[uml-devel] SIGSEGV and SA_NODEFER

[Jeff D. <jd...@ad...>]

It turns out that caker's crashes were being caused by the lack of SA_NODEFER
in the SIGSEGV handler registration.

I know I fixed this, and I have no idea where the fix went.  Do you have any
clue what happened to it?

Patch below...

				Jeff

Index: 2.6.10/arch/um/kernel/process.c
===================================================================
--- 2.6.10.orig/arch/um/kernel/process.c        2005-01-17 12:27:47.000000000 -0500
+++ 2.6.10/arch/um/kernel/process.c     2005-01-18 13:55:28.000000000 -0500
@@ -60,7 +60,10 @@
 {
        int flags = altstack ? SA_ONSTACK : 0;
 
-       set_handler(SIGSEGV, (__sighandler_t) sig_handler, flags,
+       /* SIGSEGV needs to be SA_NODEFER because segfaults can happen while
+        * the segfault handler is on the stack.
+        */
+       set_handler(SIGSEGV, (__sighandler_t) sig_handler, flags | SA_NODEFER,
                    SIGUSR1, SIGIO, SIGWINCH, SIGALRM, SIGVTALRM, -1);
        set_handler(SIGTRAP, (__sighandler_t) sig_handler, flags, 
                    SIGUSR1, SIGIO, SIGWINCH, SIGALRM, SIGVTALRM, -1);