[rtems-libbsd commit] rtems-kernel-page: Panic on recursive reclaim

[Sebastian Huber]

Module:    rtems-libbsd
Branch:    master
Commit:    651710509430eee6731807801bd5ad85d28f4db4
Changeset: http://git.rtems.org/rtems-libbsd/commit/?id=651710509430eee6731807801bd5ad85d28f4db4

Author:    Sebastian Huber <sebastian.huber at embedded-brains.de>
Date:      Thu Nov 10 10:38:04 2016 +0100

rtems-kernel-page: Panic on recursive reclaim

---

 rtemsbsd/rtems/rtems-kernel-page.c | 51 +++++++++++++++++++++++---------------
 1 file changed, 31 insertions(+), 20 deletions(-)

diff --git a/rtemsbsd/rtems/rtems-kernel-page.c b/rtemsbsd/rtems/rtems-kernel-page.c
index cfcbb1a..f20abd2 100644
--- a/rtemsbsd/rtems/rtems-kernel-page.c
+++ b/rtemsbsd/rtems/rtems-kernel-page.c
@@ -58,40 +58,51 @@ void **rtems_bsd_page_object_table;
 
 uintptr_t rtems_bsd_page_area_begin;
 
-static rtems_rbheap_control page_heap;
-
-struct mtx page_heap_mtx;
+static struct {
+	struct mtx mtx;
+	rtems_rbheap_control heap;
+	bool reclaim_in_progress;
+} page_alloc;
 
 void *
 rtems_bsd_page_alloc(uintptr_t size_in_bytes, int wait)
 {
 	void *addr;
 
-	mtx_lock(&page_heap_mtx);
+	mtx_lock(&page_alloc.mtx);
 
-	addr = rtems_rbheap_allocate(&page_heap, size_in_bytes);
+	addr = rtems_rbheap_allocate(&page_alloc.heap, size_in_bytes);
 	if (addr == NULL && wait) {
 		int i;
 
+		if (page_alloc.reclaim_in_progress) {
+			panic("rtems_bsd_page_alloc: recursive reclaim");
+		}
+
+		page_alloc.reclaim_in_progress = true;
+
 		for (i = 0; i < 8; i++) {
-			mtx_unlock(&page_heap_mtx);
+			mtx_unlock(&page_alloc.mtx);
 			uma_reclaim();
-			mtx_lock(&page_heap_mtx);
+			mtx_lock(&page_alloc.mtx);
 
-			addr = rtems_rbheap_allocate(&page_heap, size_in_bytes);
+			addr = rtems_rbheap_allocate(&page_alloc.heap,
+			    size_in_bytes);
 			if (addr != NULL)
 				break;
 
-			msleep(&page_heap, &page_heap_mtx, 0,
+			msleep(&page_alloc.heap, &page_alloc.mtx, 0,
 			    "page alloc", (hz / 4) * (i + 1));
 		}
 
-		if (i == 8) {
+		page_alloc.reclaim_in_progress = false;
+
+		if (addr == NULL) {
 			panic("rtems_bsd_page_alloc: page starvation");
 		}
 	}
 
-	mtx_unlock(&page_heap_mtx);
+	mtx_unlock(&page_alloc.mtx);
 
 #ifdef INVARIANTS
 	if (addr != NULL) {
@@ -105,10 +116,10 @@ rtems_bsd_page_alloc(uintptr_t size_in_bytes, int wait)
 void
 rtems_bsd_page_free(void *addr)
 {
-	mtx_lock(&page_heap_mtx);
-	rtems_rbheap_free(&page_heap, addr);
-	wakeup(&page_heap);
-	mtx_unlock(&page_heap_mtx);
+	mtx_lock(&page_alloc.mtx);
+	rtems_rbheap_free(&page_alloc.heap, addr);
+	wakeup(&page_alloc.heap);
+	mtx_unlock(&page_alloc.mtx);
 }
 
 static void
@@ -122,7 +133,7 @@ rtems_bsd_page_init(void *arg)
 	size_t n;
 	uintptr_t heap_size;
 
-	mtx_init(&page_heap_mtx, "page heap", NULL, MTX_DEF);
+	mtx_init(&page_alloc.mtx, "page heap", NULL, MTX_DEF);
 
 	heap_size = rtems_bsd_get_allocator_domain_size(
 	    RTEMS_BSD_ALLOCATOR_DOMAIN_PAGE);
@@ -131,11 +142,11 @@ rtems_bsd_page_init(void *arg)
 	    0);
 	BSD_ASSERT(area != NULL);
 
-	sc = rtems_rbheap_initialize(&page_heap, area, heap_size, PAGE_SIZE,
-	    rtems_rbheap_extend_descriptors_with_malloc, NULL);
+	sc = rtems_rbheap_initialize(&page_alloc.heap, area, heap_size,
+	    PAGE_SIZE, rtems_rbheap_extend_descriptors_with_malloc, NULL);
 	BSD_ASSERT(sc == RTEMS_SUCCESSFUL);
 
-	rtems_rbheap_set_extend_descriptors(&page_heap,
+	rtems_rbheap_set_extend_descriptors(&page_alloc.heap,
 	    rtems_rbheap_extend_descriptors_never);
 
 	n = heap_size / PAGE_SIZE;
@@ -144,7 +155,7 @@ rtems_bsd_page_init(void *arg)
 	BSD_ASSERT(chunks != NULL);
 
 	for (i = 0; i < n; ++i) {
-		rtems_rbheap_add_to_spare_descriptor_chain(&page_heap,
+		rtems_rbheap_add_to_spare_descriptor_chain(&page_alloc.heap,
 		    &chunks[i]);
 	}