From: Jerome Glisse <jglisse@redhat.com>
To: Jason Gunthorpe <jgg@ziepe.ca>
Cc: Ralph Campbell <rcampbell@nvidia.com>,
John Hubbard <jhubbard@nvidia.com>,
Felix.Kuehling@amd.com, 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>,
Jason Gunthorpe <jgg@mellanox.com>
Subject: Re: [PATCH hmm 03/15] mm/hmm: allow hmm_range to be used with a mmu_range_notifier or hmm_mirror
Date: Mon, 21 Oct 2019 14:33:51 -0400 [thread overview]
Message-ID: <20191021183351.GD3177@redhat.com> (raw)
In-Reply-To: <20191015181242.8343-4-jgg@ziepe.ca>
On Tue, Oct 15, 2019 at 03:12:30PM -0300, Jason Gunthorpe wrote:
> From: Jason Gunthorpe <jgg@mellanox.com>
>
> hmm_mirror's handling of ranges does not use a sequence count which
> results in this bug:
>
> CPU0 CPU1
> hmm_range_wait_until_valid(range)
> valid == true
> hmm_range_fault(range)
> hmm_invalidate_range_start()
> range->valid = false
> hmm_invalidate_range_end()
> range->valid = true
> hmm_range_valid(range)
> valid == true
>
> Where the hmm_range_valid should not have succeeded.
>
> Adding the required sequence count would make it nearly identical to the
> new mmu_range_notifier. Instead replace the hmm_mirror stuff with
> mmu_range_notifier.
>
> Co-existence of the two APIs is the first step.
>
> Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>
Reviewed-by: Jérôme Glisse <jglisse@redhat.com>
> ---
> include/linux/hmm.h | 5 +++++
> mm/hmm.c | 25 +++++++++++++++++++------
> 2 files changed, 24 insertions(+), 6 deletions(-)
>
> diff --git a/include/linux/hmm.h b/include/linux/hmm.h
> index 3fec513b9c00f1..8ac1fd6a81af8f 100644
> --- a/include/linux/hmm.h
> +++ b/include/linux/hmm.h
> @@ -145,6 +145,9 @@ enum hmm_pfn_value_e {
> /*
> * struct hmm_range - track invalidation lock on virtual address range
> *
> + * @notifier: an optional mmu_range_notifier
> + * @notifier_seq: when notifier is used this is the result of
> + * mmu_range_read_begin()
> * @hmm: the core HMM structure this range is active against
> * @vma: the vm area struct for the range
> * @list: all range lock are on a list
> @@ -159,6 +162,8 @@ enum hmm_pfn_value_e {
> * @valid: pfns array did not change since it has been fill by an HMM function
> */
> struct hmm_range {
> + struct mmu_range_notifier *notifier;
> + unsigned long notifier_seq;
> struct hmm *hmm;
> struct list_head list;
> unsigned long start;
> diff --git a/mm/hmm.c b/mm/hmm.c
> index 902f5fa6bf93ad..22ac3595771feb 100644
> --- a/mm/hmm.c
> +++ b/mm/hmm.c
> @@ -852,6 +852,14 @@ void hmm_range_unregister(struct hmm_range *range)
> }
> EXPORT_SYMBOL(hmm_range_unregister);
>
> +static bool needs_retry(struct hmm_range *range)
> +{
> + if (range->notifier)
> + return mmu_range_check_retry(range->notifier,
> + range->notifier_seq);
> + return !range->valid;
> +}
> +
> static const struct mm_walk_ops hmm_walk_ops = {
> .pud_entry = hmm_vma_walk_pud,
> .pmd_entry = hmm_vma_walk_pmd,
> @@ -892,18 +900,23 @@ long hmm_range_fault(struct hmm_range *range, unsigned int flags)
> const unsigned long device_vma = VM_IO | VM_PFNMAP | VM_MIXEDMAP;
> unsigned long start = range->start, end;
> struct hmm_vma_walk hmm_vma_walk;
> - struct hmm *hmm = range->hmm;
> + struct mm_struct *mm;
> struct vm_area_struct *vma;
> int ret;
>
> - lockdep_assert_held(&hmm->mmu_notifier.mm->mmap_sem);
> + if (range->notifier)
> + mm = range->notifier->mm;
> + else
> + mm = range->hmm->mmu_notifier.mm;
> +
> + lockdep_assert_held(&mm->mmap_sem);
>
> do {
> /* If range is no longer valid force retry. */
> - if (!range->valid)
> + if (needs_retry(range))
> return -EBUSY;
>
> - vma = find_vma(hmm->mmu_notifier.mm, start);
> + vma = find_vma(mm, start);
> if (vma == NULL || (vma->vm_flags & device_vma))
> return -EFAULT;
>
> @@ -933,7 +946,7 @@ long hmm_range_fault(struct hmm_range *range, unsigned int flags)
> start = hmm_vma_walk.last;
>
