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Date: Mon, 28 Mar 2016 13:46:08 -0700 (PDT)
From: Hugh Dickins <hughd@google.com>
X-X-Sender: hugh@eggly.anvils
To: Dave Jones <davej@codemonkey.org.uk>,
        Linux Kernel <linux-kernel@vger.kernel.org>, linux-mm@kvack.org
Subject: Re: 4.5 shmem lockdep/out-of-bound/list corruption disaster
In-Reply-To: <20160328171757.GA21665@codemonkey.org.uk>
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On Mon, 28 Mar 2016, Dave Jones wrote:

> I hit this a few days ago.  I'm not 100% what kernel it was running,
> but I'm pretty sure it was a post 4.5 kernel from this merge window.

Thanks for the report.  All consistent with shmem_fallocate() somehow
getting through its wake_up_all() without removing shmem_fault_wait
from the shmem_falloc_waitq: things get interesting once finish_wait()
thinks it's still on the queue, but the spinlock is now on stale stack.

(And if you think that code is strange, yes, and it's really only
there for trinity itself, while minimizing the cost to other users.)

I don't see that anything relevant has changed here recently (neither
at the shmem.c end nor at the wait.c end), and I don't see how it would
come about.  Sorry, I can't suggest better than waiting to see if it
happens again.

Hugh

> 
> WARNING: CPU: 2 PID: 28919 at kernel/locking/lockdep.c:3198 __lock_acquire+0x74d/0x1c60
> DEBUG_LOCKS_WARN_ON(class_idx > MAX_LOCKDEP_KEYS)
> CPU: 2 PID: 28919 Comm: trinity-c30 Not tainted 4.5.0-think+ #6 
>  ffffffffba141ccd 000000001ded0b05 ffff8803e4b67480 ffffffffba575c0b
>  ffff8803e4b674f8 0000000000000000 ffff8803e4b674c8 ffffffffba0b3eb1
>  ffff88045fbe37c0 00000c7ee4b674e0 ffffed007c96ce9b 0000000000000000
> Call Trace:
>  [<ffffffffba141ccd>] ? __lock_acquire+0x74d/0x1c60
>  [<ffffffffba575c0b>] dump_stack+0x68/0x9d
>  [<ffffffffba0b3eb1>] __warn+0x111/0x130
>  [<ffffffffba0b3f84>] warn_slowpath_fmt+0xb4/0xf0
>  [<ffffffffba0b3ed0>] ? __warn+0x130/0x130
>  [<ffffffffba1409cb>] ? mark_lock+0x45b/0x800
>  [<ffffffffba141ccd>] __lock_acquire+0x74d/0x1c60
>  [<ffffffffba1611aa>] ? debug_lockdep_rcu_enabled.part.18+0x1a/0x30
>  [<ffffffffba1611f5>] ? debug_lockdep_rcu_enabled+0x35/0x40
>  [<ffffffffba141580>] ? debug_check_no_locks_freed+0x1b0/0x1b0
>  [<ffffffffba141580>] ? debug_check_no_locks_freed+0x1b0/0x1b0
>  [<ffffffffbad456b2>] ? _raw_spin_unlock_irq+0x32/0x50
>  [<ffffffffba0f77aa>] ? preempt_count_sub+0x1a/0x130
>  [<ffffffffba143dcf>] lock_acquire+0xcf/0x2a0
>  [<ffffffffba12eba8>] ? finish_wait+0x68/0xc0
>  [<ffffffffbad4541c>] _raw_spin_lock_irqsave+0x4c/0x90
>  [<ffffffffba12eba8>] ? finish_wait+0x68/0xc0
>  [<ffffffffba12eba8>] finish_wait+0x68/0xc0
