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| author | David Hildenbrand <dahi@linux.vnet.ibm.com> | 2015-05-11 17:52:11 +0200 |
|---|---|---|
| committer | Ingo Molnar <mingo@kernel.org> | 2015-05-19 08:39:15 +0200 |
| commit | 70ffdb9393a7264a069265edded729078dcf0425 (patch) | |
| tree | 9f93a018845ab2b02be1ee7cba83ae77f5191022 /arch/um/kernel | |
| parent | ce01948eb85da733558fa77c2a554144a57ab0fb (diff) | |
| download | linux-70ffdb9393a7264a069265edded729078dcf0425.tar.bz2 | |
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/um/kernel')
| -rw-r--r-- | arch/um/kernel/trap.c | 4 |
1 files changed, 2 insertions, 2 deletions
diff --git a/arch/um/kernel/trap.c b/arch/um/kernel/trap.c index 8e4daf44e980..f9c9e5a6beba 100644 --- a/arch/um/kernel/trap.c +++ b/arch/um/kernel/trap.c @@ -35,10 +35,10 @@ int handle_page_fault(unsigned long address, unsigned long ip, *code_out = SEGV_MAPERR; /* - * If the fault was during atomic operation, don't take the fault, just + * If the fault was with pagefaults disabled, don't take the fault, just * fail. */ - if (in_atomic()) + if (faulthandler_disabled()) goto out_nosemaphore; if (is_user) |