Warn once when part of the kernel is lacking memory

* kern/printf.h (printf_once): New macro.
* ipc/mach_port.c (mach_port_names, mach_port_get_set_status): Warn when
returning KERN_RESOURCE_SHORTAGE.
* vm/vm_kern.c: Include printf.h.
(kmem_alloc, kmem_realloc, kmem_alloc_wired, kmem_alloc_aligned,
kmem_alloc_pageable): Warn when failing.
* vm/vm_resident.c (vm_page_grab_contiguous_pages): Warn when returning
KERN_RESOURCE_SHORTAGE.

4 files changed, 26 insertions, 3 deletions

diff --git a/ipc/mach_port.c b/ipc/mach_port.c
index 122d5d9..904fd14 100644
--- a/ipc/mach_port.c
+++ b/ipc/mach_port.c
@@ -205,11 +205,14 @@ mach_port_names(
 		size = size_needed;
 
 		kr = vm_allocate(ipc_kernel_map, &addr1, size, TRUE);
-		if (kr != KERN_SUCCESS)
+		if (kr != KERN_SUCCESS) {
+			printf_once("no more room in ipc_kernel_map\n");
 			return KERN_RESOURCE_SHORTAGE;
+		}
 
 		kr = vm_allocate(ipc_kernel_map, &addr2, size, TRUE);
 		if (kr != KERN_SUCCESS) {
+			printf_once("no more room in ipc_kernel_map\n");
 			kmem_free(ipc_kernel_map, addr1, size);
 			return KERN_RESOURCE_SHORTAGE;
 		}
@@ -982,8 +985,10 @@ mach_port_get_set_status(
 		ipc_pset_t pset;
 
 		kr = vm_allocate(ipc_kernel_map, &addr, size, TRUE);
-		if (kr != KERN_SUCCESS)
+		if (kr != KERN_SUCCESS) {
+			printf_once("no more room in ipc_kernel_map\n");
 			return KERN_RESOURCE_SHORTAGE;
+		}
 
 		/* can't fault while we hold locks */
 
diff --git a/kern/printf.h b/kern/printf.h
index 1383198..c5effe5 100644
--- a/kern/printf.h
+++ b/kern/printf.h
@@ -43,6 +43,15 @@ extern int sprintf (char *buf, const char *fmt, ...);
 
 extern int printf (const char *fmt, ...);
 
+#define printf_once(fmt, ...)			\
+	MACRO_BEGIN				\
+	static int __once = 0;			\
+	if (!__once) {				\
+		printf(fmt, ##__VA_ARGS__);	\
+		__once = 1;			\
+	}					\
+	MACRO_END
+
 extern int indent;
 extern void iprintf (const char *fmt, ...);
 
diff --git a/vm/vm_kern.c b/vm/vm_kern.c
index dc7f7e4..cfa33ff 100644
--- a/vm/vm_kern.c
+++ b/vm/vm_kern.c
@@ -43,6 +43,7 @@
 #include <kern/debug.h>
 #include <kern/lock.h>
 #include <kern/thread.h>
+#include <kern/printf.h>
 #include <vm/pmap.h>
 #include <vm/vm_fault.h>
 #include <vm/vm_kern.h>
@@ -387,6 +388,7 @@ kmem_alloc(map, addrp, size)
 	kr = vm_map_find_entry(map, &addr, size, (vm_offset_t) 0,
 			       VM_OBJECT_NULL, &entry);
 	if (kr != KERN_SUCCESS) {
+		printf_once("no more room for kmem_alloc in %p\n", map);
 		vm_map_unlock(map);
 		vm_object_deallocate(object);
 		return kr;
@@ -453,6 +455,7 @@ kern_return_t kmem_realloc(map, oldaddr, oldsize, newaddrp, newsize)
 			       VM_OBJECT_NULL, &newentry);
 	if (kr != KERN_SUCCESS) {
 		vm_map_unlock(map);
+		printf_once("no more room for kmem_realloc in %p\n", map);
 		return kr;
 	}
 
@@ -537,6 +540,7 @@ kmem_alloc_wired(map, addrp, size)
 	kr = vm_map_find_entry(map, &addr, size, (vm_offset_t) 0,
 			       kernel_object, &entry);
 	if (kr != KERN_SUCCESS) {
+		printf_once("no more room for kmem_alloc_wired in %p\n", map);
 		vm_map_unlock(map);
 		return kr;
 	}
@@ -611,6 +615,7 @@ kmem_alloc_aligned(map, addrp, size)
 	kr = vm_map_find_entry(map, &addr, size, size - 1,
 			       kernel_object, &entry);
 	if (kr != KERN_SUCCESS) {
+		printf_once("no more rooom for kmem_alloc_aligned in %p\n", map);
 		vm_map_unlock(map);
 		return kr;
 	}
@@ -672,8 +677,10 @@ kmem_alloc_pageable(map, addrp, size)
 			  (vm_offset_t) 0, TRUE,
 			  VM_OBJECT_NULL, (vm_offset_t) 0, FALSE,
 			  VM_PROT_DEFAULT, VM_PROT_ALL, VM_INHERIT_DEFAULT);
-	if (kr != KERN_SUCCESS)
+	if (kr != KERN_SUCCESS) {
+		printf_once("no more room for kmem_alloc_pageable in %p\n", map);
 		return kr;
+	}
 
 	*addrp = addr;
 	return KERN_SUCCESS;
diff --git a/vm/vm_resident.c b/vm/vm_resident.c
index b23e0f3..a633498 100644
--- a/vm/vm_resident.c
+++ b/vm/vm_resident.c
@@ -976,6 +976,7 @@ vm_page_grab_contiguous_pages(
 
 	if ((vm_page_free_count < vm_page_free_reserved)
 	    || (vm_page_external_count >= vm_page_external_limit)) {
+		printf_once("no more room for vm_page_grab_contiguous_pages");
 		simple_unlock(&vm_page_queue_free_lock);
 		return KERN_RESOURCE_SHORTAGE;
 	}
@@ -1064,6 +1065,7 @@ count_ones:
 	 */
 	simple_unlock(&vm_page_queue_free_lock);
 
+	printf_once("no contiguous room for vm_page_grab_contiguous_pages");
 	ret = KERN_RESOURCE_SHORTAGE;
 	goto out;