From: Helge Deller Date: Tue, 1 Oct 2013 19:54:46 +0000 (+0200) Subject: parisc: fix interruption handler to respect pagefault_disable() X-Git-Tag: v3.2.53~22 X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=d6c0dfc93890ac6621b64a33ceeefa283aebec64;p=pandora-kernel.git parisc: fix interruption handler to respect pagefault_disable() commit 59b33f148cc08fb33cbe823fca1e34f7f023765e upstream. 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 Signed-off-by: John David Anglin Signed-off-by: Helge Deller Signed-off-by: Ben Hutchings --- Reading git-diff-tree failed