From: Christoph Hellwig <hch@lst.de>
To: "Dan Williams" <dan.j.williams@intel.com>,
"Jérôme Glisse" <jglisse@redhat.com>,
"Jason Gunthorpe" <jgg@mellanox.com>,
"Ben Skeggs" <bskeggs@redhat.com>
Cc: Ira Weiny <ira.weiny@intel.com>,
linux-mm@kvack.org, nouveau@lists.freedesktop.org,
dri-devel@lists.freedesktop.org, linux-nvdimm@lists.01.org,
linux-pci@vger.kernel.org, linux-kernel@vger.kernel.org,
John Hubbard <jhubbard@nvidia.com>,
Ralph Campbell <rcampbell@nvidia.com>,
Philip Yang <Philip.Yang@amd.com>
Subject: [PATCH 08/22] mm/hmm: Hold a mmgrab from hmm to mm
Date: Mon, 1 Jul 2019 08:20:06 +0200 [thread overview]
Message-ID: <20190701062020.19239-9-hch@lst.de> (raw)
In-Reply-To: <20190701062020.19239-1-hch@lst.de>
From: Jason Gunthorpe <jgg@mellanox.com>
So long as a struct hmm pointer exists, so should the struct mm it is
linked too. Hold the mmgrab() as soon as a hmm is created, and mmdrop() it
once the hmm refcount goes to zero.
Since mmdrop() (ie a 0 kref on struct mm) is now impossible with a !NULL
mm->hmm delete the hmm_hmm_destroy().
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: Ira Weiny <ira.weiny@intel.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Tested-by: Philip Yang <Philip.Yang@amd.com>
---
include/linux/hmm.h | 3 ---
kernel/fork.c | 1 -
mm/hmm.c | 22 ++++------------------
3 files changed, 4 insertions(+), 22 deletions(-)
diff --git a/include/linux/hmm.h b/include/linux/hmm.h
index 1fba6979adf4..1d97b6d62c5b 100644
--- a/include/linux/hmm.h
+++ b/include/linux/hmm.h
@@ -577,14 +577,11 @@ static inline int hmm_vma_fault(struct hmm_mirror *mirror,
}
/* Below are for HMM internal use only! Not to be used by device driver! */
-void hmm_mm_destroy(struct mm_struct *mm);
-
static inline void hmm_mm_init(struct mm_struct *mm)
{
mm->hmm = NULL;
}
#else /* IS_ENABLED(CONFIG_HMM_MIRROR) */
-static inline void hmm_mm_destroy(struct mm_struct *mm) {}
static inline void hmm_mm_init(struct mm_struct *mm) {}
#endif /* IS_ENABLED(CONFIG_HMM_MIRROR) */
diff --git a/kernel/fork.c b/kernel/fork.c
index 75675b9bf6df..c704c3cedee7 100644
--- a/kernel/fork.c
+++ b/kernel/fork.c
@@ -673,7 +673,6 @@ void __mmdrop(struct mm_struct *mm)
WARN_ON_ONCE(mm == current->active_mm);
mm_free_pgd(mm);
destroy_context(mm);
- hmm_mm_destroy(mm);
mmu_notifier_mm_destroy(mm);
check_mm(mm);
put_user_ns(mm->user_ns);
diff --git a/mm/hmm.c b/mm/hmm.c
index 22a97ada108b..080b17a2e87e 100644
--- a/mm/hmm.c
+++ b/mm/hmm.c
@@ -20,6 +20,7 @@
#include <linux/swapops.h>
#include <linux/hugetlb.h>
#include <linux/memremap.h>
+#include <linux/sched/mm.h>
#include <linux/jump_label.h>
#include <linux/dma-mapping.h>
#include <linux/mmu_notifier.h>
@@ -73,6 +74,7 @@ static struct hmm *hmm_get_or_create(struct mm_struct *mm)
hmm->notifiers = 0;
hmm->dead = false;
hmm->mm = mm;
+ mmgrab(hmm->mm);
spin_lock(&mm->page_table_lock);
if (!mm->hmm)
@@ -100,6 +102,7 @@ static struct hmm *hmm_get_or_create(struct mm_struct *mm)
mm->hmm = NULL;
spin_unlock(&mm->page_table_lock);
error:
+ mmdrop(hmm->mm);
kfree(hmm);
return NULL;
}
@@ -121,6 +124,7 @@ static void hmm_free(struct kref *kref)
mm->hmm = NULL;
spin_unlock(&mm->page_table_lock);
+ mmdrop(hmm->mm);
mmu_notifier_call_srcu(&hmm->rcu, hmm_free_rcu);
}
@@ -129,24 +133,6 @@ static inline void hmm_put(struct hmm *hmm)
kref_put(&hmm->kref, hmm_free);
}
-void hmm_mm_destroy(struct mm_struct *mm)
-{
- struct hmm *hmm;
-
- spin_lock(&mm->page_table_lock);
- hmm = mm_get_hmm(mm);