> /* Keep trying while the range is valid. */
> - } while (ret == -EBUSY && range->valid);
> + } while (ret == -EBUSY && !needs_retry(range));
>
> if (ret) {
> unsigned long i;
> @@ -991,7 +1004,7 @@ long hmm_range_dma_map(struct hmm_range *range, struct device *device,
> continue;
>
> /* Check if range is being invalidated */
> - if (!range->valid) {
> + if (needs_retry(range)) {
> ret = -EBUSY;
> goto unmap;
> }
> --
> 2.23.0
>
next prev parent reply other threads:[~2019-10-21 18:33 UTC|newest]
Thread overview: 58+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-10-15 18:12 [PATCH hmm 00/15] Consolidate the mmu notifier interval_tree and locking Jason Gunthorpe
2019-10-15 18:12 ` [PATCH hmm 01/15] mm/mmu_notifier: define the header pre-processor parts even if disabled Jason Gunthorpe
2019-10-21 18:32 ` Jerome Glisse
2019-10-15 18:12 ` [PATCH hmm 02/15] mm/mmu_notifier: add an interval tree notifier Jason Gunthorpe
2019-10-21 18:30 ` Jerome Glisse
2019-10-21 18:54 ` Jason Gunthorpe
2019-10-21 19:11 ` Jerome Glisse
2019-10-21 19:24 ` Jason Gunthorpe
2019-10-21 19:47 ` Jerome Glisse
2019-10-27 23:15 ` Jason Gunthorpe
2019-10-15 18:12 ` [PATCH hmm 03/15] mm/hmm: allow hmm_range to be used with a mmu_range_notifier or hmm_mirror Jason Gunthorpe
2019-10-21 18:33 ` Jerome Glisse [this message]
2019-10-15 18:12 ` [PATCH hmm 04/15] mm/hmm: define the pre-processor related parts of hmm.h even if disabled Jason Gunthorpe
2019-10-21 18:31 ` Jerome Glisse
2019-10-15 18:12 ` [PATCH hmm 05/15] RDMA/odp: Use mmu_range_notifier_insert() Jason Gunthorpe
2019-11-04 20:25 ` Jason Gunthorpe
2019-10-15 18:12 ` [PATCH hmm 06/15] RDMA/hfi1: Use mmu_range_notifier_inset for user_exp_rcv Jason Gunthorpe
2019-10-29 12:15 ` Dennis Dalessandro
2019-10-15 18:12 ` [PATCH hmm 07/15] drm/radeon: use mmu_range_notifier_insert Jason Gunthorpe
2019-10-15 18:12 ` [PATCH hmm 08/15] xen/gntdev: Use select for DMA_SHARED_BUFFER Jason Gunthorpe
2019-10-16 5:11 ` Jürgen Groß
2019-10-16 6:35 ` Oleksandr Andrushchenko
2019-10-21 19:12 ` Jason Gunthorpe
2019-10-28 6:25 ` [Xen-devel] " Oleksandr Andrushchenko
2019-10-15 18:12 ` [PATCH hmm 09/15] xen/gntdev: use mmu_range_notifier_insert Jason Gunthorpe
2019-10-15 18:12 ` [PATCH hmm 10/15] nouveau: use mmu_notifier directly for invalidate_range_start Jason Gunthorpe
2019-10-15 18:12 ` [PATCH hmm 11/15] nouveau: use mmu_range_notifier instead of hmm_mirror Jason Gunthorpe
2019-10-15 18:12 ` [PATCH hmm 12/15] drm/amdgpu: Call find_vma under mmap_sem Jason Gunthorpe
2019-10-15 18:12 ` [PATCH hmm 13/15] drm/amdgpu: Use mmu_range_insert instead of hmm_mirror Jason Gunthorpe
2019-10-15 18:12 ` [PATCH hmm 14/15] drm/amdgpu: Use mmu_range_notifier " Jason Gunthorpe
2019-10-15 18:12 ` [PATCH hmm 15/15] mm/hmm: remove hmm_mirror and related Jason Gunthorpe
2019-10-21 18:38 ` Jerome Glisse
2019-10-21 18:57 ` Jason Gunthorpe
2019-10-21 19:19 ` Jerome Glisse
2019-10-16 8:58 ` [PATCH hmm 00/15] Consolidate the mmu notifier interval_tree and locking Christian König
2019-10-16 16:04 ` Jason Gunthorpe
2019-10-17 8:54 ` Christian König
2019-10-17 16:26 ` Yang, Philip
2019-10-17 16:47 ` Koenig, Christian
2019-10-18 20:36 ` Jason Gunthorpe
2019-10-20 14:21 ` Koenig, Christian
2019-10-21 13:57 ` Jason Gunthorpe
2019-10-21 14:28 ` Koenig, Christian
2019-10-21 15:12 ` Jason Gunthorpe
2019-10-22 7:57 ` Daniel Vetter
2019-10-22 15:01 ` Jason Gunthorpe
2019-10-23 9:08 ` Daniel Vetter
2019-10-23 9:32 ` Christian König
2019-10-23 16:52 ` Jerome Glisse
2019-10-23 17:24 ` Jason Gunthorpe
2019-10-24 2:16 ` Christoph Hellwig
2019-10-21 15:55 ` Dennis Dalessandro
2019-10-21 16:58 ` Jason Gunthorpe
2019-10-22 11:56 ` Dennis Dalessandro
2019-10-22 14:37 ` Jason Gunthorpe
2019-10-21 18:40 ` Jerome Glisse
2019-10-21 19:06 ` Jason Gunthorpe
2019-10-23 20:26 ` Jerome Glisse
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