From 3c7b4e6b8be4c16f1e6e5c558e33b7ff0db2dfaf Mon Sep 17 00:00:00 2001 From: Catalin Marinas Date: Thu, 11 Jun 2009 13:22:39 +0100 Subject: kmemleak: Add the base support This patch adds the base support for the kernel memory leak detector. It traces the memory allocation/freeing in a way similar to the Boehm's conservative garbage collector, the difference being that the unreferenced objects are not freed but only shown in /sys/kernel/debug/kmemleak. Enabling this feature introduces an overhead to memory allocations. Signed-off-by: Catalin Marinas Cc: Ingo Molnar Acked-by: Pekka Enberg Cc: Andrew Morton Reviewed-by: Paul E. McKenney --- include/linux/kmemleak.h | 96 ++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 96 insertions(+) create mode 100644 include/linux/kmemleak.h (limited to 'include') diff --git a/include/linux/kmemleak.h b/include/linux/kmemleak.h new file mode 100644 index 00000000000..7796aed6cdd --- /dev/null +++ b/include/linux/kmemleak.h @@ -0,0 +1,96 @@ +/* + * include/linux/kmemleak.h + * + * Copyright (C) 2008 ARM Limited + * Written by Catalin Marinas + * + * This program is free software; you can redistribute it and/or modify + * it under the terms of the GNU General Public License version 2 as + * published by the Free Software Foundation. + * + * This program is distributed in the hope that it will be useful, + * but WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the + * GNU General Public License for more details. + * + * You should have received a copy of the GNU General Public License + * along with this program; if not, write to the Free Software + * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA + */ + +#ifndef __KMEMLEAK_H +#define __KMEMLEAK_H + +#ifdef CONFIG_DEBUG_KMEMLEAK + +extern void kmemleak_init(void); +extern void kmemleak_alloc(const void *ptr, size_t size, int min_count, + gfp_t gfp); +extern void kmemleak_free(const void *ptr); +extern void kmemleak_padding(const void *ptr, unsigned long offset, + size_t size); +extern void kmemleak_not_leak(const void *ptr); +extern void kmemleak_ignore(const void *ptr); +extern void kmemleak_scan_area(const void *ptr, unsigned long offset, + size_t length, gfp_t gfp); +extern void kmemleak_no_scan(const void *ptr); + +static inline void kmemleak_alloc_recursive(const void *ptr, size_t size, + int min_count, unsigned long flags, + gfp_t gfp) +{ + if (!(flags & SLAB_NOLEAKTRACE)) + kmemleak_alloc(ptr, size, min_count, gfp); +} + +static inline void kmemleak_free_recursive(const void *ptr, unsigned long flags) +{ + if (!(flags & SLAB_NOLEAKTRACE)) + kmemleak_free(ptr); +} + +static inline void kmemleak_erase(void **ptr) +{ + *ptr = NULL; +} + +#else + +static inline void kmemleak_init(void) +{ +} +static inline void kmemleak_alloc(const void *ptr, size_t size, int min_count, + gfp_t gfp) +{ +} +static inline void kmemleak_alloc_recursive(const void *ptr, size_t size, + int min_count, unsigned long flags, + gfp_t gfp) +{ +} +static inline void kmemleak_free(const void *ptr) +{ +} +static inline void kmemleak_free_recursive(const void *ptr, unsigned long flags) +{ +} +static inline void kmemleak_not_leak(const void *ptr) +{ +} +static inline void kmemleak_ignore(const void *ptr) +{ +} +static inline void kmemleak_scan_area(const void *ptr, unsigned long offset, + size_t length, gfp_t gfp) +{ +} +static inline void kmemleak_erase(void **ptr) +{ +} +static inline void kmemleak_no_scan(const