[PATCH] mm, arch: Complete pagefault_disable abstraction

From: Peter Zijlstra
Date: Wed Oct 05 2011 - 09:10:13 EST

Subject: mm, arch: Complete pagefault_disable abstraction
From: Peter Zijlstra <a.p.zijlstra@xxxxxxxxx>
Date: Wed Oct 05 14:22:37 CEST 2011

Currently we already have pagefault_{disable,enable}() but they're
nothing more than a glorified preempt_{disable,enable}().

For -rt we want to make pagefault_disable() regions preemptible and
for that we need to complete the abstraction, replace the current
in_atomic() tests that are relevant to pagefault_disable() usage with
pagefault_disabled().

Signed-off-by: Peter Zijlstra <a.p.zijlstra@xxxxxxxxx>
---
arch/alpha/mm/fault.c | 2 +-
arch/arm/mm/fault.c | 2 +-
arch/avr32/mm/fault.c | 2 +-
arch/cris/mm/fault.c | 2 +-
arch/frv/mm/fault.c | 2 +-
arch/ia64/mm/fault.c | 2 +-
arch/m32r/mm/fault.c | 2 +-
arch/m68k/mm/fault.c | 2 +-
arch/microblaze/mm/fault.c | 2 +-
arch/mips/mm/fault.c | 2 +-
arch/mn10300/mm/fault.c | 2 +-
arch/parisc/mm/fault.c | 2 +-
arch/powerpc/mm/fault.c | 2 +-
arch/s390/mm/fault.c | 6 ++++--
arch/score/mm/fault.c | 2 +-
arch/sh/mm/fault_32.c | 2 +-
arch/sparc/mm/fault_32.c | 4 ++--
arch/sparc/mm/fault_64.c | 2 +-
arch/tile/mm/fault.c | 2 +-
arch/um/kernel/trap.c | 2 +-
arch/unicore32/mm/fault.c | 2 +-
arch/x86/mm/fault.c | 2 +-
arch/xtensa/mm/fault.c | 2 +-
include/linux/sched.h | 6 ++++++
mm/filemap.c | 2 +-
25 files changed, 34 insertions(+), 26 deletions(-)

Index: linux-2.6/arch/alpha/mm/fault.c
===================================================================
--- linux-2.6.orig/arch/alpha/mm/fault.c
+++ linux-2.6/arch/alpha/mm/fault.c
@@ -107,7 +107,7 @@ do_page_fault(unsigned long address, uns

/* If we're in an interrupt context, or have no user context,
we must not take the fault. */
- if (!mm || in_atomic())
+ if (!mm || pagefault_disabled())
goto no_context;

#ifdef CONFIG_ALPHA_LARGE_VMALLOC
Index: linux-2.6/arch/arm/mm/fault.c
===================================================================
--- linux-2.6.orig/arch/arm/mm/fault.c
+++ linux-2.6/arch/arm/mm/fault.c
@@ -293,7 +293,7 @@ do_page_fault(unsigned long addr, unsign
* If we're in an interrupt or have no user
* context, we must not take the fault..
*/
- if (in_atomic() || !mm)
+ if (!mm || pagefault_disabled())
goto no_context;

/*
Index: linux-2.6/arch/avr32/mm/fault.c
===================================================================
--- linux-2.6.orig/arch/avr32/mm/fault.c
+++ linux-2.6/arch/avr32/mm/fault.c
@@ -81,7 +81,7 @@ asmlinkage void do_page_fault(unsigned l
* If we're in an interrupt or have no user context, we must
* not take the fault...
*/
- if (in_atomic() || !mm || regs->sr & SYSREG_BIT(GM))
+ if (!mm || regs->sr & SYSREG_BIT(GM) || pagefault_disabled())
goto no_context;

local_irq_enable();
Index: linux-2.6/arch/cris/mm/fault.c
===================================================================
--- linux-2.6.orig/arch/cris/mm/fault.c
+++ linux-2.6/arch/cris/mm/fault.c
@@ -111,7 +111,7 @@ do_page_fault(unsigned long address, str
* user context, we must not take the fault.
*/

