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Subject: Re: [PATCH v11 1/4] kasan: support backing vmalloc space with real
 shadow memory
To:     Dmitry Vyukov <dvyukov@google.com>
Cc:     Daniel Axtens <dja@axtens.net>, Qian Cai <cai@lca.pw>,
        kasan-dev <kasan-dev@googlegroups.com>,
        Linux-MM <linux-mm@kvack.org>,
        the arch/x86 maintainers <x86@kernel.org>,
        Alexander Potapenko <glider@google.com>,
        Andy Lutomirski <luto@kernel.org>,
        LKML <linux-kernel@vger.kernel.org>,
        Mark Rutland <mark.rutland@arm.com>,
        Christophe Leroy <christophe.leroy@c-s.fr>,
        linuxppc-dev <linuxppc-dev@lists.ozlabs.org>,
        Vasily Gorbik <gor@linux.ibm.com>
References: <20191031093909.9228-1-dja@axtens.net>
 <20191031093909.9228-2-dja@axtens.net> <1573835765.5937.130.camel@lca.pw>
 <871ru5hnfh.fsf@dja-thinkpad.axtens.net>
 <952ec26a-9492-6f71-bab1-c1def887e528@virtuozzo.com>
 <CACT4Y+ZGO8b88fUyFe-WtV3Ubr11ChLY2mqk8YKWN9o0meNtXA@mail.gmail.com>
 <CACT4Y+Z+VhfVpkfg-WFq_kFMY=DE+9b_DCi-mCSPK-udaf_Arg@mail.gmail.com>
 <CACT4Y+Yog=PHF1SsLuoehr2rcbmfvLUW+dv7Vo+1RfdTOx7AUA@mail.gmail.com>
From:   Andrey Ryabinin <aryabinin@virtuozzo.com>
Message-ID: <2297c356-0863-69ce-85b6-8608081295ed@virtuozzo.com>
Date:   Fri, 29 Nov 2019 14:38:03 +0300
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On 11/29/19 2:02 PM, Dmitry Vyukov wrote:
> On Fri, Nov 29, 2019 at 11:58 AM Dmitry Vyukov <dvyukov@google.com> wrote:
>>
>> On Fri, Nov 29, 2019 at 11:43 AM Dmitry Vyukov <dvyukov@google.com> wrote:
>>>
>>> On Tue, Nov 19, 2019 at 10:54 AM Andrey Ryabinin
>>> <aryabinin@virtuozzo.com> wrote:
>>>> On 11/18/19 6:29 AM, Daniel Axtens wrote:
>>>>> Qian Cai <cai@lca.pw> writes:
>>>>>
>>>>>> On Thu, 2019-10-31 at 20:39 +1100, Daniel Axtens wrote:
>>>>>>>     /*
>>>>>>>      * In this function, newly allocated vm_struct has VM_UNINITIALIZED
>>>>>>>      * flag. It means that vm_struct is not fully initialized.
>>>>>>> @@ -3377,6 +3411,9 @@ struct vm_struct **pcpu_get_vm_areas(const unsigned long *offsets,
>>>>>>>
>>>>>>>             setup_vmalloc_vm_locked(vms[area], vas[area], VM_ALLOC,
>>>>>>>                              pcpu_get_vm_areas);
>>>>>>> +
>>>>>>> +           /* assume success here */
>>>>>>> +           kasan_populate_vmalloc(sizes[area], vms[area]);
>>>>>>>     }
>>>>>>>     spin_unlock(&vmap_area_lock);
>>>>>>
>>>>>> Here it is all wrong. GFP_KERNEL with in_atomic().
>>>>>
>>>>> I think this fix will work, I will do a v12 with it included.
>>>>
>>>> You can send just the fix. Andrew will fold it into the original patch before sending it to Linus.
