2018-11-06 12:06:09

by Souptick Joarder

Subject: [PATCH v3] mm: Create the new vm_fault_t type

Page fault handlers are supposed to return VM_FAULT codes,
but some drivers/file systems mistakenly return error
numbers. Now that all drivers/file systems have been converted
to use the vm_fault_t return type, change the type definition
to no longer be compatible with 'int'. By making it an unsigned
int, the function prototype becomes incompatible with a function
which returns int. Sparse will detect any attempts to return a
value which is not a VM_FAULT code.

VM_FAULT_SET_HINDEX and VM_FAULT_GET_HINDEX values are changed
to avoid conflict with other VM_FAULT codes.

Signed-off-by: Souptick Joarder <[email protected]>
---
v2: Updated the change log and corrected the document part.
name added to the enum that kernel-doc able to parse it.

v3: Corrected the documentation.

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..cb25016 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_reason - Page fault handlers return a bitmask of
+ * these values to tell the core VM what happened when handling the
+ * fault. Used to decide whether a process gets delivered SIGBUS or
+ * just gets major/minor fault counters bumped up.
+ *
+ * @VM_FAULT_OOM: Out Of Memory
+ * @VM_FAULT_SIGBUS: Bad access
+ * @VM_FAULT_MAJOR: Page read from storage
+ * @VM_FAULT_WRITE: Special case for get_user_pages
+ * @VM_FAULT_HWPOISON: Hit poisoned small page
+ * @VM_FAULT_HWPOISON_LARGE: Hit poisoned large page. Index encoded
+ * in upper bits
+ * @VM_FAULT_SIGSEGV: segmentation fault
+ * @VM_FAULT_NOPAGE: ->fault installed the pte, not return page
+ * @VM_FAULT_LOCKED: ->fault locked the returned page
+ * @VM_FAULT_RETRY: ->fault blocked, must retry
+ * @VM_FAULT_FALLBACK: huge page fault failed, fall back to small
+ * @VM_FAULT_DONE_COW: ->fault has fully handled COW
+ * @VM_FAULT_NEEDDSYNC: ->fault did not modify page tables and needs
+ * fsync() to complete (for synchronous page faults
+ * in DAX)
+ * @VM_FAULT_HINDEX_MASK: mask HINDEX value
+ *
+ */
+enum vm_fault_reason {
+ VM_FAULT_OOM = (__force vm_fault_t)0x000001,
+ VM_FAULT_SIGBUS = (__force vm_fault_t)0x000002,
+ VM_FAULT_MAJOR = (__force vm_fault_t)0x000004,
+ VM_FAULT_WRITE = (__force vm_fault_t)0x000008,
+ VM_FAULT_HWPOISON = (__force vm_fault_t)0x000010,
+ VM_FAULT_HWPOISON_LARGE = (__force vm_fault_t)0x000020,
+ VM_FAULT_SIGSEGV = (__force vm_fault_t)0x000040,
+ VM_FAULT_NOPAGE = (__force vm_fault_t)0x000100,
+ VM_FAULT_LOCKED = (__force vm_fault_t)0x000200,
+ VM_FAULT_RETRY = (__force vm_fault_t)0x000400,
+ VM_FAULT_FALLBACK = (__force vm_fault_t)0x000800,
+ VM_FAULT_DONE_COW = (__force vm_fault_t)0x001000,
+ VM_FAULT_NEEDDSYNC = (__force vm_fault_t)0x002000,
+ VM_FAULT_HINDEX_MASK = (__force vm_fault_t)0x0f0000,
+};
+
+/* Encode hstate index for a hwpoisoned large page */
+#define VM_FAULT_SET_HINDEX(x) ((__force vm_fault_t)((x) << 16))
+#define VM_FAULT_GET_HINDEX(x) (((x) >> 16) & 0xf)
+
+#define VM_FAULT_ERROR (VM_FAULT_OOM | VM_FAULT_SIGBUS | \
+ VM_FAULT_SIGSEGV | VM_FAULT_HWPOISON | \
+ VM_FAULT_HWPOISON_LARGE | VM_FAULT_FALLBACK)
+
+#define VM_FAULT_RESULT_TRACE \
+ { VM_FAULT_OOM, "OOM" }, \
+ { VM_FAULT_SIGBUS, "SIGBUS" }, \
+ { VM_FAULT_MAJOR, "MAJOR" }, \
+ { VM_FAULT_WRITE, "WRITE" }, \
+ { VM_FAULT_HWPOISON, "HWPOISON" }, \
+ { VM_FAULT_HWPOISON_LARGE, "HWPOISON_LARGE" }, \
+ { VM_FAULT_SIGSEGV, "SIGSEGV" }, \
+ { VM_FAULT_NOPAGE, "NOPAGE" }, \
+ { VM_FAULT_LOCKED, "LOCKED" }, \
+ { VM_FAULT_RETRY, "RETRY" }, \
+ { VM_FAULT_FALLBACK, "FALLBACK" }, \
+ { VM_FAULT_DONE_COW, "DONE_COW" }, \
+ { VM_FAULT_NEEDDSYNC, "NEEDDSYNC" }
+
struct vm_special_mapping {
const char *name; /* The name, e.g. "[vdso]". */

