From: Souptick Joarder <jrdr.linux@xxxxxxxxx> Subject: mm: create the new vm_fault_t type Page fault handlers are supposed to return VM_FAULT codes, but some drivers/file systems mistakenly return error numbers. Now that all drivers/file systems have been converted to use the vm_fault_t return type, change the type definition to no longer be compatible with 'int'. By making it an unsigned int, the function prototype becomes incompatible with a function which returns int. Sparse will detect any attempts to return a value which is not a VM_FAULT code. VM_FAULT_SET_HINDEX and VM_FAULT_GET_HINDEX values are changed to avoid conflict with other VM_FAULT codes. [jrdr.linux@xxxxxxxxx: fix warnings] Link: http://lkml.kernel.org/r/20190109183742.GA24326@jordon-HP-15-Notebook-PC Link: http://lkml.kernel.org/r/20190108183041.GA12137@jordon-HP-15-Notebook-PC Signed-off-by: Souptick Joarder <jrdr.linux@xxxxxxxxx> Reviewed-by: William Kucharski <william.kucharski@xxxxxxxxxx> Reviewed-by: Mike Rapoport <rppt@xxxxxxxxxxxxx> Reviewed-by: Matthew Wilcox <willy@xxxxxxxxxxxxx> Cc: Michal Hocko <mhocko@xxxxxxxx> Cc: Dan Williams <dan.j.williams@xxxxxxxxx> Cc: Kirill A. Shutemov <kirill.shutemov@xxxxxxxxxxxxxxx> Cc: Rik van Riel <riel@xxxxxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- --- a/arch/x86/mm/fault.c~mm-create-the-new-vm_fault_t-type +++ a/arch/x86/mm/fault.c @@ -1031,7 +1031,7 @@ bad_area_access_error(struct pt_regs *re static void do_sigbus(struct pt_regs *regs, unsigned long error_code, unsigned long address, - unsigned int fault) + vm_fault_t fault) { struct task_struct *tsk = current; --- a/include/linux/mm.h~mm-create-the-new-vm_fault_t-type +++ a/include/linux/mm.h @@ -1323,52 +1323,6 @@ static inline void clear_page_pfmemalloc } /* - * Different kinds of faults, as returned by handle_mm_fault(). - * Used to decide whether a process gets delivered SIGBUS or - * just gets major/minor fault counters bumped up. - */ - -#define VM_FAULT_OOM 0x0001 -#define VM_FAULT_SIGBUS 0x0002 -#define VM_FAULT_MAJOR 0x0004 -#define VM_FAULT_WRITE 0x0008 /* Special case for get_user_pages */ -#define VM_FAULT_HWPOISON 0x0010 /* Hit poisoned small page */ -#define VM_FAULT_HWPOISON_LARGE 0x0020 /* Hit poisoned large page. Index encoded in upper bits */ -#define VM_FAULT_SIGSEGV 0x0040 - -#define VM_FAULT_NOPAGE 0x0100 /* ->fault installed the pte, not return page */ -#define VM_FAULT_LOCKED 0x0200 /* ->fault locked the returned page */ -#define VM_FAULT_RETRY 0x0400 /* ->fault blocked, must retry */ -#define VM_FAULT_FALLBACK 0x0800 /* huge page fault failed, fall back to small */ -#define VM_FAULT_DONE_COW 0x1000 /* ->fault has fully handled COW */ -#define VM_FAULT_NEEDDSYNC 0x2000 /* ->fault did not modify page tables - * and needs fsync() to complete (for - * synchronous page faults in DAX) */ - -#define VM_FAULT_ERROR (VM_FAULT_OOM | VM_FAULT_SIGBUS | VM_FAULT_SIGSEGV | \ - VM_FAULT_HWPOISON | VM_FAULT_HWPOISON_LARGE | \ - VM_FAULT_FALLBACK) - -#define VM_FAULT_RESULT_TRACE \ - { VM_FAULT_OOM, "OOM" }, \ - { VM_FAULT_SIGBUS, "SIGBUS" }, \ - { VM_FAULT_MAJOR, "MAJOR" }, \ - { VM_FAULT_WRITE, "WRITE" }, \ - { VM_FAULT_HWPOISON, "HWPOISON" }, \ - { VM_FAULT_HWPOISON_LARGE, "HWPOISON_LARGE" }, \ - { VM_FAULT_SIGSEGV, "SIGSEGV" }, \ - { VM_FAULT_NOPAGE, "NOPAGE" }, \ - { VM_FAULT_LOCKED, "LOCKED" }, \ - { VM_FAULT_RETRY, "RETRY" }, \ - { VM_FAULT_FALLBACK, "FALLBACK" }, \ - { VM_FAULT_DONE_COW, "DONE_COW" }, \ - { VM_FAULT_NEEDDSYNC, "NEEDDSYNC" } - -/* Encode hstate index for a hwpoisoned large page */ -#define VM_FAULT_SET_HINDEX(x) ((x) << 12) -#define VM_FAULT_GET_HINDEX(x) (((x) >> 12) & 0xf) - -/* * Can be called by the pagefault handler when it gets a VM_FAULT_OOM. */ extern void pagefault_out_of_memory(void); --- a/include/linux/mm_types.h~mm-create-the-new-vm_fault_t-type +++ a/include/linux/mm_types.h @@ -22,7 +22,6 @@ #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; @@ -621,6 +620,78 @@ static inline bool mm_tlb_flush_nested(s struct vm_fault; +/** + * typedef vm_fault_t - Return type for page fault handlers. + * + * Page fault handlers return a bitmask of %VM_FAULT values. + */ +typedef __bitwise unsigned int vm_fault_t; + +/** + * enum vm_fault_reason - Page fault handlers return a bitmask of + * these values to tell the core VM what happened when handling the + * fault. Used to decide whether a process gets delivered SIGBUS or + * just gets major/minor fault counters bumped up. + * + * @VM_FAULT_OOM: Out Of Memory + * @VM_FAULT_SIGBUS: Bad access + * @VM_FAULT_MAJOR: Page read from storage + * @VM_FAULT_WRITE: Special case for get_user_pages + * @VM_FAULT_HWPOISON: Hit poisoned small page + * @VM_FAULT_HWPOISON_LARGE: Hit poisoned large page. Index encoded + * in upper bits + * @VM_FAULT_SIGSEGV: segmentation fault + * @VM_FAULT_NOPAGE: ->fault installed the pte, not return page + * @VM_FAULT_LOCKED: ->fault locked the returned page + * @VM_FAULT_RETRY: ->fault blocked, must retry + * @VM_FAULT_FALLBACK: huge page fault failed, fall back to small + * @VM_FAULT_DONE_COW: ->fault has fully handled COW + * @VM_FAULT_NEEDDSYNC: ->fault did not modify page tables and needs + * fsync() to complete (for synchronous page faults + * in DAX) + * @VM_FAULT_HINDEX_MASK: mask HINDEX value + * + */ +enum vm_fault_reason { + VM_FAULT_OOM = (__force vm_fault_t)0x000001, + VM_FAULT_SIGBUS = (__force vm_fault_t)0x000002, + VM_FAULT_MAJOR = (__force vm_fault_t)0x000004, + VM_FAULT_WRITE = (__force vm_fault_t)0x000008, + VM_FAULT_HWPOISON = (__force vm_fault_t)0x000010, + VM_FAULT_HWPOISON_LARGE = (__force vm_fault_t)0x000020, + VM_FAULT_SIGSEGV = (__force vm_fault_t)0x000040, + VM_FAULT_NOPAGE = (__force vm_fault_t)0x000100, + VM_FAULT_LOCKED = (__force vm_fault_t)0x000200, + VM_FAULT_RETRY = (__force vm_fault_t)0x000400, + VM_FAULT_FALLBACK = (__force vm_fault_t)0x000800, + VM_FAULT_DONE_COW = (__force vm_fault_t)0x001000, + VM_FAULT_NEEDDSYNC = (__force vm_fault_t)0x002000, + VM_FAULT_HINDEX_MASK = (__force vm_fault_t)0x0f0000, +}; + +/* Encode hstate index for a hwpoisoned large page */ +#define VM_FAULT_SET_HINDEX(x) ((__force vm_fault_t)((x) << 16)) +#define VM_FAULT_GET_HINDEX(x) (((x) >> 16) & 0xf) + +#define VM_FAULT_ERROR (VM_FAULT_OOM | VM_FAULT_SIGBUS | \ + VM_FAULT_SIGSEGV | VM_FAULT_HWPOISON | \ + VM_FAULT_HWPOISON_LARGE | VM_FAULT_FALLBACK) + +#define VM_FAULT_RESULT_TRACE \ + { VM_FAULT_OOM, "OOM" }, \ + { VM_FAULT_SIGBUS, "SIGBUS" }, \ + { VM_FAULT_MAJOR, "MAJOR" }, \ + { VM_FAULT_WRITE, "WRITE" }, \ + { VM_FAULT_HWPOISON, "HWPOISON" }, \ + { VM_FAULT_HWPOISON_LARGE, "HWPOISON_LARGE" }, \ + { VM_FAULT_SIGSEGV, "SIGSEGV" }, \ + { VM_FAULT_NOPAGE, "NOPAGE" }, \ + { VM_FAULT_LOCKED, "LOCKED" }, \ + { VM_FAULT_RETRY, "RETRY" }, \ + { VM_FAULT_FALLBACK, "FALLBACK" }, \ + { VM_FAULT_DONE_COW, "DONE_COW" }, \ + { VM_FAULT_NEEDDSYNC, "NEEDDSYNC" } + struct vm_special_mapping { const char *name; /* The name, e.g. "[vdso]". */ _
