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Souptick Joardersfrothwell
Souptick Joarder
authored and
sfrothwell
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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. Link: http://lkml.kernel.org/r/20190108183041.GA12137@jordon-HP-15-Notebook-PC Signed-off-by: Souptick Joarder <jrdr.linux@gmail.com> Reviewed-by: William Kucharski <william.kucharski@oracle.com> Reviewed-by: Mike Rapoport <rppt@linux.ibm.com> Reviewed-by: Matthew Wilcox <willy@infradead.org> Cc: Michal Hocko <mhocko@suse.com> Cc: Dan Williams <dan.j.williams@intel.com> Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Cc: Rik van Riel <riel@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Stephen Rothwell <sfr@canb.auug.org.au>
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‎include/linux/mm.h

Lines changed: 0 additions & 46 deletions
Original file line numberDiff line numberDiff line change
@@ -1323,52 +1323,6 @@ static inline void clear_page_pfmemalloc(struct page *page)
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page->index = 0;
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}
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/*
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* Different kinds of faults, as returned by handle_mm_fault().
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* Used to decide whether a process gets delivered SIGBUS or
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* just gets major/minor fault counters bumped up.
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*/
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#define VM_FAULT_OOM 0x0001
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#define VM_FAULT_SIGBUS 0x0002
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#define VM_FAULT_MAJOR 0x0004
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#define VM_FAULT_WRITE 0x0008 /* Special case for get_user_pages */
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#define VM_FAULT_HWPOISON 0x0010 /* Hit poisoned small page */
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#define VM_FAULT_HWPOISON_LARGE 0x0020 /* Hit poisoned large page. Index encoded in upper bits */
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#define VM_FAULT_SIGSEGV 0x0040
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#define VM_FAULT_NOPAGE 0x0100 /* ->fault installed the pte, not return page */
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#define VM_FAULT_LOCKED 0x0200 /* ->fault locked the returned page */
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#define VM_FAULT_RETRY 0x0400 /* ->fault blocked, must retry */
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#define VM_FAULT_FALLBACK 0x0800 /* huge page fault failed, fall back to small */
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#define VM_FAULT_DONE_COW 0x1000 /* ->fault has fully handled COW */
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#define VM_FAULT_NEEDDSYNC 0x2000 /* ->fault did not modify page tables
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* and needs fsync() to complete (for
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* synchronous page faults in DAX) */
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#define VM_FAULT_ERROR (VM_FAULT_OOM | VM_FAULT_SIGBUS | VM_FAULT_SIGSEGV | \
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VM_FAULT_HWPOISON | VM_FAULT_HWPOISON_LARGE | \
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VM_FAULT_FALLBACK)
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#define VM_FAULT_RESULT_TRACE \
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{ VM_FAULT_OOM, "OOM" }, \
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{ VM_FAULT_SIGBUS, "SIGBUS" }, \
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{ VM_FAULT_MAJOR, "MAJOR" }, \
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{ VM_FAULT_WRITE, "WRITE" }, \
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{ VM_FAULT_HWPOISON, "HWPOISON" }, \
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{ VM_FAULT_HWPOISON_LARGE, "HWPOISON_LARGE" }, \
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{ VM_FAULT_SIGSEGV, "SIGSEGV" }, \
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{ VM_FAULT_NOPAGE, "NOPAGE" }, \
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{ VM_FAULT_LOCKED, "LOCKED" }, \
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{ VM_FAULT_RETRY, "RETRY" }, \
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{ VM_FAULT_FALLBACK, "FALLBACK" }, \
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{ VM_FAULT_DONE_COW, "DONE_COW" }, \
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{ VM_FAULT_NEEDDSYNC, "NEEDDSYNC" }
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/* Encode hstate index for a hwpoisoned large page */
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#define VM_FAULT_SET_HINDEX(x) ((x) << 12)
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#define VM_FAULT_GET_HINDEX(x) (((x) >> 12) & 0xf)
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/*
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* Can be called by the pagefault handler when it gets a VM_FAULT_OOM.
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*/

