[syzbot] kernel BUG in mpage_prepare_extent_to_map

syzbot
2021-05-31T07:15:46Z

Hello,

syzbot found the following issue on:

HEAD commit: 7ac3a1c1 Merge tag 'mtd/fixes-for-5.13-rc4' of git://git.k..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=12d276efd00000
kernel config: https://syzkaller.appspot.com/x/.config?x=9f3da44a01882e99
dashboard link: https://syzkaller.appspot.com/bug?extid=99043e2052d9c50c81fc

Unfortunately, I don't have any reproducer for this issue yet.

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+99043e2052d9c50c81fc@syzkaller.appspotmail.com

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kernel BUG at fs/ext4/inode.c:2625!
invalid opcode: 0000 [#1] PREEMPT SMP KASAN
CPU: 1 PID: 1259 Comm: kworker/u17:7 Not tainted 5.13.0-rc3-syzkaller #0
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.14.0-2 04/01/2014
Workqueue: writeback wb_workfn
(flush-8:0)
RIP: 0010:mpage_prepare_extent_to_map+0xb69/0xe20 fs/ext4/inode.c:2625
Code: 8d 5d ff e9 46 fc ff ff e8 d4 02 69 ff 0f 0b e8 cd 02 69 ff 48 c7 c6 80 75 7f 89 4c 89 ef e8 ae 23 9b ff 0f 0b e8 b7 02 69 ff <0f> 0b 45 31 ff e8 ad 02 69 ff 0f b6 9c 24 b8 00 00 00 31 ff 89 de
RSP: 0000:ffffc90004467238 EFLAGS: 00010293
RAX: 0000000000000000 RBX: 0000000000000040 RCX: 0000000000000000
RDX: ffff888016d3c240 RSI: ffffffff820b0ae9 RDI: 0000000000000003
RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000000
R10: ffffffff820b0874 R11: 0000000000000000 R12: dffffc0000000000
R13: ffffea00015cf440 R14: ffffc900044675c8 R15: 0000000000000000
FS: 0000000000000000(0000) GS:ffff88802cb00000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007fd171e3e73f CR3: 0000000045f64000 CR4: 0000000000150ee0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
ext4_writepages+0x941/0x3b70 fs/ext4/inode.c:2754
do_writepages+0xec/0x290 mm/page-writeback.c:2352
__writeback_single_inode+0x126/0xfd0 fs/fs-writeback.c:1467
writeback_sb_inodes+0x53d/0xef0 fs/fs-writeback.c:1732
__writeback_inodes_wb+0xc6/0x280 fs/fs-writeback.c:1801
wb_writeback+0x814/0xc40 fs/fs-writeback.c:1907
wb_check_start_all fs/fs-writeback.c:2031 [inline]
wb_do_writeback fs/fs-writeback.c:2057 [inline]
wb_workfn+0xb98/0x12d0 fs/fs-writeback.c:2091
process_one_work+0x98d/0x1600 kernel/workqueue.c:2276
worker_thread+0x64c/0x1120 kernel/workqueue.c:2422
kthread+0x3b1/0x4a0 kernel/kthread.c:313
ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:294
Modules linked in:

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