- if (in_atomic() || !mm)
+ if (!mm || pagefault_disabled())
goto no_context;

down_read(&mm->mmap_sem);
Index: linux-2.6/arch/frv/mm/fault.c
===================================================================
--- linux-2.6.orig/arch/frv/mm/fault.c
+++ linux-2.6/arch/frv/mm/fault.c
@@ -79,7 +79,7 @@ asmlinkage void do_page_fault(int datamm
* If we're in an interrupt or have no user
* context, we must not take the fault..
*/
- if (in_atomic() || !mm)
+ if (!mm || pagefault_disabled())
goto no_context;

down_read(&mm->mmap_sem);
Index: linux-2.6/arch/ia64/mm/fault.c
===================================================================
--- linux-2.6.orig/arch/ia64/mm/fault.c
+++ linux-2.6/arch/ia64/mm/fault.c
@@ -89,7 +89,7 @@ ia64_do_page_fault (unsigned long addres
/*
* If we're in an interrupt or have no user context, we must not take the fault..
*/
- if (in_atomic() || !mm)
+ if (!mm || pagefault_disabled())
goto no_context;

#ifdef CONFIG_VIRTUAL_MEM_MAP
Index: linux-2.6/arch/m32r/mm/fault.c
===================================================================
--- linux-2.6.orig/arch/m32r/mm/fault.c
+++ linux-2.6/arch/m32r/mm/fault.c
@@ -115,7 +115,7 @@ asmlinkage void do_page_fault(struct pt_
* If we're in an interrupt or have no user context or are running in an
* atomic region then we must not take the fault..
*/
- if (in_atomic() || !mm)
+ if (!mm || pagefault_disabled())
goto bad_area_nosemaphore;

/* When running in the kernel we expect faults to occur only to
Index: linux-2.6/arch/m68k/mm/fault.c
===================================================================
--- linux-2.6.orig/arch/m68k/mm/fault.c
+++ linux-2.6/arch/m68k/mm/fault.c
@@ -85,7 +85,7 @@ int do_page_fault(struct pt_regs *regs,
* If we're in an interrupt or have no user
* context, we must not take the fault..
*/
- if (in_atomic() || !mm)
+ if (!mm || pagefault_disabled())
goto no_context;

down_read(&mm->mmap_sem);
Index: linux-2.6/arch/microblaze/mm/fault.c
===================================================================
--- linux-2.6.orig/arch/microblaze/mm/fault.c
+++ linux-2.6/arch/microblaze/mm/fault.c
@@ -107,7 +107,7 @@ void do_page_fault(struct pt_regs *regs,
if ((error_code & 0x13) == 0x13 || (error_code & 0x11) == 0x11)
is_write = 0;

- if (unlikely(in_atomic() || !mm)) {
+ if (unlikely(!mm || pagefault_disabled())) {
if (kernel_mode(regs))
goto bad_area_nosemaphore;

Index: linux-2.6/arch/mips/mm/fault.c
===================================================================
--- linux-2.6.orig/arch/mips/mm/fault.c
+++ linux-2.6/arch/mips/mm/fault.c
@@ -88,7 +88,7 @@ asmlinkage void __kprobes do_page_fault(
* If we're in an interrupt or have no user
* context, we must not take the fault..
*/
- if (in_atomic() || !mm)
+ if (!mm || pagefault_disabled())
goto bad_area_nosemaphore;

down_read(&mm->mmap_sem);
Index: linux-2.6/arch/mn10300/mm/fault.c
===================================================================
--- linux-2.6.orig/arch/mn10300/mm/fault.c
+++ linux-2.6/arch/mn10300/mm/fault.c
@@ -168,7 +168,7 @@ asmlinkage void do_page_fault(struct pt_
* If we're in an interrupt or have no user
* context, we must not take the fault..
*/
- if (in_atomic() || !mm)
+ if (!mm || pagefault_disabled())
goto no_context;

down_read(&mm->mmap_sem);
Index: linux-2.6/arch/parisc/mm/fault.c
===================================================================
--- linux-2.6.orig/arch/parisc/mm/fault.c
+++ linux-2.6/arch/parisc/mm/fault.c
@@ -176,7 +176,7 @@ void do_page_fault(struct pt_regs *regs,
unsigned long acc_type;
int fault;

