From: Ralph Campbell <rcampbell@nvidia.com>
To: "Christoph Hellwig" <hch@lst.de>,
"Dan Williams" <dan.j.williams@intel.com>,
"Jérôme Glisse" <jglisse@redhat.com>,
"Jason Gunthorpe" <jgg@mellanox.com>,
"Ben Skeggs" <bskeggs@redhat.com>
Cc: <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>
Subject: Re: [PATCH 10/22] memremap: add a migrate callback to struct dev_pagemap_ops
Date: Thu, 13 Jun 2019 16:42:07 -0700 [thread overview]
Message-ID: <d6916d71-c17e-74df-58f2-c28ff8044b96@nvidia.com> (raw)
In-Reply-To: <20190613094326.24093-11-hch@lst.de>
On 6/13/19 2:43 AM, Christoph Hellwig wrote:
> This replaces the hacky ->fault callback, which is currently directly
> called from common code through a hmm specific data structure as an
> exercise in layering violations.
>
> Signed-off-by: Christoph Hellwig <hch@lst.de>
> ---
> include/linux/hmm.h | 6 ------
> include/linux/memremap.h | 6 ++++++
> include/linux/swapops.h | 15 ---------------
> kernel/memremap.c | 31 -------------------------------
> mm/hmm.c | 13 +++++--------
> mm/memory.c | 9 ++-------
> 6 files changed, 13 insertions(+), 67 deletions(-)
>
> diff --git a/include/linux/hmm.h b/include/linux/hmm.h
> index 5761a39221a6..3c9a59dbfdb8 100644
> --- a/include/linux/hmm.h
> +++ b/include/linux/hmm.h
> @@ -658,11 +658,6 @@ struct hmm_devmem_ops {
> * chunk, as an optimization. It must, however, prioritize the faulting address
> * over all the others.
> */
> -typedef vm_fault_t (*dev_page_fault_t)(struct vm_area_struct *vma,
> - unsigned long addr,
> - const struct page *page,
> - unsigned int flags,
> - pmd_t *pmdp);
>
> struct hmm_devmem {
> struct completion completion;
> @@ -673,7 +668,6 @@ struct hmm_devmem {
> struct dev_pagemap pagemap;
> const struct hmm_devmem_ops *ops;
> struct percpu_ref ref;
> - dev_page_fault_t page_fault;
> };
>
> /*
> diff --git a/include/linux/memremap.h b/include/linux/memremap.h
> index 96a3a6d564ad..03a4099be701 100644
> --- a/include/linux/memremap.h
> +++ b/include/linux/memremap.h
> @@ -75,6 +75,12 @@ struct dev_pagemap_ops {
> * Transition the percpu_ref in struct dev_pagemap to the dead state.
> */
> void (*kill)(struct dev_pagemap *pgmap);
> +
> + /*
> + * Used for private (un-addressable) device memory only. Must migrate
> + * the page back to a CPU accessible page.
> + */
> + vm_fault_t (*migrate)(struct vm_fault *vmf);
> };
>
> /**
> diff --git a/include/linux/swapops.h b/include/linux/swapops.h
> index 4d961668e5fc..15bdb6fe71e5 100644
> --- a/include/linux/swapops.h
> +++ b/include/linux/swapops.h
> @@ -129,12 +129,6 @@ static inline struct page *device_private_entry_to_page(swp_entry_t entry)
> {
> return pfn_to_page(swp_offset(entry));
> }
> -
> -vm_fault_t device_private_entry_fault(struct vm_area_struct *vma,
> - unsigned long addr,
> - swp_entry_t entry,
> - unsigned int flags,
> - pmd_t *pmdp);
> #else /* CONFIG_DEVICE_PRIVATE */
> static inline swp_entry_t make_device_private_entry(struct page *page, bool write)
> {
> @@ -164,15 +158,6 @@ static inline struct page *device_private_entry_to_page(swp_entry_t entry)
> {
> return NULL;
> }
> -
> -static inline vm_fault_t device_private_entry_fault(struct vm_area_struct *vma,
> - unsigned long addr,
> - swp_entry_t entry,
> - unsigned int flags,
> - pmd_t *pmdp)
> -{
> - return VM_FAULT_SIGBUS;
> -}
> #endif /* CONFIG_DEVICE_PRIVATE */
>
> #ifdef CONFIG_MIGRATION
> diff --git a/kernel/memremap.c b/kernel/memremap.c
> index 6a3183cac764..7167e717647d 100644
> --- a/kernel/memremap.c
> +++ b/kernel/memremap.c