>>>>
>>>>
>>>>
>>>>> diff --git a/mm/vmalloc.c b/mm/vmalloc.c
>>>>> index a4b950a02d0b..bf030516258c 100644
>>>>> --- a/mm/vmalloc.c
>>>>> +++ b/mm/vmalloc.c
>>>>> @@ -3417,11 +3417,14 @@ struct vm_struct **pcpu_get_vm_areas(const unsigned long *offsets,
>>>>>
>>>>>                 setup_vmalloc_vm_locked(vms[area], vas[area], VM_ALLOC,
>>>>>                                  pcpu_get_vm_areas);
>>>>> +       }
>>>>> +       spin_unlock(&vmap_area_lock);
>>>>>
>>>>> +       /* populate the shadow space outside of the lock */
>>>>> +       for (area = 0; area < nr_vms; area++) {
>>>>>                 /* assume success here */
>>>>>                 kasan_populate_vmalloc(sizes[area], vms[area]);
>>>>>         }
>>>>> -       spin_unlock(&vmap_area_lock);
>>>>>
>>>>>         kfree(vas);
>>>>>         return vms;
>>>
>>> Hi,
>>>
>>> I am testing this support on next-20191129 and seeing the following warnings:
>>>
>>> BUG: sleeping function called from invalid context at mm/page_alloc.c:4681
>>> in_atomic(): 1, irqs_disabled(): 0, non_block: 0, pid: 44, name: kworker/1:1
>>> 4 locks held by kworker/1:1/44:
>>>  #0: ffff888067c26d28 ((wq_completion)events){+.+.}, at:
>>> __write_once_size include/linux/compiler.h:247 [inline]
>>>  #0: ffff888067c26d28 ((wq_completion)events){+.+.}, at:
>>> arch_atomic64_set arch/x86/include/asm/atomic64_64.h:34 [inline]
>>>  #0: ffff888067c26d28 ((wq_completion)events){+.+.}, at: atomic64_set
>>> include/asm-generic/atomic-instrumented.h:868 [inline]
>>>  #0: ffff888067c26d28 ((wq_completion)events){+.+.}, at:
>>> atomic_long_set include/asm-generic/atomic-long.h:40 [inline]
>>>  #0: ffff888067c26d28 ((wq_completion)events){+.+.}, at: set_work_data
>>> kernel/workqueue.c:615 [inline]
>>>  #0: ffff888067c26d28 ((wq_completion)events){+.+.}, at:
>>> set_work_pool_and_clear_pending kernel/workqueue.c:642 [inline]
>>>  #0: ffff888067c26d28 ((wq_completion)events){+.+.}, at:
>>> process_one_work+0x88b/0x1750 kernel/workqueue.c:2235
>>>  #1: ffffc900002afdf0 (pcpu_balance_work){+.+.}, at:
>>> process_one_work+0x8c0/0x1750 kernel/workqueue.c:2239
>>>  #2: ffffffff8943f080 (pcpu_alloc_mutex){+.+.}, at:
>>> pcpu_balance_workfn+0xcc/0x13e0 mm/percpu.c:1845
>>>  #3: ffffffff89450c78 (vmap_area_lock){+.+.}, at: spin_lock
>>> include/linux/spinlock.h:338 [inline]
>>>  #3: ffffffff89450c78 (vmap_area_lock){+.+.}, at:
>>> pcpu_get_vm_areas+0x1449/0x3df0 mm/vmalloc.c:3431
>>> Preemption disabled at:
>>> [<ffffffff81a84199>] spin_lock include/linux/spinlock.h:338 [inline]
>>> [<ffffffff81a84199>] pcpu_get_vm_areas+0x1449/0x3df0 mm/vmalloc.c:3431
>>> CPU: 1 PID: 44 Comm: kworker/1:1 Not tainted 5.4.0-next-20191129+ #5
>>> Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.12.0-1 04/01/2014
>>> Workqueue: events pcpu_balance_workfn
>>> Call Trace:
>>>  __dump_stack lib/dump_stack.c:77 [inline]
>>>  dump_stack+0x199/0x216 lib/dump_stack.c:118
>>>  ___might_sleep.cold.97+0x1f5/0x238 kernel/sched/core.c:6800
>>>  __might_sleep+0x95/0x190 kernel/sched/core.c:6753
>>>  prepare_alloc_pages mm/page_alloc.c:4681 [inline]
>>>  __alloc_pages_nodemask+0x3cd/0x890 mm/page_alloc.c:4730
>>>  alloc_pages_current+0x10c/0x210 mm/mempolicy.c:2211
>>>  alloc_pages include/linux/gfp.h:532 [inline]
>>>  __get_free_pages+0xc/0x40 mm/page_alloc.c:4786
>>>  kasan_populate_vmalloc_pte mm/kasan/common.c:762 [inline]
>>>  kasan_populate_vmalloc_pte+0x2f/0x1b0 mm/kasan/common.c:753
>>>  apply_to_pte_range mm/memory.c:2041 [inline]
>>>  apply_to_pmd_range mm/memory.c:2068 [inline]
>>>  apply_to_pud_range mm/memory.c:2088 [inline]
>>>  apply_to_p4d_range mm/memory.c:2108 [inline]
>>>  apply_to_page_range+0x5ca/0xa00 mm/memory.c:2133
>>>  kasan_populate_vmalloc+0x69/0xa0 mm/kasan/common.c:791
>>>  pcpu_get_vm_areas+0x1596/0x3df0 mm/vmalloc.c:3439
>>>  pcpu_create_chunk+0x240/0x7f0 mm/percpu-vm.c:340
>>>  pcpu_balance_workfn+0x1033/0x13e0 mm/percpu.c:1934
>>>  process_one_work+0x9b5/0x1750 kernel/workqueue.c:2264
>>>  worker_thread+0x8b/0xd20 kernel/workqueue.c:2410
>>>  kthread+0x365/0x450 kernel/kthread.c:255
>>>  ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:352
>>>
>>>
>>> Not sure if it's the same or not. Is it addressed by something in flight?
>>>
>>> My config:
>>> https://gist.githubusercontent.com/dvyukov/36c7be311fdec9cd51c649f7c3cb2ddb/raw/39c6f864fdd0ffc53f0822b14c354a73c1695fa1/gistfile1.txt
>>
>>
>> I've tried this fix for pcpu_get_vm_areas:
>> https://groups.google.com/d/msg/kasan-dev/t_F2X1MWKwk/h152Z3q2AgAJ
>> and it helps. But this will break syzbot on linux-next soon.
> 
> 
> Can this be related as well?
> Crashes on accesses to shadow on the ion memory...

Nope, it's vm_map_ram() not being handled