From: Ran Xiaokai There is a boot failure when both CONFIG_DEBUG_KMEMLEAK and CONFIG_MEM_ALLOC_PROFILING are enabled. BUG: kernel NULL pointer dereference, address: 0000000000000000 RIP: 0010:__alloc_tagging_slab_alloc_hook+0x181/0x2f0 Call Trace: kmem_cache_alloc_noprof+0x1c8/0x5c0 __alloc_object+0x2f/0x290 __create_object+0x22/0x80 kmemleak_init+0x122/0x190 mm_core_init+0xb6/0x160 start_kernel+0x39f/0x920 x86_64_start_reservations+0x18/0x30 x86_64_start_kernel+0x104/0x120 common_startup_64+0x12c/0x138 In kmemleak, mem_pool_alloc() directly calls kmem_cache_alloc_noprof(), as a result, the alloc_tag structure associated with object_cache is not defined neither initialized. So current->alloc_tag is NULL, leading to a null pointer dereference. Move the checks for SLAB_NO_OBJ_EXT, SLAB_NOLEAKTRACE, and __GFP_NO_OBJ_EXT to the parent function __alloc_tagging_slab_alloc_hook() to fix this. Also this distinguishes the SLAB_NOLEAKTRACE case between the actual memory allocation failures case, make CODETAG_FLAG_INACCURATE more accurate. Fixes: b9e2f58ffb84 ("alloc_tag: mark inaccurate allocation counters in /proc/allocinfo output") Signed-off-by: Ran Xiaokai --- mm/slub.c | 18 +++++++++--------- 1 file changed, 9 insertions(+), 9 deletions(-) diff --git a/mm/slub.c b/mm/slub.c index 867a07260acf..09cbe580842c 100644 --- a/mm/slub.c +++ b/mm/slub.c @@ -2197,15 +2197,6 @@ prepare_slab_obj_exts_hook(struct kmem_cache *s, gfp_t flags, void *p) { struct slab *slab; - if (!p) - return NULL; - - if (s->flags & (SLAB_NO_OBJ_EXT | SLAB_NOLEAKTRACE)) - return NULL; - - if (flags & __GFP_NO_OBJ_EXT) - return NULL; - slab = virt_to_slab(p); if (!slab_obj_exts(slab) && alloc_slab_obj_exts(slab, s, flags, false)) { @@ -2223,6 +2214,15 @@ __alloc_tagging_slab_alloc_hook(struct kmem_cache *s, void *object, gfp_t flags) { struct slabobj_ext *obj_exts; + if (!object) + return; + + if (s->flags & (SLAB_NO_OBJ_EXT | SLAB_NOLEAKTRACE)) + return; + + if (flags & __GFP_NO_OBJ_EXT) + return; + obj_exts = prepare_slab_obj_exts_hook(s, flags, object); /* * Currently obj_exts is used only for allocation profiling. -- 2.25.1