Date:   Tue, 2 Jul 2019 11:52:35 +0200 (CEST)
From:   Marta Rybczynska <mrybczyn@...ray.eu>
To:     Hannes Reinecke <hare@...e.de>
Cc:     kbusch <kbusch@...nel.org>, axboe <axboe@...com>,
        Christoph Hellwig <hch@....de>,
        Sagi Grimberg <sagi@...mberg.me>,
        linux-nvme <linux-nvme@...ts.infradead.org>,
        linux-kernel <linux-kernel@...r.kernel.org>,
        Samuel Jones <sjones@...ray.eu>,
        Jean-Baptiste Riaux <jbriaux@...ray.eu>
Subject: Re: [PATCH] nvme: fix multipath crash when ANA deactivated

----- On 2 Jul, 2019, at 11:31, Hannes Reinecke hare@...e.de wrote:

> On 7/1/19 12:10 PM, Marta Rybczynska wrote:
>> Fix a crash with multipath activated. It happends when ANA log
>> page is larger than MDTS and because of that ANA is disabled.
>> When connecting the target, the driver in nvme_parse_ana_log
>> then tries to access nvme_mpath_init.ctrl->ana_log_buf that is
>> unallocated. The signature is as follows:
>> 
>> [  300.433586] nvme nvme0: ANA log page size (8208) larger than MDTS (8192).
>> [  300.435387] nvme nvme0: disabling ANA support.
>> [  300.437835] nvme nvme0: creating 4 I/O queues.
>> [  300.459132] nvme nvme0: new ctrl: NQN "nqn.0.0.0", addr 10.91.0.1:8009
>> [  300.464609] BUG: unable to handle kernel NULL pointer dereference at
>> 0000000000000008
>> [  300.466342] #PF error: [normal kernel read fault]
>> [  300.467385] PGD 0 P4D 0
>> [  300.467987] Oops: 0000 [#1] SMP PTI
>> [  300.468787] CPU: 3 PID: 50 Comm: kworker/u8:1 Not tainted 5.0.20kalray+ #4
>> [  300.470264] Hardware name: Red Hat KVM, BIOS 0.5.1 01/01/2011
>> [  300.471532] Workqueue: nvme-wq nvme_scan_work [nvme_core]
>> [  300.472724] RIP: 0010:nvme_parse_ana_log+0x21/0x140 [nvme_core]
>> [  300.474038] Code: 45 01 d2 d8 48 98 c3 66 90 0f 1f 44 00 00 41 57 41 56 41 55
>> 41 54 55 53 48 89 fb 48 83 ec 08 48 8b af 20 0a 00 00 48 89 34 24 <66> 83 7d 08
>> 00 0f 84 c6 00 00 00 44 8b 7d 14 49 89 d5 8b 55 10 48
>> [  300.477374] RSP: 0018:ffffa50e80fd7cb8 EFLAGS: 00010296
>> [  300.478334] RAX: 0000000000000001 RBX: ffff9130f1872258 RCX: 0000000000000000
>> [  300.479784] RDX: ffffffffc06c4c30 RSI: ffff9130edad4280 RDI: ffff9130f1872258
>> [  300.481488] RBP: 0000000000000000 R08: 0000000000000001 R09: 0000000000000044
>> [  300.483203] R10: 0000000000000220 R11: 0000000000000040 R12: ffff9130f18722c0
>> [  300.484928] R13: ffff9130f18722d0 R14: ffff9130edad4280 R15: ffff9130f18722c0
>> [  300.486626] FS:  0000000000000000(0000) GS:ffff9130f7b80000(0000)
>> knlGS:0000000000000000
>> [  300.488538] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
>> [  300.489907] CR2: 0000000000000008 CR3: 00000002365e6000 CR4: 00000000000006e0
>> [  300.491612] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
>> [  300.493303] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
>> [  300.494991] Call Trace:
>> [  300.495645]  nvme_mpath_add_disk+0x5c/0xb0 [nvme_core]
>> [  300.496880]  nvme_validate_ns+0x2ef/0x550 [nvme_core]
>> [  300.498105]  ? nvme_identify_ctrl.isra.45+0x6a/0xb0 [nvme_core]
>> [  300.499539]  nvme_scan_work+0x2b4/0x370 [nvme_core]
>> [  300.500717]  ? __switch_to_asm+0x35/0x70
>> [  300.501663]  process_one_work+0x171/0x380
>> [  300.502340]  worker_thread+0x49/0x3f0
>> [  300.503079]  kthread+0xf8/0x130
>> [  300.503795]  ? max_active_store+0x80/0x80
>> [  300.504690]  ? kthread_bind+0x10/0x10
>> [  300.505502]  ret_from_fork+0x35/0x40
>> [  300.506280] Modules linked in: nvme_tcp nvme_rdma rdma_cm iw_cm ib_cm ib_core
>> nvme_fabrics nvme_core xt_physdev ip6table_raw ip6table_mangle ip6table_filter
>> ip6_tables xt_comment iptable_nat nf_nat_ipv4 nf_nat nf_conntrack
>> nf_defrag_ipv6 nf_defrag_ipv4 xt_CHECKSUM iptable_mangle iptable_filter veth
>> ebtable_filter ebtable_nat ebtables iptable_raw vxlan ip6_udp_tunnel udp_tunnel
>> sunrpc joydev pcspkr virtio_balloon br_netfilter bridge stp llc ip_tables xfs
>> libcrc32c ata_generic pata_acpi virtio_net virtio_console net_failover
>> virtio_blk failover ata_piix serio_raw libata virtio_pci virtio_ring virtio
