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Message-ID: <1568144988.5576.132.camel@lca.pw>
Subject: Re: page_alloc.shuffle=1 + CONFIG_PROVE_LOCKING=y = arm64 hang
From:   Qian Cai <cai@lca.pw>
To:     Petr Mladek <pmladek@suse.com>,
        Steven Rostedt <rostedt@goodmis.org>,
        Catalin Marinas <catalin.marinas@arm.com>,
        Will Deacon <will@kernel.org>, Theodore Ts'o <tytso@mit.edu>
Cc:     Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com>,
        Dan Williams <dan.j.williams@intel.com>, linux-mm@kvack.org,
        linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org,
        Peter Zijlstra <peterz@infradead.org>,
        Waiman Long <longman@redhat.com>,
        Thomas Gleixner <tglx@linutronix.de>
Date:   Tue, 10 Sep 2019 15:49:48 -0400
In-Reply-To: <1568128954.5576.129.camel@lca.pw>
References: <1566509603.5576.10.camel@lca.pw>
         <1567717680.5576.104.camel@lca.pw> <1568128954.5576.129.camel@lca.pw>
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On Tue, 2019-09-10 at 11:22 -0400, Qian Cai wrote:
> On Thu, 2019-09-05 at 17:08 -0400, Qian Cai wrote:
> > Another data point is if change CONFIG_DEBUG_OBJECTS_TIMERS from =y to =n, it
> > will also fix it.
> > 
> > On Thu, 2019-08-22 at 17:33 -0400, Qian Cai wrote:
> > > https://raw.githubusercontent.com/cailca/linux-mm/master/arm64.config
> > > 
> > > Booting an arm64 ThunderX2 server with page_alloc.shuffle=1 [1] +
> > > CONFIG_PROVE_LOCKING=y results in hanging.
> > > 
> > > [1] https://lore.kernel.org/linux-mm/154899811208.3165233.17623209031065121886.s
> > > tgit@dwillia2-desk3.amr.corp.intel.com/
> > > 
> > > ...
> > > [  125.142689][    T1] arm-smmu-v3 arm-smmu-v3.2.auto: option mask 0x2
> > > [  125.149687][    T1] arm-smmu-v3 arm-smmu-v3.2.auto: ias 44-bit, oas 44-bit
> > > (features 0x0000170d)
> > > [  125.165198][    T1] arm-smmu-v3 arm-smmu-v3.2.auto: allocated 524288 entries
> > > for cmdq
> > > [  125.239425][ [  125.251484][    T1] arm-smmu-v3 arm-smmu-v3.3.auto: option
> > > mask 0x2
> > > [  125.258233][    T1] arm-smmu-v3 arm-smmu-v3.3.auto: ias 44-bit, oas 44-bit
> > > (features 0x0000170d)
> > > [  125.282750][    T1] arm-smmu-v3 arm-smmu-v3.3.auto: allocated 524288 entries
> > > for cmdq
> > > [  125.320097][    T1] arm-smmu-v3 arm-smmu-v3.3.auto: allocated 524288 entries
> > > for evtq
> > > [  125.332667][    T1] arm-smmu-v3 arm-smmu-v3.4.auto: option mask 0x2
> > > [  125.339427][    T1] arm-smmu-v3 arm-smmu-v3.4.auto: ias 44-bit, oas 44-bit
> > > (features 0x0000170d)
> > > [  125.354846][    T1] arm-smmu-v3 arm-smmu-v3.4.auto: allocated 524288 entries
> > > for cmdq
> > > [  125.375295][    T1] arm-smmu-v3 arm-smmu-v3.4.auto: allocated 524288 entries
> > > for evtq
> > > [  125.387371][    T1] arm-smmu-v3 arm-smmu-v3.5.auto: option mask 0x2
> > > [  125.393955][    T1] arm-smmu-v3 arm-smmu-v3.5.auto: ias 44-bit, oas 44-bit
> > > (features 0x0000170d)
> > > [  125.522605][    T1] arm-smmu-v3 arm-smmu-v3.5.auto: allocated 524288 entries
> > > for cmdq
> > > [  125.543338][    T1] arm-smmu-v3 arm-smmu-v3.5.auto: allocated 524288 entries
> > > for evtq
> > > [  126.694742][    T1] EFI Variables Facility v0.08 2004-May-17
> > > [  126.799291][    T1] NET: Registered protocol family 17
> > > [  126.978632][    T1] zswap: loaded using pool lzo/zbud
> > > [  126.989168][    T1] kmemleak: Kernel memory leak detector initialized
> > > [  126.989191][ T1577] kmemleak: Automatic memory scanning thread started
> > > [  127.044079][ T1335] pcieport 0000:0f:00.0: Adding to iommu group 0
> > > [  127.388074][    T1] Freeing unused kernel memory: 22528K
> > > [  133.527005][    T1] Checked W+X mappings: passed, no W+X pages found
> > > [  133.533474][    T1] Run /init as init process
> > > [  133.727196][    T1] systemd[1]: System time before build time, advancing
> > > clock.