- if (in_atomic() || !mm)
+ if (!mm || pagefault_disabled())
goto no_context;

down_read(&mm->mmap_sem);
Index: linux-2.6/arch/powerpc/mm/fault.c
===================================================================
--- linux-2.6.orig/arch/powerpc/mm/fault.c
+++ linux-2.6/arch/powerpc/mm/fault.c
@@ -162,7 +162,7 @@ int __kprobes do_page_fault(struct pt_re
}
#endif

- if (in_atomic() || mm == NULL) {
+ if (!mm || pagefault_disabled()) {
if (!user_mode(regs))
return SIGSEGV;
/* in_atomic() in user mode is really bad,
Index: linux-2.6/arch/s390/mm/fault.c
===================================================================
--- linux-2.6.orig/arch/s390/mm/fault.c
+++ linux-2.6/arch/s390/mm/fault.c
@@ -295,7 +295,8 @@ static inline int do_exception(struct pt
* user context.
*/
fault = VM_FAULT_BADCONTEXT;
- if (unlikely(!user_space_fault(trans_exc_code) || in_atomic() || !mm))
+ if (unlikely(!user_space_fault(trans_exc_code) ||
+ !mm || pagefault_disabled()))
goto out;

address = trans_exc_code & __FAIL_ADDR_MASK;
@@ -426,7 +427,8 @@ void __kprobes do_asce_exception(struct
struct mm_struct *mm = current->mm;
struct vm_area_struct *vma;

- if (unlikely(!user_space_fault(trans_exc_code) || in_atomic() || !mm))
+ if (unlikely(!user_space_fault(trans_exc_code) ||
+ !mm || pagefault_disabled()))
goto no_context;

down_read(&mm->mmap_sem);
Index: linux-2.6/arch/score/mm/fault.c
===================================================================
--- linux-2.6.orig/arch/score/mm/fault.c
+++ linux-2.6/arch/score/mm/fault.c
@@ -72,7 +72,7 @@ asmlinkage void do_page_fault(struct pt_
* If we're in an interrupt or have no user
* context, we must not take the fault..
*/
- if (in_atomic() || !mm)
+ if (!mm || pagefault_disabled())
goto bad_area_nosemaphore;

down_read(&mm->mmap_sem);
Index: linux-2.6/arch/sh/mm/fault_32.c
===================================================================
--- linux-2.6.orig/arch/sh/mm/fault_32.c
+++ linux-2.6/arch/sh/mm/fault_32.c
@@ -166,7 +166,7 @@ asmlinkage void __kprobes do_page_fault(
* If we're in an interrupt, have no user context or are running
* in an atomic region then we must not take the fault:
*/
- if (in_atomic() || !mm)
+ if (!mm || pagefault_disabled())
goto no_context;

down_read(&mm->mmap_sem);
Index: linux-2.6/arch/sparc/mm/fault_32.c
===================================================================
--- linux-2.6.orig/arch/sparc/mm/fault_32.c
+++ linux-2.6/arch/sparc/mm/fault_32.c
@@ -248,8 +248,8 @@ asmlinkage void do_sparc_fault(struct pt
* If we're in an interrupt or have no user
* context, we must not take the fault..
*/
- if (in_atomic() || !mm)
- goto no_context;
+ if (!mm || pagefault_disabled())
+ goto no_context;

perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS, 1, regs, address);

