| Message ID | 20181106074934.GA27620@jordon-HP-15-Notebook-PC (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | [v2] mm: Create the new vm_fault_t type | expand |
On Tue, Nov 06, 2018 at 01:19:34PM +0530, Souptick Joarder wrote: > 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. > > Signed-off-by: Souptick Joarder <jrdr.linux@gmail.com> > --- > v2: Updated the change log and corrected the document part. > name added to the enum that kernel-doc able to parse it. > > include/linux/mm.h | 46 ------------------------------ > include/linux/mm_types.h | 73 +++++++++++++++++++++++++++++++++++++++++++++++- > 2 files changed, 72 insertions(+), 47 deletions(-) > > diff --git a/include/linux/mm.h b/include/linux/mm.h > index fcf9cc9..511a3ce 100644 > --- a/include/linux/mm.h > +++ b/include/linux/mm.h > @@ -1267,52 +1267,6 @@ static inline void clear_page_pfmemalloc(struct page *page) > } > > /* > - * 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); > diff --git a/include/linux/mm_types.h b/include/linux/mm_types.h > index 5ed8f62..beee607 100644 > --- a/include/linux/mm_types.h > +++ b/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; > @@ -609,6 +608,78 @@ 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 code It should be 'enum vm_fault_reason' here. A more elaborate brief description would also be nice. > + * > + * 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) > + */ > +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]". */ > > -- > 1.9.1 >
On Tue, Nov 6, 2018 at 1:56 PM Mike Rapoport <rppt@linux.ibm.com> wrote: > > On Tue, Nov 06, 2018 at 01:19:34PM +0530, Souptick Joarder wrote: > > 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. > > > > Signed-off-by: Souptick Joarder <jrdr.linux@gmail.com> > > --- > > v2: Updated the change log and corrected the document part. > > name added to the enum that kernel-doc able to parse it. > > > > include/linux/mm.h | 46 ------------------------------ > > include/linux/mm_types.h | 73 +++++++++++++++++++++++++++++++++++++++++++++++- > > 2 files changed, 72 insertions(+), 47 deletions(-) > > > > diff --git a/include/linux/mm.h b/include/linux/mm.h > > index fcf9cc9..511a3ce 100644 > > --- a/include/linux/mm.h > > +++ b/include/linux/mm.h > > @@ -1267,52 +1267,6 @@ static inline void clear_page_pfmemalloc(struct page *page) > > } > > > > /* > > - * 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); > > diff --git a/include/linux/mm_types.h b/include/linux/mm_types.h > > index 5ed8f62..beee607 100644 > > --- a/include/linux/mm_types.h > > +++ b/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; > > @@ -609,6 +608,78 @@ 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 code > > It should be 'enum vm_fault_reason' here. Sorry, missed it. > A more elaborate brief description would also be nice. This much description is not sufficient to explain the enum ? > > > + * > > + * 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) > > + */ > > +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]". */ > > > > -- > > 1.9.1 > > > > -- > Sincerely yours, > Mike. >
On Tue, Nov 06, 2018 at 02:04:54PM +0530, Souptick Joarder wrote: > On Tue, Nov 6, 2018 at 1:56 PM Mike Rapoport <rppt@linux.ibm.com> wrote: > > > > On Tue, Nov 06, 2018 at 01:19:34PM +0530, Souptick Joarder wrote: > > > 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. > > > > > > Signed-off-by: Souptick Joarder <jrdr.linux@gmail.com> > > > --- > > > v2: Updated the change log and corrected the document part. > > > name added to the enum that kernel-doc able to parse it. > > > > > > include/linux/mm.h | 46 ------------------------------ > > > include/linux/mm_types.h | 73 +++++++++++++++++++++++++++++++++++++++++++++++- > > > 2 files changed, 72 insertions(+), 47 deletions(-) > > > > > > diff --git a/include/linux/mm.h b/include/linux/mm.h > > > index fcf9cc9..511a3ce 100644 > > > --- a/include/linux/mm.h > > > +++ b/include/linux/mm.h > > > @@ -1267,52 +1267,6 @@ static inline void clear_page_pfmemalloc(struct