Re: v4.16-rc2: virtio-block + ext4 lockdep splats / sleeping from invalid context

From: Jan Kara
Date: Mon Feb 26 2018 - 05:53:06 EST

On Fri 23-02-18 15:47:36, Mark Rutland wrote:
> 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?

No, it's likely a bug in detection whether IO completion should be deferred
to a workqueue or not. Does attached patch fix the problem? I don't see
exactly this being triggered by the syzkaller but it's close enough :)

Honza


> 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$setstatus(r0, 0x4, 0x10000)
> ftruncate(r0, 0x400)
> io_setup(0x1f, &(0x7f0000018000)=<r1=>0x0)
> io_submit(r1, 0x1, &(0x7f000001d000-0x28)=[&(0x7f000001b000)={0x0, 0x0, 0x0, 0x1, 0x0, r0, &(0x7f0000022000-0x1000)="00000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000
> 00000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000", 0x200, 0x0, 0x0, 0x0, 0x0}])
> bpf$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..
--
Jan Kara <jack@xxxxxxxx>
SUSE Labs, CR