Re: [PATCH] pipe_read: don't wake up the writer if the pipe is still full

[Alexey Gladkov]

On Tue, Feb 25, 2025 at 12:57:37PM +0100, Oleg Nesterov wrote:
> On 02/24, Oleg Nesterov wrote:
> >
> > Just in case, did you use
> >
> > 	https://git.kernel.org/pub/scm/utils/rt-tests/rt-tests.git/tree/src/hackbench/hackbench.c
> >
> > ?
> 
> Or did you use another version?
> 
> Exactly what parameters did you use?
> 
> If possible, please reproduce the hang again. How many threads/processes
> sleeping in pipe_read() or pipe_write() do you see? (you can look at
> /proc/$pid/stack).
> 
> Please pick one sleeping writer, and do
> 
> 	$ strace -p pidof_that_write
> 
> this should wake this writer up. If a missed wakeup is the only problem,
> hackbench should continue.
> 
> The more info you can provide the better ;)

I was also able to reproduce the hackbench hang with the parameters
mentioned earlier (threads and processes) on the kernel from master.

-- 
Rgrds, legion