alloc_tag: populate memory for module tags as needed

The memory reserved for module tags does not need to be backed by physical
pages until there are tags to store there.  Change the way we reserve this
memory to allocate only virtual area for the tags and populate it with
physical pages as needed when we load a module.

[surenb@google.com: avoid execmem_vmap() when !MMU]
  Link: https://lkml.kernel.org/r/20241031233611.3833002-1-surenb@google.com
Link: https://lkml.kernel.org/r/20241023170759.999909-5-surenb@google.com
Signed-off-by: Suren Baghdasaryan <surenb@google.com>
Reviewed-by: Pasha Tatashin <pasha.tatashin@soleen.com>
Cc: Ard Biesheuvel <ardb@kernel.org>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Borislav Petkov (AMD) <bp@alien8.de>
Cc: Christoph Hellwig <hch@infradead.org>
Cc: Daniel Gomez <da.gomez@samsung.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: Davidlohr Bueso <dave@stgolabs.net>
Cc: David Rientjes <rientjes@google.com>
Cc: Dennis Zhou <dennis@kernel.org>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: John Hubbard <jhubbard@nvidia.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Kalesh Singh <kaleshsingh@google.com>
Cc: Kees Cook <keescook@chromium.org>
Cc: Kent Overstreet <kent.overstreet@linux.dev>
Cc: Liam R. Howlett <Liam.Howlett@Oracle.com>
Cc: Luis Chamberlain <mcgrof@kernel.org>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Mike Rapoport (Microsoft) <rppt@kernel.org>
Cc: Minchan Kim <minchan@google.com>
Cc: Paul E. McKenney <paulmck@kernel.org>
Cc: Petr Pavlu <petr.pavlu@suse.com>
Cc: Roman Gushchin <roman.gushchin@linux.dev>
Cc: Sami Tolvanen <samitolvanen@google.com>
Cc: Sourav Panda <souravpanda@google.com>
Cc: Steven Rostedt (Google) <rostedt@goodmis.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Thomas Huth <thuth@redhat.com>
Cc: Uladzislau Rezki (Sony) <urezki@gmail.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Xiongwei Song <xiongwei.song@windriver.com>
Cc: Yu Zhao <yuzhao@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

1 files changed, 64 insertions, 9 deletions

diff --git a/lib/alloc_tag.c b/lib/alloc_tag.c
index 5f9cd1642d58..4a7fc081b789 100644
--- a/lib/alloc_tag.c
+++ b/lib/alloc_tag.c
@@ -8,14 +8,15 @@
 #include <linux/proc_fs.h>
 #include <linux/seq_buf.h>
 #include <linux/seq_file.h>
+#include <linux/vmalloc.h>
 
 #define ALLOCINFO_FILE_NAME		"allocinfo"
 #define MODULE_ALLOC_TAG_VMAP_SIZE	(100000UL * sizeof(struct alloc_tag))
 
 #ifdef CONFIG_MEM_ALLOC_PROFILING_ENABLED_BY_DEFAULT
-static bool mem_profiling_support __meminitdata = true;
+static bool mem_profiling_support = true;
 #else
-static bool mem_profiling_support __meminitdata;
+static bool mem_profiling_support;
 #endif
 
 static struct codetag_type *alloc_tag_cttype;
@@ -154,7 +155,7 @@ size_t alloc_tag_top_users(struct codetag_bytes *tags, size_t count, bool can_sl
 	return nr;
 }
 
-static void __init shutdown_mem_profiling(void)
+static void shutdown_mem_profiling(void)
 {
 	if (mem_alloc_profiling_enabled())
 		static_branch_disable(&mem_alloc_profiling_key);
@@ -179,6 +180,7 @@ static void __init procfs_init(void)
 #ifdef CONFIG_MODULES
 
 static struct maple_tree mod_area_mt = MTREE_INIT(mod_area_mt, MT_FLAGS_ALLOC_RANGE);
+static struct vm_struct *vm_module_tags;
 /* A dummy object used to indicate an unloaded module */
 static struct module unloaded_mod;
 /* A dummy object used to indicate a module prepended area */
@@ -252,6 +254,33 @@ repeat:
 	return false;
 }
 
