[PATCHSET 0/2] Avoid spurious syzbot induced hung task panics

[Jens Axboe <axboe@kernel.dk>]

Hi,

For details, see this saga:

https://lore.kernel.org/io-uring/68a2decc.050a0220.e29e5.0099.GAE@google.com/

where the tldr is that there's no real bug here, it's just syzbot doing
hundreds of 2GB /dev/msr* reads in a tiny vm and with a bunch of
debugging enabled. That leads to triggering the hung task detector when
we wait on io-wq workers to exit. I did queue a patch for 6.19 that
makes this less likely to occur, as it'll only run the very first of
the items before noticing the cancelation:

https://lore.kernel.org/io-uring/937c3e38-368e-43eb-9d7e-2dcc0697799f@kernel.dk/

but even that isn't quite enough due to how much syzbot overloads the
system.

This will still throw a WARN_ON_ONCE(), which perhaps should just be a
printk() of some sort as the trace isn't THAT interesting. But it will
avoid hitting the hung task timeout detector, which for syzbot leads
to a panic + reboot.

 io_uring/io-wq.c    | 22 +++++++++++++++++++++-
 io_uring/io_uring.c |  2 +-
 io_uring/io_uring.h |  6 ++++++
 3 files changed, 28 insertions(+), 2 deletions(-)

-- 
Jens Axboe