Index: linux-2.6/arch/sparc/mm/fault_64.c
===================================================================
--- linux-2.6.orig/arch/sparc/mm/fault_64.c
+++ linux-2.6/arch/sparc/mm/fault_64.c
@@ -322,7 +322,7 @@ asmlinkage void __kprobes do_sparc64_fau
* If we're in an interrupt or have no user
* context, we must not take the fault..
*/
- if (in_atomic() || !mm)
+ if (!mm || pagefault_disabled())
goto intr_or_no_mm;

perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS, 1, regs, address);
Index: linux-2.6/arch/tile/mm/fault.c
===================================================================
--- linux-2.6.orig/arch/tile/mm/fault.c
+++ linux-2.6/arch/tile/mm/fault.c
@@ -346,7 +346,7 @@ static int handle_page_fault(struct pt_r
* If we're in an interrupt, have no user context or are running in an
* atomic region then we must not take the fault.
*/
- if (in_atomic() || !mm) {
+ if (!mm || pagefault_disabled()) {
vma = NULL; /* happy compiler */
goto bad_area_nosemaphore;
}
Index: linux-2.6/arch/um/kernel/trap.c
===================================================================
--- linux-2.6.orig/arch/um/kernel/trap.c
+++ linux-2.6/arch/um/kernel/trap.c
@@ -37,7 +37,7 @@ int handle_page_fault(unsigned long addr
* If the fault was during atomic operation, don't take the fault, just
* fail.
*/
- if (in_atomic())
+ if (!mm || pagefault_disabled())
goto out_nosemaphore;

down_read(&mm->mmap_sem);
Index: linux-2.6/arch/unicore32/mm/fault.c
===================================================================
--- linux-2.6.orig/arch/unicore32/mm/fault.c
+++ linux-2.6/arch/unicore32/mm/fault.c
@@ -225,7 +225,7 @@ static int do_pf(unsigned long addr, uns
* If we're in an interrupt or have no user
* context, we must not take the fault..
*/
- if (in_atomic() || !mm)
+ if (!mm || pagefault_disabled())
goto no_context;

/*
Index: linux-2.6/arch/x86/mm/fault.c
===================================================================
--- linux-2.6.orig/arch/x86/mm/fault.c
+++ linux-2.6/arch/x86/mm/fault.c
@@ -1084,7 +1084,7 @@ do_page_fault(struct pt_regs *regs, unsi
* If we're in an interrupt, have no user context or are running
* in an atomic region then we must not take the fault:
*/
- if (unlikely(in_atomic() || !mm)) {
+ if (unlikely(!mm || pagefault_disabled())) {
bad_area_nosemaphore(regs, error_code, address);
return;
}
Index: linux-2.6/arch/xtensa/mm/fault.c
===================================================================
--- linux-2.6.orig/arch/xtensa/mm/fault.c
+++ linux-2.6/arch/xtensa/mm/fault.c
@@ -57,7 +57,7 @@ void do_page_fault(struct pt_regs *regs)
/* If we're in an interrupt or have no user
* context, we must not take the fault..
*/
- if (in_atomic() || !mm) {
+ if (!mm || pagefault_disabled()) {
bad_page_fault(regs, address, SIGSEGV);
return;
}
Index: linux-2.6/include/linux/sched.h
===================================================================
--- linux-2.6.orig/include/linux/sched.h
+++ linux-2.6/include/linux/sched.h
@@ -91,6 +91,7 @@ struct sched_param {
#include <linux/latencytop.h>
#include <linux/cred.h>
#include <linux/llist.h>
+#include <linux/hardirq.h>

#include <asm/processor.h>

@@ -1575,6 +1576,11 @@ struct task_struct {
/* Future-safe accessor for struct task_struct's cpus_allowed. */
#define tsk_cpus_allowed(tsk) (&(tsk)->cpus_allowed)

+static inline bool pagefault_disabled(void)
+{
+ return in_atomic();
+}
+
/*
* Priority of a process goes from 0..MAX_PRIO-1, valid RT
* priority is 0..MAX_RT_PRIO-1, and SCHED_NORMAL/SCHED_BATCH
Index: linux-2.6/mm/filemap.c
===================================================================
--- linux-2.6.orig/mm/filemap.c
+++ linux-2.6/mm/filemap.c
@@ -2061,7 +2061,7 @@ size_t iov_iter_copy_from_user_atomic(st
char *kaddr;
size_t copied;

- BUG_ON(!in_atomic());
+ BUG_ON(!pagefault_disabled());
kaddr = kmap_atomic(page, KM_USER0);
if (likely(i->nr_segs == 1)) {
int left;

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