Re: [PATCH] mm: Remove mm argument from mm_get_unmapped_area()

Liam R. Howlett
2024-05-06T16:33:04Z

* Rick Edgecombe <rick.p.edgecombe@intel.com> [240506 12:08]:
> Recently the get_unmapped_area() pointer on mm_struct was removed in
> favor of direct callable function that can determines which of two
> handlers to call based on an mm flag. This function,
> mm_get_unmapped_area(), checks the flag of the mm passed as an argument.
>
> Dan Williams pointed out (see link) that all callers pass curret->mm, so
> the mm argument is unneeded. It could be conceivable for a caller to want
> to pass a different mm in the future, but in this case a new helper could
> easily be added.
>
> So remove the mm argument, and rename the function
> current_get_unmapped_area().

I like this patch.

I think the context of current->mm is implied. IOW, could we call it
get_unmapped_area() instead? There are other functions today that use
current->mm that don't start with current_<whatever>. I probably should
have responded to Dan's suggestion with my comment.

Either way, this is a minor thing so feel free to add:
Reviewed-by: Liam R. Howlett <Liam.Howlett@oracle.com>

>
> Fixes: 529ce23a764f ("mm: switch mm->get_unmapped_area() to a flag")
> Suggested-by: Dan Williams <dan.j.williams@intel.com>
> Signed-off-by: Rick Edgecombe <rick.p.edgecombe@intel.com>
> Link: https://lore.kernel.org/lkml/6603bed6662a_4a98a2949e@dwillia2-mobl3.amr.corp.intel.com.notmuch/
> ---
> Based on linux-next.
> ---
> arch/sparc/kernel/sys_sparc_64.c | 9 +++++----
> arch/x86/kernel/cpu/sgx/driver.c | 2 +-
> drivers/char/mem.c | 2 +-
> drivers/dax/device.c | 6 +++---
> fs/proc/inode.c | 2 +-
> fs/ramfs/file-mmu.c | 2 +-
> include/linux/sched/mm.h | 6 +++---
> io_uring/memmap.c | 2 +-
> kernel/bpf/arena.c | 2 +-
> kernel/bpf/syscall.c | 2 +-
> mm/mmap.c | 11 +++++------
> mm/shmem.c | 9 ++++-----
> 12 files changed, 27 insertions(+), 28 deletions(-)
>
> diff --git a/arch/sparc/kernel/sys_sparc_64.c b/arch/sparc/kernel/sys_sparc_64.c
> index d9c3b34ca744..cf0b4ace5bf9 100644
> --- a/arch/sparc/kernel/sys_sparc_64.c
> +++ b/arch/sparc/kernel/sys_sparc_64.c
> @@ -220,7 +220,7 @@ unsigned long get_fb_unmapped_area(struct file *filp, unsigned long orig_addr, u
>
> if (flags & MAP_FIXED) {
> /* Ok, don't mess with it. */
> - return mm_get_unmapped_area(current->mm, NULL, orig_addr, len, pgoff, flags);
> + return current_get_unmapped_area(NULL, orig_addr, len, pgoff, flags);
> }
> flags &= ~MAP_SHARED;
>
> @@ -233,8 +233,9 @@ unsigned long get_fb_unmapped_area(struct file *filp, unsigned long orig_addr, u
> align_goal = (64UL * 1024);
>
> do {
> - addr = mm_get_unmapped_area(current->mm, NULL, orig_addr,
> - len + (align_goal - PAGE_SIZE), pgoff, flags);
> + addr = current_get_unmapped_area(NULL, orig_addr,
> + len + (align_goal - PAGE_SIZE),
> + pgoff, flags);
> if (!(addr & ~PAGE_MASK)) {
> addr = (addr + (align_goal - 1UL)) & ~(align_goal - 1UL);
> break;
> @@ -252,7 +253,7 @@ unsigned long get_fb_unmapped_area(struct file *filp, unsigned long orig_addr, u
> * be obtained.
> */
> if (addr & ~PAGE_MASK)
> - addr = mm_get_unmapped_area(current->mm, NULL, orig_addr, len, pgoff, flags);
> + addr = current_get_unmapped_area(NULL, orig_addr, len, pgoff, flags);
>
> return addr;
> }
> diff --git a/arch/x86/kernel/cpu/sgx/driver.c b/arch/x86/kernel/cpu/sgx/driver.c
> index 22b65a5f5ec6..5f7bfd9035f7 100644
> --- a/arch/x86/kernel/cpu/sgx/driver.c
> +++ b/arch/x86/kernel/cpu/sgx/driver.c
> @@ -113,7 +113,7 @@ static unsigned long sgx_get_unmapped_area(struct file *file,
