* [PATCH v2] mm: Create the new vm_fault_t type
@ 2018-11-06 7:49 Souptick Joarder
2018-11-06 8:26 ` Mike Rapoport
2018-11-06 13:27 ` kbuild test robot
0 siblings, 2 replies; 5+ messages in thread
From: Souptick Joarder @ 2018-11-06 7:49 UTC (permalink / raw)
To: willy, akpm, mhocko, kirill.shutemov, dan.j.williams, vbabka, riel, rppt
Cc: linux-mm, linux-kernel
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
+ *
+ * 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
^ permalink raw reply related [flat|nested] 5+ messages in thread
* Re: [PATCH v2] mm: Create the new vm_fault_t type
2018-11-06 7:49 [PATCH v2] mm: Create the new vm_fault_t type Souptick Joarder
@ 2018-11-06 8:26 ` Mike Rapoport
2018-11-06 8:34 ` Souptick Joarder
2018-11-06 13:27 ` kbuild test robot
1 sibling, 1 reply; 5+ messages in thread
From: Mike Rapoport @ 2018-11-06 8:26 UTC (permalink / raw)
To: Souptick Joarder
Cc: willy, akpm, mhocko, kirill.shutemov, dan.j.williams, vbabka,
riel, linux-mm, linux-kernel
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
>
--
Sincerely yours,
Mike.
^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: [PATCH v2] mm: Create the new vm_fault_t type
2018-11-06 8:26 ` Mike Rapoport
@ 2018-11-06 8:34 ` Souptick Joarder
2018-11-06 9:00 ` Mike Rapoport
0 siblings, 1 reply; 5+ messages in thread
From: Souptick Joarder @ 2018-11-06 8:34 UTC (permalink / raw)
To: rppt
Cc: Matthew Wilcox, Andrew Morton, Michal Hocko, Kirill A. Shutemov,
Dan Williams, vbabka, riel, Linux-MM, linux-kernel
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.
>
^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: [PATCH v2] mm: Create the new vm_fault_t type
2018-11-06 8:34 ` Souptick Joarder
@ 2018-11-06 9:00 ` Mike Rapoport
0 siblings, 0 replies; 5+ messages in thread
From: Mike Rapoport @ 2018-11-06 9:00 UTC (permalink / raw)
To: Souptick Joarder
Cc: Matthew Wilcox, Andrew Morton, Michal Hocko, Kirill A. Shutemov,
Dan Williams, vbabka, riel, Linux-MM, linux-kernel
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.
> >
>
--
Sincerely yours,
Mike.
^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: [PATCH v2] mm: Create the new vm_fault_t type
2018-11-06 7:49 [PATCH v2] mm: Create the new vm_fault_t type Souptick Joarder
2018-11-06 8:26 ` Mike Rapoport
@ 2018-11-06 13:27 ` kbuild test robot
1 sibling, 0 replies; 5+ messages in thread
From: kbuild test robot @ 2018-11-06 13:27 UTC (permalink / raw)
To: Souptick Joarder
Cc: kbuild-all, willy, akpm, mhocko, kirill.shutemov, dan.j.williams,
vbabka, riel, rppt, linux-mm, linux-kernel
[-- Attachment #1: Type: text/plain, Size: 1545 bytes --]
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
[-- Attachment #2: .config.gz --]
[-- Type: application/gzip, Size: 31349 bytes --]
^ permalink raw reply [flat|nested] 5+ messages in thread
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2018-11-06 8:26 ` Mike Rapoport
2018-11-06 8:34 ` Souptick Joarder
2018-11-06 9:00 ` Mike Rapoport
2018-11-06 13:27 ` kbuild test robot
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