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Subject: mm: raw_pagefault_disable
From: Peter Zijlstra <a.p.zijlstra@chello.nl>
Date: Fri Aug 05 17:16:58 CEST 2011
Adding migrate_disable() to pagefault_disable() to preserve the
per-cpu thing for kmap_atomic might not have been the best of choices.
But short of adding preempt_disable/migrate_disable foo all over the
kmap code it still seems the best way.
It does however yield the below borkage as well as wreck !-rt builds
since !-rt does rely on pagefault_disable() not preempting. So fix all
that up by adding raw_pagefault_disable().
<NMI> [<ffffffff81076d5c>] warn_slowpath_common+0x85/0x9d
[<ffffffff81076e17>] warn_slowpath_fmt+0x46/0x48
[<ffffffff814f7fca>] ? _raw_spin_lock+0x6c/0x73
[<ffffffff810cac87>] ? watchdog_overflow_callback+0x9b/0xd0
[<ffffffff810caca3>] watchdog_overflow_callback+0xb7/0xd0
[<ffffffff810f51bb>] __perf_event_overflow+0x11c/0x1fe
[<ffffffff810f298f>] ? perf_event_update_userpage+0x149/0x151
[<ffffffff810f2846>] ? perf_event_task_disable+0x7c/0x7c
[<ffffffff810f5b7c>] perf_event_overflow+0x14/0x16
[<ffffffff81046e02>] x86_pmu_handle_irq+0xcb/0x108
[<ffffffff814f9a6b>] perf_event_nmi_handler+0x46/0x91
[<ffffffff814fb2ba>] notifier_call_chain+0x79/0xa6
[<ffffffff814fb34d>] __atomic_notifier_call_chain+0x66/0x98
[<ffffffff814fb2e7>] ? notifier_call_chain+0xa6/0xa6
[<ffffffff814fb393>] atomic_notifier_call_chain+0x14/0x16
[<ffffffff814fb3c3>] notify_die+0x2e/0x30
[<ffffffff814f8f75>] do_nmi+0x7e/0x22b
[<ffffffff814f8bca>] nmi+0x1a/0x2c
[<ffffffff814fb130>] ? sub_preempt_count+0x4b/0xaa
<<EOE>> <IRQ> [<ffffffff812d44cc>] delay_tsc+0xac/0xd1
[<ffffffff812d4399>] __delay+0xf/0x11
[<ffffffff812d95d9>] do_raw_spin_lock+0xd2/0x13c
[<ffffffff814f813e>] _raw_spin_lock_irqsave+0x6b/0x85
[<ffffffff8106772a>] ? task_rq_lock+0x35/0x8d
[<ffffffff8106772a>] task_rq_lock+0x35/0x8d
[<ffffffff8106fe2f>] migrate_disable+0x65/0x12c
[<ffffffff81114e69>] pagefault_disable+0xe/0x1f
[<ffffffff81039c73>] dump_trace+0x21f/0x2e2
[<ffffffff8103ad79>] show_trace_log_lvl+0x54/0x5d
[<ffffffff8103ad97>] show_trace+0x15/0x17
[<ffffffff814f4f5f>] dump_stack+0x77/0x80
[<ffffffff812d94b0>] spin_bug+0x9c/0xa3
[<ffffffff81067745>] ? task_rq_lock+0x50/0x8d
[<ffffffff812d954e>] do_raw_spin_lock+0x47/0x13c
[<ffffffff814f7fbe>] _raw_spin_lock+0x60/0x73
[<ffffffff81067745>] ? task_rq_lock+0x50/0x8d
[<ffffffff81067745>] task_rq_lock+0x50/0x8d
[<ffffffff8106fe2f>] migrate_disable+0x65/0x12c
[<ffffffff81114e69>] pagefault_disable+0xe/0x1f
[<ffffffff81039c73>] dump_trace+0x21f/0x2e2
[<ffffffff8104369b>] save_stack_trace+0x2f/0x4c
[<ffffffff810a7848>] save_trace+0x3f/0xaf
[<ffffffff810aa2bd>] mark_lock+0x228/0x530
[<ffffffff810aac27>] __lock_acquire+0x662/0x1812