--
1.9.1

2018-11-06 12:10:44

by Michal Hocko

Subject: Re: [PATCH v3] mm: Create the new vm_fault_t type

[off-list]
Please do not submit a new version of the patch just after a minor
feedback to the documentation. Wait for some more feedback. Sending 3
versions in about 2 days is just way too much.

Thanks!
--
Michal Hocko
SUSE Labs

2018-11-14 05:14:27

by Souptick Joarder

Subject: Re: [PATCH v3] mm: Create the new vm_fault_t type

On Tue, Nov 6, 2018 at 5:33 PM Souptick Joarder <[email protected]> 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 <[email protected]>

Any further comment on this patch ?
> ---
> v2: Updated the change log and corrected the document part.
> name added to the enum that kernel-doc able to parse it.
>
> v3: Corrected the documentation.
>
> 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..cb25016 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_reason - Page fault handlers return a bitmask of
> + * these values to tell the core VM what happened when handling the
> + * fault. Used to decide whether a process gets delivered SIGBUS or
> + * just gets major/minor fault counters bumped up.
> + *
> + * @VM_FAULT_OOM: Out Of Memory
> + * @VM_FAULT_SIGBUS: Bad access
> + * @VM_FAULT_MAJOR: Page read from storage
> + * @VM_FAULT_WRITE: Special case for get_user_pages
> + * @VM_FAULT_HWPOISON: Hit poisoned small page
> + * @VM_FAULT_HWPOISON_LARGE: Hit poisoned large page. Index encoded
> + * in upper bits
> + * @VM_FAULT_SIGSEGV: segmentation fault
> + * @VM_FAULT_NOPAGE: ->fault installed the pte, not return page
> + * @VM_FAULT_LOCKED: ->fault locked the returned page
> + * @VM_FAULT_RETRY: ->fault blocked, must retry
> + * @VM_FAULT_FALLBACK: huge page fault failed, fall back to small
> + * @VM_FAULT_DONE_COW: ->fault has fully handled COW
> + * @VM_FAULT_NEEDDSYNC: ->fault did not modify page tables and needs
> + * fsync() to complete (for synchronous page faults
> + * in DAX)
> + * @VM_FAULT_HINDEX_MASK: mask HINDEX value
> + *
> + */
> +enum vm_fault_reason {
> + VM_FAULT_OOM = (__force vm_fault_t)0x000001,
> + VM_FAULT_SIGBUS = (__force vm_fault_t)0x000002,
> + VM_FAULT_MAJOR = (__force vm_fault_t)0x000004,
> + VM_FAULT_WRITE = (__force vm_fault_t)0x000008,
> + VM_FAULT_HWPOISON = (__force vm_fault_t)0x000010,
> + VM_FAULT_HWPOISON_LARGE = (__force vm_fault_t)0x000020,
> + VM_FAULT_SIGSEGV = (__force vm_fault_t)0x000040,
> + VM_FAULT_NOPAGE = (__force vm_fault_t)0x000100,
> + VM_FAULT_LOCKED = (__force vm_fault_t)0x000200,
> + VM_FAULT_RETRY = (__force vm_fault_t)0x000400,
> + VM_FAULT_FALLBACK = (__force vm_fault_t)0x000800,
> + VM_FAULT_DONE_COW = (__force vm_fault_t)0x001000,
> + VM_FAULT_NEEDDSYNC = (__force vm_fault_t)0x002000,
> + VM_FAULT_HINDEX_MASK = (__force vm_fault_t)0x0f0000,
> +};
> +
> +/* Encode hstate index for a hwpoisoned large page */
> +#define VM_FAULT_SET_HINDEX(x) ((__force vm_fault_t)((x) << 16))
> +#define VM_FAULT_GET_HINDEX(x) (((x) >> 16) & 0xf)
> +
> +#define VM_FAULT_ERROR (VM_FAULT_OOM | VM_FAULT_SIGBUS | \
> + VM_FAULT_SIGSEGV | VM_FAULT_HWPOISON | \
> + VM_FAULT_HWPOISON_LARGE | VM_FAULT_FALLBACK)
> +
> +#define VM_FAULT_RESULT_TRACE \
> + { VM_FAULT_OOM, "OOM" }, \
> + { VM_FAULT_SIGBUS, "SIGBUS" }, \
> + { VM_FAULT_MAJOR, "MAJOR" }, \
> + { VM_FAULT_WRITE, "WRITE" }, \
> + { VM_FAULT_HWPOISON, "HWPOISON" }, \
> + { VM_FAULT_HWPOISON_LARGE, "HWPOISON_LARGE" }, \
> + { VM_FAULT_SIGSEGV, "SIGSEGV" }, \
> + { VM_FAULT_NOPAGE, "NOPAGE" }, \
> + { VM_FAULT_LOCKED, "LOCKED" }, \
> + { VM_FAULT_RETRY, "RETRY" }, \
> + { VM_FAULT_FALLBACK, "FALLBACK" }, \
> + { VM_FAULT_DONE_COW, "DONE_COW" }, \
> + { VM_FAULT_NEEDDSYNC, "NEEDDSYNC" }
> +
> struct vm_special_mapping {
> const char *name; /* The name, e.g. "[vdso]". */
>
> --
> 1.9.1
>

