Re: [syzbot] [netfs?] INFO: task hung in netfs_unbuffered_write_iter

[Dominique Martinet]

Thanks for the traces.

w/ revert
K Prateek Nayak wrote on Tue, Mar 25, 2025 at 08:19:26PM +0530:
>    kworker/100:1-1803    [100] .....   286.618822: p9_fd_poll: p9_fd_poll rd poll
>    kworker/100:1-1803    [100] .....   286.618822: p9_fd_poll: p9_fd_request wr poll
>    kworker/100:1-1803    [100] .....   286.618823: p9_read_work: Data read wait 7

new behavior
>            repro-4076    [031] .....    95.011394: p9_fd_poll: p9_fd_poll rd poll
>            repro-4076    [031] .....    95.011394: p9_fd_poll: p9_fd_request wr poll
>            repro-4076    [031] .....    99.731970: p9_client_rpc: Wait event killable (-512)

For me the problem isn't so much that this gets ERESTARTSYS but that it
nevers gets to read the 7 bytes that are available?

If the repro has already written the bytes in both cases then there's no
reason to wait 5 seconds here...

OTOH syzbot 9p code is silly and might have been depending on something
that's not supposed to work e.g. they might be missing a flush or
equivalent for all I know (I still haven't looked at the repro)

-- 
Dominique