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 [off-list ref]
SUSE Labs, CR