mm: make __access_remote_vm() static

Patch series "various improvements to the GUP interface", v2.

A series of fixes to simplify and improve the GUP interface with an eye to
providing groundwork to future improvements:-

* __access_remote_vm() and access_remote_vm() are functionally identical,
  so make the former static such that in future we can potentially change
  the external-facing implementation details of this function.

* Extend is_valid_gup_args() to cover the missing FOLL_TOUCH case, and
  simplify things by defining INTERNAL_GUP_FLAGS to check against.

* Adjust __get_user_pages_locked() to explicitly treat a failure to pin any
  pages as an error in all circumstances other than FOLL_NOWAIT being
  specified, bringing it in line with the nommu implementation of this
  function.

* (With many thanks to Arnd who suggested this in the first instance)
  Update get_user_page_vma_remote() to explicitly only return a page or an
  error, simplifying the interface and avoiding the questionable
  IS_ERR_OR_NULL() pattern.

This patch (of 4):

access_remote_vm() passes through parameters to __access_remote_vm()
directly, so remove the __access_remote_vm() function from mm.h and use
access_remote_vm() in the one caller that needs it (ptrace_access_vm()).

This allows future adjustments to the GUP-internal __access_remote_vm()
function while keeping the access_remote_vm() function stable.

Link: https://lkml.kernel.org/r/cover.1696288092.git.lstoakes@gmail.com
Link: https://lkml.kernel.org/r/f7877c5039ce1c202a514a8aeeefc5cdd5e32d19.1696288092.git.lstoakes@gmail.com
Signed-off-by: Lorenzo Stoakes <lstoakes@gmail.com>
Reviewed-by: Arnd Bergmann <arnd@arndb.de>
Reviewed-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Jason Gunthorpe <jgg@nvidia.com>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Arnaldo Carvalho de Melo <acme@kernel.org>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Ian Rogers <irogers@google.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: John Hubbard <jhubbard@nvidia.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Richard Cochran <richardcochran@gmail.com>
Cc: Will Deacon <will@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

diff --git a/include/linux/mm.h b/include/linux/mm.h
index 52c40b3d08136899dbf205beee6b5e75a832e144..7b89f7bd420d6d6eb3209a8b30d6f37b4f0a9b03 100644 (file)
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -2415,8 +2415,6 @@ extern int access_process_vm(struct task_struct *tsk, unsigned long addr,
                void *buf, int len, unsigned int gup_flags);
 extern int access_remote_vm(struct mm_struct *mm, unsigned long addr,
                void *buf, int len, unsigned int gup_flags);
-extern int __access_remote_vm(struct mm_struct *mm, unsigned long addr,
-                             void *buf, int len, unsigned int gup_flags);
 
 long get_user_pages_remote(struct mm_struct *mm,
                           unsigned long start, unsigned long nr_pages,

diff --git a/kernel/ptrace.c b/kernel/ptrace.c
index 443057bee87cb7469990f3ad1d6abe09a42c22f3..d8b5e13a2229f4ab4f6aed871cd702dbea4e01aa 100644 (file)
--- a/kernel/ptrace.c
+++ b/kernel/ptrace.c
@@ -59,7 +59,7 @@ int ptrace_access_vm(struct task_struct *tsk, unsigned long addr,
                return 0;
        }
 
-       ret = __access_remote_vm(mm, addr, buf, len, gup_flags);
+       ret = access_remote_vm(mm, addr, buf, len, gup_flags);
        mmput(mm);
 
        return ret;

diff --git a/mm/memory.c b/mm/memory.c
index 22784d3b886d01b39d4c0d9e4d4a36b8140f7fa6..e47c36c0aef0e720f85cb28593f519169fc13b84 100644 (file)
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -5791,8 +5791,8 @@ EXPORT_SYMBOL_GPL(generic_access_phys);
 /*
  * Access another process' address space as given in mm.
  */
-int __access_remote_vm(struct mm_struct *mm, unsigned long addr, void *buf,
-                      int len, unsigned int gup_flags)
+static int __access_remote_vm(struct mm_struct *mm, unsigned long addr,
+                             void *buf, int len, unsigned int gup_flags)
 {
        void *old_buf = buf;
        int write = gup_flags & FOLL_WRITE;

diff --git a/mm/nommu.c b/mm/nommu.c
index 7f9e9e5a0e12ee5217191937a3725ac89ce28047..f9553579389bfc3931e892d6813508813d8e5d74 100644 (file)
--- a/mm/nommu.c
+++ b/mm/nommu.c
@@ -1651,8 +1651,8 @@ vm_fault_t filemap_map_pages(struct vm_fault *vmf,
 }
 EXPORT_SYMBOL(filemap_map_pages);
 
-int __access_remote_vm(struct mm_struct *mm, unsigned long addr, void *buf,
-                      int len, unsigned int gup_flags)
+static int __access_remote_vm(struct mm_struct *mm, unsigned long addr,
+                             void *buf, int len, unsigned int gup_flags)
 {
        struct vm_area_struct *vma;
        int write = gup_flags & FOLL_WRITE;