>  [<ffffffffba2a6453>] shmem_fault+0x323/0x390
>  [<ffffffffba2a6130>] ? shmem_file_splice_read+0x720/0x720
>  [<ffffffffba12f180>] ? prepare_to_wait_event+0x200/0x200
>  [<ffffffffba1611f5>] ? debug_lockdep_rcu_enabled+0x35/0x40
>  [<ffffffffba14063f>] ? mark_lock+0xcf/0x800
>  [<ffffffffba2c3eb8>] __do_fault+0x138/0x2e0
>  [<ffffffffba2c3d80>] ? wp_page_copy.isra.79+0x850/0x850
>  [<ffffffffba2c9a5b>] handle_mm_fault+0x42b/0x2400
>  [<ffffffffba141e38>] ? __lock_acquire+0x8b8/0x1c60
>  [<ffffffffba14063f>] ? mark_lock+0xcf/0x800
>  [<ffffffffba1611aa>] ? debug_lockdep_rcu_enabled.part.18+0x1a/0x30
>  [<ffffffffba035e36>] ? native_sched_clock+0x66/0x160
>  [<ffffffffba2c9630>] ? copy_page_range+0xec0/0xec0
>  [<ffffffffba0f7a9e>] ? ___might_sleep.part.86+0x1de/0x2c0
>  [<ffffffffba2bd8ad>] ? vmacache_find+0xed/0x140
>  [<ffffffffba0722d2>] __do_page_fault+0x1d2/0x5a0
>  [<ffffffffba4dd0d0>] ? SyS_shmget+0x100/0x100
>  [<ffffffffba0726c0>] do_page_fault+0x20/0x70
>  [<ffffffffbad469d7>] ? native_iret+0x7/0x7
>  [<ffffffffbad47cdf>] page_fault+0x1f/0x30
>  [<ffffffffba4dd0d0>] ? SyS_shmget+0x100/0x100
>  [<ffffffffba58c112>] ? copy_user_enhanced_fast_string+0x2/0x10
>  [<ffffffffba4dcb7f>] ? shmctl_nolock.constprop.24+0x5ff/0x690
>  [<ffffffffba4dc847>] ? shmctl_nolock.constprop.24+0x2c7/0x690
>  [<ffffffffba141580>] ? debug_check_no_locks_freed+0x1b0/0x1b0
>  [<ffffffffba4dc580>] ? newseg+0x5e0/0x5e0
>  [<ffffffffba5a7247>] ? debug_smp_processor_id+0x17/0x20
>  [<ffffffffba0f7849>] ? preempt_count_sub+0xb9/0x130
>  [<ffffffffba4dd0d0>] ? SyS_shmget+0x100/0x100
>  [<ffffffffba4dd412>] SyS_shmctl+0x342/0x490
>  [<ffffffffba003aa4>] do_syscall_64+0xf4/0x240
>  [<ffffffffbad4605a>] entry_SYSCALL64_slow_path+0x25/0x25
> ---[ end trace 638c142c3cb9ddb1 ]---
> ==================================================================
> BUG: KASAN: stack-out-of-bounds in do_raw_spin_trylock+0x14/0x70 at addr ffff8803ee067ba0
> Read of size 4 by task trinity-c30/28919
> page:ffffea000fb819c0 count:0 mapcount:0 mapping:          (null) index:0x0
> flags: 0x8000000000000000()
> page dumped because: kasan: bad access detected
> CPU: 2 PID: 28919 Comm: trinity-c30 Tainted: G        W       4.5.0-think+ #6
>  ffff8803e4b678b0 000000001ded0b05 ffff8803e4b676a0 ffffffffba575c0b
>  ffff8803e4b67738 ffff8803ee067ba0 ffff8803e4b67728 ffffffffba308cb3
>  0000000000000003 dffffc0000000000 0000000000000082 0000000000000001
> Call Trace:
>  [<ffffffffba575c0b>] dump_stack+0x68/0x9d
>  [<ffffffffba308cb3>] kasan_report_error+0x503/0x530
>  [<ffffffffbad456b2>] ? _raw_spin_unlock_irq+0x32/0x50
>  [<ffffffffba0f77aa>] ? preempt_count_sub+0x1a/0x130
