From: Hyeonggon Yoo <42.hyeyoo@gmail.com>
To: John Thomson <lists@johnthomson.fastmail.com.au>
Cc: Feng Tang <feng.tang@intel.com>, Vlastimil Babka <vbabka@suse.cz>,
Andrew Morton <akpm@linux-foundation.org>,
Christoph Lameter <cl@linux.com>,
Pekka Enberg <penberg@kernel.org>,
David Rientjes <rientjes@google.com>,
Joonsoo Kim <iamjoonsoo.kim@lge.com>,
Roman Gushchin <roman.gushchin@linux.dev>,
Dmitry Vyukov <dvyukov@google.com>,
Jonathan Corbet <corbet@lwn.net>,
Andrey Konovalov <andreyknvl@gmail.com>,
"Hansen, Dave" <dave.hansen@intel.com>,
"linux-mm@kvack.org" <linux-mm@kvack.org>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
"kasan-dev@googlegroups.com" <kasan-dev@googlegroups.com>,
Robin Murphy <robin.murphy@arm.com>,
John Garry <john.garry@huawei.com>,
Kefeng Wang <wangkefeng.wang@huawei.com>,
Thomas Bogendoerfer <tsbogend@alpha.franken.de>,
linux-mips@vger.kernel.org
Subject: Re: [PATCH v6 1/4] mm/slub: enable debugging memory wasting of kmalloc
Date: Tue, 1 Nov 2022 18:31:47 +0900 [thread overview]
Message-ID: <Y2DngwUc7cLB0dG7@hyeyoo> (raw)
In-Reply-To: <53b53476-bb1e-402e-9f65-fd7f0ecf94c2@app.fastmail.com>
On Tue, Nov 01, 2022 at 09:20:21AM +0000, John Thomson wrote:
> 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@app.fastmail.com/
>
> 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);
Great. Would you try calling dump_stack(); when we observed s == NULL?
That would give more information about who passed s == NULL to these
functions.
--
Thanks,
Hyeonggon
next prev parent reply other threads:[~2022-11-01 9:31 UTC|newest]
Thread overview: 48+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-09-13 6:54 [PATCH v6 0/4] mm/slub: some debug enhancements for kmalloc Feng Tang
2022-09-13 6:54 ` [PATCH v6 1/4] mm/slub: enable debugging memory wasting of kmalloc Feng Tang
2022-09-23 11:43 ` Vlastimil Babka
2022-09-24 7:08 ` Feng Tang
2022-10-30 19:23 ` John Thomson
2022-10-30 21:30 ` Vlastimil Babka
2022-10-31 2:36 ` Feng Tang
2022-10-31 10:05 ` John Thomson
2022-10-31 11:36 ` Hyeonggon Yoo
2022-10-31 11:42 ` Feng Tang
2022-11-01 0:18 ` John Thomson
2022-11-01 2:41 ` John Thomson
2022-11-01 7:57 ` Feng Tang
2022-11-01 9:20 ` John Thomson
2022-11-01 9:31 ` Hyeonggon Yoo [this message]
2022-11-01 10:33 ` John Thomson
2022-11-01 10:42 ` Hyeonggon Yoo
2022-11-01 13:55 ` Feng Tang
2022-11-01 19:39 ` John Thomson
2022-11-02 6:08 ` Feng Tang
2022-11-02 7:16 ` Hyeonggon Yoo
2022-11-03 7:18 ` Feng Tang
2022-11-03 7:45 ` John Thomson
2022-11-03 8:16 ` Feng Tang
2022-11-02 8:22 ` Vlastimil Babka
2022-11-03 5:54 ` Feng Tang
2022-11-03 8:33 ` Vlastimil Babka
2022-11-03 14:16 ` Feng Tang
2022-11-03 14:36 ` Hyeonggon Yoo
2022-11-03 16:57 ` Vlastimil Babka
2022-11-03 17:35 ` Vlastimil Babka
2022-11-04 3:52 ` Feng Tang
2022-09-13 6:54 ` [PATCH v6 2/4] mm/slub: only zero the requested size of buffer for kzalloc Feng Tang
2022-09-26 19:11 ` Andrey Konovalov
2022-09-26 20:15 ` Kees Cook
2022-09-27 1:22 ` Feng Tang
2022-09-27 2:42 ` Feng Tang
2022-10-13 14:00 ` Andrey Konovalov
2022-10-14 5:59 ` Feng Tang
2022-09-13 6:54 ` [PATCH v6 3/4] mm: kasan: Add free_meta size info in struct kasan_cache Feng Tang
2022-09-20 19:20 ` Andrey Konovalov
2022-09-21 12:02 ` Feng Tang
2022-09-24 18:05 ` Andrey Konovalov
2022-09-25 11:26 ` Feng Tang
2022-09-25 16:31 ` Andrey Konovalov
2022-09-27 3:03 ` Feng Tang
2022-09-13 6:54 ` [PATCH v6 4/4] mm/slub: extend redzone check to extra allocated kmalloc space than requested Feng Tang
2022-09-13 8:53 ` Hyeonggon Yoo
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