> > > [  134.576021][ T1587] modprobe (1587) used greatest stack depth: 27056 bytes
> > > left
> > > [  134.764026][    T1] systemd[1]: systemd 239 running in system mode. (+PAM
> > > +AUDIT +SELINUX +IMA -APPARMOR +SMACK +SYSVINIT +UTMP +LIBCRYPTSETUP +GCRYPT
> > > +GNUTLS +ACL +XZ +LZ4 +SECCOMP +BLKID +ELFUTILS +KMOD +IDN2 -IDN +PCRE2 default-
> > > hierarchy=legacy)
> > > [  134.799044][    T1] systemd[1]: Detected architecture arm64.
> > > [  134.804818][    T1] systemd[1]: Running in initial RAM disk.
> > > <...hang...>
> > > 
> > > Fix it by either set page_alloc.shuffle=0 or CONFIG_PROVE_LOCKING=n which allow
> > > it to continue successfully.
> > > 
> > > 
> > > [  121.093846][    T1] systemd[1]: Set hostname to <hpe-apollo-cn99xx>.
> > > [  123.157524][    T1] random: systemd: uninitialized urandom read (16 bytes
> > > read)
> > > [  123.168562][    T1] systemd[1]: Listening on Journal Socket.
> > > [  OK  ] Listening on Journal Socket.
> > > [  123.203932][    T1] random: systemd: uninitialized urandom read (16 bytes
> > > read)
> > > [  123.212813][    T1] systemd[1]: Listening on udev Kernel Socket.
> > > [  OK  ] Listening on udev Kernel Socket.
> > > ...
> 
> Not sure if the arm64 hang is just an effect of the potential console deadlock
> below. The lockdep splat can be reproduced by set,
> 
> CONFIG_DEBUG_OBJECTS_TIMER=n (=y will lead to the hang above)
> CONFIG_PROVE_LOCKING=y
> CONFIG_SLAB_FREELIST_RANDOM=y (with page_alloc.shuffle=1)
> 
> while compiling kernels,
> 
> [ 1078.214683][T43784] WARNING: possible circular locking dependency detected
> [ 1078.221550][T43784] 5.3.0-rc7-next-20190904 #14 Not tainted
> [ 1078.227112][T43784] ------------------------------------------------------
> [ 1078.233976][T43784] vi/43784 is trying to acquire lock:
> [ 1078.239192][T43784] ffff008b7cff9290 (&(&zone->lock)->rlock){-.-.}, at:
> rmqueue_bulk.constprop.21+0xb0/0x1218
> [ 1078.249111][T43784] 
> [ 1078.249111][T43784] but task is already holding lock:
> [ 1078.256322][T43784] ffff00938db47d40 (&(&port->lock)->rlock){-.-.}, at:
> pty_write+0x78/0x100
> [ 1078.264760][T43784] 
> [ 1078.264760][T43784] which lock already depends on the new lock.
> [ 1078.264760][T43784] 
> [ 1078.275008][T43784] 
> [ 1078.275008][T43784] the existing dependency chain (in reverse order) is:
> [ 1078.283869][T43784] 
> [ 1078.283869][T43784] -> #3 (&(&port->lock)->rlock){-.-.}:
> [ 1078.291350][T43784]        __lock_acquire+0x5c8/0xbb0
> [ 1078.296394][T43784]        lock_acquire+0x154/0x428
> [ 1078.301266][T43784]        _raw_spin_lock_irqsave+0x80/0xa0
> [ 1078.306831][T43784]        tty_port_tty_get+0x28/0x68
> [ 1078.311873][T43784]        tty_port_default_wakeup+0x20/0x40
> [ 1078.317523][T43784]        tty_port_tty_wakeup+0x38/0x48
> [ 1078.322827][T43784]        uart_write_wakeup+0x2c/0x50
> [ 1078.327956][T43784]        pl011_tx_chars+0x240/0x260
> [ 1078.332999][T43784]        pl011_start_tx+0x24/0xa8
> [ 1078.337868][T43784]        __uart_start+0x90/0xa0
> [ 1078.342563][T43784]        uart_write+0x15c/0x2c8
> [ 1078.347261][T43784]        do_output_char+0x1c8/0x2b0
> [ 1078.352304][T43784]        n_tty_write+0x300/0x668
> [ 1078.357087][T43784]        tty_write+0x2e8/0x430
> [ 1078.361696][T43784]        redirected_tty_write+0xcc/0xe8
> [ 1078.367086][T43784]        do_iter_write+0x228/0x270
> [ 1078.372041][T43784]        vfs_writev+0x10c/0x1c8
> [ 1078.376735][T43784]        do_writev+0xdc/0x180
> [ 1078.381257][T43784]        __arm64_sys_writev+0x50/0x60
> [ 1078.386476][T43784]        el0_svc_handler+0x11c/0x1f0
