Re: ext4: BUG: scheduling while atomic in ext4_commit_super

From: Jan Kara
Date: Wed Feb 10 2016 - 08:58:21 EST


On Sun 24-01-16 17:48:00, Dmitry Vyukov wrote:
> Hello,
>
> I've hit the following BUG while running syzkaller fuzzer:
>
> JBD2: Spotted dirty metadata buffer (dev = sda, blocknr = 1). There's
> a risk of filesystem corruption in case of system crash.
> EXT4-fs error (device sda): ext4_init_block_bitmap:194: comm
> kworker/u10:2: Checksum bad for group 3
> BUG: sleeping function called from invalid context at
> include/linux/buffer_head.h:354
> in_atomic(): 1, irqs_disabled(): 0, pid: 20922, name: kworker/u10:2
> INFO: lockdep is turned off.
> CPU: 3 PID: 20922 Comm: kworker/u10:2 Tainted: G W 4.4.0+ #276
> Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Bochs 01/01/2011
> Workqueue: writeback wb_workfn (flush-8:0)
> 00000000ffffffff ffff8800608ded00 ffffffff82999e2d ffff880067570000
> 00000000000051ba 0000000000000000 ffff8800608ded28 ffffffff813cc25b
> ffff880067570000 ffffffff864a4ba0 0000000000000162 ffff8800608ded68
> Call Trace:
> [< inline >] __dump_stack lib/dump_stack.c:15
> [<ffffffff82999e2d>] dump_stack+0x6f/0xa2 lib/dump_stack.c:50
> [<ffffffff813cc25b>] ___might_sleep+0x27b/0x3a0 kernel/sched/core.c:7703
> [<ffffffff813cc410>] __might_sleep+0x90/0x1a0 kernel/sched/core.c:7665
> [< inline >] lock_buffer include/linux/buffer_head.h:354
> [<ffffffff8186b353>] __sync_dirty_buffer+0x63/0x270 fs/buffer.c:3129
> [<ffffffff81acb8b3>] ext4_commit_super+0x713/0xa80 fs/ext4/super.c:4333
> [< inline >] save_error_info fs/ext4/super.c:316
> [<ffffffff81acc547>] __ext4_error+0xe7/0x1d0 fs/ext4/super.c:419
> [< inline >] ext4_init_block_bitmap fs/ext4/balloc.c:194

Yeah, we call ext4_error() from inappropriate place. Thanks for reporting
this. I'll send a fix in a moment.

Honza
--
Jan Kara <jack@xxxxxxxx>
SUSE Labs, CR