Support --with-lg-page values larger than system page size.

All mappings continue to be PAGE-aligned, even if the system page size
is smaller.  This change is primarily intended to provide a mechanism
for supporting multiple page sizes with the same binary; smaller page
sizes work better in conjunction with jemalloc's design.

This resolves #467.

INSTALL

@@ -219,9 +219,12 @@ any of the following arguments (not a definitive list) to 'configure':
     documentation.
 
 --with-lg-page=<lg-page>
-    Specify the base 2 log of the system page size.  This option is only useful
-    when cross compiling, since the configure script automatically determines
-    the host's page size by default.
+    Specify the base 2 log of the allocator page size, which must in turn be at
+    least as large as the system page size.  By default the configure script
+    determines the host's page size and sets the allocator page size equal to
+    the system page size, so this option need not be specified unless the
+    system page size may change between configuration and execution, e.g. when
+    cross compiling.
 
 --with-lg-page-sizes=<lg-page-sizes>
     Specify the comma-separated base 2 logs of the page sizes to support.  This

include/jemalloc/internal/pages_externs.h

@@ -16,16 +16,14 @@ static const bool pages_can_purge_forced =
 #endif
     ;
 
-void	*pages_map(void *addr, size_t size, bool *commit);
+void	*pages_map(void *addr, size_t size, size_t alignment, bool *commit);
 void	pages_unmap(void *addr, size_t size);
-void	*pages_trim(void *addr, size_t alloc_size, size_t leadsize,
-    size_t size, bool *commit);
 bool	pages_commit(void *addr, size_t size);
 bool	pages_decommit(void *addr, size_t size);
 bool	pages_purge_lazy(void *addr, size_t size);
 bool	pages_purge_forced(void *addr, size_t size);
 bool	pages_huge(void *addr, size_t size);
 bool	pages_nohuge(void *addr, size_t size);
-void	pages_boot(void);
+bool	pages_boot(void);
 
 #endif /* JEMALLOC_INTERNAL_PAGES_EXTERNS_H */

include/jemalloc/internal/private_symbols.txt

@@ -360,7 +360,6 @@ pages_map
 pages_nohuge
 pages_purge_forced
 pages_purge_lazy
-pages_trim
 pages_unmap
 percpu_arena_choose
 percpu_arena_ind_limit

src/extent_mmap.c

@@ -6,66 +6,14 @@
 
 /******************************************************************************/
 
-static void *
-extent_alloc_mmap_slow(size_t size, size_t alignment, bool *zero,
-    bool *commit) {
-	void *ret;
-	size_t alloc_size;
-
-	alloc_size = size + alignment - PAGE;
-	/* Beware size_t wrap-around. */
-	if (alloc_size < size) {
-		return NULL;
-	}
-	do {
-		void *pages;
-		size_t leadsize;
-		pages = pages_map(NULL, alloc_size, commit);
-		if (pages == NULL) {
-			return NULL;
-		}
-		leadsize = ALIGNMENT_CEILING((uintptr_t)pages, alignment) -
-		    (uintptr_t)pages;
-		ret = pages_trim(pages, alloc_size, leadsize, size, commit);
-	} while (ret == NULL);
-
-	assert(ret != NULL);
-	*zero = true;
-	return ret;
-}
-
 void *
 extent_alloc_mmap(void *new_addr, size_t size, size_t alignment, bool *zero,
     bool *commit) {
-	void *ret;
-	size_t offset;
-
-	/*
-	 * Ideally, there would be a way to specify alignment to mmap() (like
-	 * NetBSD has), but in the absence of such a feature, we have to work
-	 * hard to efficiently create aligned mappings.  The reliable, but
-	 * slow method is to create a mapping that is over-sized, then trim the
-	 * excess.  However, that always results in one or two calls to
-	 * pages_unmap().
-	 *
-	 * Optimistically try mapping precisely the right amount before falling
-	 * back to the slow method, with the expectation that the optimistic
-	 * approach works most of the time.
-	 */
-
-	assert(alignment != 0);
-
-	ret = pages_map(new_addr, size, commit);
-	if (ret == NULL || ret == new_addr) {
-		return ret;
+	void *ret = pages_map(new_addr, size, ALIGNMENT_CEILING(alignment,
+	    PAGE), commit);
+	if (ret == NULL) {
+		return NULL;
 	}
-	assert(new_addr == NULL);
-	offset = ALIGNMENT_ADDR2OFFSET(ret, alignment);
-	if (offset != 0) {
-		pages_unmap(ret, size);
-		return extent_alloc_mmap_slow(size, alignment, zero, commit);
-	}
-
 	assert(ret != NULL);
 	*zero = true;
 	return ret;

src/jemalloc.c

@@ -1220,7 +1220,9 @@ malloc_init_hard_a0_locked() {
 			}
 		}
 	}
-	pages_boot();
+	if (pages_boot()) {
+		return true;
+	}
 	if (base_boot(TSDN_NULL)) {
 		return true;
 	}

src/pages.c

@@ -12,6 +12,9 @@
 /******************************************************************************/
 /* Data. */
 
