From: Tejun Heo <tj@kernel.org>
To: Al Viro <viro@zeniv.linux.org.uk>
Cc: Zefan Li <lizefan@huawei.com>,
Linus Torvalds <torvalds@linux-foundation.org>,
linux-fsdevel@vger.kernel.org
Subject: Re: [heads-up] buggered refcounting logics in cgroup1_mount()
Date: Fri, 11 Jan 2019 12:54:51 -0800 [thread overview]
Message-ID: <20190111205451.GX2509588@devbig004.ftw2.facebook.com> (raw)
In-Reply-To: <20190111072309.GT2217@ZenIV.linux.org.uk>
Hello, Al.
On Fri, Jan 11, 2019 at 07:23:09AM +0000, Al Viro wrote:
> AFAICS, a cleaner solution would be this:
> * to hell with kernfs_pin_sb(); just try to grab a reference to
> cgroup_root on reuse.
> * have cgroup_kill_sb() treat "it's already marked killed" as
> "just drop the reference, then".
> * after cgroup_do_mount() check if cgroup_root got marked killed and
> do deactivate_locked_super() in such case (with the same
> restart_syscall() failure exit).
>
> Objections? I would love to kill kernfs_pin_sb() as
> a followup (it's a fundamentally broken API), but that's not
> a stable fodder; some fix of refcounting bugs, OTOH, should be.
cgroup1 hierarchies have really weird set of requirements and the
implementation has always been somewhat broken. I thought I fixed it
but obviously not. I have no objection whatsoever and would much
appreciate the work.
Thanks a lot and happy new year!
--
tejun
next prev parent reply other threads:[~2019-01-11 20:54 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-01-11 7:23 [heads-up] buggered refcounting logics in cgroup1_mount() Al Viro
2019-01-11 20:54 ` Tejun Heo [this message]
2019-01-12 5:38 ` Al Viro
2019-01-12 21:52 ` Al Viro
2019-01-15 15:26 ` Tejun Heo
2019-01-14 1:31 ` Zefan Li
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