Date:   Fri, 23 Feb 2018 15:47:36 +0000
From:   Mark Rutland <mark.rutland@....com>
To:     linux-kernel@...r.kernel.org
Cc:     linux-block@...r.kernel.org,
        virtualization@...ts.linux-foundation.org,
        linux-ext4@...r.kernel.org, Jens Axboe <axboe@...nel.dk>,
        "Michael S. Tsirkin" <mst@...hat.com>,
        Jason Wang <jasowang@...hat.com>,
        Theodore Ts'o <tytso@....edu>, Jan Kara <jack@...e.com>
Subject: v4.16-rc2: virtio-block + ext4 lockdep splats / sleeping from
 invalid context

Hi all,

While fuzzing arm64/v4.16-rc2 with syzkaller, I simultaneously hit a
number of splats in the block layer:

* inconsistent {HARDIRQ-ON-W} -> {IN-HARDIRQ-R} usage in
  jbd2_trans_will_send_data_barrier

* BUG: sleeping function called from invalid context at mm/mempool.c:320

* WARNING: CPU: 0 PID: 0 at block/blk.h:297 generic_make_request_checks+0x670/0x750

... I've included the full splats at the end of the mail.

These all happen in the context of the virtio block IRQ handler, so I
wonder if this calls something that doesn't expect to be called from IRQ
context. Is it valid to call blk_mq_complete_request() or
blk_mq_end_request() from an IRQ handler?

Syzkaller came up with a minimized reproducer, but it's a bit wacky (the
fcntl and bpf calls should have no practical effect), and I haven't
managed to come up with a C reproducer.

Any ideas?

Thanks,
Mark.


Syzkaller reproducer:
# {Threaded:true Collide:true Repeat:false Procs:1 Sandbox:setuid Fault:false FaultCall:-1 FaultNth:0 EnableTun:true UseTmpDir:true HandleSegv:true WaitRepeat:false Debug:false Repro:false}
mmap(&(0x7f0000000000/0x24000)=nil, 0x24000, 0x3, 0x32, 0xffffffffffffffff, 0x0)
r0 = openat(0xffffffffffffff9c, &(0x7f0000019000-0x8)='./file0\x00', 0x42, 0x0)
fcntl$setstatus(r0, 0x4, 0x10000)
ftruncate(r0, 0x400)
io_setup(0x1f, &(0x7f0000018000)=<r1=>0x0)
io_submit(r1, 0x1, &(0x7f000001d000-0x28)=[&(0x7f000001b000)={0x0, 0x0, 0x0, 0x1, 0x0, r0, &(0x7f0000022000-0x1000)="0000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000", 0x200, 0x0, 0x0, 0x0, 0x0}])
bpf$BPF_PROG_ATTACH(0xffffffff, &(0x7f000001b000)={0x0, 0x0, 0x3, 0x2}, 0x40000000)