2018-11-14 10:00:29

by William Kucharski

Subject: Re: [PATCH v3] mm: Create the new vm_fault_t type

> On Nov 13, 2018, at 10:13 PM, Souptick Joarder <[email protected]> wrote:
>
> On Tue, Nov 6, 2018 at 5:33 PM Souptick Joarder <[email protected]> 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 <[email protected]>
>
> Any further comment on this patch ?

Reviewed-by: William Kucharski <[email protected]>

2018-11-15 01:50:50

by Mike Rapoport

Subject: Re: [PATCH v3] mm: Create the new vm_fault_t type

On Tue, Nov 06, 2018 at 05:36:42PM +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 <[email protected]>

For the docs part
Reviewed-by: Mike Rapoport <[email protected]>

> ---
> v2: Updated the change log and corrected the document part.
> name added to the enum that kernel-doc able to parse it.
>
> v3: Corrected the documentation.
>
> 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..cb25016 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_reason - Page fault handlers return a bitmask of
> + * these values to tell the core VM what happened when handling the
> + * fault. Used to decide whether a process gets delivered SIGBUS or
> + * just gets major/minor fault counters bumped up.
> + *
> + * @VM_FAULT_OOM: Out Of Memory
> + * @VM_FAULT_SIGBUS: Bad access
> + * @VM_FAULT_MAJOR: Page read from storage
> + * @VM_FAULT_WRITE: Special case for get_user_pages
> + * @VM_FAULT_HWPOISON: Hit poisoned small page
> + * @VM_FAULT_HWPOISON_LARGE: Hit poisoned large page. Index encoded
> + * in upper bits
> + * @VM_FAULT_SIGSEGV: segmentation fault
> + * @VM_FAULT_NOPAGE: ->fault installed the pte, not return page
> + * @VM_FAULT_LOCKED: ->fault locked the returned page
> + * @VM_FAULT_RETRY: ->fault blocked, must retry
> + * @VM_FAULT_FALLBACK: huge page fault failed, fall back to small
> + * @VM_FAULT_DONE_COW: ->fault has fully handled COW
> + * @VM_FAULT_NEEDDSYNC: ->fault did not modify page tables and needs
> + * fsync() to complete (for synchronous page faults
> + * in DAX)
> + * @VM_FAULT_HINDEX_MASK: mask HINDEX value
> + *
> + */
> +enum vm_fault_reason {
> + VM_FAULT_OOM = (__force vm_fault_t)0x000001,
> + VM_FAULT_SIGBUS = (__force vm_fault_t)0x000002,
> + VM_FAULT_MAJOR = (__force vm_fault_t)0x000004,
