From: Murphy Zhou <jencce.kernel@gmail.com>
To: Konstantin Khorenko <khorenko@virtuozzo.com>
Cc: Kirill Gorkunov <kgorkunov@virtuozzo.com>,
Andrey Vagin <avagin@virtuozzo.com>,
Benjamin Coddington <bcodding@redhat.com>,
Jeff Layton <jlayton@kernel.org>,
"J. Bruce Fields" <bfields@fieldses.org>,
Alexander Viro <viro@zeniv.linux.org.uk>,
Vasily Averin <vvs@virtuozzo.com>,
Linux-Fsdevel <linux-fsdevel@vger.kernel.org>,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH 0/2] fs/lock: show locks info owned by dead/invisible processes
Date: Thu, 9 Aug 2018 15:16:05 +0800 [thread overview]
Message-ID: <CADJHv_uWB=kS0=rFnaAUFk1X+xy3BWHH=6pOk+uJQNBQS04hcg@mail.gmail.com> (raw)
In-Reply-To: <20180608142712.32460-1-khorenko@virtuozzo.com>
Hi,
Looks like this missed v4.18 ?
Thanks,
Murphy
On Fri, Jun 8, 2018 at 10:27 PM, Konstantin Khorenko
<khorenko@virtuozzo.com> wrote:
> The behavior has been changed after 9d5b86ac13c5 ("fs/locks: Remove fl_nspid
> and use fs-specific l_pid for remote locks")
> and now /proc/$PID/fdinfo/$FD does not show the info about the lock
> * if the flock owner process is dead and its pid has been already freed
> or
> * if the lock owner is not visible in current pidns.
>
> CRIU uses this interface to store locks info during dump and thus can break
> on v4.13 and newer.
>
> So let's show info about locks anyway in described cases (like it was before
> 9d5b86ac13c5), but show pid number saved in file_lock struct if we are in
> init_pid_ns (patch 1) or just zero otherwise (patch 2) like we do with SID.
>
> Reproducer:
> process A process A1 process A2
> fork()--------->
> exit() open()
> flock()
> fork()--------->
> exit() sleep()
>
> Before the patch:
> ================
> (root@vz7)/: cat /proc/${PID_A2}/fdinfo/3
> pos: 4
> flags: 02100002
> mnt_id: 257
> lock: (root@vz7)/:
>
> After the patch:
> ===============
> (root@vz7)/:cat /proc/${PID_A2}/fdinfo/3
> pos: 4
> flags: 02100002
> mnt_id: 295
> lock: 1: FLOCK ADVISORY WRITE ${PID_A1} b6:f8a61:529946 0 EOF
>
> ===============
> # cat flock1.c
>
> #include <stdio.h>
> #include <stdlib.h>
> #include <unistd.h>
> #include <sys/types.h>
> #include <sys/stat.h>
> #include <sys/file.h>
> #include <fcntl.h>
>
> int main(void)
> {
> int fd;
> int err;
> pid_t child_pid;
>
> child_pid = fork();
> if (child_pid == -1)
> perror("fork failed");
> if (child_pid) {
> exit(0);
> }
>
> fd = open("/tmp/a", O_CREAT | O_RDWR);
> if (fd == -1)
> perror("Failed to open the file");
>
> err = flock(fd, LOCK_EX);
> if (err == -1)
> perror("flock failed");
>
> child_pid = fork();
> if (child_pid == -1)
> perror("fork failed");
> if (child_pid)
> exit(0);
>
> sleep(10000);
>
> return 0;
> }
>
> Konstantin Khorenko (2):
> fs/lock: skip lock owner pid translation in case we are in init_pid_ns
> fs/lock: show locks taken by processes from another pidns
>
> fs/locks.c | 15 ++++++++++-----
> 1 file changed, 10 insertions(+), 5 deletions(-)
>
> --
> 2.15.1
>
next prev parent reply other threads:[~2018-08-09 9:39 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-06-08 14:27 [PATCH 0/2] fs/lock: show locks info owned by dead/invisible processes Konstantin Khorenko
2018-06-08 14:27 ` [PATCH 1/2] fs/lock: skip lock owner pid translation in case we are in init_pid_ns Konstantin Khorenko
2018-06-12 4:35 ` Andrey Vagin
2018-06-08 14:27 ` [PATCH 2/2] fs/lock: show locks taken by processes from another pidns Konstantin Khorenko
2018-06-12 4:53 ` Andrey Vagin
2018-06-14 11:00 ` Jeff Layton
2018-06-19 20:25 ` Andrey Vagin
2018-06-08 16:02 ` [PATCH 0/2] fs/lock: show locks info owned by dead/invisible processes Cyrill Gorcunov
2018-06-14 10:41 ` Jeff Layton
2018-06-14 11:13 ` Benjamin Coddington
2018-08-09 7:16 ` Murphy Zhou [this message]
2018-08-09 8:20 ` Konstantin Khorenko
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