>> [  300.514984] CR2: 0000000000000008
>> [  300.515569] ---[ end trace faa2eefad7e7f218 ]---
>> [  300.516354] RIP: 0010:nvme_parse_ana_log+0x21/0x140 [nvme_core]
>> [  300.517330] Code: 45 01 d2 d8 48 98 c3 66 90 0f 1f 44 00 00 41 57 41 56 41 55
>> 41 54 55 53 48 89 fb 48 83 ec 08 48 8b af 20 0a 00 00 48 89 34 24 <66> 83 7d 08
>> 00 0f 84 c6 00 00 00 44 8b 7d 14 49 89 d5 8b 55 10 48
>> [  300.520353] RSP: 0018:ffffa50e80fd7cb8 EFLAGS: 00010296
>> [  300.521229] RAX: 0000000000000001 RBX: ffff9130f1872258 RCX: 0000000000000000
>> [  300.522399] RDX: ffffffffc06c4c30 RSI: ffff9130edad4280 RDI: ffff9130f1872258
>> [  300.523560] RBP: 0000000000000000 R08: 0000000000000001 R09: 0000000000000044
>> [  300.524734] R10: 0000000000000220 R11: 0000000000000040 R12: ffff9130f18722c0
>> [  300.525915] R13: ffff9130f18722d0 R14: ffff9130edad4280 R15: ffff9130f18722c0
>> [  300.527084] FS:  0000000000000000(0000) GS:ffff9130f7b80000(0000)
>> knlGS:0000000000000000
>> [  300.528396] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
>> [  300.529440] CR2: 0000000000000008 CR3: 00000002365e6000 CR4: 00000000000006e0
>> [  300.530739] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
>> [  300.531989] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
>> [  300.533264] Kernel panic - not syncing: Fatal exception
>> [  300.534338] Kernel Offset: 0x17c00000 from 0xffffffff81000000 (relocation
>> range: 0xffffffff80000000-0xffffffffbfffffff)
>> [  300.536227] ---[ end Kernel panic - not syncing: Fatal exception ]---
>> 
>> Signed-off-by: Marta Rybczynska <marta.rybczynska@...ray.eu>
>> Tested-by: Jean-Baptiste Riaux <jbriaux@...ray.eu>
>> ---
>>  drivers/nvme/host/multipath.c | 12 ++++++++++--
>>  drivers/nvme/host/nvme.h      |  1 +
>>  2 files changed, 11 insertions(+), 2 deletions(-)
>> 
>> diff --git a/drivers/nvme/host/multipath.c b/drivers/nvme/host/multipath.c
>> index 499acf0..61dae87 100644
>> --- a/drivers/nvme/host/multipath.c
>> +++ b/drivers/nvme/host/multipath.c
>> @@ -12,11 +12,16 @@
>>  MODULE_PARM_DESC(multipath,
>>  	"turn on native support for multiple controllers per subsystem");
>>  
>> -inline bool nvme_ctrl_use_ana(struct nvme_ctrl *ctrl)
>> +inline bool nvme_ctrl_has_ana_cap(struct nvme_ctrl *ctrl)
>>  {
>>  	return multipath && ctrl->subsys && (ctrl->subsys->cmic & (1 << 3));
>>  }
>>  
>> +inline bool nvme_ctrl_use_ana(struct nvme_ctrl *ctrl)
>> +{
>> +	return nvme_ctrl_has_ana_cap(ctrl) && ctrl->ana_enabled;
>> +}
>> +
>>  /*
>>   * If multipathing is enabled we need to always use the subsystem instance
>>   * number for numbering our devices to avoid conflicts between subsystems that
>> @@ -614,7 +619,7 @@ int nvme_mpath_init(struct nvme_ctrl *ctrl, struct
>> nvme_id_ctrl *id)
>>  {
>>  	int error;
>>  
>> -	if (!nvme_ctrl_use_ana(ctrl))
>> +	if (!nvme_ctrl_has_ana_cap(ctrl))
>>  		return 0;
>>  
>>  	ctrl->anacap = id->anacap;
>> @@ -647,6 +652,8 @@ int nvme_mpath_init(struct nvme_ctrl *ctrl, struct
>> nvme_id_ctrl *id)
>>  	error = nvme_read_ana_log(ctrl, true);
>>  	if (error)
>>  		goto out_free_ana_log_buf;
>> +
>> +	ctrl->ana_enabled = true;
>>  	return 0;
>>  out_free_ana_log_buf:
>>  	kfree(ctrl->ana_log_buf);
>> @@ -659,5 +666,6 @@ void nvme_mpath_uninit(struct nvme_ctrl *ctrl)
>>  {
>>  	kfree(ctrl->ana_log_buf);
>>  	ctrl->ana_log_buf = NULL;
>> +	ctrl->ana_enabled = false;
>>  }
>>  
>> diff --git a/drivers/nvme/host/nvme.h b/drivers/nvme/host/nvme.h
>> index 55553d2..8daefeb 100644
>> --- a/drivers/nvme/host/nvme.h
>> +++ b/drivers/nvme/host/nvme.h
>> @@ -219,6 +219,7 @@ struct nvme_ctrl {
>>  	u8 anatt;
>>  	u32 anagrpmax;
>>  	u32 nanagrpid;
>> +	bool ana_enabled;
>>  	struct mutex ana_lock;
>>  	struct nvme_ana_rsp_hdr *ana_log_buf;
>>  	size_t ana_log_size;
>> 
> They idea was to use a 'ana_log_buf == NULL' as an indicator that ANA is
> disabled, so there is no need to have an additional flag.

OK, still keeping the split of the helper functions?

Marta

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