> @@ -11,7 +11,6 @@
> #include <linux/types.h>
> #include <linux/wait_bit.h>
> #include <linux/xarray.h>
> -#include <linux/hmm.h>
>
> static DEFINE_XARRAY(pgmap_array);
> #define SECTION_MASK ~((1UL << PA_SECTION_SHIFT) - 1)
> @@ -48,36 +47,6 @@ static inline int dev_pagemap_enable(struct device *dev)
> }
> #endif /* CONFIG_DEV_PAGEMAP_OPS */
>
> -#if IS_ENABLED(CONFIG_DEVICE_PRIVATE)
> -vm_fault_t device_private_entry_fault(struct vm_area_struct *vma,
> - unsigned long addr,
> - swp_entry_t entry,
> - unsigned int flags,
> - pmd_t *pmdp)
> -{
> - struct page *page = device_private_entry_to_page(entry);
> - struct hmm_devmem *devmem;
> -
> - devmem = container_of(page->pgmap, typeof(*devmem), pagemap);
> -
> - /*
> - * The page_fault() callback must migrate page back to system memory
> - * so that CPU can access it. This might fail for various reasons
> - * (device issue, device was unsafely unplugged, ...). When such
> - * error conditions happen, the callback must return VM_FAULT_SIGBUS.
> - *
> - * Note that because memory cgroup charges are accounted to the device
> - * memory, this should never fail because of memory restrictions (but
> - * allocation of regular system page might still fail because we are
> - * out of memory).
> - *
> - * There is a more in-depth description of what that callback can and
> - * cannot do, in include/linux/memremap.h
> - */
> - return devmem->page_fault(vma, addr, page, flags, pmdp);
> -}
> -#endif /* CONFIG_DEVICE_PRIVATE */
> -
> static void pgmap_array_delete(struct resource *res)
> {
> xa_store_range(&pgmap_array, PHYS_PFN(res->start), PHYS_PFN(res->end),
> diff --git a/mm/hmm.c b/mm/hmm.c
> index 6dc769feb2e1..aab799677c7d 100644
> --- a/mm/hmm.c
> +++ b/mm/hmm.c
> @@ -1330,15 +1330,12 @@ static void hmm_devmem_ref_kill(struct dev_pagemap *pgmap)
> percpu_ref_kill(pgmap->ref);
> }
>
> -static vm_fault_t hmm_devmem_fault(struct vm_area_struct *vma,
> - unsigned long addr,
> - const struct page *page,
> - unsigned int flags,
> - pmd_t *pmdp)
> +static vm_fault_t hmm_devmem_migrate(struct vm_fault *vmf)
> {
> - struct hmm_devmem *devmem = page->pgmap->data;
> + struct hmm_devmem *devmem = vmf->page->pgmap->data;
>
> - return devmem->ops->fault(devmem, vma, addr, page, flags, pmdp);
> + return devmem->ops->fault(devmem, vmf->vma, vmf->address, vmf->page,
> + vmf->flags, vmf->pmd);
> }
>
> static void hmm_devmem_free(struct page *page, void *data)
> @@ -1351,6 +1348,7 @@ static void hmm_devmem_free(struct page *page, void *data)
> static const struct dev_pagemap_ops hmm_pagemap_ops = {
> .page_free = hmm_devmem_free,
> .kill = hmm_devmem_ref_kill,
> + .migrate = hmm_devmem_migrate,
> };
>
> /*
> @@ -1405,7 +1403,6 @@ struct hmm_devmem *hmm_devmem_add(const struct hmm_devmem_ops *ops,
> devmem->pfn_first = devmem->resource->start >> PAGE_SHIFT;
> devmem->pfn_last = devmem->pfn_first +
> (resource_size(devmem->resource) >> PAGE_SHIFT);
> - devmem->page_fault = hmm_devmem_fault;
>
> devmem->pagemap.type = MEMORY_DEVICE_PRIVATE;
> devmem->pagemap.res = *devmem->resource;
> diff --git a/mm/memory.c b/mm/memory.c
> index ddf20bd0c317..cbf3cb598436 100644
> --- a/mm/memory.c
> +++ b/mm/memory.c
> @@ -2782,13 +2782,8 @@ vm_fault_t do_swap_page(struct vm_fault *vmf)
> migration_entry_wait(vma->vm_mm, vmf->pmd,
> vmf->address);
> } else if (is_device_private_entry(entry)) {
> - /*
> - * For un-addressable device memory we call the pgmap
> - * fault handler callback. The callback must migrate
> - * the page back to some CPU accessible page.
