linux-kernel - Re: Question on KASAN calltrace record in RT

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Date:   Tue, 13 Apr 2021 17:29:51 +0200
From:   Dmitry Vyukov <dvyukov@...gle.com>
To:     "Zhang, Qiang" <Qiang.Zhang@...driver.com>
Cc:     Andrew Halaney <ahalaney@...hat.com>,
        "andreyknvl@...il.com" <andreyknvl@...il.com>,
        "ryabinin.a.a@...il.com" <ryabinin.a.a@...il.com>,
        "akpm@...ux-foundation.org" <akpm@...ux-foundation.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "kasan-dev@...glegroups.com" <kasan-dev@...glegroups.com>
Subject: Re: Question on KASAN calltrace record in RT

On Tue, Apr 6, 2021 at 10:26 AM Zhang, Qiang <Qiang.Zhang@...driver.com> wrote:
>
> Hello everyone
>
> In RT system,   after  Andrew test,   found the following calltrace ,
> in KASAN, we record callstack through stack_depot_save(), in this function, may be call alloc_pages,  but in RT, the spin_lock replace with
> rt_mutex in alloc_pages(), if before call this function, the irq is disabled,
> will trigger following calltrace.
>
> maybe  add array[KASAN_STACK_DEPTH] in struct kasan_track to record callstack  in RT system.
>
> Is there a better solution ？

Hi Qiang,

Adding 2 full stacks per heap object can increase memory usage too much.
The stackdepot has a preallocation mechanism, I would start with
adding interrupts check here:
https://elixir.bootlin.com/linux/v5.12-rc7/source/lib/stackdepot.c#L294
and just not do preallocation in interrupt context. This will solve
the problem, right?


> Thanks
> Qiang
>
> BUG: sleeping function called from invalid context at kernel/locking/rtmutex.c:951
> [   14.522262] in_atomic(): 1, irqs_disabled(): 1, non_block: 0, pid: 640, name: mount
> [   14.522304] Call Trace:
> [   14.522306]  dump_stack+0x92/0xc1
> [   14.522313]  ___might_sleep.cold.99+0x1b0/0x1ef
> [   14.522319]  rt_spin_lock+0x3e/0xc0
> [   14.522329]  local_lock_acquire+0x52/0x3c0
> [   14.522332]  get_page_from_freelist+0x176c/0x3fd0
> [   14.522543]  __alloc_pages_nodemask+0x28f/0x7f0
> [   14.522559]  stack_depot_save+0x3a1/0x470
> [   14.522564]  kasan_save_stack+0x2f/0x40
> [   14.523575]  kasan_record_aux_stack+0xa3/0xb0
> [   14.523580]  insert_work+0x48/0x340
> [   14.523589]  __queue_work+0x430/0x1280
> [   14.523595]  mod_delayed_work_on+0x98/0xf0
> [   14.523607]  kblockd_mod_delayed_work_on+0x17/0x20
> [   14.523611]  blk_mq_run_hw_queue+0x151/0x2b0
> [   14.523620]  blk_mq_sched_insert_request+0x2ad/0x470
> [   14.523633]  blk_mq_submit_bio+0xd2a/0x2330
> [   14.523675]  submit_bio_noacct+0x8aa/0xfe0
> [   14.523693]  submit_bio+0xf0/0x550
> [   14.523714]  submit_bio_wait+0xfe/0x200
> [   14.523724]  xfs_rw_bdev+0x370/0x480 [xfs]
> [   14.523831]  xlog_do_io+0x155/0x320 [xfs]
> [   14.524032]  xlog_bread+0x23/0xb0 [xfs]
> [   14.524133]  xlog_find_head+0x131/0x8b0 [xfs]
> [   14.524375]  xlog_find_tail+0xc8/0x7b0 [xfs]
> [   14.524828]  xfs_log_mount+0x379/0x660 [xfs]
> [   14.524927]  xfs_mountfs+0xc93/0x1af0 [xfs]
> [   14.525424]  xfs_fs_fill_super+0x923/0x17f0 [xfs]
> [   14.525522]  get_tree_bdev+0x404/0x680
> [   14.525622]  vfs_get_tree+0x89/0x2d0
> [   14.525628]  path_mount+0xeb2/0x19d0
> [   14.525648]  do_mount+0xcb/0xf0
> [   14.525665]  __x64_sys_mount+0x162/0x1b0
> [   14.525670]  do_syscall_64+0x33/0x40
> [   14.525674]  entry_SYSCALL_64_after_hwframe+0x44/0xae
> [   14.525677] RIP: 0033:0x7fd6c15eaade