| Message ID | 20181103050504.GA3049@jordon-HP-15-Notebook-PC (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | mm: Create the new vm_fault_t type | expand |
On Sat, Nov 3, 2018 at 10:31 AM Souptick Joarder <jrdr.linux@gmail.com> 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. > > Signed-off-by: Souptick Joarder <jrdr.linux@gmail.com> > --- > include/linux/mm.h | 46 ----------------------------- > include/linux/mm_types.h | 75 +++++++++++++++++++++++++++++++++++++++++++++++- > 2 files changed, 74 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..48c2108 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 +608,80 @@ static inline bool mm_tlb_flush_nested(struct mm_struct *mm) > > struct vm_fault; > > +/** > + * typedef vm_fault_t - __bitwise unsigned int > + * > + * vm_fault_t is the new unsigned int type to return VM_FAULT > + * code by page fault handlers of drivers/file systems. Now if > + * any page fault handlers returns non VM_FAULT code instead > + * of VM_FAULT code, it will be a mismatch with function > + * prototype and sparse will detect it. > + */ > +typedef __bitwise unsigned int vm_fault_t; > + > +/** > + * enum - VM_FAULT code > + * > + * This enum is used to track the VM_FAULT code return by page > + * fault handlers. > + * > + * @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_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" } > + checkpatch.pl is throwing an error "ERROR: Macros with complex values should be enclosed in parentheses". But if I put it under macro it leads to compile error for * make allyesconfig * ( x86_64 arch). That the reason I have ignored the error in checkpatch.pl. > struct vm_special_mapping { > const char *name; /* The name, e.g. "[vdso]". */ > > -- > 1.9.1 >
On Sat, Nov 03, 2018 at 10:35:04AM +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. > -/* 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) ... > +/* 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) I think it's important to mention in the changelog that these values have been changed to avoid conflicts with other VM_FAULT codes. > +/** > + * typedef vm_fault_t - __bitwise unsigned int > + * > + * vm_fault_t is the new unsigned int type to return VM_FAULT > + * code by page fault handlers of drivers/file systems. Now if > + * any page fault handlers returns non VM_FAULT code instead > + * of VM_FAULT code, it will be a mismatch with function > + * prototype and sparse will detect it. > + */ The first line should be what the typedef *means*, not repeat the compiler's definition. The rest of the description should be information for someone coming to the type for the first time; what you've written here is changelog material. /** * 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 Can you document an anonymous enum? I've never tried. Did you run this through 'make htmldocs'? > + * This enum is used to track the VM_FAULT code return by page > + * fault handlers. * Page fault handlers return a bitmask of these values to tell the * core VM what happened when handling the fault.
On Sat, Nov 03, 2018 at 05:02:36AM -0700, Matthew Wilcox wrote: > On Sat, Nov 03, 2018 at 10:35:04AM +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. > > > > -/* 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) > ... > > +/* 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) > > I think it's important to mention in the changelog that these values > have been changed to avoid conflicts with other VM_FAULT codes. > > > +/** > > + * typedef vm_fault_t - __bitwise unsigned int > > + * > > + * vm_fault_t is the new unsigned int type to return VM_FAULT > > + * code by page fault handlers of drivers/file systems. Now if > > + * any page fault handlers returns non VM_FAULT code instead > > + * of VM_FAULT code, it will be a mismatch with function > > + * prototype and sparse will detect it. > > + */ > > The first line should be what the typedef *means*, not repeat the > compiler's definition. The rest of the description should be information > for someone coming to the type for the first time; what you've written > here is changelog material. > > /** > * 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 > > Can you document an anonymous enum? I've never tried. Did you run this > through 'make htmldocs'? You cannot document an anonymous enum. > > + * This enum is used to track the VM_FAULT code return by page > > + * fault handlers. > > * Page fault handlers return a bitmask of these values to tell the > * core VM what happened when handling the fault. >