+static int vm_module_tags_populate(void)
+{
+	unsigned long phys_size = vm_module_tags->nr_pages << PAGE_SHIFT;
+
+	if (phys_size < module_tags.size) {
+		struct page **next_page = vm_module_tags->pages + vm_module_tags->nr_pages;
+		unsigned long addr = module_tags.start_addr + phys_size;
+		unsigned long more_pages;
+		unsigned long nr;
+
+		more_pages = ALIGN(module_tags.size - phys_size, PAGE_SIZE) >> PAGE_SHIFT;
+		nr = alloc_pages_bulk_array_node(GFP_KERNEL | __GFP_NOWARN,
+						 NUMA_NO_NODE, more_pages, next_page);
+		if (nr < more_pages ||
+		    vmap_pages_range(addr, addr + (nr << PAGE_SHIFT), PAGE_KERNEL,
+				     next_page, PAGE_SHIFT) < 0) {
+			/* Clean up and error out */
+			for (int i = 0; i < nr; i++)
+				__free_page(next_page[i]);
+			return -ENOMEM;
+		}
+		vm_module_tags->nr_pages += nr;
+	}
+
+	return 0;
+}
+
 static void *reserve_module_tags(struct module *mod, unsigned long size,
 				 unsigned int prepend, unsigned long align)
 {
@@ -310,8 +339,18 @@ unlock:
 	if (IS_ERR(ret))
 		return ret;
 
-	if (module_tags.size < offset + size)
+	if (module_tags.size < offset + size) {
+		int grow_res;
+
 		module_tags.size = offset + size;
+		grow_res = vm_module_tags_populate();
+		if (grow_res) {
+			shutdown_mem_profiling();
+			pr_err("Failed to allocate memory for allocation tags in the module %s. Memory allocation profiling is disabled!\n",
+			       mod->name);
+			return ERR_PTR(grow_res);
+		}
+	}
 
 	return (struct alloc_tag *)(module_tags.start_addr + offset);
 }
@@ -372,12 +411,23 @@ static void replace_module(struct module *mod, struct module *new_mod)
 
 static int __init alloc_mod_tags_mem(void)
 {
-	/* Allocate space to copy allocation tags */
-	module_tags.start_addr = (unsigned long)execmem_alloc(EXECMEM_MODULE_DATA,
-							      MODULE_ALLOC_TAG_VMAP_SIZE);
-	if (!module_tags.start_addr)
+	/* Map space to copy allocation tags */
+	vm_module_tags = execmem_vmap(MODULE_ALLOC_TAG_VMAP_SIZE);
+	if (!vm_module_tags) {
+		pr_err("Failed to map %lu bytes for module allocation tags\n",
+			MODULE_ALLOC_TAG_VMAP_SIZE);
+		module_tags.start_addr = 0;
 		return -ENOMEM;
+	}
 
+	vm_module_tags->pages = kmalloc_array(get_vm_area_size(vm_module_tags) >> PAGE_SHIFT,
+					sizeof(struct page *), GFP_KERNEL | __GFP_ZERO);
+	if (!vm_module_tags->pages) {
+		free_vm_area(vm_module_tags);
+		return -ENOMEM;
+	}
+
+	module_tags.start_addr = (unsigned long)vm_module_tags->addr;
 	module_tags.end_addr = module_tags.start_addr + MODULE_ALLOC_TAG_VMAP_SIZE;
 
 	return 0;
@@ -385,8 +435,13 @@ static int __init alloc_mod_tags_mem(void)
 
 static void __init free_mod_tags_mem(void)
 {
-	execmem_free((void *)module_tags.start_addr);
+	int i;
+
 	module_tags.start_addr = 0;
+	for (i = 0; i < vm_module_tags->nr_pages; i++)
+		__free_page(vm_module_tags->pages[i]);
+	kfree(vm_module_tags->pages);
+	free_vm_area(vm_module_tags);
 }
 
 #else /* CONFIG_MODULES */