From: Jason Gunthorpe <jgg@ziepe.ca>
To: Christoph Hellwig <hch@infradead.org>
Cc: Andrea Arcangeli <aarcange@redhat.com>,
Philip Yang <Philip.Yang@amd.com>,
Ralph Campbell <rcampbell@nvidia.com>,
linux-rdma@vger.kernel.org, John Hubbard <jhubbard@nvidia.com>,
Felix.Kuehling@amd.com, dri-devel@lists.freedesktop.org,
linux-mm@kvack.org, Jerome Glisse <jglisse@redhat.com>,
amd-gfx@lists.freedesktop.org, Ben Skeggs <bskeggs@redhat.com>
Subject: Re: [PATCH v3 hmm 08/12] mm/hmm: Remove racy protection against double-unregistration
Date: Tue, 18 Jun 2019 10:13:24 -0300 [thread overview]
Message-ID: <20190618131324.GF6961@ziepe.ca> (raw)
In-Reply-To: <20190615141612.GH17724@infradead.org>
On Sat, Jun 15, 2019 at 07:16:12AM -0700, Christoph Hellwig wrote:
> On Thu, Jun 13, 2019 at 09:44:46PM -0300, Jason Gunthorpe wrote:
> > From: Jason Gunthorpe <jgg@mellanox.com>
> >
> > No other register/unregister kernel API attempts to provide this kind of
> > protection as it is inherently racy, so just drop it.
> >
> > Callers should provide their own protection, it appears nouveau already
> > does, but just in case drop a debugging POISON.
>
> I don't even think we even need to bother with the POISON, normal list
> debugging will already catch a double unregistration anyway.
mirror->hmm isn't a list so list debugging won't help.
My concern when I wrote this was that one of the in flight patches I
can't see might be depending on this double-unregister-is-safe
behavior, so I wanted them to crash reliably.
It is a really overly conservative thing to do..
Thanks,
Jason
_______________________________________________
dri-devel mailing list
dri-devel@lists.freedesktop.org
https://lists.freedesktop.org/mailman/listinfo/dri-devel
next prev parent reply other threads:[~2019-06-18 13:13 UTC|newest]
Thread overview: 45+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-06-14 0:44 [PATCH v3 hmm 00/12] mm/hmm: Various revisions from a locking/code review Jason Gunthorpe
2019-06-14 0:44 ` [PATCH v3 hmm 01/12] mm/hmm: fix use after free with struct hmm in the mmu notifiers Jason Gunthorpe
[not found] ` <20190614004450.20252-2-jgg-uk2M96/98Pc@public.gmane.org>
2019-06-15 13:56 ` Christoph Hellwig
2019-06-14 0:44 ` [PATCH v3 hmm 02/12] mm/hmm: Use hmm_mirror not mm as an argument for hmm_range_register Jason Gunthorpe
[not found] ` <20190614004450.20252-3-jgg-uk2M96/98Pc@public.gmane.org>
2019-06-15 13:59 ` Christoph Hellwig
2019-06-18 13:05 ` Jason Gunthorpe
[not found] ` <20190618130544.GC6961-uk2M96/98Pc@public.gmane.org>
2019-06-19 8:14 ` Christoph Hellwig
2019-06-14 0:44 ` [PATCH v3 hmm 03/12] mm/hmm: Hold a mmgrab from hmm to mm Jason Gunthorpe
[not found] ` <20190614004450.20252-4-jgg-uk2M96/98Pc@public.gmane.org>
2019-06-15 13:59 ` Christoph Hellwig
2019-06-14 0:44 ` [PATCH v3 hmm 04/12] mm/hmm: Simplify hmm_get_or_create and make it reliable Jason Gunthorpe
[not found] ` <20190614004450.20252-5-jgg-uk2M96/98Pc@public.gmane.org>
2019-06-15 14:12 ` Christoph Hellwig
2019-06-18 0:36 ` Jason Gunthorpe
2019-06-18 18:55 ` Jason Gunthorpe
2019-06-14 0:44 ` [PATCH v3 hmm 05/12] mm/hmm: Remove duplicate condition test before wait_event_timeout Jason Gunthorpe
[not found] ` <20190614004450.20252-6-jgg-uk2M96/98Pc@public.gmane.org>
