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authorDavid Hildenbrand <dahi@linux.vnet.ibm.com>2015-05-11 17:52:11 +0200
committerIngo Molnar <mingo@kernel.org>2015-05-19 08:39:15 +0200
commit70ffdb9393a7264a069265edded729078dcf0425 (patch)
tree9f93a018845ab2b02be1ee7cba83ae77f5191022 /arch/mn10300
parentce01948eb85da733558fa77c2a554144a57ab0fb (diff)
downloadlinux-linaro-stable-70ffdb9393a7264a069265edded729078dcf0425.tar.gz
mm/fault, arch: Use pagefault_disable() to check for disabled pagefaults in the handler
Introduce faulthandler_disabled() and use it to check for irq context and disabled pagefaults (via pagefault_disable()) in the pagefault handlers. Please note that we keep the in_atomic() checks in place - to detect whether in irq context (in which case preemption is always properly disabled). In contrast, preempt_disable() should never be used to disable pagefaults. With !CONFIG_PREEMPT_COUNT, preempt_disable() doesn't modify the preempt counter, and therefore the result of in_atomic() differs. We validate that condition by using might_fault() checks when calling might_sleep(). Therefore, add a comment to faulthandler_disabled(), describing why this is needed. faulthandler_disabled() and pagefault_disable() are defined in linux/uaccess.h, so let's properly add that include to all relevant files. This patch is based on a patch from Thomas Gleixner. 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/1431359540-32227-7-git-send-email-dahi@linux.vnet.ibm.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
Diffstat (limited to 'arch/mn10300')
-rw-r--r--arch/mn10300/mm/fault.c4
1 files changed, 2 insertions, 2 deletions
diff --git a/arch/mn10300/mm/fault.c b/arch/mn10300/mm/fault.c
index 0c2cc5d39c8e..4a1d181ed32f 100644
--- a/arch/mn10300/mm/fault.c
+++ b/arch/mn10300/mm/fault.c
@@ -23,8 +23,8 @@
#include <linux/interrupt.h>
#include <linux/init.h>
#include <linux/vt_kern.h> /* For unblank_screen() */
+#include <linux/uaccess.h>
-#include <asm/uaccess.h>
#include <asm/pgalloc.h>
#include <asm/hardirq.h>
#include <asm/cpu-regs.h>
@@ -168,7 +168,7 @@ asmlinkage void do_page_fault(struct pt_regs *regs, unsigned long fault_code,
* If we're in an interrupt or have no user
* context, we must not take the fault..
*/
- if (in_atomic() || !mm)
+ if (faulthandler_disabled() || !mm)
goto no_context;
if ((fault_code & MMUFCR_xFC_ACCESS) == MMUFCR_xFC_ACCESS_USR)