From: Cyrill Gorcunov <gorcunov@gmail.com>
To: Pavel Tikhomirov <ptikhomirov@virtuozzo.com>
Cc: Jeff Layton <jlayton@poochiereds.net>,
Jeff Layton <jlayton@kernel.org>,
"J. Bruce Fields" <bfields@fieldses.org>,
Alexander Viro <viro@zeniv.linux.org.uk>,
linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org,
Andrei Vagin <avagin@gmail.com>
Subject: Re: [PATCH] fcntl: make F_GETOWN(EX) return 0 on dead owner task
Date: Wed, 3 Feb 2021 22:32:01 +0300 [thread overview]
Message-ID: <20210203193201.GD2172@grain> (raw)
In-Reply-To: <20210203124156.425775-1-ptikhomirov@virtuozzo.com>
On Wed, Feb 03, 2021 at 03:41:56PM +0300, Pavel Tikhomirov wrote:
> Currently there is no way to differentiate the file with alive owner
> from the file with dead owner but pid of the owner reused. That's why
> CRIU can't actually know if it needs to restore file owner or not,
> because if it restores owner but actual owner was dead, this can
> introduce unexpected signals to the "false"-owner (which reused the
> pid).
Hi! Thanks for the patch. You know I manage to forget the fowner internals.
Could you please enlighten me -- when owner is set with some pid we do
f_setown_ex
__f_setown
f_modown
filp->f_owner.pid = get_pid(pid);
Thus pid get refcount incremented. Then the owner exits but refcounter
should be still up and running and pid should not be reused, no? Or
I miss something obvious?
The patch itself looks ok on a first glance.
next prev parent reply other threads:[~2021-02-03 19:33 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-02-03 12:41 [PATCH] fcntl: make F_GETOWN(EX) return 0 on dead owner task Pavel Tikhomirov
2021-02-03 19:32 ` Cyrill Gorcunov [this message]
2021-02-03 21:35 ` Pavel Tikhomirov
2021-02-03 22:17 ` Cyrill Gorcunov
2021-02-08 12:31 ` Jeff Layton
2021-02-08 12:57 ` Pavel Tikhomirov
2021-02-08 13:18 ` Jeff Layton
2021-02-08 7:39 ` Cyrill Gorcunov
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