PATCH 2.4.18-rc2-ac1: hang on spinlock in "expand_stack"

[Kevin Buhr]

Alan:

I've enclosed a patch against 2.4.18-rc2-ac1, but it appears the same
bug still exists in 2.4.19-pre1-ac1.  The "ac"-branch version of
"expand_stack" in "mm/mmap.c" has a code path that doesn't unlock the
spinlock.  I noticed when a "gdb" bug tickled it and locked up my
machine.

Kevin Buhr <[e-mail]>

                        *       *       *

--- linux-2.4.18-rc2-ac1/mm/mmap.c	Tue Feb 19 19:13:57 2002
+++ linux-2.4.18-rc2-ac1-local/mm/mmap.c	Sat Mar  2 17:58:47 2002
@@ -762,8 +762,10 @@
 	grow = (vma->vm_start - address) >> PAGE_SHIFT;
 
 	/* Overcommit.. */
-	if(!vm_enough_memory(grow, 1))
+	if(!vm_enough_memory(grow, 1)) {
+		spin_unlock(&vma->vm_mm->page_table_lock);
 		return -ENOMEM;
+	}
 	
 	if (vma->vm_end - address > current->rlim[RLIMIT_STACK].rlim_cur ||
 	    ((vma->vm_mm->total_vm + grow) << PAGE_SHIFT) > current->rlim[RLIMIT_AS].rlim_cur) {