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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>
This commit is contained in:
Lorenzo Stoakes 2023-10-03 00:14:51 +01:00 committed by Andrew Morton
parent 8c2214fc9a
commit c43cfa4254
4 changed files with 5 additions and 7 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

2
include/linux/mm.h
View File

@ -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,

2
kernel/ptrace.c
View File

@ -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;

4
mm/memory.c
View File

@ -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;

4
mm/nommu.c
View File

@ -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;