> if (flags & MAP_FIXED)
> return addr;
>
> - return mm_get_unmapped_area(current->mm, file, addr, len, pgoff, flags);
> + return current_get_unmapped_area(file, addr, len, pgoff, flags);
> }
>
> #ifdef CONFIG_COMPAT
> diff --git a/drivers/char/mem.c b/drivers/char/mem.c
> index 7c359cc406d5..a29c4bd506d5 100644
> --- a/drivers/char/mem.c
> +++ b/drivers/char/mem.c
> @@ -546,7 +546,7 @@ static unsigned long get_unmapped_area_zero(struct file *file,
> }
>
> /* Otherwise flags & MAP_PRIVATE: with no shmem object beneath it */
> - return mm_get_unmapped_area(current->mm, file, addr, len, pgoff, flags);
> + return current_get_unmapped_area(file, addr, len, pgoff, flags);
> #else
> return -ENOSYS;
> #endif
> diff --git a/drivers/dax/device.c b/drivers/dax/device.c
> index eb61598247a9..c379902307b7 100644
> --- a/drivers/dax/device.c
> +++ b/drivers/dax/device.c
> @@ -329,14 +329,14 @@ static unsigned long dax_get_unmapped_area(struct file *filp,
> if ((off + len_align) < off)
> goto out;
>
> - addr_align = mm_get_unmapped_area(current->mm, filp, addr, len_align,
> - pgoff, flags);
> + addr_align = current_get_unmapped_area(filp, addr, len_align,
> + pgoff, flags);
> if (!IS_ERR_VALUE(addr_align)) {
> addr_align += (off - addr_align) & (align - 1);
> return addr_align;
> }
> out:
> - return mm_get_unmapped_area(current->mm, filp, addr, len, pgoff, flags);
> + return current_get_unmapped_area(filp, addr, len, pgoff, flags);
> }
>
> static const struct address_space_operations dev_dax_aops = {
> diff --git a/fs/proc/inode.c b/fs/proc/inode.c
> index d19434e2a58e..24a6aeac3de5 100644
> --- a/fs/proc/inode.c
> +++ b/fs/proc/inode.c
> @@ -455,7 +455,7 @@ pde_get_unmapped_area(struct proc_dir_entry *pde, struct file *file, unsigned lo
> return pde->proc_ops->proc_get_unmapped_area(file, orig_addr, len, pgoff, flags);
>
> #ifdef CONFIG_MMU
> - return mm_get_unmapped_area(current->mm, file, orig_addr, len, pgoff, flags);
> + return current_get_unmapped_area(file, orig_addr, len, pgoff, flags);
> #endif
>
> return orig_addr;
> diff --git a/fs/ramfs/file-mmu.c b/fs/ramfs/file-mmu.c
> index b45c7edc3225..85f57de31102 100644
> --- a/fs/ramfs/file-mmu.c
> +++ b/fs/ramfs/file-mmu.c
> @@ -35,7 +35,7 @@ static unsigned long ramfs_mmu_get_unmapped_area(struct file *file,
> unsigned long addr, unsigned long len, unsigned long pgoff,
> unsigned long flags)
> {
> - return mm_get_unmapped_area(current->mm, file, addr, len, pgoff, flags);
> + return current_get_unmapped_area(file, addr, len, pgoff, flags);
> }
>
> const struct file_operations ramfs_file_operations = {
> diff --git a/include/linux/sched/mm.h b/include/linux/sched/mm.h
> index 91546493c43d..c67c7de05c7a 100644
> --- a/include/linux/sched/mm.h
> +++ b/include/linux/sched/mm.h
> @@ -187,9 +187,9 @@ arch_get_unmapped_area_topdown(struct file *filp, unsigned long addr,
> unsigned long len, unsigned long pgoff,
> unsigned long flags);
>
> -unsigned long mm_get_unmapped_area(struct mm_struct *mm, struct file *filp,
> - unsigned long addr, unsigned long len,
> - unsigned long pgoff, unsigned long flags);
> +unsigned long current_get_unmapped_area(struct file *filp, unsigned long addr,
> + unsigned long len, unsigned long pgoff,
> + unsigned long flags);
>
> unsigned long
> arch_get_unmapped_area_vmflags(struct file *filp, unsigned long addr,
> diff --git a/io_uring/memmap.c b/io_uring/memmap.c
> index 4785d6af5fee..1aaea32c797c 100644
> --- a/io_uring/memmap.c
> +++ b/io_uring/memmap.c
> @@ -305,7 +305,7 @@ unsigned long io_uring_get_unmapped_area(struct file *filp, unsigned long addr,