Full splat:
[  162.337073] ================================
[  162.338055] WARNING: inconsistent lock state
[  162.339017] 4.16.0-rc2 #1 Not tainted
[  162.339797] --------------------------------
[  162.340725] inconsistent {HARDIRQ-ON-W} -> {IN-HARDIRQ-R} usage.
[  162.342030] swapper/0/0 [HC1[1]:SC0[0]:HE0:SE1] takes:
[  162.343061]  (&journal->j_state_lock){+?++}, at: [<000000003b9c3e4b>] jbd2_trans_will_send_data_barrier+0x44/0xc8
[  162.353187] {HARDIRQ-ON-W} state was registered at:
[  162.354433]   lock_acquire+0x48/0x68
[  162.358640]   _raw_write_lock+0x3c/0x50
[  162.360716]   ext4_init_journal_params.isra.6+0x40/0xa0
[  162.363445]   ext4_fill_super+0x25cc/0x2e88
[  162.364481]   mount_bdev+0x19c/0x1d8
[  162.365345]   ext4_mount+0x14/0x20
[  162.366130]   mount_fs+0x34/0x160
[  162.366790]   vfs_kern_mount.part.8+0x54/0x160
[  162.367874]   do_mount+0x540/0xd40
[  162.373776]   SyS_mount+0x68/0x100
[  162.374467]   mount_block_root+0x11c/0x28c
[  162.376558]   mount_root+0x130/0x164
[  162.380753]   prepare_namespace+0x138/0x180
[  162.381729]   kernel_init_freeable+0x25c/0x280
[  162.382625]   kernel_init+0x10/0x100
[  162.383337]   ret_from_fork+0x10/0x18
[  162.384072] irq event stamp: 3670810
[  162.384787] hardirqs last  enabled at (3670805): [<00000000fa98454e>] arch_cpu_idle+0x14/0x28
[  162.386505] hardirqs last disabled at (3670806): [<00000000341112e2>] el1_irq+0x74/0x130
[  162.388107] softirqs last  enabled at (3670810): [<00000000d00bd211>] _local_bh_enable+0x20/0x40
[  162.389880] softirqs last disabled at (3670809): [<00000000e929005c>] irq_enter+0x54/0x70
[  162.391443]
[  162.391443] other info that might help us debug this:
[  162.392680]  Possible unsafe locking scenario:
[  162.392680]
[  162.405967]        CPU0
[  162.406513]        ----
[  162.407055]   lock(&journal->j_state_lock);
[  162.407880]   <Interrupt>
[  162.408400]     lock(&journal->j_state_lock);
[  162.409287]
[  162.409287]  *** DEADLOCK ***
[  162.409287]
[  162.410447] 2 locks held by swapper/0/0:
[  162.411248]  #0:  (&(&vblk->vqs[i].lock)->rlock){-.-.}, at: [<00000000b75553ae>] virtblk_done+0x50/0xf8
[  162.413101]  #1:  (rcu_read_lock){....}, at: [<000000002bf2a216>] hctx_lock+0x1c/0xe8
[  162.414630]
[  162.414630] stack backtrace:
[  162.415492] CPU: 0 PID: 0 Comm: swapper/0 Not tainted 4.16.0-rc2 #1
[  162.429624] Hardware name: linux,dummy-virt (DT)
[  162.430631] Call trace:
[  162.431196]  dump_backtrace+0x0/0x1c8
[  162.432005]  show_stack+0x14/0x20
[  162.432747]  dump_stack+0xac/0xe4
[  162.433507]  print_usage_bug.part.28+0x258/0x270
[  162.434510]  mark_lock+0x744/0x750
[  162.435208]  __lock_acquire+0xab8/0x18c0
[  162.435982]  lock_acquire+0x48/0x68
[  162.436678]  _raw_read_lock+0x3c/0x50
[  162.449520]  jbd2_trans_will_send_data_barrier+0x44/0xc8
[  162.450681]  ext4_sync_file+0x1e0/0x330
[  162.451535]  vfs_fsync_range+0x48/0xc0
[  162.452323]  dio_complete+0x1fc/0x220
[  162.453094]  dio_bio_end_aio+0xf0/0x130
[  162.453935]  bio_endio+0xe8/0xf8
[  162.454625]  blk_update_request+0x80/0x2e8
[  162.455450]  blk_mq_end_request+0x20/0x70
[  162.456240]  virtblk_request_done+0x24/0x30
[  162.457080]  __blk_mq_complete_request+0x100/0x1b0
[  162.458047]  blk_mq_complete_request+0x60/0x98
[  162.458918]  virtblk_done+0x70/0xf8
[  162.459608]  vring_interrupt+0x38/0x50
[  162.460367]  __handle_irq_event_percpu+0x5c/0x148
[  162.472443]  handle_irq_event_percpu+0x34/0x88
[  162.477991]  handle_irq_event+0x48/0x78
[  162.480661]  handle_fasteoi_irq+0xc0/0x198
[  162.485417]  generic_handle_irq+0x24/0x38
[  162.490334]  __handle_domain_irq+0x84/0xf0
[  162.493834]  gic_handle_irq+0x58/0xa8
[  162.498464]  el1_irq+0xb4/0x130
[  162.500621]  arch_cpu_idle+0x18/0x28
[  162.504729]  default_idle_call+0x1c/0x34
[  162.508005]  do_idle+0x17c/0x1f0
[  162.510184]  cpu_startup_entry+0x20/0x28
[  162.515050]  rest_init+0x250/0x260
[  162.518228]  start_kernel+0x3f0/0x41c
[  162.522987] BUG: sleeping function called from invalid context at mm/mempool.c:320
[  162.533762] in_atomic(): 1, irqs_disabled(): 128, pid: 0, name: swapper/0
[  162.540375] INFO: lockdep is turned off.
[  162.542696] irq event stamp: 3670810
[  162.544963] hardirqs last  enabled at (3670805): [<00000000fa98454e>] arch_cpu_idle+0x14/0x28
[  162.551514] hardirqs last disabled at (3670806): [<00000000341112e2>] el1_irq+0x74/0x130