Hi Matthew, On Sun, Nov 4, 2018 at 2:06 PM Mike Rapoport <rppt@linux.ibm.com> wrote: > > On Sat, Nov 03, 2018 at 05:02:36AM -0700, Matthew Wilcox wrote: > > On Sat, Nov 03, 2018 at 10:35:04AM +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. > > > > > > > -/* 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) > > ... > > > +/* 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) > > > > I think it's important to mention in the changelog that these values > > have been changed to avoid conflicts with other VM_FAULT codes. > > > > > +/** > > > + * typedef vm_fault_t - __bitwise unsigned int > > > + * > > > + * vm_fault_t is the new unsigned int type to return VM_FAULT > > > + * code by page fault handlers of drivers/file systems. Now if > > > + * any page fault handlers returns non VM_FAULT code instead > > > + * of VM_FAULT code, it will be a mismatch with function > > > + * prototype and sparse will detect it. > > > + */ > > > > The first line should be what the typedef *means*, not repeat the > > compiler's definition. The rest of the description should be information > > for someone coming to the type for the first time; what you've written > > here is changelog material. > > > > /** > > * 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 > > > > Can you document an anonymous enum? I've never tried. Did you run this > > through 'make htmldocs'? > > You cannot document an anonymous enum. I assume, you are pointing to Document folder and I don't know if this enum need to be documented or not. I didn't run 'make htmldocs' as there is no document related changes. > > > > + * This enum is used to track the VM_FAULT code return by page > > > + * fault handlers. > > > > * Page fault handlers return a bitmask of these values to tell the > > * core VM what happened when handling the fault. > > > > -- > Sincerely yours, > Mike. >
On Mon, Nov 05, 2018 at 11:14:17AM +0530, Souptick Joarder wrote: > Hi Matthew, > > On Sun, Nov 4, 2018 at 2:06 PM Mike Rapoport <rppt@linux.ibm.com> wrote: > > > > On Sat, Nov 03, 2018 at 05:02:36AM -0700, Matthew Wilcox wrote: > > > On Sat, Nov 03, 2018 at 10:35:04AM +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. > > > > > > > > > > -/* 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) > > > ... > > > > +/* 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) > > > > > > I think it's important to mention in the changelog that these values > > > have been changed to avoid conflicts with other VM_FAULT codes. > > > > > > > +/** > > > > + * typedef vm_fault_t - __bitwise unsigned int > > > > + * > > > > + * vm_fault_t is the new unsigned int type to return VM_FAULT > > > > + * code by page fault handlers of drivers/file systems. Now if > > > > + * any page fault handlers returns non VM_FAULT code instead > > > > + * of VM_FAULT code, it will be a mismatch with function > > > > + * prototype and sparse will detect it. > > > > + */ > > > > > > The first line should be what the typedef *means*, not repeat the > > > compiler's definition. The rest of the description should be information > > > for someone coming to the type for the first time; what you've written > > > here is changelog material. > > > > > > /** > > > * 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 > > > > > > Can you document an anonymous enum? I've never tried. Did you run this > > > through 'make htmldocs'? > > > > You cannot document an anonymous enum. > > > I assume, you are pointing to Document folder and I don't know if this > enum need to be documented or not. The enum should be documented, even if it's documentation is (yet) not linked anywhere in the Documentation/ > I didn't run 'make htmldocs' as there is no document related changes. You can verify that kernel-doc can parse your documentation by running scripts/kernel-doc -none -v <filename> > > > > > > + * This enum is used to track the VM_FAULT code return by page > > > > + * fault handlers. > > > > > > * Page fault handlers return a bitmask of these values to tell the > > > * core VM what happened when handling the fault. > > > > > > > -- > > Sincerely yours, > > Mike. > > >
