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 <jrdr.linux@gmail.com> Acked-by: Michal Hocko <mhocko@suse.com> Cc: Matthew Wilcox <willy@infradead.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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@ -386,18 +386,19 @@ struct vm_operations_struct {
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void (*close)(struct vm_area_struct * area);
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int (*split)(struct vm_area_struct * area, unsigned long addr);
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int (*mremap)(struct vm_area_struct * area);
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int (*fault)(struct vm_fault *vmf);
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int (*huge_fault)(struct vm_fault *vmf, enum page_entry_size pe_size);
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vm_fault_t (*fault)(struct vm_fault *vmf);
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vm_fault_t (*huge_fault)(struct vm_fault *vmf,
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enum page_entry_size pe_size);
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void (*map_pages)(struct vm_fault *vmf,
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pgoff_t start_pgoff, pgoff_t end_pgoff);
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unsigned long (*pagesize)(struct vm_area_struct * area);
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/* notification that a previously read-only page is about to become
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* writable, if an error is returned it will cause a SIGBUS */
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int (*page_mkwrite)(struct vm_fault *vmf);
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vm_fault_t (*page_mkwrite)(struct vm_fault *vmf);
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/* same as page_mkwrite when using VM_PFNMAP|VM_MIXEDMAP */
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int (*pfn_mkwrite)(struct vm_fault *vmf);
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vm_fault_t (*pfn_mkwrite)(struct vm_fault *vmf);
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/* called by access_process_vm when get_user_pages() fails, typically
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* for use by special VMAs that can switch between memory and hardware
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@ -2424,6 +2425,44 @@ int vm_insert_mixed_mkwrite(struct vm_area_struct *vma, unsigned long addr,
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pfn_t pfn);
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int vm_iomap_memory(struct vm_area_struct *vma, phys_addr_t start, unsigned long len);
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static inline vm_fault_t vmf_insert_page(struct vm_area_struct *vma,
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unsigned long addr, struct page *page)
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{
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int err = vm_insert_page(vma, addr, page);
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if (err == -ENOMEM)
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return VM_FAULT_OOM;
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if (err < 0 && err != -EBUSY)
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return VM_FAULT_SIGBUS;
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return VM_FAULT_NOPAGE;
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}
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static inline vm_fault_t vmf_insert_mixed(struct vm_area_struct *vma,
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unsigned long addr, pfn_t pfn)
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{
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int err = vm_insert_mixed(vma, addr, pfn);
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if (err == -ENOMEM)
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return VM_FAULT_OOM;
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if (err < 0 && err != -EBUSY)
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return VM_FAULT_SIGBUS;
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return VM_FAULT_NOPAGE;
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}
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static inline vm_fault_t vmf_insert_pfn(struct vm_area_struct *vma,
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unsigned long addr, unsigned long pfn)
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{
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int err = vm_insert_pfn(vma, addr, pfn);
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if (err == -ENOMEM)
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return VM_FAULT_OOM;
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if (err < 0 && err != -EBUSY)
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return VM_FAULT_SIGBUS;
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return VM_FAULT_NOPAGE;
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}
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struct page *follow_page_mask(struct vm_area_struct *vma,
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unsigned long address, unsigned int foll_flags,
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@ -22,6 +22,8 @@
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#endif
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#define AT_VECTOR_SIZE (2*(AT_VECTOR_SIZE_ARCH + AT_VECTOR_SIZE_BASE + 1))
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typedef int vm_fault_t;
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struct address_space;
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struct mem_cgroup;
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struct hmm;
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