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sched/preempt, mm/fault: Decouple preemption from the page fault logic
As the fault handlers now all rely on the pagefault_disabled() checks and implicit preempt_disable() calls by pagefault_disable() have been made explicit, we can completely rely on the pagefault_disableD counter. So let's no longer touch the preempt count when disabling/enabling pagefaults. After a call to pagefault_disable(), pagefault_disabled() will return true, but in_atomic() won't. Reviewed-and-tested-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: David Hildenbrand <dahi@linux.vnet.ibm.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: David.Laight@ACULAB.COM Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: airlied@linux.ie Cc: akpm@linux-foundation.org Cc: benh@kernel.crashing.org Cc: bigeasy@linutronix.de Cc: borntraeger@de.ibm.com Cc: daniel.vetter@intel.com Cc: heiko.carstens@de.ibm.com Cc: herbert@gondor.apana.org.au Cc: hocko@suse.cz Cc: hughd@google.com Cc: mst@redhat.com Cc: paulus@samba.org Cc: ralf@linux-mips.org Cc: schwidefsky@de.ibm.com Cc: yang.shi@windriver.com Link: http://lkml.kernel.org/r/1431359540-32227-16-git-send-email-dahi@linux.vnet.ibm.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
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1 changed files with 2 additions and 14 deletions
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@ -1,7 +1,6 @@
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#ifndef __LINUX_UACCESS_H__
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#define __LINUX_UACCESS_H__
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#include <linux/preempt.h>
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#include <linux/sched.h>
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#include <asm/uaccess.h>
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@ -20,17 +19,11 @@ static __always_inline void pagefault_disabled_dec(void)
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* These routines enable/disable the pagefault handler. If disabled, it will
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* not take any locks and go straight to the fixup table.
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*
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* We increase the preempt and the pagefault count, to be able to distinguish
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* whether we run in simple atomic context or in a real pagefault_disable()
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* context.
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*
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* For now, after pagefault_disabled() has been called, we run in atomic
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* context. User access methods will not sleep.
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*
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* User access methods will not sleep when called from a pagefault_disabled()
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* environment.
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*/
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static inline void pagefault_disable(void)
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{
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preempt_count_inc();
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pagefault_disabled_inc();
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/*
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* make sure to have issued the store before a pagefault
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@ -47,11 +40,6 @@ static inline void pagefault_enable(void)
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*/
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barrier();
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pagefault_disabled_dec();
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#ifndef CONFIG_PREEMPT
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preempt_count_dec();
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#else
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preempt_enable();
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#endif
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}
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/*
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