Introduce CONFIG_MEM_ALLOC_PROFILING which provides definitions to easily instrument memory allocators. It also registers an "alloc_tags" codetag type with "allocations" defbugfs interface to output allocation tag information. CONFIG_MEM_ALLOC_PROFILING_DEBUG is provided for debugging the memory allocation profiling instrumentation. Co-developed-by: Kent Overstreet <kent.overstreet@xxxxxxxxx> Signed-off-by: Kent Overstreet <kent.overstreet@xxxxxxxxx> Signed-off-by: Suren Baghdasaryan <surenb@xxxxxxxxxx> --- .../admin-guide/kernel-parameters.txt | 2 + include/asm-generic/codetag.lds.h | 14 ++ include/asm-generic/vmlinux.lds.h | 3 + include/linux/alloc_tag.h | 105 +++++++++++ include/linux/sched.h | 24 +++ lib/Kconfig.debug | 19 ++ lib/Makefile | 2 + lib/alloc_tag.c | 177 ++++++++++++++++++ scripts/module.lds.S | 7 + 9 files changed, 353 insertions(+) create mode 100644 include/asm-generic/codetag.lds.h create mode 100644 include/linux/alloc_tag.h create mode 100644 lib/alloc_tag.c diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt index 9e5bab29685f..2fd8e56b7af8 100644 --- a/Documentation/admin-guide/kernel-parameters.txt +++ b/Documentation/admin-guide/kernel-parameters.txt @@ -3770,6 +3770,8 @@ nomce [X86-32] Disable Machine Check Exception + nomem_profiling Disable memory allocation profiling. + nomfgpt [X86-32] Disable Multi-Function General Purpose Timer usage (for AMD Geode machines). diff --git a/include/asm-generic/codetag.lds.h b/include/asm-generic/codetag.lds.h new file mode 100644 index 000000000000..64f536b80380 --- /dev/null +++ b/include/asm-generic/codetag.lds.h @@ -0,0 +1,14 @@ +/* SPDX-License-Identifier: GPL-2.0-only */ +#ifndef __ASM_GENERIC_CODETAG_LDS_H +#define __ASM_GENERIC_CODETAG_LDS_H + +#define SECTION_WITH_BOUNDARIES(_name) \ + . = ALIGN(8); \ + __start_##_name = .; \ + KEEP(*(_name)) \ + __stop_##_name = .; + +#define CODETAG_SECTIONS() \ + SECTION_WITH_BOUNDARIES(alloc_tags) + +#endif /* __ASM_GENERIC_CODETAG_LDS_H */ diff --git a/include/asm-generic/vmlinux.lds.h b/include/asm-generic/vmlinux.lds.h index d1f57e4868ed..985ff045c2a2 100644 --- a/include/asm-generic/vmlinux.lds.h +++ b/include/asm-generic/vmlinux.lds.h @@ -50,6 +50,8 @@ * [__nosave_begin, __nosave_end] for the nosave data */ +#include <asm-generic/codetag.lds.h> + #ifndef LOAD_OFFSET #define LOAD_OFFSET 0 #endif @@ -374,6 +376,7 @@ . = ALIGN(8); \ BOUNDED_SECTION_BY(__dyndbg_classes, ___dyndbg_classes) \ BOUNDED_SECTION_BY(__dyndbg, ___dyndbg) \ + CODETAG_SECTIONS() \ LIKELY_PROFILE() \ BRANCH_PROFILE() \ TRACE_PRINTKS() \ diff --git a/include/linux/alloc_tag.h b/include/linux/alloc_tag.h new file mode 100644 index 000000000000..d913f8d9a7d8 --- /dev/null +++ b/include/linux/alloc_tag.h @@ -0,0 +1,105 @@ +/* SPDX-License-Identifier: GPL-2.0 */ +/* + * allocation tagging + */ +#ifndef _LINUX_ALLOC_TAG_H +#define _LINUX_ALLOC_TAG_H + +#include <linux/bug.h> +#include <linux/codetag.h> +#include <linux/container_of.h> +#include <linux/lazy-percpu-counter.h> +#include <linux/static_key.h> + +/* + * An instance of this structure is created in a special ELF section at every + * allocation callsite. At runtime, the special section is treated as + * an array of these. Embedded codetag utilizes codetag framework. + */ +struct alloc_tag { + struct codetag ct; + struct