From 70ffdb9393a7264a069265edded729078dcf0425 Mon Sep 17 00:00:00 2001 From: David Hildenbrand Date: Mon, 11 May 2015 17:52:11 +0200 Subject: 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 Signed-off-by: David Hildenbrand Signed-off-by: Peter Zijlstra (Intel) Cc: David.Laight@ACULAB.COM Cc: Linus Torvalds Cc: Peter Zijlstra Cc: Thomas Gleixner 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 --- arch/cris/mm/fault.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) (limited to 'arch/cris') diff --git a/arch/cris/mm/fault.c b/arch/cris/mm/fault.c index 83f12f2ed9e3..3066d40a6db1 100644 --- a/arch/cris/mm/fault.c +++ b/arch/cris/mm/fault.c @@ -8,7 +8,7 @@ #include #include #include -#include +#include #include extern int find_fixup_code(struct pt_regs *); @@ -109,11 +109,11 @@ do_page_fault(unsigned long address, struct pt_regs *regs, info.si_code = SEGV_MAPERR; /* - * If we're in an interrupt or "atomic" operation or have no + * If we're in an interrupt, have pagefaults disabled or have no * user context, we must not take the fault. */ - if (in_atomic() || !mm) + if (faulthandler_disabled() || !mm) goto no_context; if (user_mode(regs)) -- cgit v1.2.3