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From: Andrea Arcangeli <aarcange@redhat.com>
To: Michal Hocko <mhocko@kernel.org>
Cc: Mike Rapoport <rppt@linux.vnet.ibm.com>,
	Andrew Morton <akpm@linux-foundation.org>,
	"Dr. David Alan Gilbert" <dgilbert@redhat.com>,
	Pavel Emelyanov <xemul@virtuozzo.com>,
	linux-mm <linux-mm@kvack.org>,
	lkml <linux-kernel@vger.kernel.org>,
	stable@vger.kernel.org
Subject: Re: [PATCH] userfaultfd_zeropage: return -ENOSPC in case mm has gone
Date: Wed, 2 Aug 2017 18:40:01 +0200	[thread overview]
Message-ID: <20170802164001.GF21775@redhat.com> (raw)
In-Reply-To: <20170802162248.GA3476@dhcp22.suse.cz>

On Wed, Aug 02, 2017 at 06:22:49PM +0200, Michal Hocko wrote:
> ESRCH refers to "no such process". Strictly speaking userfaultfd code is
> about a mm which is gone but that is a mere detail. In fact the owner of

Well this whole issue about which retval, is about a mere detail in
the first place, so I don't think you can discount all other mere
details as irrelevant in the evaluation of a change to solve a mere
detail.

> But as I've said, this might be really risky to change. My impression
> was that userfaultfd is not widely used yet and those can be fixed
> easily but if that is not the case then we have to live with the current
> ENOSPC.

The only change would be for userfaultfd non cooperative mode, and
CRIU is the main user of that. So I think it is up to Mike to decide,
I'm fine either ways. I certainly agree ESRCH could be a slightly
better fit, I only wanted to clarify it's not a 100% match either.

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WARNING: multiple messages have this Message-ID (diff)
From: Andrea Arcangeli <aarcange@redhat.com>
To: Michal Hocko <mhocko@kernel.org>
Cc: Mike Rapoport <rppt@linux.vnet.ibm.com>,
	Andrew Morton <akpm@linux-foundation.org>,
	"Dr. David Alan Gilbert" <dgilbert@redhat.com>,
	Pavel Emelyanov <xemul@virtuozzo.com>,
	linux-mm <linux-mm@kvack.org>,
	lkml <linux-kernel@vger.kernel.org>,
	stable@vger.kernel.org
Subject: Re: [PATCH] userfaultfd_zeropage: return -ENOSPC in case mm has gone
Date: Wed, 2 Aug 2017 18:40:01 +0200	[thread overview]
Message-ID: <20170802164001.GF21775@redhat.com> (raw)
In-Reply-To: <20170802162248.GA3476@dhcp22.suse.cz>

On Wed, Aug 02, 2017 at 06:22:49PM +0200, Michal Hocko wrote:
> ESRCH refers to "no such process". Strictly speaking userfaultfd code is
> about a mm which is gone but that is a mere detail. In fact the owner of

Well this whole issue about which retval, is about a mere detail in
the first place, so I don't think you can discount all other mere
details as irrelevant in the evaluation of a change to solve a mere
detail.

> But as I've said, this might be really risky to change. My impression
> was that userfaultfd is not widely used yet and those can be fixed
> easily but if that is not the case then we have to live with the current
> ENOSPC.

The only change would be for userfaultfd non cooperative mode, and
CRIU is the main user of that. So I think it is up to Mike to decide,
I'm fine either ways. I certainly agree ESRCH could be a slightly
better fit, I only wanted to clarify it's not a 100% match either.

  reply	other threads:[~2017-08-02 16:40 UTC|newest]

Thread overview: 24+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2017-07-27  6:26 [PATCH] userfaultfd_zeropage: return -ENOSPC in case mm has gone Mike Rapoport
2017-07-27  6:26 ` Mike Rapoport
2017-07-31 12:22 ` Michal Hocko
2017-07-31 12:22   ` Michal Hocko
2017-07-31 13:32   ` Andrea Arcangeli
2017-07-31 13:32     ` Andrea Arcangeli
2017-07-31 13:45     ` Michal Hocko
2017-07-31 13:45       ` Michal Hocko
2017-08-02 12:34       ` Mike Rapoport
2017-08-02 12:34         ` Mike Rapoport
2017-08-02 13:21         ` Dr. David Alan Gilbert
2017-08-02 13:21           ` Dr. David Alan Gilbert
2017-08-02 15:55         ` Andrea Arcangeli
2017-08-02 15:55           ` Andrea Arcangeli
2017-08-02 16:22           ` Michal Hocko
2017-08-02 16:22             ` Michal Hocko
2017-08-02 16:40             ` Andrea Arcangeli [this message]
2017-08-02 16:40               ` Andrea Arcangeli
2017-08-03 17:24               ` Mike Rapoport
2017-08-03 17:24                 ` Mike Rapoport
2017-08-03 21:25                 ` Andrea Arcangeli
2017-08-03 21:25                   ` Andrea Arcangeli
2017-07-31 13:36   ` Mike Rapoport
2017-07-31 13:36     ` Mike Rapoport

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