Commit 3d353901 authored by Souptick Joarder's avatar Souptick Joarder Committed by Linus Torvalds
Browse files

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@gmail.com: 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: default avatarSouptick Joarder <jrdr.linux@gmail.com>
Reviewed-by: default avatarWilliam Kucharski <william.kucharski@oracle.com>
Reviewed-by: default avatarMike Rapoport <rppt@linux.ibm.com>
Reviewed-by: default avatarMatthew 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: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent c2938eeb

arch/x86/mm/fault.c

+1 −1
Original line number Diff line number Diff line
@@ -1031,7 +1031,7 @@ bad_area_access_error(struct pt_regs *regs, unsigned long error_code, 


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;

include/linux/mm.h

+0 −46
Original line number Diff line number Diff line
@@ -1322,52 +1322,6 @@ static inline void clear_page_pfmemalloc(struct page *page) 
	page->index = 0;

}



/*

 * 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.

 */

include/linux/mm_types.h

+72 −1
Original line number Diff line number Diff line
@@ -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(struct mm_struct *mm) 


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]". */

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