Added in my test directory. Thanks.
Coly Li
> 2023年3月17日 18:49，Yi Li <yili@xxxxxxxxxxx> 写道：
>
> This causes a wild pointer dereference in the path:
>
> btree_gc_rewrite_node()
> -> btree_node_alloc_replacement() // will return -EAGIN(-11)
> -> bch_btree_node_write_sync(-EAGIN)
> ...
> -> mutex_lock(&b->write_lock)
> ..write_lock Offset of structure btree is 152
> ..b->write_lock addr is 000000000000008d (-11 + 152)
> .. BUG!
>
> BUG: unable to handle kernel NULL pointer dereference at 000000000000008d
> Caching disabled for sde2
> PGD 0 P4D 0
> Oops: 0002 [#1] SMP NOPTI
> CPU: 32 PID: 5050 Comm: bcache_gc Kdump: loaded Tainted: G W
> 4.19.90-22.0401.87d4c7a.ckv.x86_64 #1 Hardware name: XFUSION 2288H
> V5/BC11SPSCB10, BIOS 8.27 03/08/2022
> RIP: 0010:mutex_lock+0x19/0x30
> Code: 90 0f 1f 44 00 00 be 02 00 00 00 e9 51 fb ff ff 90 0f 1f 44 00 00 53 48 89 fb e8
> 02 e4 ff ff 65 48 8b 14 25 80 5c 01 00 31 c0 <f0> 48 0f b1 13 75 02 5b c3 48
> 89 df 5b eb c8 0f 1f 84 00 00 00 00
> RSP: 0018:ffffab1b0aba3b70 EFLAGS:
> 00010246 RAX: 0000000000000000 RBX: 000000000000008d RCX: 0000000000000000
> RDX: ffff89d3a7060000 RSI: 0000000000000000 RDI: 000000000000008d RBP:
> fffffffffffffff5 R08: ffff89e3a6860d70 R09: ffff89e3bcc32000 R10:
> 0000000000000001 R11: 000007ffffffffff R12: 000000000000008d R13:
> ffff89e3bb2a8c00 R14: ffffab1b0aba3e08 R15: 0000000000000000 FS:
> 0000000000000000(0000) GS:ffff89d3bff00000(0000) knlGS:0000000000000000 CS:
> 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 000000000000008d CR3:
> 0000001bd1e0a001 CR4: 00000000007606e0 DR0: 0000000000000000 DR1:
> 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6:
> 00000000fffe0ff0 DR7: 0000000000000400 PKRU: 55555554
> Call Trace:
> bch_btree_node_write_sync+0x45/0xa0 [bcache]
> btree_gc_rewrite_node+0x8f/0x160 [bcache]
> ? btree_gc_mark_node+0x64/0x220 [bcache]
> btree_gc_recurse+0x30a/0x3c0 [bcache]
> ? call_rwsem_down_write_failed+0x13/0x20
> ? bch_btree_gc+0x3e5/0x660 [bcache]
> bch_btree_gc+0x3e5/0x660 [bcache]
> ? finish_wait+0x80/0x80 ?
> bch_btree_gc+0x660/0x660 [bcache]
> Buffer I/O error on dev bcache1, logical block 468885310, lost async page write
> bch_gc_thread+0x30/0x1e0 [bcache]
> ? finish_wait+0x80/0x80
> Buffer I/O error on dev bcache1, logical block 468885311, lost async page write
> kthread+0x113/0x130 ?
> kthread_create_worker_on_cpu+0x70/0x70
> ret_from_fork+0x1f/0x4
>
> Signed-off-by: Yi Li <yili@xxxxxxxxxxx>
> Signed-off-by: Guo Chao <guochao@xxxxxxxxxxx>
> ---
> drivers/md/bcache/btree.c | 2 ++
> 1 file changed, 2 insertions(+)
>
> diff --git a/drivers/md/bcache/btree.c b/drivers/md/bcache/btree.c
> index 147c493a989a..5d41331e96f2 100644
> --- a/drivers/md/bcache/btree.c
> +++ b/drivers/md/bcache/btree.c
> @@ -1505,6 +1505,8 @@ static int btree_gc_rewrite_node(struct btree *b, struct btree_op *op,
>
> n = btree_node_alloc_replacement(replace, NULL);
>
> + if (IS_ERR_OR_NULL(n))
> + return -EINTR;
> /* recheck reserve after allocating replacement node */
> if (btree_check_reserve(b, NULL)) {
> btree_node_free(n);
> --
> 2.25.4
>
