From: Ingo Molnar <mingo@kernel•org>
To: Colin Cross <ccross@android•com>
Cc: linux-kernel@vger•kernel.org,
Trond Myklebust <Trond.Myklebust@netapp•com>,
Len Brown <len.brown@intel•com>, Pavel Machek <pavel@ucw•cz>,
"Rafael J. Wysocki" <rjw@sisk•pl>,
Peter Zijlstra <peterz@infradead•org>,
Ingo Molnar <mingo@redhat•com>,
"J. Bruce Fields" <bfields@fieldses•org>,
"David S. Miller" <davem@davemloft•net>,
Andrew Morton <akpm@linux-foundation•org>,
Mandeep Singh Baines <msb@chromium•org>,
Paul Walmsley <paul@pwsan•com>, Al Viro <viro@zeniv•linux.org.uk>,
"Eric W. Biederman" <ebiederm@xmission•com>,
Oleg Nesterov <oleg@redhat•com>,
linux-nfs@vger•kernel.org, linux-pm@vger•kernel.org,
netdev@vger•kernel.org,
Linus Torvalds <torvalds@linux-foundation•org>,
Tejun Heo <tj@kernel•org>, Ben Chan <benchan@chromium•org>
Subject: Re: [PATCH 1/2] freezer: add unsafe versions of freezable helpers
Date: Sun, 5 May 2013 11:23:18 +0200 [thread overview]
Message-ID: <20130505092318.GD22239@gmail.com> (raw)
In-Reply-To: <1367615050-3894-1-git-send-email-ccross@android.com>
* Colin Cross <ccross@android•com> wrote:
> NFS calls the freezable helpers with locks held, which is unsafe
> and caused lockdep warnings when 6aa9707 "lockdep: check that no
> locks held at freeze time" was applied (reverted in dbf520a).
> Add new *_unsafe versions of the helpers that will not run the
> lockdep test when 6aa9707 is reapplied, and call them from NFS.
>
> Signed-off-by: Colin Cross <ccross@android•com>
> ---
> fs/nfs/inode.c | 2 +-
> fs/nfs/nfs3proc.c | 2 +-
> fs/nfs/nfs4proc.c | 4 ++--
> include/linux/freezer.h | 42 +++++++++++++++++++++++++++++++++++++++++-
> net/sunrpc/sched.c | 2 +-
> 5 files changed, 46 insertions(+), 6 deletions(-)
>
> diff --git a/fs/nfs/inode.c b/fs/nfs/inode.c
> index 1f94167..53cbee5 100644
> --- a/fs/nfs/inode.c
> +++ b/fs/nfs/inode.c
> @@ -79,7 +79,7 @@ int nfs_wait_bit_killable(void *word)
> {
> if (fatal_signal_pending(current))
> return -ERESTARTSYS;
> - freezable_schedule();
> + freezable_schedule_unsafe();
I'd suggest naming such variants _unkillable() instead of _unsafe().
There's nothing inherently 'unsafe' about it: the user asked for a hard
NFS mount and is getting it: with the side effect that it exposes the
machine to network delays in a 'hard' way as well. Which means suspend may
block indefinitely as well on network failure.
So it's two conflicting user requirements: 'hard NFS mount' and 'suspend
now'. We pick the lesser evil, the requirement that is considered higher
prio: the hard NFS mount in this case.
Thanks,
Ingo
next prev parent reply other threads:[~2013-05-05 9:23 UTC|newest]
Thread overview: 35+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-05-03 21:04 [PATCH 1/2] freezer: add unsafe versions of freezable helpers Colin Cross
2013-05-03 21:04 ` [PATCH 2/2] lockdep: check that no locks held at freeze time Colin Cross
[not found] ` <1367615050-3894-2-git-send-email-ccross-z5hGa2qSFaRBDgjK7y7TUQ@public.gmane.org>
2013-05-04 13:04 ` Pavel Machek
2013-05-04 20:27 ` Colin Cross
2013-05-04 22:57 ` Pavel Machek
[not found] ` <20130504225715.GB24276-tWAi6jLit6GreWDznjuHag@public.gmane.org>
2013-05-04 23:49 ` Colin Cross
2013-05-05 0:05 ` Pavel Machek
[not found] ` <20130505000528.GA25454-tWAi6jLit6GreWDznjuHag@public.gmane.org>
2013-05-05 0:23 ` Colin Cross
[not found] ` <CAMbhsRQso4fW_DVL6U3zfbX3YbLsTy8-rUA-fo61Aw93bU+sQQ-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
2013-05-05 1:13 ` Pavel Machek
2013-05-05 9:18 ` Ingo Molnar
[not found] ` <20130505091844.GC22239-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
2013-05-06 8:55 ` Peter Zijlstra
2013-05-06 12:11 ` Pavel Machek
2013-05-06 14:33 ` Linus Torvalds
2013-05-06 14:42 ` Peter Zijlstra
2013-05-06 19:01 ` Tejun Heo
2013-05-06 19:30 ` Colin Cross
2013-05-06 19:33 ` Tejun Heo
2013-05-06 20:06 ` Rafael J. Wysocki
2013-05-04 13:00 ` [PATCH 1/2] freezer: add unsafe versions of freezable helpers Pavel Machek
2013-05-04 20:23 ` Colin Cross
[not found] ` <CAMbhsRS6+hjTmrihVzgu3Dtyp8XAhJJ4VKMj=28G6xH3H73=6Q-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
2013-05-04 22:55 ` Pavel Machek
2013-05-05 9:23 ` Ingo Molnar [this message]
[not found] ` <20130505092318.GD22239-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
2013-05-05 22:12 ` Pavel Machek
[not found] ` <1367615050-3894-1-git-send-email-ccross-z5hGa2qSFaRBDgjK7y7TUQ@public.gmane.org>
2013-05-06 8:50 ` Peter Zijlstra
2013-05-06 10:58 ` Jeff Layton
2013-05-06 18:55 ` Tejun Heo
2013-05-06 10:56 ` Jeff Layton
2013-05-06 19:57 ` Colin Cross
[not found] ` <CAMbhsRQsFT2j_CuPL45J03itymcp3PNP8ckt3fAAo+hzavNrbw-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
2013-05-06 21:43 ` Jeff Layton
[not found] ` <20130506174336.447d0d75-9yPaYZwiELC+kQycOl6kW4xkIHaj4LzF@public.gmane.org>
2013-05-06 21:54 ` Colin Cross
2013-05-06 21:58 ` Linus Torvalds
2013-05-06 22:05 ` Jeff Layton
2013-05-06 22:11 ` Colin Cross
2013-05-06 22:14 ` Tejun Heo
2013-05-06 21:59 ` Jeff Layton
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