2019-06-15 14:12 ` Christoph Hellwig
2019-06-14 0:44 ` [PATCH v3 hmm 06/12] mm/hmm: Hold on to the mmget for the lifetime of the range Jason Gunthorpe
[not found] ` <20190614004450.20252-7-jgg-uk2M96/98Pc@public.gmane.org>
2019-06-15 14:14 ` Christoph Hellwig
2019-06-18 15:11 ` Jason Gunthorpe
[not found] ` <20190618151100.GI6961-uk2M96/98Pc@public.gmane.org>
2019-06-19 8:18 ` Christoph Hellwig
2019-06-19 11:34 ` Jason Gunthorpe
[not found] ` <20190619113452.GB9360-uk2M96/98Pc@public.gmane.org>
2019-06-19 11:54 ` Christoph Hellwig
2019-06-14 0:44 ` [PATCH v3 hmm 07/12] mm/hmm: Use lockdep instead of comments Jason Gunthorpe
[not found] ` <20190614004450.20252-8-jgg-uk2M96/98Pc@public.gmane.org>
2019-06-15 14:14 ` Christoph Hellwig
2019-06-14 0:44 ` [PATCH v3 hmm 08/12] mm/hmm: Remove racy protection against double-unregistration Jason Gunthorpe
[not found] ` <20190614004450.20252-9-jgg-uk2M96/98Pc@public.gmane.org>
2019-06-15 14:16 ` Christoph Hellwig
2019-06-18 13:13 ` Jason Gunthorpe [this message]
[not found] ` <20190618131324.GF6961-uk2M96/98Pc@public.gmane.org>
2019-06-18 13:27 ` Christoph Hellwig
2019-06-18 18:57 ` Jason Gunthorpe
[not found] ` <20190618185757.GP6961-uk2M96/98Pc@public.gmane.org>
2019-06-19 8:19 ` Christoph Hellwig
2019-06-14 0:44 ` [PATCH v3 hmm 09/12] mm/hmm: Poison hmm_range during unregister Jason Gunthorpe
[not found] ` <20190614004450.20252-10-jgg-uk2M96/98Pc@public.gmane.org>
2019-06-15 14:17 ` Christoph Hellwig
2019-06-18 18:04 ` Jason Gunthorpe
2019-06-14 0:44 ` [PATCH v3 hmm 10/12] mm/hmm: Do not use list*_rcu() for hmm->ranges Jason Gunthorpe
[not found] ` <20190614004450.20252-11-jgg-uk2M96/98Pc@public.gmane.org>
2019-06-15 14:18 ` Christoph Hellwig
2019-06-18 0:38 ` Jason Gunthorpe
2019-06-14 0:44 ` [PATCH v3 hmm 11/12] mm/hmm: Remove confusing comment and logic from hmm_release Jason Gunthorpe
[not found] ` <20190614004450.20252-12-jgg-uk2M96/98Pc@public.gmane.org>
2019-06-15 14:21 ` Christoph Hellwig
2019-06-18 0:45 ` Jason Gunthorpe
[not found] ` <20190618004509.GE30762-uk2M96/98Pc@public.gmane.org>
2019-06-18 5:37 ` Christoph Hellwig
[not found] ` <20190618053733.GA25048-wEGCiKHe2LqWVfeAwA7xHQ@public.gmane.org>
2019-06-19 0:53 ` Kuehling, Felix
[not found] ` <be4f8573-6284-04a6-7862-23bb357bfe3c-5C7GfCeVMHo@public.gmane.org>
2019-06-19 8:07 ` Christoph Hellwig
2019-06-19 11:56 ` Jason Gunthorpe
[not found] ` <20190619115632.GC9360-uk2M96/98Pc@public.gmane.org>
2019-06-19 12:03 ` Christoph Hellwig
2019-06-14 0:44 ` [PATCH v3 hmm 12/12] mm/hmm: Fix error flows in hmm_invalidate_range_start Jason Gunthorpe
[not found] ` <20190614004450.20252-13-jgg-uk2M96/98Pc@public.gmane.org>
2019-06-15 14:25 ` Christoph Hellwig
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20190618131324.GF6961@ziepe.ca \
--to=jgg@ziepe.ca \
--cc=Felix.Kuehling@amd.com \
--cc=Philip.Yang@amd.com \
--cc=aarcange@redhat.com \
--cc=amd-gfx@lists.freedesktop.org \
--cc=bskeggs@redhat.com \
--cc=dri-devel@lists.freedesktop.org \
--cc=hch@infradead.org \
--cc=jglisse@redhat.com \
--cc=jhubbard@nvidia.com \
--cc=linux-mm@kvack.org \
--cc=linux-rdma@vger.kernel.org \
--cc=rcampbell@nvidia.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).