> - */
> - ret = device_private_entry_fault(vma, vmf->address, entry,
> - vmf->flags, vmf->pmd);
> + vmf->page = device_private_entry_to_page(entry);
> + ret = page->pgmap->ops->migrate(vmf);
This needs to either initialize "page" or be changed to "vmf->page".
Otherwise, it is a NULL pointer dereference.
> } else if (is_hwpoison_entry(entry)) {
> ret = VM_FAULT_HWPOISON;
> } else {
>
You can add:
Reviewed-by: Ralph Campbell <rcampbell@nvidia.com>
next prev parent reply other threads:[~2019-06-13 23:42 UTC|newest]
Thread overview: 103+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-06-13 9:43 dev_pagemap related cleanups Christoph Hellwig
2019-06-13 9:43 ` [PATCH 01/22] mm: remove the unused ARCH_HAS_HMM_DEVICE Kconfig option Christoph Hellwig
2019-06-13 18:30 ` Jason Gunthorpe
2019-06-13 9:43 ` [PATCH 02/22] mm: remove the struct hmm_device infrastructure Christoph Hellwig
2019-06-13 18:46 ` Jason Gunthorpe
2019-06-13 23:06 ` [Nouveau] " John Hubbard
2019-06-13 9:43 ` [PATCH 03/22] mm: remove hmm_devmem_add_resource Christoph Hellwig
2019-06-13 18:52 ` Jason Gunthorpe
2019-06-14 6:19 ` Christoph Hellwig
2019-06-14 0:54 ` [Nouveau] " John Hubbard
2019-06-20 19:32 ` Michal Hocko
2019-06-13 9:43 ` [PATCH 04/22] mm: don't clear ->mapping in hmm_devmem_free Christoph Hellwig
2019-06-13 19:05 ` Jason Gunthorpe
2019-06-14 6:21 ` Christoph Hellwig
2019-06-14 1:46 ` John Hubbard
2019-06-20 19:36 ` Michal Hocko
2019-06-13 9:43 ` [PATCH 05/22] mm: export alloc_pages_vma Christoph Hellwig
2019-06-14 1:47 ` John Hubbard
2019-06-14 6:23 ` Christoph Hellwig
2019-06-20 19:17 ` Michal Hocko
2019-06-24 18:24 ` Dan Williams
2019-06-25 7:23 ` Christoph Hellwig
2019-06-25 15:00 ` Michal Hocko
2019-06-25 18:03 ` Dan Williams
2019-06-25 19:00 ` Michal Hocko
2019-06-25 19:52 ` Dan Williams
2019-06-26 5:46 ` Michal Hocko
2019-06-26 16:14 ` Dan Williams
2019-06-27 6:41 ` Michal Hocko
2019-06-13 9:43 ` [PATCH 06/22] mm: factor out a devm_request_free_mem_region helper Christoph Hellwig
2019-06-13 19:16 ` Jason Gunthorpe
2019-06-14 6:24 ` Christoph Hellwig
2019-06-15 2:21 ` John Hubbard
2019-06-15 14:30 ` Christoph Hellwig
2019-06-13 9:43 ` [PATCH 07/22] memremap: move dev_pagemap callbacks into a separate structure Christoph Hellwig
2019-06-13 19:18 ` Jason Gunthorpe
2019-06-13 20:14 ` Logan Gunthorpe
2019-06-13 9:43 ` [PATCH 08/22] memremap: pass a struct dev_pagemap to ->kill Christoph Hellwig
2019-06-13 19:26 ` Jason Gunthorpe
2019-06-13 20:12 ` Logan Gunthorpe
2019-06-13 20:15 ` Dan Williams
2019-06-13 9:43 ` [PATCH 09/22] memremap: lift the devmap_enable manipulation into devm_memremap_pages Christoph Hellwig
2019-06-13 19:34 ` Jason Gunthorpe
2019-06-13 20:13 ` Dan Williams
2019-06-14 6:28 ` Christoph Hellwig
