diff options
authorHelge Deller <>2013-10-01 21:54:46 +0200
committerHelge Deller <>2013-10-13 17:45:20 +0200
commit59b33f148cc08fb33cbe823fca1e34f7f023765e (patch)
parenta60ac4b5f0b630889a01293db52ac65003a01e98 (diff)
parisc: fix interruption handler to respect pagefault_disable()
Running an "echo t > /proc/sysrq-trigger" crashes the parisc kernel. The problem is, that in print_worker_info() we try to read the workqueue info via the probe_kernel_read() functions which use pagefault_disable() to avoid crashes like this: probe_kernel_read(&pwq, &worker->current_pwq, sizeof(pwq)); probe_kernel_read(&wq, &pwq->wq, sizeof(wq)); probe_kernel_read(name, wq->name, sizeof(name) - 1); The problem here is, that the first probe_kernel_read(&pwq) might return zero in pwq and as such the following probe_kernel_reads() try to access contents of the page zero which is read protected and generate a kernel segfault. With this patch we fix the interruption handler to call parisc_terminate() directly only if pagefault_disable() was not called (in which case preempt_count()==0). Otherwise we hand over to the pagefault handler which will try to look up the faulting address in the fixup tables. Signed-off-by: Helge Deller <> Cc: <> # v3.0+ Signed-off-by: John David Anglin <> Signed-off-by: Helge Deller <>
1 files changed, 3 insertions, 3 deletions
diff --git a/arch/parisc/kernel/traps.c b/arch/parisc/kernel/traps.c
index ebc877c28583..1cd1d0c83b6d 100644
--- a/arch/parisc/kernel/traps.c
+++ b/arch/parisc/kernel/traps.c
@@ -800,14 +800,14 @@ void notrace handle_interruption(int code, struct pt_regs *regs)
else {
- * The kernel should never fault on its own address space.
+ * The kernel should never fault on its own address space,
+ * unless pagefault_disable() was called before.
- if (fault_space == 0)
+ if (fault_space == 0 && !in_atomic())
parisc_terminate("Kernel Fault", regs, code, fault_address);