> + VM_FAULT_WRITE = (__force vm_fault_t)0x000008,
> + VM_FAULT_HWPOISON = (__force vm_fault_t)0x000010,
> + VM_FAULT_HWPOISON_LARGE = (__force vm_fault_t)0x000020,
> + VM_FAULT_SIGSEGV = (__force vm_fault_t)0x000040,
> + VM_FAULT_NOPAGE = (__force vm_fault_t)0x000100,
> + VM_FAULT_LOCKED = (__force vm_fault_t)0x000200,
> + VM_FAULT_RETRY = (__force vm_fault_t)0x000400,
> + VM_FAULT_FALLBACK = (__force vm_fault_t)0x000800,
> + VM_FAULT_DONE_COW = (__force vm_fault_t)0x001000,
> + VM_FAULT_NEEDDSYNC = (__force vm_fault_t)0x002000,
> + VM_FAULT_HINDEX_MASK = (__force vm_fault_t)0x0f0000,
> +};
> +
> +/* Encode hstate index for a hwpoisoned large page */
> +#define VM_FAULT_SET_HINDEX(x) ((__force vm_fault_t)((x) << 16))
> +#define VM_FAULT_GET_HINDEX(x) (((x) >> 16) & 0xf)
> +
> +#define VM_FAULT_ERROR (VM_FAULT_OOM | VM_FAULT_SIGBUS | \
> + VM_FAULT_SIGSEGV | VM_FAULT_HWPOISON | \
> + VM_FAULT_HWPOISON_LARGE | VM_FAULT_FALLBACK)
> +
> +#define VM_FAULT_RESULT_TRACE \
> + { VM_FAULT_OOM, "OOM" }, \
> + { VM_FAULT_SIGBUS, "SIGBUS" }, \
> + { VM_FAULT_MAJOR, "MAJOR" }, \
> + { VM_FAULT_WRITE, "WRITE" }, \
> + { VM_FAULT_HWPOISON, "HWPOISON" }, \
> + { VM_FAULT_HWPOISON_LARGE, "HWPOISON_LARGE" }, \
> + { VM_FAULT_SIGSEGV, "SIGSEGV" }, \
> + { VM_FAULT_NOPAGE, "NOPAGE" }, \
> + { VM_FAULT_LOCKED, "LOCKED" }, \
> + { VM_FAULT_RETRY, "RETRY" }, \
> + { VM_FAULT_FALLBACK, "FALLBACK" }, \
> + { VM_FAULT_DONE_COW, "DONE_COW" }, \
> + { VM_FAULT_NEEDDSYNC, "NEEDDSYNC" }
> +
> struct vm_special_mapping {
> const char *name; /* The name, e.g. "[vdso]". */
>
> --
> 1.9.1
>

--
Sincerely yours,
Mike.

2018-11-24 09:01:53

by Souptick Joarder

Subject: Re: [PATCH v3] mm: Create the new vm_fault_t type

On Thu, Nov 15, 2018 at 7:17 AM Mike Rapoport <[email protected]> wrote:
>
> On Tue, Nov 06, 2018 at 05:36:42PM +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 <[email protected]>
>
> For the docs part
> Reviewed-by: Mike Rapoport <[email protected]>
>
> > ---
> > v2: Updated the change log and corrected the document part.
> > name added to the enum that kernel-doc able to parse it.
> >
> > v3: Corrected the documentation.

If no further comment, can we get this patch in queue for 4.21 ?