+/* Actual operating system page size, detected during bootstrap, <= PAGE. */
+static size_t	os_page;
+
 #ifndef _WIN32
 #  define PAGES_PROT_COMMIT (PROT_READ | PROT_WRITE)
 #  define PAGES_PROT_DECOMMIT (PROT_NONE)
@@ -20,20 +23,26 @@ static int	mmap_flags;
 static bool	os_overcommits;
 
 /******************************************************************************/
+/*
+ * Function prototypes for static functions that are referenced prior to
+ * definition.
+ */
 
-void *
-pages_map(void *addr, size_t size, bool *commit) {
-	assert(PAGE_ADDR2BASE(addr) == addr);
-	assert(PAGE_CEILING(size) == size);
+static void os_pages_unmap(void *addr, size_t size);
 
-	void *ret;
+/******************************************************************************/
 
+static void *
+os_pages_map(void *addr, size_t size, size_t alignment, bool *commit) {
+	assert(ALIGNMENT_ADDR2BASE(addr, os_page) == addr);
+	assert(ALIGNMENT_CEILING(size, os_page) == size);
 	assert(size != 0);
 
 	if (os_overcommits) {
 		*commit = true;
 	}
 
+	void *ret;
 #ifdef _WIN32
 	/*
 	 * If VirtualAlloc can't allocate at the given address when one is
@@ -59,19 +68,48 @@ pages_map(void *addr, size_t size, bool *commit) {
 		/*
 		 * We succeeded in mapping memory, but not in the right place.
 		 */
-		pages_unmap(ret, size);
+		os_pages_unmap(ret, size);
 		ret = NULL;
 	}
 #endif
-	assert(ret == NULL || (addr == NULL && ret != addr)
-	    || (addr != NULL && ret == addr));
+	assert(ret == NULL || (addr == NULL && ret != addr) || (addr != NULL &&
+	    ret == addr));
 	return ret;
 }
 
-void
-pages_unmap(void *addr, size_t size) {
-	assert(PAGE_ADDR2BASE(addr) == addr);
-	assert(PAGE_CEILING(size) == size);
+static void *
+os_pages_trim(void *addr, size_t alloc_size, size_t leadsize, size_t size,
+    bool *commit) {
+	void *ret = (void *)((uintptr_t)addr + leadsize);
+
+	assert(alloc_size >= leadsize + size);
+#ifdef _WIN32
+	os_pages_unmap(addr, alloc_size);
+	void *new_addr = os_pages_map(ret, size, PAGE, commit);
+	if (new_addr == ret) {
+		return ret;
+	}
+	if (new_addr != NULL) {
+		os_pages_unmap(new_addr, size);
+	}
+	return NULL;
+#else
+	size_t trailsize = alloc_size - leadsize - size;
+
+	if (leadsize != 0) {
+		os_pages_unmap(addr, leadsize);
+	}
+	if (trailsize != 0) {
+		os_pages_unmap((void *)((uintptr_t)ret + size), trailsize);
+	}
+	return ret;
+#endif
+}
+
+static void
+os_pages_unmap(void *addr, size_t size) {
+	assert(ALIGNMENT_ADDR2BASE(addr, os_page) == addr);
+	assert(ALIGNMENT_CEILING(size, os_page) == size);
 
 #ifdef _WIN32
 	if (VirtualFree(addr, 0, MEM_RELEASE) == 0)
@@ -84,50 +122,80 @@ pages_unmap(void *addr, size_t size) {
 		buferror(get_errno(), buf, sizeof(buf));
 		malloc_printf("<jemalloc>: Error in "
 #ifdef _WIN32
-		              "VirtualFree"
+		    "VirtualFree"
 #else
-		              "munmap"
+		    "munmap"
 #endif
-		              "(): %s\n", buf);
+		    "(): %s\n", buf);
 		if (opt_abort) {
 			abort();
 		}
 	}
 }
 
-void *
-pages_trim(void *addr, size_t alloc_size, size_t leadsize, size_t size,
-    bool *commit) {
-	void *ret = (void *)((uintptr_t)addr + leadsize);
-
-	assert(alloc_size >= leadsize + size);
-#ifdef _WIN32
-	{
-		void *new_addr;
-
-		pages_unmap(addr, alloc_size);
-		new_addr = pages_map(ret, size, commit);
-		if (new_addr == ret) {
-			return ret;
-		}
-		if (new_addr) {
-			pages_unmap(new_addr, size);
-		}
+static void *
+pages_map_slow(size_t size, size_t alignment, bool *commit) {
+	size_t alloc_size = size + alignment - os_page;
+	/* Beware size_t wrap-around. */
+	if (alloc_size < size) {
 		return NULL;
 	}
-#else
-	{
-		size_t trailsize = alloc_size - leadsize - size;
 
