On 2019/11/14 3:46 上午, Marc Smith wrote: > Hi, > > I'm using bcache on Linux 4.14.154 and I'm hitting a BUG_ON() in > writeback.c, which occurs quite a bit on my systems (using write-back > mode). This occurs typically after the backing device is assembled, > and the bcache udev rule registers it. Here are the kernel messages > when this occurs: > > [ 186.463146] md: md126 stopped. > [ 186.475151] md/raid:md126: device sdc operational as raid disk 0 > [ 186.475155] md/raid:md126: device sdn operational as raid disk 11 > [ 186.475157] md/raid:md126: device sdm operational as raid disk 10 > [ 186.475158] md/raid:md126: device sdl operational as raid disk 9 > [ 186.475160] md/raid:md126: device sdk operational as raid disk 8 > [ 186.475161] md/raid:md126: device sdj operational as raid disk 7 > [ 186.475163] md/raid:md126: device sdi operational as raid disk 6 > [ 186.475165] md/raid:md126: device sdh operational as raid disk 5 > [ 186.475166] md/raid:md126: device sdg operational as raid disk 4 > [ 186.475168] md/raid:md126: device sdf operational as raid disk 3 > [ 186.475169] md/raid:md126: device sde operational as raid disk 2 > [ 186.475170] md/raid:md126: device sdd operational as raid disk 1 > [ 186.476349] md/raid:md126: raid level 6 active with 12 out of 12 > devices, algorithm 2 > [ 186.487142] md126: detected capacity change from 0 to 12001083392000 > [ 186.745889] bcache: register_bdev() registered backing device md126 > [ 186.757725] bcache: bch_cached_dev_attach() Caching md126 as > bcache0 on set 81c4d4e3-4feb-4f88-8fcb-00f367e69906 > [ 186.758120] ------------[ cut here ]------------ > [ 186.758123] kernel BUG at drivers/md/bcache/writeback.c:324! > [ 186.758128] invalid opcode: 0000 [#1] SMP NOPTI > [ 186.758301] Modules linked in: qla2xxx(O) bonding ntb_transport > ntb_hw_switchtec(OE) cls_switchtec(OE) mlx5_ib mlx5_core bna ib_umad > rdma_ucm rdma_cm iw_cm ib_uverbs ib_srp ib_cm iw_nes iw_cxgb4 cxgb4 > iw_cxgb3 ib_qib rdmavt mlx4_ib mlx4_core ib_mthca ib_core > [ 186.758741] CPU: 13 PID: 2109 Comm: bcache_writebac Tainted: G > OE 4.14.154-esos.prod #1 > [ 186.758945] Hardware name: Red Hat KVM, BIOS 0.5.1 01/01/2011 > [ 186.759101] task: ffff888327af0000 task.stack: ffffc90003014000 > [ 186.759262] RIP: 0010:dirty_pred+0x17/0x21 > [ 186.759391] RSP: 0018:ffffc90003017ca0 EFLAGS: 00010202 > [ 186.759537] RAX: 9000001000200002 RBX: ffff888329840b90 RCX: 0000000000000003 > [ 186.760235] RDX: 0000000000000002 RSI: ffff888327b01f10 RDI: ffff888329840b90 > [ 186.760922] RBP: ffff888327b01f10 R08: 0000000000000000 R09: 000007ffffffffff > [ 186.761603] R10: 0000000000000001 R11: 0000000000000001 R12: ffffc90003017dd8 > [ 186.762289] R13: 0000000000000000 R14: ffff88842b503800 R15: ffff88842b5038c8 > [ 186.762977] FS: 0000000000000000(0000) GS:ffff88842f540000(0000) > knlGS:0000000000000000 > [ 186.764185] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 > [ 186.764856] CR2: 00007f5fd478ee80 CR3: 00000003af48a000 CR4: 00000000000006e0 > [ 186.765541] Call Trace: > [ 186.766160] refill_keybuf_fn+0x64/0x19b > [ 186.766799] ? bch_btree_gc_finish+0x2b9/0x2b9 > [ 186.767441] bch_btree_map_keys_recurse+0x6a/0x140 > [ 186.768983] bch_btree_map_keys+0x98/0xfb > [ 186.769626] ? bch_btree_gc_finish+0x2b9/0x2b9 > [ 186.770269] ? write_dirty+0xcb/0xcb > [ 186.770904] bch_refill_keybuf+0xa0/0x1ab > [ 186.771544] ? wait_woken+0x6a/0x6a > [ 186.772178] ? write_dirty+0xcb/0xcb > [ 186.772812] bch_writeback_thread+0x2a8/0x73d > [ 186.773458] ? __switch_to+0x31b/0x342 > [ 186.774096] ? read_dirty_submit+0x55/0x55 > [ 186.774744] kthread+0x117/0x11f > [ 186.775369] ? kthread_create_on_node+0x36/0x36 > [ 186.776019] ret_from_fork+0x35/0x40 > [ 186.776656] Code: 5b be 01 00 00 20 48 c7 45 18 20 73 a2 81 5d e9 > 2d 0a ff ff 48 8b 06 8b 8f f8 f4 ff ff 48 89 c2 81 e2 ff ff 0f 00 48 > 39 d1 74 02 <0f> 0b 48 c1 e8 24 83 e0 01 c3 55 48 89 fd f0 ff 47 28 48 > 83 c7 > [ 186.778552] RIP: dirty_pred+0x17/0x21 RSP: ffffc90003017ca0 > [ 186.779240] ---[ end trace f9cfb637b4062277 ]--- > > > I had experienced this same issue on 4.14.120 as well. I noticed some > bug fixes since that patch release so I updated to .154 but the issue > still persists. Perhaps it's worth noting this kernel is built with > GCC 9.x -- I saw another patch for a stack corruption issue involving > GCC 9.x (4.14.128). > > The 4.14.154 kernel is vanilla from 'kernel.org' (not a distro variant). > > Any hints on where to start would be greatly appreciated. Hi Marc, This is new in my memory. v4.14.154 already has the fix "bcache: fix stack corruption by PRECEDING_KEY()", so I guess this issue might be new. Is it possible to try Linux v5.3, or later kernel ? There are quite a lot fixes from v4.14 to v5.3, if you may still observe the issue from v5.3, I can try to look into it. Thanks. -- Coly Li