> >
> > 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..cb25016 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_reason - Page fault handlers return a bitmask of
> > + * these values to tell the core VM what happened when handling the
> > + * fault. Used to decide whether a process gets delivered SIGBUS or
> > + * just gets major/minor fault counters bumped up.
> > + *
> > + * @VM_FAULT_OOM: Out Of Memory
> > + * @VM_FAULT_SIGBUS: Bad access
> > + * @VM_FAULT_MAJOR: Page read from storage
> > + * @VM_FAULT_WRITE: Special case for get_user_pages
> > + * @VM_FAULT_HWPOISON: Hit poisoned small page
> > + * @VM_FAULT_HWPOISON_LARGE: Hit poisoned large page. Index encoded
> > + * in upper bits
> > + * @VM_FAULT_SIGSEGV: segmentation fault
> > + * @VM_FAULT_NOPAGE: ->fault installed the pte, not return page
> > + * @VM_FAULT_LOCKED: ->fault locked the returned page
> > + * @VM_FAULT_RETRY: ->fault blocked, must retry
> > + * @VM_FAULT_FALLBACK: huge page fault failed, fall back to small
> > + * @VM_FAULT_DONE_COW: ->fault has fully handled COW
> > + * @VM_FAULT_NEEDDSYNC: ->fault did not modify page tables and needs
> > + * fsync() to complete (for synchronous page faults
> > + * in DAX)
> > + * @VM_FAULT_HINDEX_MASK: mask HINDEX value
> > + *
> > + */
> > +enum vm_fault_reason {
> > + VM_FAULT_OOM = (__force vm_fault_t)0x000001,
> > + VM_FAULT_SIGBUS = (__force vm_fault_t)0x000002,
> > + VM_FAULT_MAJOR = (__force vm_fault_t)0x000004,
> > + VM_FAULT_WRITE = (__force vm_fault_t)0x000008,
> > + VM_FAULT_HWPOISON = (__force vm_fault_t)0x000010,
> > + VM_FAULT_HWPOISON_LARGE = (__force vm_fault_t)0x000020,
> > + VM_FAULT_SIGSEGV = (__force vm_fault_t)0x000040,
> > + VM_FAULT_NOPAGE = (__force vm_fault_t)0x000100,
> > + VM_FAULT_LOCKED = (__force vm_fault_t)0x000200,
> > + VM_FAULT_RETRY = (__force vm_fault_t)0x000400,
> > + VM_FAULT_FALLBACK = (__force vm_fault_t)0x000800,
> > + VM_FAULT_DONE_COW = (__force vm_fault_t)0x001000,
> > + VM_FAULT_NEEDDSYNC = (__force vm_fault_t)0x002000,
> > + VM_FAULT_HINDEX_MASK = (__force vm_fault_t)0x0f0000,
> > +};
> > +
> > +/* Encode hstate index for a hwpoisoned large page */
> > +#define VM_FAULT_SET_HINDEX(x) ((__force vm_fault_t)((x) << 16))
> > +#define VM_FAULT_GET_HINDEX(x) (((x) >> 16) & 0xf)
> > +
> > +#define VM_FAULT_ERROR (VM_FAULT_OOM | VM_FAULT_SIGBUS | \
> > + VM_FAULT_SIGSEGV | VM_FAULT_HWPOISON | \
> > + VM_FAULT_HWPOISON_LARGE | VM_FAULT_FALLBACK)
> > +
> > +#define VM_FAULT_RESULT_TRACE \
> > + { VM_FAULT_OOM, "OOM" }, \
> > + { VM_FAULT_SIGBUS, "SIGBUS" }, \
> > + { VM_FAULT_MAJOR, "MAJOR" }, \
> > + { VM_FAULT_WRITE, "WRITE" }, \
> > + { VM_FAULT_HWPOISON, "HWPOISON" }, \
> > + { VM_FAULT_HWPOISON_LARGE, "HWPOISON_LARGE" }, \
> > + { VM_FAULT_SIGSEGV, "SIGSEGV" }, \
> > + { VM_FAULT_NOPAGE, "NOPAGE" }, \
> > + { VM_FAULT_LOCKED, "LOCKED" }, \
> > + { VM_FAULT_RETRY, "RETRY" }, \
> > + { VM_FAULT_FALLBACK, "FALLBACK" }, \
> > + { VM_FAULT_DONE_COW, "DONE_COW" }, \
> > + { VM_FAULT_NEEDDSYNC, "NEEDDSYNC" }
> > +
> > struct vm_special_mapping {
> > const char *name; /* The name, e.g. "[vdso]". */
> >
> > --
> > 1.9.1
> >
>
> --
> Sincerely yours,
> Mike.
>

2018-12-14 05:06:57

by Souptick Joarder

Subject: Re: [PATCH v3] mm: Create the new vm_fault_t type

Hi Andrew,

On Sat, Nov 24, 2018 at 10:16 AM Souptick Joarder <[email protected]> wrote:
>
> On Thu, Nov 15, 2018 at 7:17 AM Mike Rapoport <[email protected]> wrote:
> >
> > On Tue, Nov 06, 2018 at 05:36:42PM +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 <[email protected]>
> >
> > For the docs part
> > Reviewed-by: Mike Rapoport <[email protected]>
> >
> > > ---
> > > v2: Updated the change log and corrected the document part.
> > > name added to the enum that kernel-doc able to parse it.
> > >
> > > v3: Corrected the documentation.
>
> If no further comment, can we get this patch in queue for 4.21 ?

