From: Jason Gunthorpe <jgg-uk2M96/98Pc@public.gmane.org>
To: Jerome Glisse <jglisse-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>,
Ralph Campbell
<rcampbell-DDmLM1+adcrQT0dZR+AlfA@public.gmane.org>,
John Hubbard <jhubbard-DDmLM1+adcrQT0dZR+AlfA@public.gmane.org>,
Felix.Kuehling-5C7GfCeVMHo@public.gmane.org
Cc: Andrea Arcangeli
<aarcange-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>,
Philip Yang <Philip.Yang-5C7GfCeVMHo@public.gmane.org>,
linux-rdma-u79uwXL29TY76Z2rM5mHXA@public.gmane.org,
amd-gfx-PD4FTy7X32lNgt0PjOBp9y5qC8QIuHrW@public.gmane.org,
linux-mm-Bw31MaZKKs3YtjvyW6yDsg@public.gmane.org,
Jason Gunthorpe <jgg-VPRAkNaXOzVWk0Htik3J/w@public.gmane.org>,
dri-devel-PD4FTy7X32lNgt0PjOBp9y5qC8QIuHrW@public.gmane.org,
Ira Weiny <ira.weiny-ral2JQCrhuEAvxtiuMwx3w@public.gmane.org>,
Christoph Hellwig <hch-jcswGhMUV9g@public.gmane.org>,
Ben Skeggs <bskeggs-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>
Subject: [PATCH v4 hmm 09/12] mm/hmm: Remove racy protection against double-unregistration
Date: Mon, 24 Jun 2019 18:01:07 -0300 [thread overview]
Message-ID: <20190624210110.5098-10-jgg@ziepe.ca> (raw)
In-Reply-To: <20190624210110.5098-1-jgg-uk2M96/98Pc@public.gmane.org>
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, and it appears nouveau
already does.
Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>
Reviewed-by: Jérôme Glisse <jglisse@redhat.com>
Reviewed-by: John Hubbard <jhubbard@nvidia.com>
Reviewed-by: Ralph Campbell <rcampbell@nvidia.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Tested-by: Philip Yang <Philip.Yang@amd.com>
---
v3
- Drop poison, looks like there are no new patches that will use this
wrong (Christoph)
---
mm/hmm.c | 8 +-------
1 file changed, 1 insertion(+), 7 deletions(-)
diff --git a/mm/hmm.c b/mm/hmm.c
index 6f5dc6d568feb1..2ef14b2b5505f6 100644
--- a/mm/hmm.c
+++ b/mm/hmm.c
@@ -276,17 +276,11 @@ EXPORT_SYMBOL(hmm_mirror_register);
*/
void hmm_mirror_unregister(struct hmm_mirror *mirror)
{
- struct hmm *hmm = READ_ONCE(mirror->hmm);
-
- if (hmm == NULL)
- return;
+ struct hmm *hmm = mirror->hmm;
down_write(&hmm->mirrors_sem);
list_del_init(&mirror->list);
- /* To protect us against double unregister ... */
- mirror->hmm = NULL;
up_write(&hmm->mirrors_sem);
-
hmm_put(hmm);
}
EXPORT_SYMBOL(hmm_mirror_unregister);
--
2.22.0
_______________________________________________
amd-gfx mailing list
amd-gfx@lists.freedesktop.org
https://lists.freedesktop.org/mailman/listinfo/amd-gfx
WARNING: multiple messages have this Message-ID (diff)
From: Jason Gunthorpe <jgg@ziepe.ca>
To: Jerome Glisse <jglisse@redhat.com>,
Ralph Campbell <rcampbell@nvidia.com>,
John Hubbard <jhubbard@nvidia.com>,
Felix.Kuehling@amd.com
Cc: linux-rdma@vger.kernel.org, linux-mm@kvack.org,
Andrea Arcangeli <aarcange@redhat.com>,
dri-devel@lists.freedesktop.org, amd-gfx@lists.freedesktop.org,
Ben Skeggs <bskeggs@redhat.com>, Christoph Hellwig <hch@lst.de>,
Philip Yang <Philip.Yang@amd.com>,
Ira Weiny <ira.weiny@intel.com>,
Jason Gunthorpe <jgg@mellanox.com>
Subject: [PATCH v4 hmm 09/12] mm/hmm: Remove racy protection against double-unregistration
Date: Mon, 24 Jun 2019 18:01:07 -0300 [thread overview]
Message-ID: <20190624210110.5098-10-jgg@ziepe.ca> (raw)
In-Reply-To: <20190624210110.5098-1-jgg@ziepe.ca>
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, and it appears nouveau
already does.
Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>
Reviewed-by: Jérôme Glisse <jglisse@redhat.com>
Reviewed-by: John Hubbard <jhubbard@nvidia.com>
Reviewed-by: Ralph Campbell <rcampbell@nvidia.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Tested-by: Philip Yang <Philip.Yang@amd.com>
---
v3
- Drop poison, looks like there are no new patches that will use this
wrong (Christoph)
---
mm/hmm.c | 8 +-------
1 file changed, 1 insertion(+), 7 deletions(-)
diff --git a/mm/hmm.c b/mm/hmm.c
index 6f5dc6d568feb1..2ef14b2b5505f6 100644
--- a/mm/hmm.c
+++ b/mm/hmm.c
@@ -276,17 +276,11 @@ EXPORT_SYMBOL(hmm_mirror_register);
*/
void hmm_mirror_unregister(struct hmm_mirror *mirror)
{
- struct hmm *hmm = READ_ONCE(mirror->hmm);
-
- if (hmm == NULL)
- return;
+ struct hmm *hmm = mirror->hmm;
down_write(&hmm->mirrors_sem);
list_del_init(&mirror->list);
- /* To protect us against double unregister ... */
- mirror->hmm = NULL;
up_write(&hmm->mirrors_sem);
-
hmm_put(hmm);
}
EXPORT_SYMBOL(hmm_mirror_unregister);
--
2.22.0
next prev parent reply other threads:[~2019-06-24 21:01 UTC|newest]
Thread overview: 36+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-06-24 21:00 [PATCH v4 hmm 00/12] Jason Gunthorpe
2019-06-24 21:00 ` Jason Gunthorpe
[not found] ` <20190624210110.5098-1-jgg-uk2M96/98Pc@public.gmane.org>
2019-06-24 21:00 ` [PATCH v4 hmm 01/12] mm/hmm: fix use after free with struct hmm in the mmu notifiers Jason Gunthorpe
2019-06-24 21:00 ` Jason Gunthorpe
2019-06-24 21:01 ` [PATCH v4 hmm 02/12] mm/hmm: Use hmm_mirror not mm as an argument for hmm_range_register Jason Gunthorpe
2019-06-24 21:01 ` Jason Gunthorpe
2019-06-24 21:01 ` [PATCH v4 hmm 03/12] mm/hmm: Hold a mmgrab from hmm to mm Jason Gunthorpe
2019-06-24 21:01 ` Jason Gunthorpe
2019-06-24 21:01 ` [PATCH v4 hmm 04/12] mm/hmm: Simplify hmm_get_or_create and make it reliable Jason Gunthorpe
2019-06-24 21:01 ` Jason Gunthorpe
[not found] ` <20190624210110.5098-5-jgg-uk2M96/98Pc@public.gmane.org>
2019-06-25 7:02 ` Christoph Hellwig
2019-06-25 7:02 ` Christoph Hellwig
2019-06-24 21:01 ` [PATCH v4 hmm 05/12] mm/hmm: Remove duplicate condition test before wait_event_timeout Jason Gunthorpe
2019-06-24 21:01 ` Jason Gunthorpe
2019-06-24 21:01 ` [PATCH v4 hmm 06/12] mm/hmm: Do not use list*_rcu() for hmm->ranges Jason Gunthorpe
2019-06-24 21:01 ` Jason Gunthorpe
2019-06-24 21:01 ` [PATCH v4 hmm 07/12] mm/hmm: Hold on to the mmget for the lifetime of the range Jason Gunthorpe
2019-06-24 21:01 ` Jason Gunthorpe
2019-06-24 21:01 ` [PATCH v4 hmm 08/12] mm/hmm: Use lockdep instead of comments Jason Gunthorpe
2019-06-24 21:01 ` Jason Gunthorpe
2019-06-24 21:01 ` Jason Gunthorpe [this message]
2019-06-24 21:01 ` [PATCH v4 hmm 09/12] mm/hmm: Remove racy protection against double-unregistration Jason Gunthorpe
2019-06-24 21:01 ` [PATCH v4 hmm 10/12] mm/hmm: Poison hmm_range during unregister Jason Gunthorpe
2019-06-24 21:01 ` Jason Gunthorpe
2019-06-24 21:01 ` [PATCH v4 hmm 11/12] mm/hmm: Remove confusing comment and logic from hmm_release Jason Gunthorpe
2019-06-24 21:01 ` Jason Gunthorpe
[not found] ` <20190624210110.5098-12-jgg-uk2M96/98Pc@public.gmane.org>
2019-06-25 7:03 ` Christoph Hellwig
2019-06-25 7:03 ` Christoph Hellwig
2019-06-24 21:01 ` [PATCH v4 hmm 12/12] mm/hmm: Fix error flows in hmm_invalidate_range_start Jason Gunthorpe
2019-06-24 21:01 ` Jason Gunthorpe
2019-06-26 18:18 ` Ralph Campbell
2019-06-26 18:18 ` Ralph Campbell
[not found] ` <035fa354-6caa-3738-b84d-20804813009a-DDmLM1+adcrQT0dZR+AlfA@public.gmane.org>
2019-06-27 16:06 ` Jason Gunthorpe
2019-06-27 16:06 ` Jason Gunthorpe
2019-06-29 1:26 ` [PATCH v4 hmm 00/12] Jason Gunthorpe
2019-06-29 1:26 ` Jason Gunthorpe
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