[RFC][PATCH 1/4] mm: arch do_page_fault() vs in_atomic()

[Peter Zijlstra]

In light of the recent pagefault and filemap_copy_from_user work I've
gone through all the arch pagefault handlers to make sure the 
inc_preempt_count() 'feature' works as expected.

Several sections of code (including the new filemap_copy_from_user) rely
on the fact that faults do not take locks under increased preempt count.

arch/x86_64 - good
arch/powerpc - good
arch/cris - fixed
arch/i386 - good
arch/parisc - fixed
arch/sh - good
arch/sparc - good
arch/s390 - good
arch/m68k - fixed
arch/ppc - good
arch/alpha - fixed
arch/mips - good
arch/sparc64 - good
arch/ia64 - good
arch/arm - fixed
arch/um - NA
arch/avr32 - good
arch/h8300 - NA
arch/m32r - good
arch/v850 - good
arch/frv - fixed
arch/m68knommu - NA
arch/arm26 - fixed
arch/sh64 - fixed
arch/xtensa - good

Signed-off-by: Peter Zijlstra <a.p.zijlstra@xxxxxxxxx>
---
 arch/alpha/mm/fault.c  |    2 +-
 arch/arm/mm/fault.c    |    2 +-
 arch/arm26/mm/fault.c  |    2 +-
 arch/cris/mm/fault.c   |    2 +-
 arch/frv/mm/fault.c    |    2 +-
 arch/m68k/mm/fault.c   |    2 +-
 arch/parisc/mm/fault.c |    2 +-
 arch/sh64/mm/fault.c   |    2 +-
 8 files changed, 8 insertions(+), 8 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
@@ -108,7 +108,7 @@ 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_interrupt())
+	if (!mm || in_atomic())
 		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
@@ -230,7 +230,7 @@ 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_interrupt() || !mm)
+	if (in_atomic() || !mm)
 		goto no_context;
 
 	/*
Index: linux-2.6/arch/arm26/mm/fault.c
===================================================================
--- linux-2.6.orig/arch/arm26/mm/fault.c
+++ linux-2.6/arch/arm26/mm/fault.c
@@ -215,7 +215,7 @@ int do_page_fault(unsigned long addr, un
 	 * If we're in an interrupt or have no user
 	 * context, we must not take the fault..
 	 */
-	if (in_interrupt() || !mm)
+	if (in_atomic() || !mm)
 		goto no_context;
 
 	down_read(&mm->mmap_sem);
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
@@ -232,7 +232,7 @@ do_page_fault(unsigned long address, str
 	 * context, we must not take the fault..
 	 */
 
-	if (in_interrupt() || !mm)
+	if (in_atomic() || !mm)
 		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
@@ -78,7 +78,7 @@ 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_interrupt() || !mm)
+	if (in_atomic() || !mm)
 		goto no_context;
 
 	down_read(&mm->mmap_sem);
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
@@ -99,7 +99,7 @@ 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_interrupt() || !mm)
+	if (in_atomic() || !mm)
 		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
@@ -152,7 +152,7 @@ void do_page_fault(struct pt_regs *regs,
 	const struct exception_table_entry *fix;
 	unsigned long acc_type;
 
-	if (in_interrupt() || !mm)
+	if (in_atomic() || !mm)
 		goto no_context;
 
 	down_read(&mm->mmap_sem);
Index: linux-2.6/arch/sh64/mm/fault.c
===================================================================
--- linux-2.6.orig/arch/sh64/mm/fault.c
+++ linux-2.6/arch/sh64/mm/fault.c
@@ -154,7 +154,7 @@ 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_interrupt() || !mm)
+	if (in_atomic() || !mm)
 		goto no_context;
 
 	/* TLB misses upon some cache flushes get done under cli() */

--

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