On Tue, Sep 9, 2025 at 2:16 AM Yu Kuai <yukuai1@xxxxxxxxxxxxxxx> wrote:
>
> Hi,
>
> 在 2025/09/08 17:40, Eric Dumazet 写道:
> > On Mon, Sep 8, 2025 at 2:34 AM Yu Kuai <yukuai1@xxxxxxxxxxxxxxx> wrote:
> >>
> >> Hi,
> >>
> >> 在 2025/09/08 17:07, Eric Dumazet 写道:
> >>> On Mon, Sep 8, 2025 at 1:52 AM Yu Kuai <yukuai1@xxxxxxxxxxxxxxx> wrote:
> >>>>
> >>>> Hi,
> >>>>
> >>>> 在 2025/09/06 17:16, Eric Dumazet 写道:
> >>>>> On Fri, Sep 5, 2025 at 1:03 PM Eric Dumazet <edumazet@xxxxxxxxxx> wrote:
> >>>>>>
> >>>>>> On Fri, Sep 5, 2025 at 1:00 PM syzbot
> >>>>>> <syzbot+e1cd6bd8493060bd701d@xxxxxxxxxxxxxxxxxxxxxxxxx> wrote:
> >>>>>
> >>>>> Note to NBD maintainers : I held about 20 syzbot reports all pointing
> >>>>> to NBD accepting various sockets, I can release them if needed, if you prefer
> >>>>> to triage them.
> >>>>>
> >>>> I'm not NBD maintainer, just trying to understand the deadlock first.
> >>>>
> >>>> Is this deadlock only possible for some sepecific socket types? Take
> >>>> a look at the report here:
> >>>>
> >>>> Usually issue IO will require the order:
> >>>>
> >>>> q_usage_counter -> cmd lock -> tx lock -> sk lock
> >>>>
> >>>
> >>> I have not seen the deadlock being reported with normal TCP sockets.
> >>>
> >>> NBD sets sk->sk_allocation to GFP_NOIO | __GFP_MEMALLOC;
> >>> from __sock_xmit(), and TCP seems to respect this.
> >>> .
> >>>
> >>
> >> What aboud iscsi and nvme-tcp? and probably other drivers, where
> >> sk_allocation is GFP_ATOMIC, do they have similar problem?
> >>
> >
> > AFAIK after this fix, iscsi was fine.
> >
> > commit f4f82c52a0ead5ab363d207d06f81b967d09ffb8
> > Author: Eric Dumazet <edumazet@xxxxxxxxxx>
> > Date: Fri Sep 15 17:11:11 2023 +0000
> >
> > scsi: iscsi_tcp: restrict to TCP sockets
> >
> > Nothing prevents iscsi_sw_tcp_conn_bind() to receive file descriptor
> > pointing to non TCP socket (af_unix for example).
> >
> > Return -EINVAL if this is attempted, instead of crashing the kernel.
> >
> > Fixes: 7ba247138907 ("[SCSI] open-iscsi/linux-iscsi-5 Initiator:
> > Initiator code")
> > Signed-off-by: Eric Dumazet <edumazet@xxxxxxxxxx>
> > Cc: Lee Duncan <lduncan@xxxxxxxx>
> > Cc: Chris Leech <cleech@xxxxxxxxxx>
> > Cc: Mike Christie <michael.christie@xxxxxxxxxx>
> > Cc: "James E.J. Bottomley" <jejb@xxxxxxxxxxxxx>
> > Cc: "Martin K. Petersen" <martin.petersen@xxxxxxxxxx>
> > Cc: open-iscsi@xxxxxxxxxxxxxxxx
> > Cc: linux-scsi@xxxxxxxxxxxxxxx
> > Reviewed-by: Mike Christie <michael.christie@xxxxxxxxxx>
> > Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx>
> > .
> >
>
> Yes, now I also agree similiar fix in nbd make sense. Perhaps can you
> cook a patch?
Sure I will send it ASAP.