page *page) > > > } > > > > > > /* > > > - * 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); > > > diff --git a/include/linux/mm_types.h b/include/linux/mm_types.h > > > index 5ed8f62..beee607 100644 > > > --- a/include/linux/mm_types.h > > > +++ b/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; > > > @@ -609,6 +608,78 @@ 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 code > > > > It should be 'enum vm_fault_reason' here. > > Sorry, missed it. > > > A more elaborate brief description would also be nice. > > This much description is not sufficient to explain the enum ? > > The description below is fine, but kernel-doc will use "VM_FAULT code" as the "short description" and the explanation will be used as "long description". So either replace "VM_FAULT code" with something like "page fault handler return codes" or put the long explanation next to 'enum vm_fault_reason': /** * enum vm_fault_reason - page fault handlers return a bitmask of these * values ... * ... */ Please take a look at "Structure, union, and enumeration documentation" in Documentation/doc-guide/kernel-doc.rst [1]. [1] https://www.kernel.org/doc/html/latest/doc-guide/kernel-doc.html#structure-union-and-enumeration-documentation > > > + * > > > + * 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) > > > + */ > > > +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]". */ > > > > > > -- > > > 1.9.1 > > > > > > > -- > > Sincerely yours, > > Mike. > > >
Hi Souptick,
Thank you for the patch! Perhaps something to improve:
[auto build test WARNING on linus/master]
[also build test WARNING on v4.20-rc1 next-20181106]
[if your patch is applied to the wrong git tree, please drop us a note to help improve the system]
url: https://github.com/0day-ci/linux/commits/Souptick-Joarder/mm-Create-the-new-vm_fault_t-type/20181106-171908
config: i386-randconfig-h1-11061829 (attached as .config)
compiler: gcc-4.9 (Debian 4.9.4-2) 4.9.4
reproduce:
# save the attached .config to linux build tree
make ARCH=i386
All warnings (new ones prefixed by >>):
>> drivers//dma-buf/udmabuf.c:34:2: warning: initialization from incompatible pointer type
.fault = udmabuf_vm_fault,
^
drivers//dma-buf/udmabuf.c:34:2: warning: (near initialization for 'udmabuf_vm_ops.fault')
vim +34 drivers//dma-buf/udmabuf.c
fbb0de79 Gerd Hoffmann 2018-08-27 32
fbb0de79 Gerd Hoffmann 2018-08-27 33 static const struct vm_operations_struct udmabuf_vm_ops = {
fbb0de79 Gerd Hoffmann 2018-08-27 @34 .fault = udmabuf_vm_fault,
fbb0de79 Gerd Hoffmann 2018-08-27 35 };
fbb0de79 Gerd Hoffmann 2018-08-27 36
:::::: The code at line 34 was first introduced by commit
:::::: fbb0de795078190a9834b3409e4b009cfb18a6d4 Add udmabuf misc device
:::::: TO: Gerd Hoffmann <kraxel@redhat.com>
:::::: CC: Gerd Hoffmann <kraxel@redhat.com>
---
0-DAY kernel test infrastructure Open Source Technology Center
https://lists.01.org/pipermail/kbuild-all Intel Corporation
diff --git a/include/linux/mm.h b/include/linux/mm.h index fcf9cc9..511a3ce 100644 --- a/include/linux/mm.h +++ b/include/linux/mm.h @@ -1267,52 +1267,6 @@ static inline void clear_page_pfmemalloc(struct page *page) } /* - * 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); diff --git a/include/linux/mm_types.h b/include/linux/mm_types.h index 5ed8f62..beee607 100644 --- a/include/linux/mm_types.h +++ b/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; @@ -609,6 +608,78 @@ 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 code + * + * 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) + */ +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]". */
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. Signed-off-by: Souptick Joarder <jrdr.linux@gmail.com> --- v2: Updated the change log and corrected the document part. name added to the enum that kernel-doc able to parse it. include/linux/mm.h | 46 ------------------------------ include/linux/mm_types.h | 73 +++++++++++++++++++++++++++++++++++++++++++++++- 2 files changed, 72 insertions(+), 47 deletions(-)