linux-kernel - Re: [PATCH] epoll: try to be a _bit

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Message-ID: <CAHk-=wgC+QpveKCJpeqsaORu7htoNNKA8mp+d9mvJEXmSKjhbw@mail.gmail.com>
Date: Fri, 3 May 2024 14:52:38 -0700
From: Linus Torvalds <torvalds@...ux-foundation.org>
To: Al Viro <viro@...iv.linux.org.uk>
Cc: keescook@...omium.org, axboe@...nel.dk, brauner@...nel.org, 
	christian.koenig@....com, dri-devel@...ts.freedesktop.org, 
	io-uring@...r.kernel.org, jack@...e.cz, laura@...bott.name, 
	linaro-mm-sig@...ts.linaro.org, linux-fsdevel@...r.kernel.org, 
	linux-kernel@...r.kernel.org, linux-media@...r.kernel.org, 
	minhquangbui99@...il.com, sumit.semwal@...aro.org, 
	syzbot+045b454ab35fd82a35fb@...kaller.appspotmail.com, 
	syzkaller-bugs@...glegroups.com
Subject: Re: [PATCH] epoll: try to be a _bit_ better about file lifetimes

On Fri, 3 May 2024 at 14:45, Al Viro <viro@...iv.linux.org.uk> wrote:
>
> How do you get through eventpoll_release_file() while someone
> has entered ep_item_poll()?

Doesn't matter.

Look, it's enough that the file count has gone down to zero. You may
not even have gotten to eventpoll_release_file() yet - the important
part is that you're on your *way* to it.

That means that the file will be released - and it means that you have
violated all the refcounting rules for poll().

So I think you're barking up the wrong tree.

                  Linus