> [ 1078.391606][T43784]        el0_svc+0x8/0xc
> [ 1078.395691][T43784] 
> [ 1078.395691][T43784] -> #2 (&port_lock_key){-.-.}:
> [ 1078.402561][T43784]        __lock_acquire+0x5c8/0xbb0
> [ 1078.407604][T43784]        lock_acquire+0x154/0x428
> [ 1078.412474][T43784]        _raw_spin_lock+0x68/0x88
> [ 1078.417343][T43784]        pl011_console_write+0x2ac/0x318
> [ 1078.422820][T43784]        console_unlock+0x3c4/0x898
> [ 1078.427863][T43784]        vprintk_emit+0x2d4/0x460
> [ 1078.432732][T43784]        vprintk_default+0x48/0x58
> [ 1078.437688][T43784]        vprintk_func+0x194/0x250
> [ 1078.442557][T43784]        printk+0xbc/0xec
> [ 1078.446732][T43784]        register_console+0x4a8/0x580
> [ 1078.451947][T43784]        uart_add_one_port+0x748/0x878
> [ 1078.457250][T43784]        pl011_register_port+0x98/0x128
> [ 1078.462639][T43784]        sbsa_uart_probe+0x398/0x480
> [ 1078.467772][T43784]        platform_drv_probe+0x70/0x108
> [ 1078.473075][T43784]        really_probe+0x15c/0x5d8
> [ 1078.477944][T43784]        driver_probe_device+0x94/0x1d0
> [ 1078.483335][T43784]        __device_attach_driver+0x11c/0x1a8
> [ 1078.489072][T43784]        bus_for_each_drv+0xf8/0x158
> [ 1078.494201][T43784]        __device_attach+0x164/0x240
> [ 1078.499331][T43784]        device_initial_probe+0x24/0x30
> [ 1078.504721][T43784]        bus_probe_device+0xf0/0x100
> [ 1078.509850][T43784]        device_add+0x63c/0x960
> [ 1078.514546][T43784]        platform_device_add+0x1ac/0x3b8
> [ 1078.520023][T43784]        platform_device_register_full+0x1fc/0x290
> [ 1078.526373][T43784]        acpi_create_platform_device.part.0+0x264/0x3a8
> [ 1078.533152][T43784]        acpi_create_platform_device+0x68/0x80
> [ 1078.539150][T43784]        acpi_default_enumeration+0x34/0x78
> [ 1078.544887][T43784]        acpi_bus_attach+0x340/0x3b8
> [ 1078.550015][T43784]        acpi_bus_attach+0xf8/0x3b8
> [ 1078.555057][T43784]        acpi_bus_attach+0xf8/0x3b8
> [ 1078.560099][T43784]        acpi_bus_attach+0xf8/0x3b8
> [ 1078.565142][T43784]        acpi_bus_scan+0x9c/0x100
> [ 1078.570015][T43784]        acpi_scan_init+0x16c/0x320
> [ 1078.575058][T43784]        acpi_init+0x330/0x3b8
> [ 1078.579666][T43784]        do_one_initcall+0x158/0x7ec
> [ 1078.584797][T43784]        kernel_init_freeable+0x9a8/0xa70
> [ 1078.590360][T43784]        kernel_init+0x18/0x138
> [ 1078.595055][T43784]        ret_from_fork+0x10/0x1c
> [ 1078.599835][T43784] 
> [ 1078.599835][T43784] -> #1 (console_owner){-...}:
> [ 1078.606618][T43784]        __lock_acquire+0x5c8/0xbb0
> [ 1078.611661][T43784]        lock_acquire+0x154/0x428
> [ 1078.616530][T43784]        console_unlock+0x298/0x898
> [ 1078.621573][T43784]        vprintk_emit+0x2d4/0x460
> [ 1078.626442][T43784]        vprintk_default+0x48/0x58
> [ 1078.631398][T43784]        vprintk_func+0x194/0x250
> [ 1078.636267][T43784]        printk+0xbc/0xec
> [ 1078.640443][T43784]        _warn_unseeded_randomness+0xb4/0xd0
> [ 1078.646267][T43784]        get_random_u64+0x4c/0x100
> [ 1078.651224][T43784]        add_to_free_area_random+0x168/0x1a0
> [ 1078.657047][T43784]        free_one_page+0x3dc/0xd08
> [ 1078.662003][T43784]        __free_pages_ok+0x490/0xd00
> [ 1078.667132][T43784]        __free_pages+0xc4/0x118
> [ 1078.671914][T43784]        __free_pages_core+0x2e8/0x428
> [ 1078.677219][T43784]        memblock_free_pages+0xa4/0xec
> [ 1078.682522][T43784]        memblock_free_all+0x264/0x330
> [ 1078.687825][T43784]        mem_init+0x90/0x148
> [ 1078.692259][T43784]        start_kernel+0x368/0x684
> [ 1078.697126][T43784] 
