Re: [syzbot] [fs?] [mm?] INFO: task hung in v9fs_file_fsync

[Dominique Martinet]

Hi Oleg,

Oleg Nesterov wrote on Mon, Aug 18, 2025 at 02:56:26PM +0200:
> On 08/18, syzbot wrote:
> > syzbot has tested the proposed patch and the reproducer did not trigger any issue:

(I hate that syzbot identified "hung in v9fs_file_fsync" but doesn't
bother to Cc 9p folks... all the time..)

> Dominique, David,
> 
> Perhaps you can reconsider the fix that Prateek and I tried to propose
> in this thread
> 
> 	[syzbot] [netfs?] INFO: task hung in netfs_unbuffered_write_iter
> 	https://lore.kernel.org/all/67dedd2f.050a0220.31a16b.003f.GAE@xxxxxxxxxx/

I've re-read that thread, and I still think this must be a problem
specific to syzbot doing obviously bogus things (e.g. replying before
request, or whatever it is this particular repro is doing), but I guess
your patch is also sane enough and the 9p optimization is probably not
really needed here

Please resend as a proper patch, and I'll just run some quick check (and
a trivial benchmark) and pick it up

Thanks,
-- 
Dominique Martinet | Asmadeus