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mm: raw_pagefault_disable 

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
This commit is contained in:
Peter Zijlstra 2011-08-05 17:16:58 +02:00 committed by Alibek Omarov
parent 93aee95b49
commit fa749cd375
2 changed files with 40 additions and 8 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

40
include/linux/uaccess.h
View File

@ -8,8 +8,44 @@
* 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)
{
preempt_count_inc();
/*
* make sure to have issued the store before a pagefault
* can hit.
*/
barrier();
}
static inline void raw_pagefault_enable(void)
{
#ifndef CONFIG_PREEMPT
/*
* make sure to issue those last loads/stores before enabling
* the pagefault handler again.
*/
barrier();
preempt_count_dec();
#else
preempt_enable();
#endif
}
#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 +86,9 @@ static inline unsigned long __copy_from_user_nocache(void *to,
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; \
})

8
mm/memory.c
View File

@ -3696,6 +3696,7 @@ unlock:
return 0;
}
#ifdef CONFIG_PREEMPT_RT_FULL
void pagefault_disable(void)
{
preempt_count_inc();
@ -3710,21 +3711,16 @@ EXPORT_SYMBOL(pagefault_disable);
void pagefault_enable(void)
{
#ifndef CONFIG_PREEMPT
/*
* make sure to issue those last loads/stores before enabling
* the pagefault handler again.
*/
barrier();
current->pagefault_disabled--;
preempt_count_dec();
#else
barrier();
current->pagefault_disabled--;
preempt_enable();
#endif
}
EXPORT_SYMBOL(pagefault_enable);
#endif
/*
* By the time we get here, we already hold the mm semaphore