> [ 1078.697126][T43784] -> #0 (&(&zone->lock)->rlock){-.-.}:
> [ 1078.704604][T43784]        check_prev_add+0x120/0x1138
> [ 1078.709733][T43784]        validate_chain+0x888/0x1270
> [ 1078.714863][T43784]        __lock_acquire+0x5c8/0xbb0
> [ 1078.719906][T43784]        lock_acquire+0x154/0x428
> [ 1078.724776][T43784]        _raw_spin_lock+0x68/0x88
> [ 1078.729645][T43784]        rmqueue_bulk.constprop.21+0xb0/0x1218
> [ 1078.735643][T43784]        get_page_from_freelist+0x898/0x24a0
> [ 1078.741467][T43784]        __alloc_pages_nodemask+0x2a8/0x1d08
> [ 1078.747291][T43784]        alloc_pages_current+0xb4/0x150
> [ 1078.752682][T43784]        allocate_slab+0xab8/0x2350
> [ 1078.757725][T43784]        new_slab+0x98/0xc0
> [ 1078.762073][T43784]        ___slab_alloc+0x66c/0xa30
> [ 1078.767029][T43784]        __slab_alloc+0x68/0xc8
> [ 1078.771725][T43784]        __kmalloc+0x3d4/0x658
> [ 1078.776333][T43784]        __tty_buffer_request_room+0xd4/0x220
> [ 1078.782244][T43784]        tty_insert_flip_string_fixed_flag+0x6c/0x128
> [ 1078.788849][T43784]        pty_write+0x98/0x100
> [ 1078.793370][T43784]        n_tty_write+0x2a0/0x668
> [ 1078.798152][T43784]        tty_write+0x2e8/0x430
> [ 1078.802760][T43784]        __vfs_write+0x5c/0xb0
> [ 1078.807368][T43784]        vfs_write+0xf0/0x230
> [ 1078.811890][T43784]        ksys_write+0xd4/0x180
> [ 1078.816498][T43784]        __arm64_sys_write+0x4c/0x60
> [ 1078.821627][T43784]        el0_svc_handler+0x11c/0x1f0
> [ 1078.826756][T43784]        el0_svc+0x8/0xc
> [ 1078.830842][T43784] 
> [ 1078.830842][T43784] other info that might help us debug this:
> [ 1078.830842][T43784] 
> [ 1078.840918][T43784] Chain exists of:
> [ 1078.840918][T43784]   &(&zone->lock)->rlock --> &port_lock_key --> &(&port-
> > lock)->rlock
> 
> [ 1078.840918][T43784] 
> [ 1078.854731][T43784]  Possible unsafe locking scenario:
> [ 1078.854731][T43784] 
> [ 1078.862029][T43784]        CPU0                    CPU1
> [ 1078.867243][T43784]        ----                    ----
> [ 1078.872457][T43784]   lock(&(&port->lock)->rlock);
> [ 1078.877238][T43784]                                lock(&port_lock_key);
> [ 1078.883929][T43784]                                lock(&(&port->lock)-
> > rlock);
> 
> [ 1078.891228][T43784]   lock(&(&zone->lock)->rlock);
> [ 1078.896010][T43784] 
> [ 1078.896010][T43784]  *** DEADLOCK ***
> [ 1078.896010][T43784] 
> [ 1078.904004][T43784] 5 locks held by vi/43784:
> [ 1078.908351][T43784]  #0: ffff000c36240890 (&tty->ldisc_sem){++++}, at:
> ldsem_down_read+0x44/0x50
> [ 1078.917133][T43784]  #1: ffff000c36240918 (&tty->atomic_write_lock){+.+.},
> at: tty_write_lock+0x24/0x60
> [ 1078.926521][T43784]  #2: ffff000c36240aa0 (&o_tty->termios_rwsem/1){++++},
> at: n_tty_write+0x108/0x668
> [ 1078.935823][T43784]  #3: ffffa0001e0b2360 (&ldata->output_lock){+.+.}, at:
> n_tty_write+0x1d0/0x668
> [ 1078.944777][T43784]  #4: ffff00938db47d40 (&(&port->lock)->rlock){-.-.}, at:
> pty_write+0x78/0x100
> [ 1078.953644][T43784] 
> [ 1078.953644][T43784] stack backtrace:
> [ 1078.959382][T43784] CPU: 97 PID: 43784 Comm: vi Not tainted 5.3.0-rc7-next-
> 20190904 #14
> [ 1078.967376][T43784] Hardware name: HPE Apollo
> 70             /C01_APACHE_MB         , BIOS L50_5.13_1.11 06/18/2019
> [ 1078.977799][T43784] Call trace:
> [ 1078.980932][T43784]  dump_backtrace+0x0/0x228
> [ 1078.985279][T43784]  show_stack+0x24/0x30
> [ 1078.989282][T43784]  dump_stack+0xe8/0x13c
> [ 1078.993370][T43784]  print_circular_bug+0x334/0x3d8
> [ 1078.998240][T43784]  check_noncircular+0x268/0x310