Do I need to make any further improvement for this patch ?
>
> > >
> > > 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..cb25016 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_reason - Page fault handlers return a bitmask of
> > > + * these values to tell the core VM what happened when handling the
> > > + * fault. Used to decide whether a process gets delivered SIGBUS or
> > > + * just gets major/minor fault counters bumped up.
> > > + *
> > > + * @VM_FAULT_OOM: Out Of Memory
> > > + * @VM_FAULT_SIGBUS: Bad access
> > > + * @VM_FAULT_MAJOR: Page read from storage
> > > + * @VM_FAULT_WRITE: Special case for get_user_pages
> > > + * @VM_FAULT_HWPOISON: Hit poisoned small page
> > > + * @VM_FAULT_HWPOISON_LARGE: Hit poisoned large page. Index encoded
> > > + * in upper bits
> > > + * @VM_FAULT_SIGSEGV: segmentation fault
> > > + * @VM_FAULT_NOPAGE: ->fault installed the pte, not return page
> > > + * @VM_FAULT_LOCKED: ->fault locked the returned page
> > > + * @VM_FAULT_RETRY: ->fault blocked, must retry
> > > + * @VM_FAULT_FALLBACK: huge page fault failed, fall back to small
> > > + * @VM_FAULT_DONE_COW: ->fault has fully handled COW
> > > + * @VM_FAULT_NEEDDSYNC: ->fault did not modify page tables and needs
> > > + * fsync() to complete (for synchronous page faults
> > > + * in DAX)
> > > + * @VM_FAULT_HINDEX_MASK: mask HINDEX value
> > > + *
> > > + */
> > > +enum vm_fault_reason {
> > > + VM_FAULT_OOM = (__force vm_fault_t)0x000001,
> > > + VM_FAULT_SIGBUS = (__force vm_fault_t)0x000002,
> > > + VM_FAULT_MAJOR = (__force vm_fault_t)0x000004,
> > > + VM_FAULT_WRITE = (__force vm_fault_t)0x000008,
> > > + VM_FAULT_HWPOISON = (__force vm_fault_t)0x000010,
> > > + VM_FAULT_HWPOISON_LARGE = (__force vm_fault_t)0x000020,
> > > + VM_FAULT_SIGSEGV = (__force vm_fault_t)0x000040,
> > > + VM_FAULT_NOPAGE = (__force vm_fault_t)0x000100,
> > > + VM_FAULT_LOCKED = (__force vm_fault_t)0x000200,
> > > + VM_FAULT_RETRY = (__force vm_fault_t)0x000400,
> > > + VM_FAULT_FALLBACK = (__force vm_fault_t)0x000800,
> > > + VM_FAULT_DONE_COW = (__force vm_fault_t)0x001000,
> > > + VM_FAULT_NEEDDSYNC = (__force vm_fault_t)0x002000,
> > > + VM_FAULT_HINDEX_MASK = (__force vm_fault_t)0x0f0000,
> > > +};
> > > +
> > > +/* Encode hstate index for a hwpoisoned large page */
> > > +#define VM_FAULT_SET_HINDEX(x) ((__force vm_fault_t)((x) << 16))
> > > +#define VM_FAULT_GET_HINDEX(x) (((x) >> 16) & 0xf)
> > > +
> > > +#define VM_FAULT_ERROR (VM_FAULT_OOM | VM_FAULT_SIGBUS | \
> > > + VM_FAULT_SIGSEGV | VM_FAULT_HWPOISON | \
> > > + VM_FAULT_HWPOISON_LARGE | VM_FAULT_FALLBACK)
> > > +
> > > +#define VM_FAULT_RESULT_TRACE \
> > > + { VM_FAULT_OOM, "OOM" }, \
> > > + { VM_FAULT_SIGBUS, "SIGBUS" }, \
> > > + { VM_FAULT_MAJOR, "MAJOR" }, \
> > > + { VM_FAULT_WRITE, "WRITE" }, \
> > > + { VM_FAULT_HWPOISON, "HWPOISON" }, \
> > > + { VM_FAULT_HWPOISON_LARGE, "HWPOISON_LARGE" }, \
> > > + { VM_FAULT_SIGSEGV, "SIGSEGV" }, \
> > > + { VM_FAULT_NOPAGE, "NOPAGE" }, \
> > > + { VM_FAULT_LOCKED, "LOCKED" }, \
> > > + { VM_FAULT_RETRY, "RETRY" }, \
> > > + { VM_FAULT_FALLBACK, "FALLBACK" }, \
> > > + { VM_FAULT_DONE_COW, "DONE_COW" }, \
> > > + { VM_FAULT_NEEDDSYNC, "NEEDDSYNC" }
> > > +
> > > struct vm_special_mapping {
> > > const char *name; /* The name, e.g. "[vdso]". */
> > >
> > > --
> > > 1.9.1
> > >
> >
> > --
> > Sincerely yours,
> > Mike.
> >

