On Mon, Oct 26, 2020 at 12:41:37AM -0700, John Hubbard wrote:
> Despite a comment that said that page fault accounting would be charged
> to whatever task_struct* was passed into __access_remote_vm(), the tsk
> argument was actually unused.
>
> Delete both the comment, and the argument.
I'd also mention that making page fault accounting actually use this
task struct is quite a project, so there is no point to keep tsk
argument.
> Signed-off-by: John Hubbard <jhubbard@xxxxxxxxxx>
> Cc: Oleg Nesterov <oleg@xxxxxxxxxx>
FWIW:
Reviewed-by: Mike Rapoport <rppt@xxxxxxxxxxxxx>
> ---
>
> Hi,
>
> Just something that caught my eye when I was reviewing a semi-related
> patchset.
>
> thanks,
> John Hubbard
> NVIDIA
>
> include/linux/mm.h | 4 ++--
> kernel/ptrace.c | 2 +-
> mm/memory.c | 11 +++++------
> mm/nommu.c | 8 ++++----
> 4 files changed, 12 insertions(+), 13 deletions(-)
>
> diff --git a/include/linux/mm.h b/include/linux/mm.h
> index ef360fe70aaf..b3b85a5c5937 100644
> --- a/include/linux/mm.h
> +++ b/include/linux/mm.h
> @@ -1716,8 +1716,8 @@ 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 task_struct *tsk, 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 43d6179508d6..fbbe32443b18 100644
> --- a/kernel/ptrace.c
> +++ b/kernel/ptrace.c
> @@ -57,7 +57,7 @@ int ptrace_access_vm(struct task_struct *tsk, unsigned long addr,
> return 0;
> }
>
> - ret = __access_remote_vm(tsk, 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 c48f8df6e502..25b28bc251d5 100644
> --- a/mm/memory.c
> +++ b/mm/memory.c
> @@ -4874,11 +4874,10 @@ EXPORT_SYMBOL_GPL(generic_access_phys);
> #endif
>
> /*
> - * Access another process' address space as given in mm. If non-NULL, use the
> - * given task for page fault accounting.
> + * Access another process' address space as given in mm.
> */
> -int __access_remote_vm(struct task_struct *tsk, struct mm_struct *mm,
> - unsigned long addr, void *buf, int len, unsigned int gup_flags)
> +int __access_remote_vm(struct mm_struct *mm, unsigned long addr, void *buf,
> + int len, unsigned int gup_flags)
> {
> struct vm_area_struct *vma;
> void *old_buf = buf;
> @@ -4955,7 +4954,7 @@ int __access_remote_vm(struct task_struct *tsk, struct mm_struct *mm,
> int access_remote_vm(struct mm_struct *mm, unsigned long addr,
> void *buf, int len, unsigned int gup_flags)
> {
> - return __access_remote_vm(NULL, mm, addr, buf, len, gup_flags);
> + return __access_remote_vm(mm, addr, buf, len, gup_flags);
> }
>
> /*
> @@ -4973,7 +4972,7 @@ int access_process_vm(struct task_struct *tsk, unsigned long addr,
> if (!mm)
> return 0;
>
> - ret = __access_remote_vm(tsk, mm, addr, buf, len, gup_flags);
> + ret = __access_remote_vm(mm, addr, buf, len, gup_flags);
>
> mmput(mm);
>
> diff --git a/mm/nommu.c b/mm/nommu.c
> index 0faf39b32cdb..870fea12823e 100644
> --- a/mm/nommu.c
> +++ b/mm/nommu.c
> @@ -1675,8 +1675,8 @@ void filemap_map_pages(struct vm_fault *vmf,
> }
> EXPORT_SYMBOL(filemap_map_pages);
>
> -int __access_remote_vm(struct task_struct *tsk, struct mm_struct *mm,
> - unsigned long addr, void *buf, int len, unsigned int gup_flags)
> +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;
> @@ -1722,7 +1722,7 @@ int __access_remote_vm(struct task_struct *tsk, struct mm_struct *mm,
> int access_remote_vm(struct mm_struct *mm, unsigned long addr,
> void *buf, int len, unsigned int gup_flags)
> {
> - return __access_remote_vm(NULL, mm, addr, buf, len, gup_flags);
> + return __access_remote_vm(mm, addr, buf, len, gup_flags);
> }
>
> /*
> @@ -1741,7 +1741,7 @@ int access_process_vm(struct task_struct *tsk, unsigned long addr, void *buf, in
> if (!mm)
> return 0;
>
> - len = __access_remote_vm(tsk, mm, addr, buf, len, gup_flags);
> + len = __access_remote_vm(mm, addr, buf, len, gup_flags);
>
> mmput(mm);
> return len;
>
> base-commit: 3650b228f83adda7e5ee532e2b90429c03f7b9ec
> --
> 2.29.0
>
>
--
Sincerely yours,
Mike.