> #else
> addr = 0UL;
> #endif
> - return mm_get_unmapped_area(current->mm, filp, addr, len, pgoff, flags);
> + return current_get_unmapped_area(filp, addr, len, pgoff, flags);
> }
>
> #else /* !CONFIG_MMU */
> diff --git a/kernel/bpf/arena.c b/kernel/bpf/arena.c
> index 4a1be699bb82..054486f7c453 100644
> --- a/kernel/bpf/arena.c
> +++ b/kernel/bpf/arena.c
> @@ -314,7 +314,7 @@ static unsigned long arena_get_unmapped_area(struct file *filp, unsigned long ad
> return -EINVAL;
> }
>
> - ret = mm_get_unmapped_area(current->mm, filp, addr, len * 2, 0, flags);
> + ret = current_get_unmapped_area(filp, addr, len * 2, 0, flags);
> if (IS_ERR_VALUE(ret))
> return ret;
> if ((ret >> 32) == ((ret + len - 1) >> 32))
> diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c
> index 2222c3ff88e7..d9ff2843f6ef 100644
> --- a/kernel/bpf/syscall.c
> +++ b/kernel/bpf/syscall.c
> @@ -992,7 +992,7 @@ static unsigned long bpf_get_unmapped_area(struct file *filp, unsigned long addr
> if (map->ops->map_get_unmapped_area)
> return map->ops->map_get_unmapped_area(filp, addr, len, pgoff, flags);
> #ifdef CONFIG_MMU
> - return mm_get_unmapped_area(current->mm, filp, addr, len, pgoff, flags);
> + return current_get_unmapped_area(filp, addr, len, pgoff, flags);
> #else
> return addr;
> #endif
> diff --git a/mm/mmap.c b/mm/mmap.c
> index 83b4682ec85c..4e98a907c53d 100644
> --- a/mm/mmap.c
> +++ b/mm/mmap.c
> @@ -1901,16 +1901,15 @@ __get_unmapped_area(struct file *file, unsigned long addr, unsigned long len,
> return error ? error : addr;
> }
>
> -unsigned long
> -mm_get_unmapped_area(struct mm_struct *mm, struct file *file,
> - unsigned long addr, unsigned long len,
> - unsigned long pgoff, unsigned long flags)
> +unsigned long current_get_unmapped_area(struct file *file, unsigned long addr,
> + unsigned long len, unsigned long pgoff,
> + unsigned long flags)
> {
> - if (test_bit(MMF_TOPDOWN, &mm->flags))
> + if (test_bit(MMF_TOPDOWN, &current->mm->flags))
> return arch_get_unmapped_area_topdown(file, addr, len, pgoff, flags);
> return arch_get_unmapped_area(file, addr, len, pgoff, flags);
> }
> -EXPORT_SYMBOL(mm_get_unmapped_area);
> +EXPORT_SYMBOL(current_get_unmapped_area);
>
> /**
> * find_vma_intersection() - Look up the first VMA which intersects the interval
> diff --git a/mm/shmem.c b/mm/shmem.c
> index f5d60436b604..c0acd7db93c8 100644
> --- a/mm/shmem.c
> +++ b/mm/shmem.c
> @@ -2276,8 +2276,7 @@ unsigned long shmem_get_unmapped_area(struct file *file,
> if (len > TASK_SIZE)
> return -ENOMEM;
>
> - addr = mm_get_unmapped_area(current->mm, file, uaddr, len, pgoff,
> - flags);
> + addr = current_get_unmapped_area(file, uaddr, len, pgoff, flags);
>
> if (!IS_ENABLED(CONFIG_TRANSPARENT_HUGEPAGE))
> return addr;
> @@ -2334,8 +2333,8 @@ unsigned long shmem_get_unmapped_area(struct file *file,
> if (inflated_len < len)
> return addr;
>
> - inflated_addr = mm_get_unmapped_area(current->mm, NULL, uaddr,
> - inflated_len, 0, flags);
> + inflated_addr = current_get_unmapped_area(NULL, uaddr,
> + inflated_len, 0, flags);
> if (IS_ERR_VALUE(inflated_addr))
> return addr;
> if (inflated_addr & ~PAGE_MASK)
> @@ -4799,7 +4798,7 @@ unsigned long shmem_get_unmapped_area(struct file *file,
> unsigned long addr, unsigned long len,
> unsigned long pgoff, unsigned long flags)
> {
> - return mm_get_unmapped_area(current->mm, file, addr, len, pgoff, flags);
> + return current_get_unmapped_area(file, addr, len, pgoff, flags);
> }
> #endif
>
>
> base-commit: 9221b2819b8a4196eecf5476d66201be60fbcf29
> --
> 2.34.1
>