[<ffffffff8103dad4>] ? native_sched_clock+0x37/0x6d
[<ffffffff810a790e>] ? trace_hardirqs_off_caller+0x1f/0x99
[<ffffffff810693f6>] ? sched_rt_period_timer+0xbd/0x218
[<ffffffff810ac403>] lock_acquire+0x145/0x18a
[<ffffffff810693f6>] ? sched_rt_period_timer+0xbd/0x218
[<ffffffff814f7f9e>] _raw_spin_lock+0x40/0x73
[<ffffffff810693f6>] ? sched_rt_period_timer+0xbd/0x218
[<ffffffff810693f6>] sched_rt_period_timer+0xbd/0x218
[<ffffffff8109aa39>] __run_hrtimer+0x1e4/0x347
[<ffffffff81069339>] ? can_migrate_task.clone.82+0x14a/0x14a
[<ffffffff8109b97c>] hrtimer_interrupt+0xee/0x1d6
[<ffffffff814fb23d>] ? add_preempt_count+0xae/0xb2
[<ffffffff814ffb38>] smp_apic_timer_interrupt+0x85/0x98
[<ffffffff814fef13>] apic_timer_interrupt+0x13/0x20
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Link: http://lkml.kernel.org/n/tip-31keae8mkjiv8esq4rl76cib@git.kernel.org
---
include/linux/uaccess.h | 30 ++++++++++++++++++++++++++++--
mm/memory.c | 2 ++
2 files changed, 30 insertions(+), 2 deletions(-)
Index: linux-stable/include/linux/uaccess.h
===================================================================
--- linux-stable.orig/include/linux/uaccess.h
+++ linux-stable/include/linux/uaccess.h
@@ -8,8 +8,34 @@
* These routines enable/disable the pagefault handler in that
* it will not take any MM locks and go straight to the fixup table.
*/
+static inline void raw_pagefault_disable(void)
+{
+ inc_preempt_count();
+ barrier();
+}
+
+static inline void raw_pagefault_enable(void)
+{
+ barrier();
+ dec_preempt_count();
+ barrier();
+ preempt_check_resched();
+}
+
+#ifndef CONFIG_PREEMPT_RT_FULL
+static inline void pagefault_disable(void)
+{
+ raw_pagefault_disable();
+}
+
+static inline void pagefault_enable(void)
+{
+ raw_pagefault_enable();
+}
+#else
extern void pagefault_disable(void);
extern void pagefault_enable(void);
+#endif
#ifndef ARCH_HAS_NOCACHE_UACCESS
@@ -50,9 +76,9 @@ static inline unsigned long __copy_from_
mm_segment_t old_fs = get_fs(); \
\
set_fs(KERNEL_DS); \
- pagefault_disable(); \
+ raw_pagefault_disable(); \
ret = __copy_from_user_inatomic(&(retval), (__force typeof(retval) __user *)(addr), sizeof(retval)); \
- pagefault_enable(); \
+ raw_pagefault_enable(); \
set_fs(old_fs); \
ret; \
})
Index: linux-stable/mm/memory.c
===================================================================
--- linux-stable.orig/mm/memory.c
+++ linux-stable/mm/memory.c
@@ -3484,6 +3484,7 @@ unlock:
return 0;
}
+#ifdef CONFIG_PREEMPT_RT_FULL
void pagefault_disable(void)
{
inc_preempt_count();
@@ -3512,6 +3513,7 @@ void pagefault_enable(void)
preempt_check_resched();
}
EXPORT_SYMBOL_GPL(pagefault_enable);
+#endif
/*
* By the time we get here, we already hold the mm semaphore
|
