Re: [PATCH v2 8/9] mm: Remove CONFIG_PER_VMA_LOCK ifdefs

[Suren Baghdasaryan <surenb@google.com>]

On Tue, Jul 11, 2023 at 1:21 PM Matthew Wilcox (Oracle)
<willy@infradead.org> wrote:
>
> Provide lock_vma_under_rcu() when CONFIG_PER_VMA_LOCK is not defined
> to eliminate ifdefs in the users.
>
> Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>

Very nice. Thanks!

Reviewed-by: Suren Baghdasaryan <surenb@google.com>

> ---
>  arch/arm64/mm/fault.c   | 2 --
>  arch/powerpc/mm/fault.c | 4 ----
>  arch/riscv/mm/fault.c   | 4 ----
>  arch/s390/mm/fault.c    | 2 --
>  arch/x86/mm/fault.c     | 4 ----
>  include/linux/mm.h      | 6 ++++++
>  6 files changed, 6 insertions(+), 16 deletions(-)
>
> diff --git a/arch/arm64/mm/fault.c b/arch/arm64/mm/fault.c
> index b8c80f7b8a5f..2e5d1e238af9 100644
> --- a/arch/arm64/mm/fault.c
> +++ b/arch/arm64/mm/fault.c
> @@ -587,7 +587,6 @@ static int __kprobes do_page_fault(unsigned long far, unsigned long esr,
>
>         perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS, 1, regs, addr);
>
> -#ifdef CONFIG_PER_VMA_LOCK
>         if (!(mm_flags & FAULT_FLAG_USER))
>                 goto lock_mmap;
>
> @@ -616,7 +615,6 @@ static int __kprobes do_page_fault(unsigned long far, unsigned long esr,
>                 return 0;
>         }
>  lock_mmap:
> -#endif /* CONFIG_PER_VMA_LOCK */
>
>  retry:
>         vma = lock_mm_and_find_vma(mm, addr, regs);
> diff --git a/arch/powerpc/mm/fault.c b/arch/powerpc/mm/fault.c
> index 82954d0e6906..b1723094d464 100644
> --- a/arch/powerpc/mm/fault.c
> +++ b/arch/powerpc/mm/fault.c
> @@ -469,7 +469,6 @@ static int ___do_page_fault(struct pt_regs *regs, unsigned long address,
>         if (is_exec)
>                 flags |= FAULT_FLAG_INSTRUCTION;
>
> -#ifdef CONFIG_PER_VMA_LOCK
>         if (!(flags & FAULT_FLAG_USER))
>                 goto lock_mmap;
>
> @@ -502,7 +501,6 @@ static int ___do_page_fault(struct pt_regs *regs, unsigned long address,
>                 return user_mode(regs) ? 0 : SIGBUS;
>
>  lock_mmap:
> -#endif /* CONFIG_PER_VMA_LOCK */
>
>         /* When running in the kernel we expect faults to occur only to
>          * addresses in user space.  All other faults represent errors in the
> @@ -552,9 +550,7 @@ static int ___do_page_fault(struct pt_regs *regs, unsigned long address,
>
>         mmap_read_unlock(current->mm);
>
> -#ifdef CONFIG_PER_VMA_LOCK
>  done:
> -#endif
>         if (unlikely(fault & VM_FAULT_ERROR))
>                 return mm_fault_error(regs, address, fault);
>
> diff --git a/arch/riscv/mm/fault.c b/arch/riscv/mm/fault.c
> index 6ea2cce4cc17..046732fcb48c 100644
> --- a/arch/riscv/mm/fault.c
> +++ b/arch/riscv/mm/fault.c
> @@ -283,7 +283,6 @@ void handle_page_fault(struct pt_regs *regs)
>                 flags |= FAULT_FLAG_WRITE;
>         else if (cause == EXC_INST_PAGE_FAULT)
>                 flags |= FAULT_FLAG_INSTRUCTION;
> -#ifdef CONFIG_PER_VMA_LOCK
>         if (!(flags & FAULT_FLAG_USER))
>                 goto lock_mmap;
>
> @@ -311,7 +310,6 @@ void handle_page_fault(struct pt_regs *regs)
>                 return;
>         }
>  lock_mmap:
> -#endif /* CONFIG_PER_VMA_LOCK */
>
>  retry:
>         vma = lock_mm_and_find_vma(mm, addr, regs);
> @@ -368,9 +366,7 @@ void handle_page_fault(struct pt_regs *regs)
>
>         mmap_read_unlock(mm);
>
> -#ifdef CONFIG_PER_VMA_LOCK
>  done:
> -#endif
>         if (unlikely(fault & VM_FAULT_ERROR)) {
>                 tsk->thread.bad_cause = cause;
>                 mm_fault_error(regs, addr, fault);
> diff --git a/arch/s390/mm/fault.c b/arch/s390/mm/fault.c
> index 40a71063949b..ac8351f172bb 100644
> --- a/arch/s390/mm/fault.c
> +++ b/arch/s390/mm/fault.c
> @@ -407,7 +407,6 @@ static inline vm_fault_t do_exception(struct pt_regs *regs, int access)
>                 access = VM_WRITE;
>         if (access == VM_WRITE)
>                 flags |= FAULT_FLAG_WRITE;
> -#ifdef CONFIG_PER_VMA_LOCK
>         if (!(flags & FAULT_FLAG_USER))
>                 goto lock_mmap;
>         vma = lock_vma_under_rcu(mm, address);
> @@ -431,7 +430,6 @@ static inline vm_fault_t do_exception(struct pt_regs *regs, int access)
>                 goto out;
>         }
>  lock_mmap:
> -#endif /* CONFIG_PER_VMA_LOCK */
>         mmap_read_lock(mm);
>
>         gmap = NULL;
> diff --git a/arch/x86/mm/fault.c b/arch/x86/mm/fault.c
> index b0f7add07aa5..ab778eac1952 100644
> --- a/arch/x86/mm/fault.c
> +++ b/arch/x86/mm/fault.c
> @@ -1350,7 +1350,6 @@ void do_user_addr_fault(struct pt_regs *regs,
>         }
>  #endif
>
> -#ifdef CONFIG_PER_VMA_LOCK
>         if (!(flags & FAULT_FLAG_USER))
>                 goto lock_mmap;
>
> @@ -1381,7 +1380,6 @@ void do_user_addr_fault(struct pt_regs *regs,
>                 return;
>         }
>  lock_mmap:
> -#endif /* CONFIG_PER_VMA_LOCK */
>
>  retry:
>         vma = lock_mm_and_find_vma(mm, address, regs);
> @@ -1441,9 +1439,7 @@ void do_user_addr_fault(struct pt_regs *regs,
>         }
>
>         mmap_read_unlock(mm);
> -#ifdef CONFIG_PER_VMA_LOCK
>  done:
> -#endif
>         if (likely(!(fault & VM_FAULT_ERROR)))
>                 return;
>
> diff --git a/include/linux/mm.h b/include/linux/mm.h
> index 46c442855df7..3c923a4bf213 100644
> --- a/include/linux/mm.h
> +++ b/include/linux/mm.h
> @@ -813,6 +813,12 @@ static inline void assert_fault_locked(struct vm_fault *vmf)
>         mmap_assert_locked(vmf->vma->vm_mm);
>  }
>
> +static inline struct vm_area_struct *lock_vma_under_rcu(struct mm_struct *mm,
> +               unsigned long address)
> +{
> +       return NULL;
> +}
> +
>  #endif /* CONFIG_PER_VMA_LOCK */
>
>  /*
> --
> 2.39.2
>