-		if (leadsize != 0) {
-			pages_unmap(addr, leadsize);
-		}
-		if (trailsize != 0) {
-			pages_unmap((void *)((uintptr_t)ret + size), trailsize);
+	void *ret;
+	do {
+		void *pages = os_pages_map(NULL, alloc_size, alignment, commit);
+		if (pages == NULL) {
+			return NULL;
 		}
+		size_t leadsize = ALIGNMENT_CEILING((uintptr_t)pages, alignment)
+		    - (uintptr_t)pages;
+		ret = os_pages_trim(pages, alloc_size, leadsize, size, commit);
+	} while (ret == NULL);
+
+	assert(ret != NULL);
+	assert(PAGE_ADDR2BASE(ret) == ret);
+	return ret;
+}
+
+void *
+pages_map(void *addr, size_t size, size_t alignment, bool *commit) {
+	assert(alignment >= PAGE);
+	assert(ALIGNMENT_ADDR2BASE(addr, alignment) == addr);
+
+	/*
+	 * Ideally, there would be a way to specify alignment to mmap() (like
+	 * NetBSD has), but in the absence of such a feature, we have to work
+	 * hard to efficiently create aligned mappings.  The reliable, but
+	 * slow method is to create a mapping that is over-sized, then trim the
+	 * excess.  However, that always results in one or two calls to
+	 * os_pages_unmap(), and it can leave holes in the process's virtual
+	 * memory map if memory grows downward.
+	 *
+	 * Optimistically try mapping precisely the right amount before falling
+	 * back to the slow method, with the expectation that the optimistic
+	 * approach works most of the time.
+	 */
+
+	void *ret = os_pages_map(addr, size, os_page, commit);
+	if (ret == NULL || ret == addr) {
 		return ret;
 	}
-#endif
+	assert(addr == NULL);
+	if (ALIGNMENT_ADDR2OFFSET(ret, alignment) != 0) {
+		os_pages_unmap(ret, size);
+		return pages_map_slow(size, alignment, commit);
+	}
+
+	assert(PAGE_ADDR2BASE(ret) == ret);
+	return ret;
+}
+
+void
+pages_unmap(void *addr, size_t size) {
+	assert(PAGE_ADDR2BASE(addr) == addr);
+	assert(PAGE_CEILING(size) == size);
+
+	os_pages_unmap(addr, size);
 }
 
 static bool
@@ -155,7 +223,7 @@ pages_commit_impl(void *addr, size_t size, bool commit) {
 			 * We succeeded in mapping memory, but not in the right
 			 * place.
 			 */
-			pages_unmap(result, size);
+			os_pages_unmap(result, size);
 			return true;
 		}
 		return false;
@@ -239,6 +307,21 @@ pages_nohuge(void *addr, size_t size) {
 #endif
 }
 
+static size_t
+os_page_detect(void) {
+#ifdef _WIN32
+	SYSTEM_INFO si;
+	GetSystemInfo(&si);
+	return si.dwPageSize;
+#else
+	long result = sysconf(_SC_PAGESIZE);
+	if (result == -1) {
+		return LG_PAGE;
+	}
+	return (size_t)result;
+#endif
+}
+
 #ifdef JEMALLOC_SYSCTL_VM_OVERCOMMIT
 static bool
 os_overcommits_sysctl(void) {
@@ -300,8 +383,17 @@ os_overcommits_proc(void) {
 }
 #endif
 
-void
+bool
 pages_boot(void) {
+	os_page = os_page_detect();
+	if (os_page > PAGE) {
+		malloc_write("<jemalloc>: Unsupported system page size\n");
+		if (opt_abort) {
+			abort();
+		}
+		return true;
+	}
+
 #ifndef _WIN32
 	mmap_flags = MAP_PRIVATE | MAP_ANON;
 #endif
@@ -318,4 +410,6 @@ pages_boot(void) {
 #else
 	os_overcommits = false;
 #endif
+
+	return false;
 }

test/unit/pack.c

@@ -6,7 +6,7 @@
 #if LG_PAGE <= 14
 #define SZ	(ZU(1) << (LG_PAGE - 2))
 #else
-#define SZ	4096
+#define SZ	ZU(4096)
 #endif
 
 /*

test/unit/pages.c

@@ -7,7 +7,7 @@ TEST_BEGIN(test_pages_huge) {
 
 	alloc_size = HUGEPAGE * 2 - PAGE;
 	commit = true;
-	pages = pages_map(NULL, alloc_size, &commit);
+	pages = pages_map(NULL, alloc_size, PAGE, &commit);
 	assert_ptr_not_null(pages, "Unexpected pages_map() error");
 
 	hugepage = (void *)(ALIGNMENT_CEILING((uintptr_t)pages, HUGEPAGE));