2019-06-13 9:43 ` [PATCH 10/22] memremap: add a migrate callback to struct dev_pagemap_ops Christoph Hellwig
2019-06-13 23:42 ` Ralph Campbell [this message]
2019-06-14 6:33 ` Christoph Hellwig
2019-06-13 9:43 ` [PATCH 11/22] memremap: remove the data field in struct dev_pagemap Christoph Hellwig
2019-06-13 19:37 ` Jason Gunthorpe
2019-06-13 9:43 ` [PATCH 12/22] memremap: provide an optional internal refcount " Christoph Hellwig
2019-06-13 9:43 ` [PATCH 13/22] device-dax: use the dev_pagemap internal refcount Christoph Hellwig
2019-06-14 0:22 ` Ira Weiny
2019-06-14 6:35 ` Christoph Hellwig
2019-06-13 9:43 ` [PATCH 14/22] nouveau: use alloc_page_vma directly Christoph Hellwig
2019-06-13 19:39 ` Jason Gunthorpe
2019-06-13 9:43 ` [PATCH 15/22] nouveau: use devm_memremap_pages directly Christoph Hellwig
2019-06-13 9:43 ` [PATCH 16/22] mm: remove hmm_vma_alloc_locked_page Christoph Hellwig
2019-06-13 9:43 ` [PATCH 17/22] mm: remove hmm_devmem_add Christoph Hellwig
2019-06-13 19:42 ` Jason Gunthorpe
2019-06-14 6:39 ` Christoph Hellwig
2019-06-13 9:43 ` [PATCH 18/22] mm: mark DEVICE_PUBLIC as broken Christoph Hellwig
2019-06-13 19:44 ` Jason Gunthorpe
2019-06-13 19:53 ` Ralph Campbell
2019-06-13 19:58 ` Jason Gunthorpe
2019-06-14 0:43 ` Ira Weiny
2019-06-14 1:23 ` John Hubbard
2019-06-19 19:27 ` Jason Gunthorpe
2019-06-19 19:46 ` Dan Williams
2019-06-26 3:15 ` John Hubbard
2019-06-26 5:45 ` Michal Hocko
2019-06-26 6:07 ` John Hubbard
2019-06-14 6:43 ` Christoph Hellwig
2019-06-20 19:26 ` Michal Hocko
2019-06-25 7:29 ` Christoph Hellwig
2019-06-25 11:44 ` Jason Gunthorpe
2019-06-25 11:59 ` Christoph Hellwig
2019-06-13 9:43 ` [PATCH 19/22] mm: simplify ZONE_DEVICE page private data Christoph Hellwig
2019-06-13 9:43 ` [PATCH 20/22] mm: sort out the DEVICE_PRIVATE Kconfig mess Christoph Hellwig
2019-06-13 19:55 ` Jason Gunthorpe
2019-06-13 9:43 ` [PATCH 21/22] mm: remove the HMM config option Christoph Hellwig
2019-06-13 20:01 ` Jason Gunthorpe
2019-06-14 6:47 ` Christoph Hellwig
2019-06-13 9:43 ` [PATCH 22/22] mm: don't select MIGRATE_VMA_HELPER from HMM_MIRROR Christoph Hellwig
2019-06-13 20:04 ` Jason Gunthorpe
2019-06-14 1:53 ` [Nouveau] " John Hubbard
2019-06-14 6:48 ` Christoph Hellwig
2019-06-13 14:16 ` dev_pagemap related cleanups Jason Gunthorpe
2019-06-14 6:12 ` Christoph Hellwig
2019-06-13 18:27 ` Dan Williams
2019-06-13 20:17 ` Logan Gunthorpe
2019-06-13 20:21 ` Dan Williams
2019-06-13 20:24 ` Logan Gunthorpe
2019-06-13 20:48 ` Andrew Morton
2019-06-13 20:40 ` Jason Gunthorpe
2019-06-13 21:21 ` Christoph Hellwig
2019-06-13 23:10 ` Jason Gunthorpe
2019-06-14 6:14 ` Christoph Hellwig
2019-06-14 0:31 ` Ira Weiny
2019-06-14 6:13 ` Christoph Hellwig
2019-06-15 1:14 ` Dan Williams
2019-06-15 8:33 ` Christoph Hellwig
2019-06-15 18:09 ` Dan Williams
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