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Date: Mon, 16 Feb 2015 18:09:35 +0300
From: Andrey Ryabinin <a.ryabinin@samsung.com>
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To: Dmitry Vyukov <dvyukov@google.com>
Cc: Rusty Russell <rusty@rustcorp.com.au>, LKML <linux-kernel@vger.kernel.org>,
        Konstantin Serebryany <kcc@google.com>,
        Dmitry Chernenkov <dmitryc@google.com>,
        Andrey Konovalov <adech.fo@gmail.com>,
        Yuri Gribov <tetra2005@gmail.com>,
        Konstantin Khlebnikov <koct9i@gmail.com>,
        Sasha Levin <sasha.levin@oracle.com>, Christoph Lameter <cl@linux.com>,
        Joonsoo Kim <iamjoonsoo.kim@lge.com>,
        Andrew Morton <akpm@linux-foundation.org>,
        Dave Hansen <dave.hansen@intel.com>, Andi Kleen <andi@firstfloor.org>,
        "x86@kernel.org" <x86@kernel.org>,
        "linux-mm@kvack.org" <linux-mm@kvack.org>,
        Thomas Gleixner <tglx@linutronix.de>, Ingo Molnar <mingo@redhat.com>,
        "H. Peter Anvin" <hpa@zytor.com>, Michal Marek <mmarek@suse.cz>,
        "open list:KERNEL BUILD + fi..." <linux-kbuild@vger.kernel.org>
Subject: Re: [PATCH v11 19/19] kasan: enable instrumentation of global variables
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On 02/16/2015 05:47 PM, Dmitry Vyukov wrote:
> Can a module be freed in an interrupt?
> 
> 

Since commit: c749637909ee ("module: fix race in kallsyms resolution during module load success.")
module's init section always freed rcu callback (rcu callbacks executed from softirq)

Currently, with DEBUG_PAGEALLOC and KASAN module loading always causing kernel crash.
It's harder to trigger this without DEBUG_PAGEALLOC because of lazy tlb flushing in vmalloc.

BUG: unable to handle kernel paging request at fffffbfff4011000
IP: [<ffffffff811d8f7b>] __asan_load8+0x2b/0xa0
PGD 7ffa3063 PUD 7ffa2063 PMD 484ea067 PTE 0
Oops: 0000 [#1] SMP DEBUG_PAGEALLOC KASAN
Dumping ftrace buffer:
   (ftrace buffer empty)
Modules linked in: ipv6
CPU: 0 PID: 30 Comm: kworker/0:1 Tainted: G        W       3.19.0-rc7-next-20150209+ #209
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.7.5-0-ge51488c-20140602_164612-nilsson.home.kraxel.org 04/01/2014
Workqueue: events free_work
task: ffff88006c5a8870 ti: ffff88006c630000 task.ti: ffff88006c630000
RIP: 0010:[<ffffffff811d8f7b>]  [<ffffffff811d8f7b>] __asan_load8+0x2b/0xa0
RSP: 0018:ffff88006c637cd8  EFLAGS: 00010286
RAX: fffffbfff4011000 RBX: ffffffffa0088000 RCX: ffffed000da000a9
RDX: dffffc0000000000 RSI: 0000000000000001 RDI: ffffffffa0088000
RBP: ffff88006c637d08 R08: 0000000000000000 R09: ffff88006d007840
R10: ffff88006d000540 R11: ffffed000da000a9 R12: ffffffffa0088000
R13: ffff88006d61a5d8 R14: ffff88006d61a5d8 R15: ffff88006d61a5c0
FS:  0000000000000000(0000) GS:ffff88006d600000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 000000008005003b
CR2: fffffbfff4011000 CR3: 000000004d967000 CR4: 00000000000006b0
Stack:
 ffff88006c637ce8 fffffbfff4011000 ffffffffa0088000 ffff88006d61a5d8
 ffff88006d61a5d8 ffff88006d61a5c0 ffff88006c637d28 ffffffff811bb1b8
 ffff88006c5bc618 ffff88006d617b28 ffff88006c637db8 ffffffff8108e1b0
Call Trace:
 [<ffffffff811bb1b8>] free_work+0x38/0x60
 [<ffffffff8108e1b0>] process_one_work+0x2a0/0x7d0
 [<ffffffff8108f653>] worker_thread+0x93/0x840
 [<ffffffff8108f5c0>] ? init_pwq.part.11+0x10/0x10
 [<ffffffff81096f37>] kthread+0x177/0x1a0
 [<ffffffff81096dc0>] ? kthread_worker_fn+0x290/0x290
 [<ffffffff81096dc0>] ? kthread_worker_fn+0x290/0x290
 [<ffffffff8158cd7c>] ret_from_fork+0x7c/0xb0
 [<ffffffff81096dc0>] ? kthread_worker_fn+0x290/0x290
Code: 48 b8 ff ff ff ff ff 7f ff ff 55 48 89 e5 48 83 ec 30 48 39 c7 76 59 48 ba 00 00 00 00 00 fc ff df 48 89 f8 48 c1 e8 03 48 01 d0 <66> 83 38 00 75 07 c9 c3 0f 1f 44 00 00 48 8d 4f 07 48 89 ce 48
RIP  [<ffffffff811d8f7b>] __asan_load8+0x2b/0xa0
 RSP <ffff88006c637cd8>
CR2: fffffbfff4011000
---[ end trace b9411d841784b6cf ]---


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