2019-01-07 06:19:53

by Souptick Joarder

Subject: Re: [PATCH v3] mm: Create the new vm_fault_t type

On Fri, Dec 14, 2018 at 10:35 AM Souptick Joarder <[email protected]> wrote:
>
> Hi Andrew,
>
> On Sat, Nov 24, 2018 at 10:16 AM Souptick Joarder <[email protected]> wrote:
> >
> > On Thu, Nov 15, 2018 at 7:17 AM Mike Rapoport <[email protected]> wrote:
> > >
> > > On Tue, Nov 06, 2018 at 05:36:42PM +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 <[email protected]>
> > >
> > > For the docs part
> > > Reviewed-by: Mike Rapoport <[email protected]>
> > >
> > > > ---
> > > > v2: Updated the change log and corrected the document part.
> > > > name added to the enum that kernel-doc able to parse it.
> > > >
> > > > v3: Corrected the documentation.
> >
> > If no further comment, can we get this patch in queue for 4.21 ?
>
> Do I need to make any further improvement for this patch ?

If no further comment, can we get this patch in queue for 5.0-rcX ?

> >
> > > >
> > > > 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..cb25016 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_reason - Page fault handlers return a bitmask of
> > > > + * these values to tell the core VM what happened when handling the
> > > > + * fault. Used to decide whether a process gets delivered SIGBUS or
> > > > + * just gets major/minor fault counters bumped up.
> > > > + *
> > > > + * @VM_FAULT_OOM: Out Of Memory
> > > > + * @VM_FAULT_SIGBUS: Bad access
> > > > + * @VM_FAULT_MAJOR: Page read from storage
> > > > + * @VM_FAULT_WRITE: Special case for get_user_pages
> > > > + * @VM_FAULT_HWPOISON: Hit poisoned small page
> > > > + * @VM_FAULT_HWPOISON_LARGE: Hit poisoned large page. Index encoded
> > > > + * in upper bits
> > > > + * @VM_FAULT_SIGSEGV: segmentation fault
> > > > + * @VM_FAULT_NOPAGE: ->fault installed the pte, not return page
> > > > + * @VM_FAULT_LOCKED: ->fault locked the returned page
> > > > + * @VM_FAULT_RETRY: ->fault blocked, must retry
> > > > + * @VM_FAULT_FALLBACK: huge page fault failed, fall back to small
> > > > + * @VM_FAULT_DONE_COW: ->fault has fully handled COW
> > > > + * @VM_FAULT_NEEDDSYNC: ->fault did not modify page tables and needs
> > > > + * fsync() to complete (for synchronous page faults
> > > > + * in DAX)
> > > > + * @VM_FAULT_HINDEX_MASK: mask HINDEX value
> > > > + *
> > > > + */
> > > > +enum vm_fault_reason {
> > > > + VM_FAULT_OOM = (__force vm_fault_t)0x000001,
> > > > + VM_FAULT_SIGBUS = (__force vm_fault_t)0x000002,
> > > > + VM_FAULT_MAJOR = (__force vm_fault_t)0x000004,
> > > > + VM_FAULT_WRITE = (__force vm_fault_t)0x000008,
> > > > + VM_FAULT_HWPOISON = (__force vm_fault_t)0x000010,
> > > > + VM_FAULT_HWPOISON_LARGE = (__force vm_fault_t)0x000020,