[  162.557422] softirqs last  enabled at (3670810): [<00000000d00bd211>] _local_bh_enable+0x20/0x40
[  162.562596] softirqs last disabled at (3670809): [<00000000e929005c>] irq_enter+0x54/0x70
[  162.568863] Preemption disabled at:
[  162.568877] [<ffff000008b59ca4>] schedule_preempt_disabled+0x1c/0x28
[  162.574673] CPU: 0 PID: 0 Comm: swapper/0 Not tainted 4.16.0-rc2 #1
[  162.580013] Hardware name: linux,dummy-virt (DT)
[  162.583234] Call trace:
[  162.585279]  dump_backtrace+0x0/0x1c8
[  162.587583]  show_stack+0x14/0x20
[  162.589047]  dump_stack+0xac/0xe4
[  162.592035]  ___might_sleep+0x164/0x238
[  162.594830]  __might_sleep+0x50/0x88
[  162.597012]  mempool_alloc+0xc0/0x198
[  162.600633]  bio_alloc_bioset+0x144/0x250
[  162.602983]  blkdev_issue_flush+0x48/0xc8
[  162.606134]  ext4_sync_file+0x220/0x330
[  162.607870]  vfs_fsync_range+0x48/0xc0
[  162.611694]  dio_complete+0x1fc/0x220
[  162.613369]  dio_bio_end_aio+0xf0/0x130
[  162.617040]  bio_endio+0xe8/0xf8
[  162.618583]  blk_update_request+0x80/0x2e8
[  162.619841]  blk_mq_end_request+0x20/0x70
[  162.621082]  virtblk_request_done+0x24/0x30
[  162.627389]  __blk_mq_complete_request+0x100/0x1b0
[  162.630482]  blk_mq_complete_request+0x60/0x98
[  162.633003]  virtblk_done+0x70/0xf8
[  162.635456]  vring_interrupt+0x38/0x50
[  162.638588]  __handle_irq_event_percpu+0x5c/0x148
[  162.640582]  handle_irq_event_percpu+0x34/0x88
[  162.642829]  handle_irq_event+0x48/0x78
[  162.644062]  handle_fasteoi_irq+0xc0/0x198
[  162.646182]  generic_handle_irq+0x24/0x38
[  162.648024]  __handle_domain_irq+0x84/0xf0
[  162.650304]  gic_handle_irq+0x58/0xa8
[  162.652917]  el1_irq+0xb4/0x130
[  162.656972]  arch_cpu_idle+0x18/0x28
[  162.658445]  default_idle_call+0x1c/0x34
[  162.660723]  do_idle+0x17c/0x1f0
[  162.664958]  cpu_startup_entry+0x20/0x28
[  162.670009]  rest_init+0x250/0x260
[  162.672763]  start_kernel+0x3f0/0x41c
[  162.677064] WARNING: CPU: 0 PID: 0 at block/blk.h:297 generic_make_request_checks+0x670/0x750
[  162.682622] Kernel panic - not syncing: panic_on_warn set ...
[  162.682622]
[  162.695097] CPU: 0 PID: 0 Comm: swapper/0 Tainted: G        W        4.16.0-rc2 #1
[  162.700355] Hardware name: linux,dummy-virt (DT)
[  162.713462] Call trace:
[  162.714859]  dump_backtrace+0x0/0x1c8
[  162.722935]  show_stack+0x14/0x20
[  162.725392]  dump_stack+0xac/0xe4
[  162.727719]  panic+0x13c/0x2b8
[  162.732313]  panic+0x0/0x2b8
[  162.735233]  report_bug+0xb4/0x158
[  162.738377]  bug_handler+0x30/0x88
[  162.740810]  brk_handler+0xd8/0x198
[  162.747677]  do_debug_exception+0x9c/0x190
[  162.752011]  el1_dbg+0x18/0x78
[  162.755197]  generic_make_request_checks+0x670/0x750
[  162.761260]  generic_make_request+0x2c/0x278
[  162.764366]  submit_bio+0x54/0x208
[  162.771402]  submit_bio_wait+0x68/0xa0
[  162.775053]  blkdev_issue_flush+0x8c/0xc8
[  162.780520]  ext4_sync_file+0x220/0x330
[  162.784815]  vfs_fsync_range+0x48/0xc0
[  162.788243]  dio_complete+0x1fc/0x220
[  162.792071]  dio_bio_end_aio+0xf0/0x130
[  162.794820]  bio_endio+0xe8/0xf8
[  162.796203]  blk_update_request+0x80/0x2e8
[  162.800883]  blk_mq_end_request+0x20/0x70
[  162.803072]  virtblk_request_done+0x24/0x30
[  162.806877]  __blk_mq_complete_request+0x100/0x1b0
[  162.809298]  blk_mq_complete_request+0x60/0x98
[  162.811408]  virtblk_done+0x70/0xf8
[  162.812461]  vring_interrupt+0x38/0x50
[  162.813467]  __handle_irq_event_percpu+0x5c/0x148
[  162.814657]  handle_irq_event_percpu+0x34/0x88
[  162.815730]  handle_irq_event+0x48/0x78
[  162.816856]  handle_fasteoi_irq+0xc0/0x198
[  162.817946]  generic_handle_irq+0x24/0x38
[  162.818948]  __handle_domain_irq+0x84/0xf0
[  162.820056]  gic_handle_irq+0x58/0xa8
[  162.821013]  el1_irq+0xb4/0x130
[  162.826572]  arch_cpu_idle+0x18/0x28
[  162.827304]  default_idle_call+0x1c/0x34
[  162.828315]  do_idle+0x17c/0x1f0
[  162.829174]  cpu_startup_entry+0x20/0x28
[  162.830072]  rest_init+0x250/0x260
[  162.830872]  start_kernel+0x3f0/0x41c
[  162.831627] SMP: stopping secondary CPUs
[  165.929235] SMP: failed to stop secondary CPUs 0,2
[  165.949001] Kernel Offset: disabled
[  165.963649] CPU features: 0x1802082
[  165.969405] Memory Limit: none
[  165.974480] Rebooting in 86400 seconds..

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