On Tue, 1 Nov 2022, at 07:57, Feng Tang wrote: > Hi Thomson, > > Thanks for testing! > > + mips maintainer and mail list. The original report is here > > https://lore.kernel.org/lkml/becf2ac3-2a90-4f3a-96d9-a70f67c66e4a@xxxxxxxxxxxxxxxx/ I am guessing my issue comes from __kmem_cache_alloc_lru accessing s->object_size when (kmem_cache) s is NULL? If that is the case, this change is not to blame, it only exposes the issue? I get the following dmesg (note very early NULL kmem_cache) with the below change atop v6.1-rc3: transfer started ......................................... transfer ok, time=2.02s setting up elf image... OK jumping to kernel code zimage at: 80B842A0 810B4EFC Uncompressing Linux at load address 80001000 Copy device tree to address 80B80EE0 Now, booting the kernel... [ 0.000000] Linux version 6.1.0-rc3+ (john@john) (mipsel-buildroot-linux-gnu-gcc.br_real (Buildroot 2021.11-4428-g6b6741b) 12.2.0, GNU ld (GNU Binutils) 2.39) #61 SMP Tue Nov 1 18:04:13 AEST 2022 [ 0.000000] slub: kmem_cache_alloc called with kmem_cache: 0x0 [ 0.000000] slub: __kmem_cache_alloc_lru called with kmem_cache: 0x0 [ 0.000000] SoC Type: MediaTek MT7621 ver:1 eco:3 [ 0.000000] printk: bootconsole [early0] enabled [ 0.000000] CPU0 revision is: 0001992f (MIPS 1004Kc) [ 0.000000] MIPS: machine is MikroTik RouterBOARD 760iGS normal boot diff --git a/mm/slub.c b/mm/slub.c index 157527d7101b..10fcdf2520d2 100644 --- a/mm/slub.c +++ b/mm/slub.c @@ -3410,7 +3410,13 @@ static __always_inline void *__kmem_cache_alloc_lru(struct kmem_cache *s, struct list_lru *lru, gfp_t gfpflags) { - void *ret = slab_alloc(s, lru, gfpflags, _RET_IP_, s->object_size); + void *ret; + if (IS_ERR_OR_NULL(s)) { + pr_warn("slub: __kmem_cache_alloc_lru called with kmem_cache: %pSR\n", s); + ret = slab_alloc(s, lru, gfpflags, _RET_IP_, 0); + } else { + ret = slab_alloc(s, lru, gfpflags, _RET_IP_, s->object_size); + } trace_kmem_cache_alloc(_RET_IP_, ret, s, gfpflags, NUMA_NO_NODE); @@ -3419,6 +3425,8 @@ void *__kmem_cache_alloc_lru(struct kmem_cache *s, struct list_lru *lru, void *kmem_cache_alloc(struct kmem_cache *s, gfp_t gfpflags) { + if (IS_ERR_OR_NULL(s)) + pr_warn("slub: kmem_cache_alloc called with kmem_cache: %pSR\n", s); return __kmem_cache_alloc_lru(s, NULL, gfpflags); } EXPORT_SYMBOL(kmem_cache_alloc); @@ -3426,6 +3434,8 @@ EXPORT_SYMBOL(kmem_cache_alloc); void *kmem_cache_alloc_lru(struct kmem_cache *s, struct list_lru *lru, gfp_t gfpflags) { + if (IS_ERR_OR_NULL(s)) + pr_warn("slub: __kmem_cache_alloc_lru called with kmem_cache: %pSR\n", s); return __kmem_cache_alloc_lru(s, lru, gfpflags); } EXPORT_SYMBOL(kmem_cache_alloc_lru); Any hints on where kmem_cache_alloc would be being called from this early? I will start looking from /init/main.c around pr_notice("%s", linux_banner); Thank you for your help. Let me know if you want me to stop replying to this mm/slub debug memory wasting email, and take this to a new email? Cheers, -- John Thomson
