Re: [PATCH v11 1/4] kasan: support backing vmalloc space with real shadow memory

[Daniel Axtens <dja@axtens.net>]

Hi Dmitry,

>> 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?

It looks like this one is the same.

There is a patch to fix it:
https://lore.kernel.org/linux-mm/20191120052719.7201-1-dja@axtens.net/

Andrew said he had picked it up on the 22nd:
https://marc.info/?l=linux-mm-commits&m=157438241512561&w=2
It's landed in mmots but not mmotm, so hopefully that will happen and
then it will land in -next very soon!

I will look into your other bug report shortly.

Regards,
Daniel

>>
>> 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.