From 1c8f422059ae5da07db7406ab916203f9417e396 Mon Sep 17 00:00:00 2001 From: Souptick Joarder Date: Thu, 5 Apr 2018 16:25:23 -0700 Subject: [PATCH] mm: change return type to vm_fault_t The plan for these patches is to introduce the typedef, initially just as documentation ("These functions should return a VM_FAULT_ status"). We'll trickle the patches to individual drivers/filesystems in through the maintainers, as far as possible. Then we'll change the typedef to an unsigned int and break the compilation of any unconverted drivers/filesystems. vmf_insert_page(), vmf_insert_mixed() and vmf_insert_pfn() are three newly added functions. The various drivers/filesystems where return value of fault(), huge_fault(), page_mkwrite() and pfn_mkwrite() get converted, will need them. These functions will return correct VM_FAULT_ code based on err value. We've had bugs before where drivers returned -EFOO. And we have this silly inefficiency where vm_insert_xxx() return an errno which (afaict) every driver then converts into a VM_FAULT code. In many cases drivers failed to return correct VM_FAULT code value despite of vm_insert_xxx() fails. We have indentified and clean up all those existing bugs and silly inefficiencies in driver/filesystems by adding these three new inline wrappers. As mentioned above, we will trickle those patches to individual drivers/filesystems in through maintainers after these three wrapper functions are merged. Eventually we can convert vm_insert_xxx() into vmf_insert_xxx() and remove these inline wrappers, but these are a good intermediate step. Link: http://lkml.kernel.org/r/20180310162351.GA7422@jordon-HP-15-Notebook-PC Signed-off-by: Souptick Joarder Acked-by: Michal Hocko Cc: Matthew Wilcox Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- include/linux/mm.h | 47 ++++++++++++++++++++++++++++++++++++---- include/linux/mm_types.h | 2 ++ 2 files changed, 45 insertions(+), 4 deletions(-) diff --git a/include/linux/mm.h b/include/linux/mm.h index 88d82ba29d72..3ad632366973 100644 --- a/include/linux/mm.h +++ b/include/linux/mm.h @@ -386,18 +386,19 @@ struct vm_operations_struct { void (*close)(struct vm_area_struct * area); int (*split)(struct vm_area_struct * area, unsigned long addr); int (*mremap)(struct vm_area_struct * area); - int (*fault)(struct vm_fault *vmf); - int (*huge_fault)(struct vm_fault *vmf, enum page_entry_size pe_size); + vm_fault_t (*fault)(struct vm_fault *vmf); + vm_fault_t (*huge_fault)(struct vm_fault *vmf, + enum page_entry_size pe_size); void (*map_pages)(struct vm_fault *vmf, pgoff_t start_pgoff, pgoff_t end_pgoff); unsigned long (*pagesize)(struct vm_area_struct * area); /* notification that a previously read-only page is about to become * writable, if an error is returned it will cause a SIGBUS */ - int (*page_mkwrite)(struct vm_fault *vmf); + vm_fault_t (*page_mkwrite)(struct vm_fault *vmf); /* same as page_mkwrite when using VM_PFNMAP|VM_MIXEDMAP */ - int (*pfn_mkwrite)(struct vm_fault *vmf); + vm_fault_t (*pfn_mkwrite)(struct vm_fault *vmf); /* called by access_process_vm when get_user_pages() fails, typically * for use by special VMAs that can switch between memory and hardware @@ -2424,6 +2425,44 @@ int vm_insert_mixed_mkwrite(struct vm_area_struct *vma, unsigned long addr, pfn_t pfn); int vm_iomap_memory(struct vm_area_struct *vma, phys_addr_t start, unsigned long len); +static inline vm_fault_t vmf_insert_page(struct vm_area_struct *vma, + unsigned long addr, struct page *page) +{ + int err = vm_insert_page(vma, addr, page); + + if (err == -ENOMEM) + return VM_FAULT_OOM; + if (err < 0 && err != -EBUSY) + return VM_FAULT_SIGBUS; + + return VM_FAULT_NOPAGE; +} + +static inline vm_fault_t vmf_insert_mixed(struct vm_area_struct *vma, + unsigned long addr, pfn_t pfn) +{ + int err = vm_insert_mixed(vma, addr, pfn); + + if (err == -ENOMEM) + return VM_FAULT_OOM; + if (err < 0 && err != -EBUSY) + return VM_FAULT_SIGBUS; + + return VM_FAULT_NOPAGE; +} + +static inline vm_fault_t vmf_insert_pfn(struct vm_area_struct *vma, + unsigned long addr, unsigned long pfn) +{ + int err = vm_insert_pfn(vma, addr, pfn); + + if (err == -ENOMEM) + return VM_FAULT_OOM; + if (err < 0 && err != -EBUSY) + return VM_FAULT_SIGBUS; + + return VM_FAULT_NOPAGE; +} struct page *follow_page_mask(struct vm_area_struct *vma, unsigned long address, unsigned int foll_flags, diff --git a/include/linux/mm_types.h b/include/linux/mm_types.h index fd1af6b9591d..21612347d311 100644 --- a/include/linux/mm_types.h +++ b/include/linux/mm_types.h @@ -22,6 +22,8 @@ #endif #define AT_VECTOR_SIZE (2*(AT_VECTOR_SIZE_ARCH + AT_VECTOR_SIZE_BASE + 1)) +typedef int vm_fault_t; + struct address_space; struct mem_cgroup; struct hmm;