Re: [PATCH] block: restore the old set_task_ioprio() behaviour wrt PF_EXITING

Jan Kara
2022-03-28T09:59:15Z

On Mon 28-03-22 10:59:28, Jiri Slaby wrote:
> PF_EXITING tasks were silently ignored before the below commits.
> Continue doing so. Otherwise python-psutil tests fail:
> ERROR: psutil.tests.test_process.TestProcess.test_zombie_process
> ----------------------------------------------------------------------
> Traceback (most recent call last):
> File "/home/abuild/rpmbuild/BUILD/psutil-5.9.0/build/lib.linux-x86_64-3.9/psutil/_pslinux.py", line 1661, in wrapper
> return fun(self, *args, **kwargs)
> File "/home/abuild/rpmbuild/BUILD/psutil-5.9.0/build/lib.linux-x86_64-3.9/psutil/_pslinux.py", line 2133, in ionice_set
> return cext.proc_ioprio_set(self.pid, ioclass, value)
> ProcessLookupError: [Errno 3] No such process
>
> During handling of the above exception, another exception occurred:
>
> Traceback (most recent call last):
> File "/home/abuild/rpmbuild/BUILD/psutil-5.9.0/psutil/tests/test_process.py", line 1313, in test_zombie_process
> succeed_or_zombie_p_exc(fun)
> File "/home/abuild/rpmbuild/BUILD/psutil-5.9.0/psutil/tests/test_process.py", line 1288, in succeed_or_zombie_p_exc
> return fun()
> File "/home/abuild/rpmbuild/BUILD/psutil-5.9.0/build/lib.linux-x86_64-3.9/psutil/__init__.py", line 792, in ionice
> return self._proc.ionice_set(ioclass, value)
> File "/home/abuild/rpmbuild/BUILD/psutil-5.9.0/build/lib.linux-x86_64-3.9/psutil/_pslinux.py", line 1665, in wrapper
> raise NoSuchProcess(self.pid, self._name)
> psutil.NoSuchProcess: process no longer exists (pid=2057)
>
> Cc: Christoph Hellwig <hch@lst.de>
> Cc: Jan Kara <jack@suse.cz>
> Cc: Jens Axboe <axboe@kernel.dk>
> Fixes: 5fc11eebb4 (block: open code create_task_io_context in set_task_ioprio)
> Fixes: a957b61254 (block: fix error in handling dead task for ioprio setting)
> Signed-off-by: Jiri Slaby <jslaby@suse.cz>

OK, as much as I find it disputable what ioprio_set() should be doing for
PF_EXITTING task, I guess there's no harm in maintaining the old behavior and
just ignoring the call. So feel free to add:

Reviewed-by: Jan Kara <jack@suse.cz>

Honza

> ---
> block/blk-ioc.c | 3 +--
> 1 file changed, 1 insertion(+), 2 deletions(-)
>
> diff --git a/block/blk-ioc.c b/block/blk-ioc.c
> index 11f49f78db32..df9cfe4ca532 100644
> --- a/block/blk-ioc.c
> +++ b/block/blk-ioc.c
> @@ -280,7 +280,6 @@ int set_task_ioprio(struct task_struct *task, int ioprio)
>
> task_lock(task);
> if (task->flags & PF_EXITING) {
> - err = -ESRCH;
> kmem_cache_free(iocontext_cachep, ioc);
> goto out;
> }
> @@ -292,7 +291,7 @@ int set_task_ioprio(struct task_struct *task, int ioprio)
> task->io_context->ioprio = ioprio;
> out:
> task_unlock(task);
> - return err;
> + return 0;
> }
> EXPORT_SYMBOL_GPL(set_task_ioprio);
>
> --
> 2.35.1
>
--
Jan Kara <jack@suse.com>
SUSE Labs, CR