On 8/23/21 4:18 AM, Pavel Begunkov wrote:

iov_iter_revert() doesn't go well with iov_iter_truncate() in all
cases, see 2/2 for the bug description. As mentioned there the current
problems is because of generic_write_checks(), but there was also a
similar case fixed in 5.12, which should have been triggerable by normal
write(2)/read(2) and others.

It may be better to enforce reexpands as a long term solution, but for
now this patchset is quickier and easier to backport.

Al, given the discussion from this weekend, are you fine with the first
patch? If so, would be great with an ack/review. Or, if you want to
funnel this for 5.14, you can add:

Reviewed-by: Jens Axboe <axboe@kernel.dk>

-- 
Jens Axboe