> [ 1079.003022][T43784]  check_prev_add+0x120/0x1138
> [ 1079.007631][T43784]  validate_chain+0x888/0x1270
> [ 1079.012241][T43784]  __lock_acquire+0x5c8/0xbb0
> [ 1079.016763][T43784]  lock_acquire+0x154/0x428
> [ 1079.021111][T43784]  _raw_spin_lock+0x68/0x88
> [ 1079.025460][T43784]  rmqueue_bulk.constprop.21+0xb0/0x1218
> [ 1079.030937][T43784]  get_page_from_freelist+0x898/0x24a0
> [ 1079.036240][T43784]  __alloc_pages_nodemask+0x2a8/0x1d08
> [ 1079.041542][T43784]  alloc_pages_current+0xb4/0x150
> [ 1079.046412][T43784]  allocate_slab+0xab8/0x2350
> [ 1079.050934][T43784]  new_slab+0x98/0xc0
> [ 1079.054761][T43784]  ___slab_alloc+0x66c/0xa30
> [ 1079.059196][T43784]  __slab_alloc+0x68/0xc8
> [ 1079.063371][T43784]  __kmalloc+0x3d4/0x658
> [ 1079.067458][T43784]  __tty_buffer_request_room+0xd4/0x220
> [ 1079.072847][T43784]  tty_insert_flip_string_fixed_flag+0x6c/0x128
> [ 1079.078932][T43784]  pty_write+0x98/0x100
> [ 1079.082932][T43784]  n_tty_write+0x2a0/0x668
> [ 1079.087193][T43784]  tty_write+0x2e8/0x430
> [ 1079.091280][T43784]  __vfs_write+0x5c/0xb0
> [ 1079.095367][T43784]  vfs_write+0xf0/0x230
> [ 1079.099368][T43784]  ksys_write+0xd4/0x180
> [ 1079.103455][T43784]  __arm64_sys_write+0x4c/0x60
> [ 1079.108064][T43784]  el0_svc_handler+0x11c/0x1f0
> [ 1079.112672][T43784]  el0_svc+0x8/0xc

Hmm, it feels like that CONFIG_SHUFFLE_PAGE_ALLOCATOR=y introduces some unique
locking patterns that the lockdep does not like via,

allocate_slab
  shuffle_freelist
    get_random_u32

Here is another splat with while compiling/installing a kernel,

[ 1254.443119][    C2] WARNING: possible circular locking dependency detected
[ 1254.450038][    C2] 5.3.0-rc5-next-20190822 #1 Not tainted
[ 1254.455559][    C2] ------------------------------------------------------
[ 1254.462988][    C2] swapper/2/0 is trying to acquire lock:
[ 1254.468509][    C2] ffffffffa2925218 (random_write_wait.lock){..-.}, at:
__wake_up_common_lock+0xc6/0x150
[ 1254.478154][    C2] 
[ 1254.478154][    C2] but task is already holding lock:
[ 1254.485896][    C2] ffff88845373fda0 (batched_entropy_u32.lock){-.-.}, at:
get_random_u32+0x4c/0xe0
[ 1254.495007][    C2] 
[ 1254.495007][    C2] which lock already depends on the new lock.
[ 1254.495007][    C2] 
[ 1254.505331][    C2] 
[ 1254.505331][    C2] the existing dependency chain (in reverse order) is:
[ 1254.514755][    C2] 
[ 1254.514755][    C2] -> #3 (batched_entropy_u32.lock){-.-.}:
[ 1254.522553][    C2]        __lock_acquire+0x5b3/0xb40
[ 1254.527638][    C2]        lock_acquire+0x126/0x280
[ 1254.533016][    C2]        _raw_spin_lock_irqsave+0x3a/0x50
[ 1254.538624][    C2]        get_random_u32+0x4c/0xe0
[ 1254.543539][    C2]        allocate_slab+0x6d6/0x19c0
[ 1254.548625][    C2]        new_slab+0x46/0x70
[ 1254.553010][    C2]        ___slab_alloc+0x58b/0x960
[ 1254.558533][    C2]        __slab_alloc+0x43/0x70
[ 1254.563269][    C2]        kmem_cache_alloc+0x354/0x460
[ 1254.568534][    C2]        fill_pool+0x272/0x4b0
[ 1254.573182][    C2]        __debug_object_init+0x86/0x7a0
[ 1254.578615][    C2]        debug_object_init+0x16/0x20
[ 1254.584256][    C2]        hrtimer_init+0x27/0x1e0
[ 1254.589079][    C2]        init_dl_task_timer+0x20/0x40
[ 1254.594342][    C2]        __sched_fork+0x10b/0x1f0
[ 1254.599253][    C2]        init_idle+0xac/0x520
[ 1254.603816][    C2]        fork_idle+0x18c/0x230
[ 1254.608933][    C2]        idle_threads_init+0xf0/0x187
[ 1254.614193][    C2]        smp_init+0x1d/0x12d
[ 1254.618671][    C2]        kernel_init_freeable+0x37e/0x76e
[ 1254.624282][    C2]        kernel_init+0x11/0x12f