On Mon, Nov 5, 2018 at 2:43 PM Mike Rapoport <rppt@linux.ibm.com> wrote: > > On Mon, Nov 05, 2018 at 11:14:17AM +0530, Souptick Joarder wrote: > > Hi Matthew, > > > > On Sun, Nov 4, 2018 at 2:06 PM Mike Rapoport <rppt@linux.ibm.com> wrote: > > > > > > On Sat, Nov 03, 2018 at 05:02:36AM -0700, Matthew Wilcox wrote: > > > > On Sat, Nov 03, 2018 at 10:35:04AM +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. > > > > > > > > > > > > > -/* 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) > > > > ... > > > > > +/* 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) > > > > > > > > I think it's important to mention in the changelog that these values > > > > have been changed to avoid conflicts with other VM_FAULT codes. > > > > > > > > > +/** > > > > > + * typedef vm_fault_t - __bitwise unsigned int > > > > > + * > > > > > + * vm_fault_t is the new unsigned int type to return VM_FAULT > > > > > + * code by page fault handlers of drivers/file systems. Now if > > > > > + * any page fault handlers returns non VM_FAULT code instead > > > > > + * of VM_FAULT code, it will be a mismatch with function > > > > > + * prototype and sparse will detect it. > > > > > + */ > > > > > > > > The first line should be what the typedef *means*, not repeat the > > > > compiler's definition. The rest of the description should be information > > > > for someone coming to the type for the first time; what you've written > > > > here is changelog material. > > > > > > > > /** > > > > * 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 > > > > > > > > Can you document an anonymous enum? I've never tried. Did you run this > > > > through 'make htmldocs'? > > > > > > You cannot document an anonymous enum. > > > > > > I assume, you are pointing to Document folder and I don't know if this > > enum need to be documented or not. > > The enum should be documented, even if it's documentation is (yet) not > linked anywhere in the Documentation/ > > > I didn't run 'make htmldocs' as there is no document related changes. > > You can verify that kernel-doc can parse your documentation by running > > scripts/kernel-doc -none -v <filename> I run "scripts/kernel-doc -none -v include/linux/mm_types.h" and it is showing below error and warning which is linked to enum in discussion. include/linux/mm_types.h:612: info: Scanning doc for typedef vm_fault_t include/linux/mm_types.h:623: info: Scanning doc for enum include/linux/mm_types.h:628: warning: contents before sections include/linux/mm_types.h:660: error: Cannot parse enum! 1 errors 1 warnings Shall I keep the documentation for enum or remove it from this patch ? > > > > > > > > > + * This enum is used to track the VM_FAULT code return by page > > > > > + * fault handlers. > > > > > > > > * Page fault handlers return a bitmask of these values to tell the > > > > * core VM what happened when handling the fault. > > > > > > > > > > -- > > > Sincerely yours, > > > Mike. > > > > > > > -- > Sincerely yours, > Mike. >
On Mon, Nov 05, 2018 at 07:23:55PM +0530, Souptick Joarder wrote: > On Mon, Nov 5, 2018 at 2:43 PM Mike Rapoport <rppt@linux.ibm.com> wrote: > > > > On Mon, Nov 05, 2018 at 11:14:17AM +0530, Souptick Joarder wrote: > > > Hi Matthew, > > > > > > On Sun, Nov 4, 2018 at 2:06 PM Mike Rapoport <rppt@linux.ibm.com> wrote: > > > > > > > > On Sat, Nov 03, 2018 at 05:02:36AM -0700, Matthew Wilcox wrote: > > > > > On Sat, Nov 03, 2018 at 10:35:04AM +0530, Souptick Joarder wrote: > > > > > > +typedef __bitwise unsigned int vm_fault_t; > > > > > > + > > > > > > +/** > > > > > > + * enum - VM_FAULT code > > > > > > > > > > Can you document an anonymous enum? I've never tried. Did you run this > > > > > through 'make htmldocs'? > > > > > > > > You cannot document an anonymous enum. > > > > > > I assume, you are pointing to Document folder and I don't know if this > > > enum need to be documented or not. > > > > The enum should be documented, even if it's documentation is (yet) not > > linked anywhere in the Documentation/ > > > > > I didn't run 'make htmldocs' as there is no document related changes. > > > > You can verify that kernel-doc can parse your documentation by running > > > > scripts/kernel-doc -none -v <filename> > > I run "scripts/kernel-doc -none -v include/linux/mm_types.h" and