- mm->hmm = NULL;
- if (hmm) {
- hmm->mm = NULL;
- hmm->dead = true;
- spin_unlock(&mm->page_table_lock);
- hmm_put(hmm);
- return;
- }
-
- spin_unlock(&mm->page_table_lock);
-}
-
static void hmm_release(struct mmu_notifier *mn, struct mm_struct *mm)
{
struct hmm *hmm = container_of(mn, struct hmm, mmu_notifier);
--
2.20.1
next prev parent reply other threads:[~2019-07-01 6:20 UTC|newest]
Thread overview: 40+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-07-01 6:19 dev_pagemap related cleanups v4 Christoph Hellwig
2019-07-01 6:19 ` [PATCH 01/22] mm/hmm.c: suppress compilation warnings when CONFIG_HUGETLB_PAGE is not set Christoph Hellwig
2019-07-01 6:20 ` [PATCH 02/22] mm/hmm: update HMM documentation Christoph Hellwig
2019-07-01 6:20 ` [PATCH 03/22] mm/hmm: clean up some coding style and comments Christoph Hellwig
2019-07-01 6:20 ` [PATCH 04/22] mm/hmm: support automatic NUMA balancing Christoph Hellwig
2019-07-01 6:20 ` [PATCH 05/22] mm/hmm: Only set FAULT_FLAG_ALLOW_RETRY for non-blocking Christoph Hellwig
2019-07-01 6:20 ` [PATCH 06/22] mm/hmm: fix use after free with struct hmm in the mmu notifiers Christoph Hellwig
2019-07-01 6:20 ` [PATCH 07/22] mm/hmm: Use hmm_mirror not mm as an argument for hmm_range_register Christoph Hellwig
2019-07-01 6:20 ` Christoph Hellwig [this message]
2019-07-01 6:20 ` [PATCH 09/22] mm/hmm: Simplify hmm_get_or_create and make it reliable Christoph Hellwig
2019-07-01 6:20 ` [PATCH 10/22] mm/hmm: Remove duplicate condition test before wait_event_timeout Christoph Hellwig
2019-07-01 6:20 ` [PATCH 11/22] mm/hmm: Do not use list*_rcu() for hmm->ranges Christoph Hellwig
2019-07-01 6:20 ` [PATCH 12/22] mm/hmm: Hold on to the mmget for the lifetime of the range Christoph Hellwig
2019-07-01 6:20 ` [PATCH 13/22] mm/hmm: Use lockdep instead of comments Christoph Hellwig
2019-07-01 6:20 ` [PATCH 14/22] mm/hmm: Remove racy protection against double-unregistration Christoph Hellwig
2019-07-01 6:20 ` [PATCH 15/22] mm/hmm: Poison hmm_range during unregister Christoph Hellwig
2019-07-01 6:20 ` [PATCH 16/22] mm/hmm: Remove confusing comment and logic from hmm_release Christoph Hellwig
2019-07-01 6:20 ` [PATCH 17/22] mm/hmm: Fix error flows in hmm_invalidate_range_start Christoph Hellwig
2019-07-01 6:20 ` [PATCH 18/22] mm: return valid info from hmm_range_unregister Christoph Hellwig
2019-07-03 17:22 ` Ralph Campbell
2019-07-01 6:20 ` [PATCH 19/22] mm: always return EBUSY for invalid ranges in hmm_range_{fault,snapshot} Christoph Hellwig
2019-07-02 21:43 ` Kuehling, Felix
2019-07-03 17:32 ` Ralph Campbell
2019-07-01 6:20 ` [PATCH 20/22] mm: move hmm_vma_fault to nouveau Christoph Hellwig
2019-07-03 17:48 ` Ralph Campbell
2019-07-03 17:50 ` [Nouveau] " Ilia Mirkin
2019-07-03 18:03 ` Jason Gunthorpe
2019-07-03 18:05 ` Christoph Hellwig
2019-07-03 18:13 ` Jason Gunthorpe
2019-07-01 6:20 ` [PATCH 21/22] nouveau: unlock mmap_sem on all errors from nouveau_range_fault Christoph Hellwig
2019-07-01 6:20 ` [PATCH 22/22] mm: remove the legacy hmm_pfn_* APIs Christoph Hellwig
2019-07-03 18:01 ` Jason Gunthorpe
2019-07-03 18:03 ` Christoph Hellwig
2019-07-03 18:15 ` Jason Gunthorpe
2019-07-01 8:25 ` dev_pagemap related cleanups v4 Christoph Hellwig
2019-07-02 18:42 ` Jason Gunthorpe
2019-07-02 22:45 ` Weiny, Ira
2019-07-02 22:47 ` Christoph Hellwig
2019-07-02 23:17 ` Dan Williams
2019-07-03 1:08 ` Jason Gunthorpe
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