lazy_percpu_counter bytes_allocated; +} __aligned(8); + +#ifdef CONFIG_MEM_ALLOC_PROFILING + +static inline struct alloc_tag *ct_to_alloc_tag(struct codetag *ct) +{ + return container_of(ct, struct alloc_tag, ct); +} + +#define DEFINE_ALLOC_TAG(_alloc_tag, _old) \ + static struct alloc_tag _alloc_tag __used __aligned(8) \ + __section("alloc_tags") = { .ct = CODE_TAG_INIT }; \ + struct alloc_tag * __maybe_unused _old = alloc_tag_save(&_alloc_tag) + +extern struct static_key_true mem_alloc_profiling_key; + +static inline bool mem_alloc_profiling_enabled(void) +{ + return static_branch_likely(&mem_alloc_profiling_key); +} + +static inline void __alloc_tag_sub(union codetag_ref *ref, size_t bytes, + bool may_allocate) +{ + struct alloc_tag *tag; + +#ifdef CONFIG_MEM_ALLOC_PROFILING_DEBUG + /* The switch should be checked before this */ + BUG_ON(!mem_alloc_profiling_enabled()); + + WARN_ONCE(ref && !ref->ct, "alloc_tag was not set\n"); +#endif + if (!ref || !ref->ct) + return; + + tag = ct_to_alloc_tag(ref->ct); + + if (may_allocate) + lazy_percpu_counter_add(&tag->bytes_allocated, -bytes); + else + lazy_percpu_counter_add_noupgrade(&tag->bytes_allocated, -bytes); + ref->ct = NULL; +} + +static inline void alloc_tag_sub(union codetag_ref *ref, size_t bytes) +{ + __alloc_tag_sub(ref, bytes, true); +} + +static inline void alloc_tag_sub_noalloc(union codetag_ref *ref, size_t bytes) +{ + __alloc_tag_sub(ref, bytes, false); +} + +static inline void alloc_tag_add(union codetag_ref *ref, struct alloc_tag *tag, size_t bytes) +{ +#ifdef CONFIG_MEM_ALLOC_PROFILING_DEBUG + /* The switch should be checked before this */ + BUG_ON(!mem_alloc_profiling_enabled()); + + WARN_ONCE(ref && ref->ct, + "alloc_tag was not cleared (got tag for %s:%u)\n",\ + ref->ct->filename, ref->ct->lineno); + + WARN_ONCE(!tag, "current->alloc_tag not set"); +#endif + if (!ref || !tag) + return; + + ref->ct = &tag->ct; + lazy_percpu_counter_add(&tag->bytes_allocated, bytes); +} + +#else + +#define DEFINE_ALLOC_TAG(_alloc_tag, _old) +static inline void alloc_tag_sub(union codetag_ref *ref, size_t bytes) {} +static inline void alloc_tag_sub_noalloc(union codetag_ref *ref, size_t bytes) {} +static inline void alloc_tag_add(union codetag_ref *ref, struct alloc_tag *tag, + size_t bytes) {} + +#endif + +#endif /* _LINUX_ALLOC_TAG_H */ diff --git a/include/linux/sched.h b/include/linux/sched.h index 35e7efdea2d9..33708bf8f191 100644 --- a/include/linux/sched.h +++ b/include/linux/sched.h @@ -763,6 +763,10 @@ struct task_struct { unsigned int flags; unsigned int ptrace; +#ifdef CONFIG_MEM_ALLOC_PROFILING + struct alloc_tag *alloc_tag; +#endif + #ifdef CONFIG_SMP int on_cpu; struct __call_single_node wake_entry; @@ -802,6 +806,7 @@ struct task_struct { struct task_group *sched_task_group; #endif + #ifdef CONFIG_UCLAMP_TASK /* * Clamp values requested for a scheduling entity. @@ -2444,4 +2449,23 @@ static inline void sched_core_fork(struct task_struct *p) { } extern void sched_set_stop_task(int cpu, struct task_struct *stop); +#ifdef CONFIG_MEM_ALLOC_PROFILING +static inline struct alloc_tag *alloc_tag_save(struct alloc_tag *tag) +{ + swap(current->alloc_tag, tag); + return tag; +} + +static inline void alloc_tag_restore(struct alloc_tag *tag, struct alloc_tag *old) +{ +#ifdef CONFIG_MEM_ALLOC_PROFILING_DEBUG + WARN(current->alloc_tag != tag, "current->alloc_tag was changed:\n"); +#endif + current->alloc_tag = old; +} +#else +static inline struct alloc_tag *alloc_tag_save(struct alloc_tag *tag) { return NULL; } +#define alloc_tag_restore(_tag, _old) +#endif + #endif diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug index 5078da7d3ffb..da0a91ea6042 100644 --- a/lib/Kconfig.debug +++ b/lib/Kconfig.debug @@ -961,6 +961,25 @@ config CODE_TAGGING bool select KALLSYMS +config MEM_ALLOC_PROFILING + bool "Enable memory allocation profiling" + default n + depends on DEBUG_FS + select CODE_TAGGING + select LAZY_PERCPU_COUNTER + help + Track allocation source code and record total allocation size + initiated at that code location. The mechanism can be used to track + memory leaks with a low performance impact. + +config MEM_ALLOC_PROFILING_DEBUG + bool "Memory allocation profiler debugging" + default n + depends on MEM_ALLOC_PROFILING + help + Adds warnings with helpful error messages for memory allocation + profiling. + source "lib/Kconfig.kasan" source "lib/Kconfig.kfence" source "lib/Kconfig.kmsan" diff --git a/lib/Makefile b/lib/Makefile index 28d70ecf2976..8d09ccb4d30c 100644 --- a/lib/Makefile +++ b/lib/Makefile @@ -229,6 +229,8 @@ obj-$(CONFIG_OF_RECONFIG_NOTIFIER_ERROR_INJECT) += \ obj-$(CONFIG_FUNCTION_ERROR_INJECTION) += error-inject.o obj-$(CONFIG_CODE_TAGGING) += codetag.o +obj-$(CONFIG_MEM_ALLOC_PROFILING) += alloc_tag.o + lib-$(CONFIG_GENERIC_BUG) += bug.o obj-$(CONFIG_HAVE_ARCH_TRACEHOOK) += syscall.o diff --git a/lib/alloc_tag.c b/lib/alloc_tag.c new file mode 100644 index 000000000000..3c4cfeb79862 --- /dev/null +++ b/lib/alloc_tag.c @@ -0,0 +1,177 @@ +// SPDX-License-Identifier: GPL-2.0-only +#include <linux/alloc_tag.h> +#include <linux/debugfs.h> +#include <linux/fs.h> +#include <linux/gfp.h> +#include <linux/module.h> +#include <linux/seq_buf.h> +#include <linux/uaccess.h> + +DEFINE_STATIC_KEY_TRUE(mem_alloc_profiling_key); + +/* + * Won't need to be exported once page allocation accounting is moved to the + * correct place: + */ +EXPORT_SYMBOL(mem_alloc_profiling_key); + +static int __init mem_alloc_profiling_disable(char *s) +{ + static_branch_disable(&mem_alloc_profiling_key); + return 1; +} +__setup("nomem_profiling", mem_alloc_profiling_disable); + +struct alloc_tag_file_iterator { + struct codetag_iterator ct_iter; + struct seq_buf buf; + char rawbuf[4096]; +}; + +struct user_buf { + char __user *buf; /* destination user buffer */ + size_t size; /* size of requested read */ + ssize_t ret; /* bytes read so far */ +}; + +static int flush_ubuf(struct user_buf *dst, struct seq_buf *src) +{ + if (src->len) { + size_t bytes = min_t(size_t, src->len, dst->size); + int err = copy_to_user(dst->buf, src->buffer, bytes); + + if (err) + return err; + + dst->ret += bytes; + dst->buf += bytes; + dst->size -= bytes; + src->len -= bytes; + memmove(src->buffer, src->buffer + bytes, src->len); + } + + return 0; +} + +static int allocations_file_open(struct inode *inode, struct file *file) +{ + struct codetag_type *cttype = inode->i_private; + struct alloc_tag_file_iterator *iter; + + iter = kzalloc(sizeof(*iter), GFP_KERNEL); + if (!iter) + return -ENOMEM; + + codetag_lock_module_list(cttype, true); + iter->ct_iter = codetag_get_ct_iter(cttype); + codetag_lock_module_list(cttype, false); + seq_buf_init(&iter->buf, iter->rawbuf, sizeof(iter->rawbuf)); + file->private_data = iter; + + return 0; +} + +static int allocations_file_release(struct inode *inode, struct file *file) +{ + struct alloc_tag_file_iterator *iter = file->private_data; + + kfree(iter); + return 0; +} + +static void alloc_tag_to_text(struct seq_buf *out, struct codetag *ct) +{ + struct alloc_tag *tag = ct_to_alloc_tag(ct); + char buf[10]; + + string_get_size(lazy_percpu_counter_read(&tag->bytes_allocated), 1, + STRING_UNITS_2, buf, sizeof(buf)); + + seq_buf_printf(out, "%8s ", buf); + codetag_to_text(out, ct); + seq_buf_putc(out, '\n'); +} + +static ssize_t allocations_file_read(struct file *file, char __user *ubuf, + size_t size, loff_t *ppos) +{ + struct alloc_tag_file_iterator *iter = file->private_data; + struct user_buf buf = { .buf = ubuf, .size = size }; + struct codetag *ct; + int err = 0; + + codetag_lock_module_list(iter->ct_iter.cttype, true); + while (1) { + err = flush_ubuf(&buf, &iter->buf); + if (err || !buf.size) + break; + + ct = codetag_next_ct(&iter->ct_iter); + if (!ct) + break; + + alloc_tag_to_text(&iter->buf, ct); + } + codetag_lock_module_list(iter->ct_iter.cttype, false); + + return err ? : buf.ret; +} + +static const struct file_operations allocations_file_ops = { + .owner = THIS_MODULE, + .open = allocations_file_open, + .release = allocations_file_release, + .read = allocations_file_read, +}; + +static int __init dbgfs_init(struct codetag_type *cttype) +{ + struct dentry *file; + + file = debugfs_create_file("allocations", 0444, NULL, cttype, + &allocations_file_ops); + + return IS_ERR(file) ? PTR_ERR(file) : 0; +} + +static bool alloc_tag_module_unload(struct codetag_type *cttype, struct codetag_module *cmod) +{ + struct codetag_iterator iter = codetag_get_ct_iter(cttype); + bool module_unused = true; + struct alloc_tag *tag; + struct codetag *ct; + size_t bytes; + + for (ct = codetag_next_ct(&iter); ct; ct = codetag_next_ct(&iter)) { + if (iter.cmod != cmod) + continue; + + tag = ct_to_alloc_tag(ct); + bytes = lazy_percpu_counter_read(&tag->bytes_allocated); + + if (!WARN(bytes, "%s:%u module %s func:%s has %zu allocated at module unload", + ct->filename, ct->lineno, ct->modname, ct->function, bytes)) + lazy_percpu_counter_exit(&tag->bytes_allocated); + else + module_unused = false; + } + + return module_unused; +} + +static int __init alloc_tag_init(void) +{ + struct codetag_type *cttype; + const struct codetag_type_desc desc = { + .section = "alloc_tags", + .tag_size = sizeof(struct alloc_tag), + .module_unload = alloc_tag_module_unload, + }; + + cttype = codetag_register_type(&desc); + if (IS_ERR_OR_NULL(cttype)) + return PTR_ERR(cttype); + + return dbgfs_init(cttype); +} +module_init(alloc_tag_init); diff --git a/scripts/module.lds.S b/scripts/module.lds.S index bf5bcf2836d8..45c67a0994f3 100644 --- a/scripts/module.lds.S +++ b/scripts/module.lds.S @@ -9,6 +9,8 @@ #define DISCARD_EH_FRAME *(.eh_frame) #endif +#include <asm-generic/codetag.lds.h> + SECTIONS { /DISCARD/ : { *(.discard) @@ -47,12 +49,17 @@ SECTIONS { .data : { *(.data .data.[0-9a-zA-Z_]*) *(.data..L*) + CODETAG_SECTIONS() } .rodata : { *(.rodata .rodata.[0-9a-zA-Z_]*) *(.rodata..L*) } +#else + .data : { + CODETAG_SECTIONS() + } #endif } -- 2.40.1.495.gc816e09b53d-goog