> > > > + VM_FAULT_SIGSEGV = (__force vm_fault_t)0x000040,
> > > > + VM_FAULT_NOPAGE = (__force vm_fault_t)0x000100,
> > > > + VM_FAULT_LOCKED = (__force vm_fault_t)0x000200,
> > > > + VM_FAULT_RETRY = (__force vm_fault_t)0x000400,
> > > > + VM_FAULT_FALLBACK = (__force vm_fault_t)0x000800,
> > > > + VM_FAULT_DONE_COW = (__force vm_fault_t)0x001000,
> > > > + VM_FAULT_NEEDDSYNC = (__force vm_fault_t)0x002000,
> > > > + VM_FAULT_HINDEX_MASK = (__force vm_fault_t)0x0f0000,
> > > > +};
> > > > +
> > > > +/* Encode hstate index for a hwpoisoned large page */
> > > > +#define VM_FAULT_SET_HINDEX(x) ((__force vm_fault_t)((x) << 16))
> > > > +#define VM_FAULT_GET_HINDEX(x) (((x) >> 16) & 0xf)
> > > > +
> > > > +#define VM_FAULT_ERROR (VM_FAULT_OOM | VM_FAULT_SIGBUS | \
> > > > + VM_FAULT_SIGSEGV | VM_FAULT_HWPOISON | \
> > > > + VM_FAULT_HWPOISON_LARGE | VM_FAULT_FALLBACK)
> > > > +
> > > > +#define VM_FAULT_RESULT_TRACE \
> > > > + { VM_FAULT_OOM, "OOM" }, \
> > > > + { VM_FAULT_SIGBUS, "SIGBUS" }, \
> > > > + { VM_FAULT_MAJOR, "MAJOR" }, \
> > > > + { VM_FAULT_WRITE, "WRITE" }, \
> > > > + { VM_FAULT_HWPOISON, "HWPOISON" }, \
> > > > + { VM_FAULT_HWPOISON_LARGE, "HWPOISON_LARGE" }, \
> > > > + { VM_FAULT_SIGSEGV, "SIGSEGV" }, \
> > > > + { VM_FAULT_NOPAGE, "NOPAGE" }, \
> > > > + { VM_FAULT_LOCKED, "LOCKED" }, \
> > > > + { VM_FAULT_RETRY, "RETRY" }, \
> > > > + { VM_FAULT_FALLBACK, "FALLBACK" }, \
> > > > + { VM_FAULT_DONE_COW, "DONE_COW" }, \
> > > > + { VM_FAULT_NEEDDSYNC, "NEEDDSYNC" }
> > > > +
> > > > struct vm_special_mapping {
> > > > const char *name; /* The name, e.g. "[vdso]". */
> > > >
> > > > --
> > > > 1.9.1
> > > >
> > >
> > > --
> > > Sincerely yours,
> > > Mike.
> > >

2019-01-07 23:10:49

by Andrew Morton

Subject: Re: [PATCH v3] mm: Create the new vm_fault_t type

On Mon, 7 Jan 2019 11:47:12 +0530 Souptick Joarder <[email protected]> wrote:

> > Do I need to make any further improvement for this patch ?
>
> If no further comment, can we get this patch in queue for 5.0-rcX ?

I stopped paying attention a while ago, sorry.

Please resend everything which you believe is ready to go.

2019-01-08 11:55:45

by Souptick Joarder

Subject: Re: [PATCH v3] mm: Create the new vm_fault_t type

On Tue, Jan 8, 2019 at 4:14 AM Andrew Morton <[email protected]> wrote:
>
> On Mon, 7 Jan 2019 11:47:12 +0530 Souptick Joarder <[email protected]> wrote:
>
> > > Do I need to make any further improvement for this patch ?
> >
> > If no further comment, can we get this patch in queue for 5.0-rcX ?
>
> I stopped paying attention a while ago, sorry.
>
> Please resend everything which you believe is ready to go.

Sure, I will resend. no prob :)