‎include/linux/mm_types.h

Lines changed: 72 additions & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -22,7 +22,6 @@
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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;
@@ -614,6 +613,78 @@ static inline bool mm_tlb_flush_nested(struct mm_struct *mm)
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struct vm_fault;
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/**
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* typedef vm_fault_t - Return type for page fault handlers.
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*
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* Page fault handlers return a bitmask of %VM_FAULT values.
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*/
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typedef __bitwise unsigned int vm_fault_t;
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/**
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* enum vm_fault_reason - Page fault handlers return a bitmask of
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* these values to tell the core VM what happened when handling the
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* fault. Used to decide whether a process gets delivered SIGBUS or
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* just gets major/minor fault counters bumped up.
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*
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* @VM_FAULT_OOM: Out Of Memory
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* @VM_FAULT_SIGBUS: Bad access
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* @VM_FAULT_MAJOR: Page read from storage
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* @VM_FAULT_WRITE: Special case for get_user_pages
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* @VM_FAULT_HWPOISON: Hit poisoned small page
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* @VM_FAULT_HWPOISON_LARGE: Hit poisoned large page. Index encoded
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* in upper bits
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* @VM_FAULT_SIGSEGV: segmentation fault
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* @VM_FAULT_NOPAGE: ->fault installed the pte, not return page
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* @VM_FAULT_LOCKED: ->fault locked the returned page
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* @VM_FAULT_RETRY: ->fault blocked, must retry
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* @VM_FAULT_FALLBACK: huge page fault failed, fall back to small
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* @VM_FAULT_DONE_COW: ->fault has fully handled COW
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* @VM_FAULT_NEEDDSYNC: ->fault did not modify page tables and needs
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* fsync() to complete (for synchronous page faults
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* in DAX)
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* @VM_FAULT_HINDEX_MASK: mask HINDEX value
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*
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*/
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enum vm_fault_reason {
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VM_FAULT_OOM = (__force vm_fault_t)0x000001,
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VM_FAULT_SIGBUS = (__force vm_fault_t)0x000002,
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VM_FAULT_MAJOR = (__force vm_fault_t)0x000004,
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VM_FAULT_WRITE = (__force vm_fault_t)0x000008,
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VM_FAULT_HWPOISON = (__force vm_fault_t)0x000010,
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VM_FAULT_HWPOISON_LARGE = (__force vm_fault_t)0x000020,
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VM_FAULT_SIGSEGV = (__force vm_fault_t)0x000040,
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VM_FAULT_NOPAGE = (__force vm_fault_t)0x000100,
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VM_FAULT_LOCKED = (__force vm_fault_t)0x000200,
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VM_FAULT_RETRY = (__force vm_fault_t)0x000400,
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VM_FAULT_FALLBACK = (__force vm_fault_t)0x000800,
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VM_FAULT_DONE_COW = (__force vm_fault_t)0x001000,
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VM_FAULT_NEEDDSYNC = (__force vm_fault_t)0x002000,
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VM_FAULT_HINDEX_MASK = (__force vm_fault_t)0x0f0000,
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};
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/* Encode hstate index for a hwpoisoned large page */
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#define VM_FAULT_SET_HINDEX(x) ((__force vm_fault_t)((x) << 16))
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#define VM_FAULT_GET_HINDEX(x) (((x) >> 16) & 0xf)
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#define VM_FAULT_ERROR (VM_FAULT_OOM | VM_FAULT_SIGBUS | \
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VM_FAULT_SIGSEGV | VM_FAULT_HWPOISON | \
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VM_FAULT_HWPOISON_LARGE | VM_FAULT_FALLBACK)
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#define VM_FAULT_RESULT_TRACE \
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{ VM_FAULT_OOM, "OOM" }, \
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{ VM_FAULT_SIGBUS, "SIGBUS" }, \
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{ VM_FAULT_MAJOR, "MAJOR" }, \
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{ VM_FAULT_WRITE, "WRITE" }, \
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{ VM_FAULT_HWPOISON, "HWPOISON" }, \
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{ VM_FAULT_HWPOISON_LARGE, "HWPOISON_LARGE" }, \
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{ VM_FAULT_SIGSEGV, "SIGSEGV" }, \
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{ VM_FAULT_NOPAGE, "NOPAGE" }, \
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{ VM_FAULT_LOCKED, "LOCKED" }, \
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{ VM_FAULT_RETRY, "RETRY" }, \
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{ VM_FAULT_FALLBACK, "FALLBACK" }, \
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{ VM_FAULT_DONE_COW, "DONE_COW" }, \
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{ VM_FAULT_NEEDDSYNC, "NEEDDSYNC" }
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617688
struct vm_special_mapping {
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const char *name; /* The name, e.g. "[vdso]". */
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