it is showing > below error and warning which is linked to enum in discussion. > > include/linux/mm_types.h:612: info: Scanning doc for typedef vm_fault_t > include/linux/mm_types.h:623: info: Scanning doc for enum > include/linux/mm_types.h:628: warning: contents before sections > include/linux/mm_types.h:660: error: Cannot parse enum! > 1 errors > 1 warnings > > Shall I keep the documentation for enum or remove it from this patch ? The documentation should be there, you just need to add a name for the enum. Then kernel-doc will be able to parse it. > > > > > > > > > > + * This enum is used to track the VM_FAULT code return by page > > > > > > + * fault handlers. > > > > > I think that the enum description should also include the text from the comment that described VM_FAULT_* defines: /* * 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. */
On Tue, Nov 6, 2018 at 11:51 AM Mike Rapoport <rppt@linux.ibm.com> wrote: > > On Mon, Nov 05, 2018 at 07:23:55PM +0530, Souptick Joarder wrote: > > On Mon, Nov 5, 2018 at 2:43 PM Mike Rapoport <rppt@linux.ibm.com> wrote: > > > > > > On Mon, Nov 05, 2018 at 11:14:17AM +0530, Souptick Joarder wrote: > > > > Hi Matthew, > > > > > > > > On Sun, Nov 4, 2018 at 2:06 PM Mike Rapoport <rppt@linux.ibm.com> wrote: > > > > > > > > > > On Sat, Nov 03, 2018 at 05:02:36AM -0700, Matthew Wilcox wrote: > > > > > > On Sat, Nov 03, 2018 at 10:35:04AM +0530, Souptick Joarder wrote: > > > > > > > > +typedef __bitwise unsigned int vm_fault_t; > > > > > > > + > > > > > > > +/** > > > > > > > + * enum - VM_FAULT code > > > > > > > > > > > > Can you document an anonymous enum? I've never tried. Did you run this > > > > > > through 'make htmldocs'? > > > > > > > > > > You cannot document an anonymous enum. > > > > > > > > I assume, you are pointing to Document folder and I don't know if this > > > > enum need to be documented or not. > > > > > > The enum should be documented, even if it's documentation is (yet) not > > > linked anywhere in the Documentation/ > > > > > > > I didn't run 'make htmldocs' as there is no document related changes. > > > > > > You can verify that kernel-doc can parse your documentation by running > > > > > > scripts/kernel-doc -none -v <filename> > > > > I run "scripts/kernel-doc -none -v include/linux/mm_types.h" and it is showing > > below error and warning which is linked to enum in discussion. > > > > include/linux/mm_types.h:612: info: Scanning doc for typedef vm_fault_t > > include/linux/mm_types.h:623: info: Scanning doc for enum > > include/linux/mm_types.h:628: warning: contents before sections > > include/linux/mm_types.h:660: error: Cannot parse enum! > > 1 errors > > 1 warnings > > > > Shall I keep the documentation for enum or remove it from this patch ? > > The documentation should be there, you just need to add a name for the > enum. Then kernel-doc will be able to parse it. > > > > > > > > > > > > > + * This enum is used to track the VM_FAULT code return by page > > > > > > > + * fault handlers. > > > > > > > > I think that the enum description should also include the text from the > comment that described VM_FAULT_* defines: > > /* > * 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. > */ > Ok, will add both in v2. Thanks.
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..48c2108 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 +608,80 @@ static inline bool mm_tlb_flush_nested(struct mm_struct *mm) struct vm_fault; +/** + * typedef vm_fault_t - __bitwise unsigned int + * + * vm_fault_t is the new unsigned int type to return VM_FAULT + * code by page fault handlers of drivers/file systems. Now if + * any page fault handlers returns non VM_FAULT code instead + * of VM_FAULT code, it will be a mismatch with function + * prototype and sparse will detect it. + */ +typedef __bitwise unsigned int vm_fault_t; + +/** + * enum - VM_FAULT code + * + * This enum is used to track the VM_FAULT code return by page + * fault handlers. + * + * @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_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. Signed-off-by: Souptick Joarder <jrdr.linux@gmail.com> --- include/linux/mm.h | 46 ----------------------------- include/linux/mm_types.h | 75 +++++++++++++++++++++++++++++++++++++++++++++++- 2 files changed, 74 insertions(+), 47 deletions(-)