From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pl1-f200.google.com (mail-pl1-f200.google.com [209.85.214.200]) by kanga.kvack.org (Postfix) with ESMTP id 6E6A66B0312 for ; Tue, 6 Nov 2018 07:03:14 -0500 (EST) Received: by mail-pl1-f200.google.com with SMTP id w10-v6so11648542plz.0 for ; Tue, 06 Nov 2018 04:03:14 -0800 (PST) Received: from mail-sor-f65.google.com (mail-sor-f65.google.com. [209.85.220.65]) by mx.google.com with SMTPS id y2sor7936365pgp.16.2018.11.06.04.03.12 for (Google Transport Security); Tue, 06 Nov 2018 04:03:12 -0800 (PST) Date: Tue, 6 Nov 2018 17:36:42 +0530 From: Souptick Joarder Subject: [PATCH v3] mm: Create the new vm_fault_t type Message-ID: <20181106120544.GA3783@jordon-HP-15-Notebook-PC> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Sender: owner-linux-mm@kvack.org List-ID: To: willy@infradead.org, akpm@linux-foundation.org, mhocko@suse.com, kirill.shutemov@linux.intel.com, dan.j.williams@intel.com, vbabka@suse.cz, riel@redhat.com, rppt@linux.ibm.com Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org 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 --- 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