[ 1254.629016][    C2]        ret_from_fork+0x27/0x50
[ 1254.634344][    C2] 
[ 1254.634344][    C2] -> #2 (&rq->lock){-.-.}:
[ 1254.640831][    C2]        __lock_acquire+0x5b3/0xb40
[ 1254.645917][    C2]        lock_acquire+0x126/0x280
[ 1254.650827][    C2]        _raw_spin_lock+0x2f/0x40
[ 1254.655741][    C2]        task_fork_fair+0x43/0x200
[ 1254.661213][    C2]        sched_fork+0x29b/0x420
[ 1254.665949][    C2]        copy_process+0xf12/0x3180
[ 1254.670947][    C2]        _do_fork+0xef/0x950
[ 1254.675422][    C2]        kernel_thread+0xa8/0xe0
[ 1254.680244][    C2]        rest_init+0x28/0x311
[ 1254.685298][    C2]        arch_call_rest_init+0xe/0x1b
[ 1254.690558][    C2]        start_kernel+0x6eb/0x724
[ 1254.695469][    C2]        x86_64_start_reservations+0x24/0x26
[ 1254.701339][    C2]        x86_64_start_kernel+0xf4/0xfb
[ 1254.706689][    C2]        secondary_startup_64+0xb6/0xc0
[ 1254.712601][    C2] 
[ 1254.712601][    C2] -> #1 (&p->pi_lock){-.-.}:
[ 1254.719263][    C2]        __lock_acquire+0x5b3/0xb40
[ 1254.724349][    C2]        lock_acquire+0x126/0x280
[ 1254.729260][    C2]        _raw_spin_lock_irqsave+0x3a/0x50
[ 1254.735317][    C2]        try_to_wake_up+0xad/0x1050
[ 1254.740403][    C2]        default_wake_function+0x2f/0x40
[ 1254.745929][    C2]        pollwake+0x10d/0x160
[ 1254.750491][    C2]        __wake_up_common+0xc4/0x2a0
[ 1254.755663][    C2]        __wake_up_common_lock+0xea/0x150
[ 1254.761756][    C2]        __wake_up+0x13/0x20
[ 1254.766230][    C2]        account.constprop.9+0x217/0x340
[ 1254.771754][    C2]        extract_entropy.constprop.7+0xcf/0x220
[ 1254.777886][    C2]        _xfer_secondary_pool+0x19a/0x3d0
[ 1254.783981][    C2]        push_to_pool+0x3e/0x230
[ 1254.788805][    C2]        process_one_work+0x52a/0xb40
[ 1254.794064][    C2]        worker_thread+0x63/0x5b0
[ 1254.798977][    C2]        kthread+0x1df/0x200
[ 1254.803451][    C2]        ret_from_fork+0x27/0x50
[ 1254.808787][    C2] 
[ 1254.808787][    C2] -> #0 (random_write_wait.lock){..-.}:
[ 1254.816409][    C2]        check_prev_add+0x107/0xea0
[ 1254.821494][    C2]        validate_chain+0x8fc/0x1200
[ 1254.826667][    C2]        __lock_acquire+0x5b3/0xb40
[ 1254.831751][    C2]        lock_acquire+0x126/0x280
[ 1254.837189][    C2]        _raw_spin_lock_irqsave+0x3a/0x50
[ 1254.842797][    C2]        __wake_up_common_lock+0xc6/0x150
[ 1254.848408][    C2]        __wake_up+0x13/0x20
[ 1254.852882][    C2]        account.constprop.9+0x217/0x340
[ 1254.858988][    C2]        extract_entropy.constprop.7+0xcf/0x220
[ 1254.865122][    C2]        crng_reseed+0xa1/0x3f0
[ 1254.869859][    C2]        _extract_crng+0xc3/0xd0
[ 1254.874682][    C2]        crng_reseed+0x21b/0x3f0
[ 1254.879505][    C2]        _extract_crng+0xc3/0xd0
[ 1254.884772][    C2]        extract_crng+0x40/0x60
[ 1254.889507][    C2]        get_random_u32+0xb4/0xe0
[ 1254.894417][    C2]        allocate_slab+0x6d6/0x19c0
[ 1254.899501][    C2]        new_slab+0x46/0x70
[ 1254.903886][    C2]        ___slab_alloc+0x58b/0x960
[ 1254.909377][    C2]        __slab_alloc+0x43/0x70
[ 1254.914112][    C2]        kmem_cache_alloc+0x354/0x460
[ 1254.919375][    C2]        __build_skb+0x23/0x60
[ 1254.924024][    C2]        __netdev_alloc_skb+0x127/0x1e0
[ 1254.929470][    C2]        tg3_poll_work+0x11b2/0x1f70 [tg3]
[ 1254.935654][    C2]        tg3_poll_msix+0x67/0x330 [tg3]
[ 1254.941092][    C2]        net_rx_action+0x24e/0x7e0
[ 1254.946089][    C2]        __do_softirq+0x123/0x767
[ 1254.951000][    C2]        irq_exit+0xd6/0xf0