>  [<ffffffffba309278>] kasan_report+0x58/0x60
>  [<ffffffffba149ca4>] ? do_raw_spin_trylock+0x14/0x70
>  [<ffffffffba307a8a>] __asan_load4+0x6a/0x70
>  [<ffffffffba149ca4>] do_raw_spin_trylock+0x14/0x70
>  [<ffffffffbad45424>] _raw_spin_lock_irqsave+0x54/0x90
>  [<ffffffffba12eba8>] ? finish_wait+0x68/0xc0
>  [<ffffffffba12eba8>] finish_wait+0x68/0xc0
>  [<ffffffffba2a6453>] shmem_fault+0x323/0x390
>  [<ffffffffba2a6130>] ? shmem_file_splice_read+0x720/0x720
>  [<ffffffffba12f180>] ? prepare_to_wait_event+0x200/0x200
>  [<ffffffffba1611f5>] ? debug_lockdep_rcu_enabled+0x35/0x40
>  [<ffffffffba14063f>] ? mark_lock+0xcf/0x800
>  [<ffffffffba2c3eb8>] __do_fault+0x138/0x2e0
>  [<ffffffffba2c3d80>] ? wp_page_copy.isra.79+0x850/0x850
>  [<ffffffffba2c9a5b>] handle_mm_fault+0x42b/0x2400
>  [<ffffffffba141e38>] ? __lock_acquire+0x8b8/0x1c60
>  [<ffffffffba14063f>] ? mark_lock+0xcf/0x800
>  [<ffffffffba1611aa>] ? debug_lockdep_rcu_enabled.part.18+0x1a/0x30
>  [<ffffffffba035e36>] ? native_sched_clock+0x66/0x160
>  [<ffffffffba2c9630>] ? copy_page_range+0xec0/0xec0
>  [<ffffffffba0f7a9e>] ? ___might_sleep.part.86+0x1de/0x2c0
>  [<ffffffffba2bd8ad>] ? vmacache_find+0xed/0x140
>  [<ffffffffba0722d2>] __do_page_fault+0x1d2/0x5a0
>  [<ffffffffba4dd0d0>] ? SyS_shmget+0x100/0x100
>  [<ffffffffba0726c0>] do_page_fault+0x20/0x70
>  [<ffffffffbad469d7>] ? native_iret+0x7/0x7
>  [<ffffffffbad47cdf>] page_fault+0x1f/0x30
>  [<ffffffffba4dd0d0>] ? SyS_shmget+0x100/0x100
>  [<ffffffffba58c112>] ? copy_user_enhanced_fast_string+0x2/0x10
>  [<ffffffffba4dcb7f>] ? shmctl_nolock.constprop.24+0x5ff/0x690
>  [<ffffffffba4dc847>] ? shmctl_nolock.constprop.24+0x2c7/0x690
>  [<ffffffffba141580>] ? debug_check_no_locks_freed+0x1b0/0x1b0
>  [<ffffffffba4dc580>] ? newseg+0x5e0/0x5e0
>  [<ffffffffba5a7247>] ? debug_smp_processor_id+0x17/0x20
>  [<ffffffffba0f7849>] ? preempt_count_sub+0xb9/0x130
>  [<ffffffffba4dd0d0>] ? SyS_shmget+0x100/0x100
>  [<ffffffffba4dd412>] SyS_shmctl+0x342/0x490
>  [<ffffffffba003aa4>] do_syscall_64+0xf4/0x240
>  [<ffffffffbad4605a>] entry_SYSCALL64_slow_path+0x25/0x25
> Memory state around the buggy address:
>  ffff8803ee067a80: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
>  ffff8803ee067b00: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
> >ffff8803ee067b80: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
>                                ^
>  ffff8803ee067c00: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
>  ffff8803ee067c80: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
> ==================================================================
> ------------[ cut here ]------------