void *ptr) +{ +} + +#endif /* CONFIG_DEBUG_KMEMLEAK */ + +#endif /* __KMEMLEAK_H */ -- cgit v1.2.3-70-g09d2 From d5cff635290aec9ad7e6ee546aa4fae895361cbb Mon Sep 17 00:00:00 2001 From: Catalin Marinas Date: Thu, 11 Jun 2009 13:22:40 +0100 Subject: kmemleak: Add the slab memory allocation/freeing hooks This patch adds the callbacks to kmemleak_(alloc|free) functions from the slab allocator. The patch also adds the SLAB_NOLEAKTRACE flag to avoid recursive calls to kmemleak when it allocates its own data structures. Signed-off-by: Catalin Marinas Reviewed-by: Pekka Enberg --- include/linux/slab.h | 2 ++ mm/slab.c | 32 ++++++++++++++++++++++++++++++-- 2 files changed, 32 insertions(+), 2 deletions(-) (limited to 'include') diff --git a/include/linux/slab.h b/include/linux/slab.h index 24c5602bee9..48803064ced 100644 --- a/include/linux/slab.h +++ b/include/linux/slab.h @@ -62,6 +62,8 @@ # define SLAB_DEBUG_OBJECTS 0x00000000UL #endif +#define SLAB_NOLEAKTRACE 0x00800000UL /* Avoid kmemleak tracing */ + /* The following flags affect the page allocator grouping pages by mobility */ #define SLAB_RECLAIM_ACCOUNT 0x00020000UL /* Objects are reclaimable */ #define SLAB_TEMPORARY SLAB_RECLAIM_ACCOUNT /* Objects are short-lived */ diff --git a/mm/slab.c b/mm/slab.c index f85831da908..859067f8e4f 100644 --- a/mm/slab.c +++ b/mm/slab.c @@ -107,6 +107,7 @@ #include #include #include +#include #include #include #include @@ -178,13 +179,13 @@ SLAB_STORE_USER | \ SLAB_RECLAIM_ACCOUNT | SLAB_PANIC | \ SLAB_DESTROY_BY_RCU | SLAB_MEM_SPREAD | \ - SLAB_DEBUG_OBJECTS) + SLAB_DEBUG_OBJECTS | SLAB_NOLEAKTRACE) #else # define CREATE_MASK (SLAB_HWCACHE_ALIGN | \ SLAB_CACHE_DMA | \ SLAB_RECLAIM_ACCOUNT | SLAB_PANIC | \ SLAB_DESTROY_BY_RCU | SLAB_MEM_SPREAD | \ - SLAB_DEBUG_OBJECTS) + SLAB_DEBUG_OBJECTS | SLAB_NOLEAKTRACE) #endif /* @@ -964,6 +965,14 @@ static struct array_cache *alloc_arraycache(int node, int entries, struct array_cache *nc = NULL; nc = kmalloc_node(memsize, GFP_KERNEL, node); + /* + * The array_cache structures contain pointers to free object. + * However, when such objects are allocated or transfered to another + * cache the pointers are not cleared and they could be counted as + * valid references during a kmemleak scan. Therefore, kmemleak must + * not scan such objects. + */ + kmemleak_no_scan(nc); if (nc) { nc->avail = 0; nc->limit = entries; @@ -2621,6 +2630,14 @@ static struct slab *alloc_slabmgmt(struct kmem_cache *cachep, void *objp, /* Slab management obj is off-slab. */ slabp = kmem_cache_alloc_node(cachep->slabp_cache, local_flags, nodeid); + /* + * If the first object in the slab is leaked (it's allocated + * but no one has a reference to it), we want to make sure + * kmemleak does not treat the ->s_mem pointer as a reference + * to the object. Otherwise we will not report the leak. + */ + kmemleak_scan_area(slabp, offsetof(struct slab, list), + sizeof(struct list_head), local_flags); if (!slabp) return NULL; } else { @@ -3141,6 +3158,12 @@ static inline void *____cache_alloc(struct kmem_cache *cachep, gfp_t flags) STATS_INC_ALLOCMISS(cachep); objp = cache_alloc_refill(cachep, flags); } + /* + * To avoid a false negative, if an object that is in one of the + * per-CPU caches is leaked, we need to make sure kmemleak doesn't + * treat the array pointers as a reference to the object. + */ + kmemleak_erase(&ac->entry[ac->avail]); return objp; } @@ -3360,6 +3383,8 @@ __cache_alloc_node(struct kmem_cache *cachep, gfp_t flags, int nodeid, out: local_irq_restore(save_flags); ptr = cache_alloc_debugcheck_after(cachep, flags, ptr, caller); + kmemleak_alloc_recursive(ptr, obj_size(cachep), 1, cachep->flags, + flags); if (unlikely((flags & __GFP_ZERO) && ptr)) memset(ptr, 0, obj_size(cachep)); @@ -3415,6 +3440,8 @@ __cache_alloc(struct kmem_cache *cachep, gfp_t flags, void *caller) objp = __do_cache_alloc(cachep, flags); local_irq_restore(save_flags); objp = cache_alloc_debugcheck_after(cachep, flags, objp, caller); + kmemleak_alloc_recursive(objp, obj_size(cachep), 1, cachep->flags, + flags); prefetchw(objp); if (unlikely((flags & __GFP_ZERO) && objp)) @@ -3530,6 +3557,7 @@ static inline void __cache_free(struct kmem_cache *cachep, void *objp) struct array_cache *ac = cpu_cache_get(cachep); check_irq_off(); + kmemleak_free_recursive(objp, cachep->flags); objp = cache_free_debugcheck(cachep, objp, __builtin_return_address(0)); /* -- cgit v1.2.3-70-g09d2 From 2e1483c995bbd0fa6cbd055ad76088a520799ba4 Mon Sep 17 00:00:00 2001 From: Catalin Marinas Date: Thu, 11 Jun 2009 13:24:13 +0100 Subject: kmemleak: Remove some of the kmemleak false positives There are allocations for which the main pointer cannot be found but they are not memory leaks. This patch fixes some of them. For more information on false positives, see Documentation/kmemleak.txt. Signed-off-by: Catalin Marinas --- drivers/char/vt.c | 7 +++++++ fs/block_dev.c | 6 ++++++ include/linux/percpu.h | 5 +++++ 3 files changed, 18 insertions(+) (limited to 'include') diff --git a/drivers/char/vt.c b/drivers/char/vt.c index 08151d4de48..961c1a788c6 100644 --- a/drivers/char/vt.c +++ b/drivers/char/vt.c @@ -104,6 +104,7 @@ #include #include #include +#include #define MAX_NR_CON_DRIVER 16 @@ -2880,6 +2881,12 @@ static int __init con_init(void) */ for (currcons = 0; currcons < MIN_NR_CONSOLES; currcons++) { vc_cons[currcons].d = vc = alloc_bootmem(sizeof(struct vc_data)); + /* + * Kmemleak does not track the memory allocated via + * alloc_bootmem() but this block contains pointers to + * other blocks allocated via kmalloc. + */ + kmemleak_alloc(vc, sizeof(struct vc_data), 1, GFP_ATOMIC); INIT_WORK(&vc_cons[currcons].SAK_work, vc_SAK); visual_init(vc, currcons, 1); vc->vc_screenbuf = (unsigned short *)alloc_bootmem(vc->vc_screenbuf_size); diff --git a/fs/block_dev.c b/fs/block_dev.c index f45dbc18dd1..d250f807fd8 100644 --- a/fs/block_dev.c +++ b/fs/block_dev.c @@ -25,6 +25,7 @@ #include #include #include +#include #include #include "internal.h" @@ -492,6 +493,11 @@ void __init bdev_cache_init(void) bd_mnt = kern_mount(&bd_type); if (IS_ERR(bd_mnt)) panic("Cannot create bdev pseudo-fs"); + /* + * This vfsmount structure is only used to obtain the + * blockdev_superblock, so tell kmemleak not to report it. + */ + kmemleak_not_leak(bd_mnt); blockdev_superblock = bd_mnt->mnt_sb; /* For writeback */ } diff --git a/include/linux/percpu.h b/include/linux/percpu.h index 1581ff235c7..26fd9d12f05 100644 --- a/include/linux/percpu.h +++ b/include/linux/percpu.h @@ -86,7 +86,12 @@ struct percpu_data { void *ptrs[1]; }; +/* pointer disguising messes up the kmemleak objects tracking */ +#ifndef CONFIG_DEBUG_KMEMLEAK #define __percpu_disguise(pdata) (struct percpu_data *)~(unsigned long)(pdata) +#else +#define __percpu_disguise(pdata) (struct percpu_data *)(pdata) +#endif #define per_cpu_ptr(ptr, cpu) \ ({ \ -- cgit v1.2.3-70-g09d2