[ 1254.955385][    C2]        do_IRQ+0xe2/0x1a0
[ 1254.960155][    C2]        ret_from_intr+0x0/0x2a
[ 1254.964896][    C2]        cpuidle_enter_state+0x156/0x8e0
[ 1254.970418][    C2]        cpuidle_enter+0x41/0x70
[ 1254.975242][    C2]        call_cpuidle+0x5e/0x90
[ 1254.979975][    C2]        do_idle+0x333/0x370
[ 1254.984972][    C2]        cpu_startup_entry+0x1d/0x1f
[ 1254.990148][    C2]        start_secondary+0x290/0x330
[ 1254.995319][    C2]        secondary_startup_64+0xb6/0xc0
[ 1255.000750][    C2] 
[ 1255.000750][    C2] other info that might help us debug this:
[ 1255.000750][    C2] 
[ 1255.011424][    C2] Chain exists of:
[ 1255.011424][    C2]   random_write_wait.lock --> &rq->lock -->
batched_entropy_u32.lock
[ 1255.011424][    C2] 
[ 1255.025245][    C2]  Possible unsafe locking scenario:
[ 1255.025245][    C2] 
[ 1255.033012][    C2]        CPU0                    CPU1
[ 1255.038270][    C2]        ----                    ----
[ 1255.043526][    C2]   lock(batched_entropy_u32.lock);
[ 1255.048610][    C2]                                lock(&rq->lock);
[
1255.054918][    C2]                                lock(batched_entropy_u32.loc
k);
[ 1255.063035][    C2]   lock(random_write_wait.lock);
[ 1255.067945][    C2] 
[ 1255.067945][    C2]  *** DEADLOCK ***
[ 1255.067945][    C2] 
[ 1255.076000][    C2] 1 lock held by swapper/2/0:
[ 1255.080558][    C2]  #0: ffff88845373fda0 (batched_entropy_u32.lock){-.-.},
at: get_random_u32+0x4c/0xe0
[ 1255.090547][    C2] 
[ 1255.090547][    C2] stack backtrace:
[ 1255.096333][    C2] CPU: 2 PID: 0 Comm: swapper/2 Not tainted 5.3.0-rc5-next-
20190822 #1
[ 1255.104473][    C2] Hardware name: HPE ProLiant DL385 Gen10/ProLiant DL385
Gen10, BIOS A40 03/09/2018
[ 1255.114276][    C2] Call Trace:
[ 1255.117439][    C2]  <IRQ>
[ 1255.120169][    C2]  dump_stack+0x86/0xca
[ 1255.124205][    C2]  print_circular_bug.cold.32+0x243/0x26e
[ 1255.129816][    C2]  check_noncircular+0x29e/0x2e0
[ 1255.135221][    C2]  ? __bfs+0x238/0x380
[ 1255.139172][    C2]  ? print_circular_bug+0x120/0x120
[ 1255.144259][    C2]  ? find_usage_forwards+0x7d/0xb0
[ 1255.149260][    C2]  check_prev_add+0x107/0xea0
[ 1255.153823][    C2]  validate_chain+0x8fc/0x1200
[ 1255.159007][    C2]  ? check_prev_add+0xea0/0xea0
[ 1255.163743][    C2]  ? check_usage_backwards+0x210/0x210
[ 1255.169091][    C2]  __lock_acquire+0x5b3/0xb40
[ 1255.173655][    C2]  lock_acquire+0x126/0x280
[ 1255.178041][    C2]  ? __wake_up_common_lock+0xc6/0x150
[ 1255.183732][    C2]  _raw_spin_lock_irqsave+0x3a/0x50
[ 1255.188817][    C2]  ? __wake_up_common_lock+0xc6/0x150
[ 1255.194076][    C2]  __wake_up_common_lock+0xc6/0x150
[ 1255.199163][    C2]  ? __wake_up_common+0x2a0/0x2a0
[ 1255.204078][    C2]  ? rcu_read_lock_any_held.part.5+0x20/0x20
[ 1255.210428][    C2]  __wake_up+0x13/0x20
[ 1255.214379][    C2]  account.constprop.9+0x217/0x340
[ 1255.219377][    C2]  extract_entropy.constprop.7+0xcf/0x220
[ 1255.224987][    C2]  ? crng_reseed+0xa1/0x3f0
[ 1255.229375][    C2]  crng_reseed+0xa1/0x3f0
[ 1255.234122][    C2]  ? rcu_read_lock_sched_held+0xac/0xe0
[ 1255.239556][    C2]  ? check_flags.part.16+0x86/0x220
[ 1255.244641][    C2]  ? extract_entropy.constprop.7+0x220/0x220
[ 1255.250511][    C2]  ? __kasan_check_read+0x11/0x20
[ 1255.255422][    C2]  ? validate_chain+0xab/0x1200
[ 1255.260742][    C2]  ? rcu_read_lock_any_held.part.5+0x20/0x20
[ 1255.266616][    C2]  _extract_crng+0xc3/0xd0
[ 1255.270915][    C2]  crng_reseed+0x21b/0x3f0
[ 1255.275215][    C2]  ? extract_entropy.constprop.7+0x220/0x220
