debug_exception+0x50/0xb8 > > Exception stack(0xffffffc00514fe30 to 0xffffffc00514ff50) > > fe20: 00000000 00000000 c1594680 0000007f > > fe40: ffffffff ffffffff 92063940 0000007f 0550dcd8 ffffffc0 00000000 00000000 > > fe60: 0514fe70 ffffffc0 000be1f8 ffffffc0 0514feb0 ffffffc0 0008948c ffffffc0 > > fe80: 00000004 00000000 0514fed0 ffffffc0 ffffffff ffffffff 9282a948 0000007f > > fea0: 00000000 00000000 9282b708 0000007f c1592820 0000007f 00083914 ffffffc0 > > fec0: 00000000 00000000 00000010 00000000 00000064 00000000 00000001 00000000 > > fee0: 005101e0 00000000 c1594680 0000007f c1594740 0000007f ffffffd8 ffffff80 > > ff00: 00000000 00000000 00000000 00000000 c1594770 0000007f c1594770 0000007f > > ff20: 00665e10 00000000 7f7f7f7f 7f7f7f7f 01010101 01010101 00000000 00000000 > > ff40: 928e4cc0 0000007f 91ff11e8 0000007f > > > > call_break_hook is called in atomic context (hard irq disabled), so replace > > the sleepable lock to rcu lock, replace relevant list operations to rcu > > version and call synchronize_rcu() in unregister_break_hook(). > > > > And, replace write lock to spinlock in {un}register_break_hook. > > > > Signed-off-by: Yang Shi <yang.shi@linaro.org> > > Looks more plausible to me. Does it look OK to you, Steven? This is already in mainline as a fix, so please shout loudly if you think it's broken (it looked ok to me and didn't cause any regressions in my testing). Will
On Fri, 9 Oct 2015 10:05:50 +0100 Will Deacon <will.deacon@arm.com> wrote: > > Looks more plausible to me. Does it look OK to you, Steven? > > This is already in mainline as a fix, so please shout loudly if you think > it's broken (it looked ok to me and didn't cause any regressions in my > testing). Looks good to me. -- Steve
diff --git a/arch/arm64/kernel/debug-monitors.c b/arch/arm64/kernel/debug-monitors.c index cebf786..13ca9cd 100644 --- a/arch/arm64/kernel/debug-monitors.c +++ b/arch/arm64/kernel/debug-monitors.c @@ -271,20 +271,21 @@ static int single_step_handler(unsigned long addr, unsigned int esr, * Use reader/writer locks instead of plain spinlock. */ static LIST_HEAD(break_hook); -static DEFINE_RWLOCK(break_hook_lock); +static DEFINE_SPINLOCK(break_hook_lock); void register_break_hook(struct break_hook *hook) { - write_lock(&break_hook_lock); - list_add(&hook->node, &break_hook); - write_unlock(&break_hook_lock); + spin_lock(&break_hook_lock); + list_add_rcu(&hook->node, &break_hook); + spin_unlock(&break_hook_lock); } void unregister_break_hook(struct break_hook *hook) { - write_lock(&break_hook_lock); - list_del(&hook->node); - write_unlock(&break_hook_lock); + spin_lock(&break_hook_lock); + list_del_rcu(&hook->node); + spin_unlock(&break_hook_lock); + synchronize_rcu(); } static int call_break_hook(struct pt_regs *regs, unsigned int esr) @@ -292,11 +293,11 @@ static int call_break_hook(struct pt_regs *regs, unsigned int esr) struct break_hook *hook; int (*fn)(struct pt_regs *regs, unsigned int esr) = NULL; - read_lock(&break_hook_lock); - list_for_each_entry(hook, &break_hook, node) + rcu_read_lock(); + list_for_each_entry_rcu(hook, &break_hook, node) if ((esr & hook->esr_mask) == hook->esr_val) fn = hook->fn; - read_unlock(&break_hook_lock); + rcu_read_unlock(); return fn ? fn(regs, esr) : DBG_HOOK_ERROR; }
BUG: sleeping function called from invalid context at kernel/locking/rtmutex.c:917 in_atomic(): 0, irqs_disabled(): 128, pid: 342, name: perf 1 lock held by perf/342: #0: (break_hook_lock){+.+...}, at: [<ffffffc0000851ac>] call_break_hook+0x34/0xd0 irq event stamp: 62224 hardirqs last enabled at (62223): [<ffffffc00010b7bc>] __call_rcu.constprop.59+0x104/0x270 hardirqs last disabled at (62224): [<ffffffc0000fbe20>] vprintk_emit+0x68/0x640 softirqs last enabled at (0): [<ffffffc000097928>] copy_process.part.8+0x428/0x17f8 softirqs last disabled at (0): [< (null)>] (null) CPU: 0 PID: 342 Comm: perf Not tainted 4.1.6-rt5 #4 Hardware name: linux,dummy-virt (DT) Call trace: [<ffffffc000089968>] dump_backtrace+0x0/0x128 [<ffffffc000089ab0>] show_stack+0x20/0x30 [<ffffffc0007030d0>] dump_stack+0x7c/0xa0 [<ffffffc0000c878c>] ___might_sleep+0x174/0x260 [<ffffffc000708ac8>] __rt_spin_lock+0x28/0x40 [<ffffffc000708db0>] rt_read_lock+0x60/0x80 [<ffffffc0000851a8>] call_break_hook+0x30/0xd0 [<ffffffc000085a70>] brk_handler+0x30/0x98 [<ffffffc000082248>] do_debug_exception+0x50/0xb8 Exception stack(0xffffffc00514fe30 to 0xffffffc00514ff50) fe20: 00000000 00000000 c1594680 0000007f fe40: ffffffff ffffffff 92063940 0000007f 0550dcd8 ffffffc0 00000000 00000000 fe60: 0514fe70 ffffffc0 000be1f8 ffffffc0 0514feb0 ffffffc0 0008948c ffffffc0 fe80: 00000004 00000000 0514fed0 ffffffc0 ffffffff ffffffff 9282a948 0000007f fea0: 00000000 00000000 9282b708 0000007f c1592820 0000007f 00083914 ffffffc0 fec0: 00000000 00000000 00000010 00000000 00000064 00000000 00000001 00000000 fee0: 005101e0 00000000 c1594680 0000007f c1594740 0000007f ffffffd8 ffffff80 ff00: 00000000 00000000 00000000 00000000 c1594770 0000007f c1594770 0000007f ff20: 00665e10 00000000 7f7f7f7f 7f7f7f7f 01010101 01010101 00000000 00000000 ff40: 928e4cc0 0000007f 91ff11e8 0000007f call_break_hook is called in atomic context (hard irq disabled), so replace the sleepable lock to rcu lock, replace relevant list operations to rcu version and call synchronize_rcu() in unregister_break_hook(). And, replace write lock to spinlock in {un}register_break_hook. Signed-off-by: Yang Shi <yang.shi@linaro.org> --- v2 -> v3 Add synchronize_rcu() in ungister_break_hook() Replace write lock to spinlock v1 -> v2 Replace list operations to rcu version. arch/arm64/kernel/debug-monitors.c | 21 +++++++++++---------- 1 file changed, 11 insertions(+), 10 deletions(-)