From 897e6365cda6ba6356e83a3aaa68dec82ef4c548 Mon Sep 17 00:00:00 2001 From: Christoph Hellwig Date: Wed, 26 Jun 2019 14:27:11 +0200 Subject: [PATCH] memremap: add a migrate_to_ram method to struct dev_pagemap_ops 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 Reviewed-by: Ralph Campbell Reviewed-by: Jason Gunthorpe Reviewed-by: Dan Williams Tested-by: Dan Williams Signed-off-by: Jason Gunthorpe --- include/linux/hmm.h | 6 ------ include/linux/memremap.h | 6 ++++++ include/linux/swapops.h | 15 --------------- kernel/memremap.c | 35 ++++------------------------------- mm/hmm.c | 13 +++++-------- mm/memory.c | 9 ++------- 6 files changed, 17 insertions(+), 67 deletions(-) diff --git a/include/linux/hmm.h b/include/linux/hmm.h index 44a5ac738bb5..ba19c19e24ed 100644 --- a/include/linux/hmm.h +++ b/include/linux/hmm.h @@ -692,11 +692,6 @@ 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; @@ -707,7 +702,6 @@ 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 b8666a0d8665..ac985bd03a7f 100644 --- a/include/linux/memremap.h +++ b/include/linux/memremap.h @@ -80,6 +80,12 @@ struct dev_pagemap_ops { * Wait for refcount in struct dev_pagemap to be idle and reap it. */ void (*cleanup)(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_to_ram)(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 3219a4c91d07..c06a5487dda7 100644 --- a/kernel/memremap.c +++ b/kernel/memremap.c @@ -11,7 +11,6 @@ #include #include #include -#include static DEFINE_XARRAY(pgmap_array); #define SECTION_MASK ~((1UL << PA_SECTION_SHIFT) - 1) @@ -46,36 +45,6 @@ static int devmap_managed_enable_get(struct device *dev, struct dev_pagemap *pgm } #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), @@ -193,6 +162,10 @@ void *devm_memremap_pages(struct device *dev, struct dev_pagemap *pgmap) WARN(1, "Device private memory not supported\n"); return ERR_PTR(-EINVAL); } + if (!pgmap->ops || !pgmap->ops->migrate_to_ram) { + WARN(1, "Missing migrate_to_ram method\n"); + return ERR_PTR(-EINVAL); + } break; case MEMORY_DEVICE_FS_DAX: if (!IS_ENABLED(CONFIG_ZONE_DEVICE) || diff --git a/mm/hmm.c b/mm/hmm.c index 5b0bd5f6a74f..96633ee066d8 100644 --- a/mm/hmm.c +++ b/mm/hmm.c @@ -1366,15 +1366,12 @@ 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_to_ram(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) @@ -1388,6 +1385,7 @@ static const struct dev_pagemap_ops hmm_pagemap_ops = { .page_free = hmm_devmem_free, .kill = hmm_devmem_ref_kill, .cleanup = hmm_devmem_ref_exit, + .migrate_to_ram = hmm_devmem_migrate_to_ram, }; /* @@ -1438,7 +1436,6 @@ 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 2d14f4c7e152..d437ccdb210c 100644 --- a/mm/memory.c +++ b/mm/memory.c @@ -2748,13 +2748,8 @@ 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 = vmf->page->pgmap->ops->migrate_to_ram(vmf); } else if (is_hwpoison_entry(entry)) { ret = VM_FAULT_HWPOISON; } else {