[ 1255.281085][    C2]  ? __kasan_check_write+0x14/0x20
[ 1255.286517][    C2]  ? do_raw_spin_lock+0x118/0x1d0
[ 1255.291428][    C2]  ? rwlock_bug.part.0+0x60/0x60
[ 1255.296251][    C2]  _extract_crng+0xc3/0xd0
[ 1255.300550][    C2]  extract_crng+0x40/0x60
[ 1255.304763][    C2]  get_random_u32+0xb4/0xe0
[ 1255.309640][    C2]  allocate_slab+0x6d6/0x19c0
[ 1255.314203][    C2]  new_slab+0x46/0x70
[ 1255.318066][    C2]  ___slab_alloc+0x58b/0x960
[ 1255.322539][    C2]  ? __build_skb+0x23/0x60
[ 1255.326841][    C2]  ? fault_create_debugfs_attr+0x140/0x140
[ 1255.333048][    C2]  ? __build_skb+0x23/0x60
[ 1255.337348][    C2]  __slab_alloc+0x43/0x70
[ 1255.341559][    C2]  ? __slab_alloc+0x43/0x70
[ 1255.345944][    C2]  ? __build_skb+0x23/0x60
[ 1255.350242][    C2]  kmem_cache_alloc+0x354/0x460
[ 1255.354978][    C2]  ? __netdev_alloc_skb+0x1c6/0x1e0
[ 1255.360626][    C2]  ? trace_hardirqs_on+0x3a/0x160
[ 1255.365535][    C2]  __build_skb+0x23/0x60
[ 1255.369660][    C2]  __netdev_alloc_skb+0x127/0x1e0
[ 1255.374576][    C2]  tg3_poll_work+0x11b2/0x1f70 [tg3]
[ 1255.379750][    C2]  ? find_held_lock+0x11b/0x150
[ 1255.385027][    C2]  ? tg3_tx_recover+0xa0/0xa0 [tg3]
[ 1255.390114][    C2]  ? _raw_spin_unlock_irqrestore+0x38/0x50
[ 1255.395809][    C2]  ? __kasan_check_read+0x11/0x20
[ 1255.400718][    C2]  ? validate_chain+0xab/0x1200
[ 1255.405455][    C2]  ? __wake_up_common+0x2a0/0x2a0
[ 1255.410761][    C2]  ? mark_held_locks+0x34/0xb0
[ 1255.415415][    C2]  tg3_poll_msix+0x67/0x330 [tg3]
[ 1255.420327][    C2]  net_rx_action+0x24e/0x7e0
[ 1255.424800][    C2]  ? find_held_lock+0x11b/0x150
[ 1255.429536][    C2]  ? napi_busy_loop+0x600/0x600
[ 1255.434733][    C2]  ? rcu_read_lock_sched_held+0xac/0xe0
[ 1255.440169][    C2]  ? __do_softirq+0xed/0x767
[ 1255.444642][    C2]  ? rcu_read_lock_any_held.part.5+0x20/0x20
[ 1255.450518][    C2]  ? lockdep_hardirqs_on+0x1b0/0x2a0
[ 1255.455693][    C2]  ? irq_exit+0xd6/0xf0
[ 1255.460280][    C2]  __do_softirq+0x123/0x767
[ 1255.464668][    C2]  irq_exit+0xd6/0xf0
[ 1255.468532][    C2]  do_IRQ+0xe2/0x1a0
[ 1255.472308][    C2]  common_interrupt+0xf/0xf
[ 1255.476694][    C2]  </IRQ>
[ 1255.479509][    C2] RIP: 0010:cpuidle_enter_state+0x156/0x8e0
[ 1255.485750][    C2] Code: bf ff 8b 05 a4 27 2d 01 85 c0 0f 8f 1d 04 00 00 31
ff e8 4d ba 92 ff 80 7d d0 00 0f 85 0b 02 00 00 e8 ae c0 a7 ff fb 45 85 ed <0f>
88 2d 02 00 00 4d 63 fd 49 83 ff 09 0f 87 91 06 00 00 4b 8d 04
[ 1255.505335][    C2] RSP: 0018:ffff888206637cf8 EFLAGS: 00000202 ORIG_RAX:
ffffffffffffffc8
[ 1255.514154][    C2] RAX: 0000000000000000 RBX: ffff889f98b44008 RCX:
ffffffffa116e980
[ 1255.522033][    C2] RDX: 0000000000000007 RSI: dffffc0000000000 RDI:
ffff8882066287ec
[ 1255.529913][    C2] RBP: ffff888206637d48 R08: fffffbfff4557aee R09:
0000000000000000
[ 1255.538278][    C2] R10: 0000000000000000 R11: 0000000000000000 R12:
ffffffffa28e8ac0
[ 1255.546158][    C2] R13: 0000000000000002 R14: 0000012412160253 R15:
ffff889f98b4400c
[ 1255.554040][    C2]  ? lockdep_hardirqs_on+0x1b0/0x2a0
[ 1255.559725][    C2]  ? cpuidle_enter_state+0x152/0x8e0
[ 1255.564898][    C2]  cpuidle_enter+0x41/0x70
[ 1255.569196][    C2]  call_cpuidle+0x5e/0x90
[ 1255.573408][    C2]  do_idle+0x333/0x370
[ 1255.577358][    C2]  ? complete+0x51/0x60
[ 1255.581394][    C2]  ? arch_cpu_idle_exit+0x40/0x40
[ 1255.586777][    C2]  ? complete+0x51/0x60
[ 1255.590814][    C2]  cpu_startup_entry+0x1d/0x1f
[ 1255.595461][    C2]  start_secondary+0x290/0x330
[ 1255.600111][    C2]  ? set_cpu_sibling_map+0x18f0/0x18f0
[ 1255.605460][    C2]  secondary_startup_64+0xb6/0xc0