> WARNING: CPU: 2 PID: 28919 at lib/list_debug.c:59 __list_del_entry+0xdc/0x100
> list_del corruption. prev->next should be ffff8803e4b678a8, but was 0000000041b58ab3
> CPU: 2 PID: 28919 Comm: trinity-c30 Tainted: G    B   W       4.5.0-think+ #6
>  ffffffffba5a743c 000000001ded0b05 ffff8803e4b67690 ffffffffba575c0b
>  ffff8803e4b67708 0000000000000000 ffff8803e4b676d8 ffffffffba0b3eb1
>  ffff88045fbe37c0 0000003bba308c0c ffffed007c96cedd ffff8803ee067be8
> Call Trace:
>  [<ffffffffba5a743c>] ? __list_del_entry+0xdc/0x100
>  [<ffffffffba575c0b>] dump_stack+0x68/0x9d
>  [<ffffffffba0b3eb1>] __warn+0x111/0x130
>  [<ffffffffba0b3f84>] warn_slowpath_fmt+0xb4/0xf0
>  [<ffffffffba0b3ed0>] ? __warn+0x130/0x130
>  [<ffffffffba58c6a4>] ? delay_tsc+0x94/0xc0
>  [<ffffffffba12eba8>] ? finish_wait+0x68/0xc0
>  [<ffffffffba5a743c>] __list_del_entry+0xdc/0x100
>  [<ffffffffba12ebb3>] finish_wait+0x73/0xc0
>  [<ffffffffba2a6453>] shmem_fault+0x323/0x390
>  [<ffffffffba2a6130>] ? shmem_file_splice_read+0x720/0x720
>  [<ffffffffba12f180>] ? prepare_to_wait_event+0x200/0x200
>  [<ffffffffba1611f5>] ? debug_lockdep_rcu_enabled+0x35/0x40
>  [<ffffffffba14063f>] ? mark_lock+0xcf/0x800
>  [<ffffffffba2c3eb8>] __do_fault+0x138/0x2e0
>  [<ffffffffba2c3d80>] ? wp_page_copy.isra.79+0x850/0x850
>  [<ffffffffba2c9a5b>] handle_mm_fault+0x42b/0x2400
>  [<ffffffffba141e38>] ? __lock_acquire+0x8b8/0x1c60
>  [<ffffffffba14063f>] ? mark_lock+0xcf/0x800
>  [<ffffffffba1611aa>] ? debug_lockdep_rcu_enabled.part.18+0x1a/0x30
>  [<ffffffffba035e36>] ? native_sched_clock+0x66/0x160
>  [<ffffffffba2c9630>] ? copy_page_range+0xec0/0xec0
>  [<ffffffffba0f7a9e>] ? ___might_sleep.part.86+0x1de/0x2c0
>  [<ffffffffba2bd8ad>] ? vmacache_find+0xed/0x140
>  [<ffffffffba0722d2>] __do_page_fault+0x1d2/0x5a0
>  [<ffffffffba4dd0d0>] ? SyS_shmget+0x100/0x100
>  [<ffffffffba0726c0>] do_page_fault+0x20/0x70
>  [<ffffffffbad469d7>] ? native_iret+0x7/0x7
>  [<ffffffffbad47cdf>] page_fault+0x1f/0x30
>  [<ffffffffba4dd0d0>] ? SyS_shmget+0x100/0x100
>  [<ffffffffba58c112>] ? copy_user_enhanced_fast_string+0x2/0x10
>  [<ffffffffba4dcb7f>] ? shmctl_nolock.constprop.24+0x5ff/0x690
>  [<ffffffffba4dc847>] ? shmctl_nolock.constprop.24+0x2c7/0x690
>  [<ffffffffba141580>] ? debug_check_no_locks_freed+0x1b0/0x1b0
>  [<ffffffffba4dc580>] ? newseg+0x5e0/0x5e0
>  [<ffffffffba5a7247>] ? debug_smp_processor_id+0x17/0x20
>  [<ffffffffba0f7849>] ? preempt_count_sub+0xb9/0x130
>  [<ffffffffba4dd0d0>] ? SyS_shmget+0x100/0x100
>  [<ffffffffba4dd412>] SyS_shmctl+0x342/0x490
>  [<ffffffffba003aa4>] do_syscall_64+0xf4/0x240
>  [<ffffffffbad4605a>] entry_SYSCALL64_slow_path+0x25/0x25
> ---[ end trace 638c142c3cb9ddb2 ]---