[PATCH] uml: Improve SIGBUS diagnostics

UML can get a SIGBUS anywhere if the tmpfs mount being used for its memory
runs out of space.  This patch adds a printk before the panic to provide a
clue as to what likely went wrong.

Signed-off-by: Jeff Dike <jdike@addtoit.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

1 files changed, 9 insertions, 2 deletions

diff --git a/arch/um/kernel/trap.c b/arch/um/kernel/trap.c
index ac70fa5a2e2a..e5eeaf2b6af1 100644
--- a/arch/um/kernel/trap.c
+++ b/arch/um/kernel/trap.c
@@ -227,9 +227,16 @@ void bad_segv(struct faultinfo fi, unsigned long ip)
 
 void relay_signal(int sig, union uml_pt_regs *regs)
 {
-        if(arch_handle_signal(sig, regs)) return;
-        if(!UPT_IS_USER(regs))
+        if(arch_handle_signal(sig, regs))
+                return;
+
+        if(!UPT_IS_USER(regs)){
+                if(sig == SIGBUS)
+                        printk("Bus error - the /dev/shm or /tmp mount likely "
+                               "just ran out of space\n");
                 panic("Kernel mode signal %d", sig);
+        }
+
         current->thread.arch.faultinfo = *UPT_FAULTINFO(regs);
         force_sig(sig, current);
 }