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Message-ID: <ZAmblL3irV1CRiKs@kernel.org>
Date: Thu, 9 Mar 2023 10:40:52 +0200
From: Mike Rapoport <rppt@...nel.org>
To: Axel Rasmussen <axelrasmussen@...gle.com>
Cc: Alexander Viro <viro@...iv.linux.org.uk>,
Andrew Morton <akpm@...ux-foundation.org>,
Hugh Dickins <hughd@...gle.com>, Jan Kara <jack@...e.cz>,
"Liam R. Howlett" <Liam.Howlett@...cle.com>,
Matthew Wilcox <willy@...radead.org>,
Mike Kravetz <mike.kravetz@...cle.com>,
Muchun Song <muchun.song@...ux.dev>,
Nadav Amit <namit@...are.com>, Peter Xu <peterx@...hat.com>,
Shuah Khan <shuah@...nel.org>,
James Houghton <jthoughton@...gle.com>,
linux-fsdevel@...r.kernel.org, linux-kernel@...r.kernel.org,
linux-mm@...ck.org, linux-kselftest@...r.kernel.org
Subject: Re: [PATCH v4 1/4] mm: userfaultfd: rename functions for clarity +
consistency
On Wed, Mar 08, 2023 at 02:19:29PM -0800, Axel Rasmussen wrote:
> The basic problem is, over time we've added new userfaultfd ioctls, and
> we've refactored the code so functions which used to handle only one
> case are now re-used to deal with several cases. While this happened, we
> didn't bother to rename the functions.
>
> Similarly, as we added new functions, we cargo-culted pieces of the
> now-inconsistent naming scheme, so those functions too ended up with
> names that don't make a lot of sense.
>
> A key point here is, "copy" in most userfaultfd code refers specifically
> to UFFDIO_COPY, where we allocate a new page and copy its contents from
> userspace. There are many functions with "copy" in the name that don't
> actually do this (at least in some cases).
>
> So, rename things into a consistent scheme. The high level idea is that
> the call stack for userfaultfd ioctls becomes:
>
> userfaultfd_ioctl
> -> userfaultfd_(particular ioctl)
> -> mfill_atomic_(particular kind of fill operation)
> -> mfill_atomic /* loops over pages in range */
> -> mfill_atomic_pte /* deals with single pages */
> -> mfill_atomic_pte_(particular kind of fill operation)
> -> mfill_atomic_install_pte
>
> There are of course some special cases (shmem, hugetlb), but this is the
> general structure which all function names now adhere to.
>
> Acked-by: Peter Xu <peterx@...hat.com>
> Signed-off-by: Axel Rasmussen <axelrasmussen@...gle.com>
Acked-by: Mike Rapoport (IBM) <rppt@...nel.org>
> ---
> fs/userfaultfd.c | 18 +++----
> include/linux/hugetlb.h | 30 +++++------
> include/linux/userfaultfd_k.h | 18 +++----
> mm/hugetlb.c | 20 +++----
> mm/userfaultfd.c | 98 +++++++++++++++++------------------
> 5 files changed, 92 insertions(+), 92 deletions(-)
>
> diff --git a/fs/userfaultfd.c b/fs/userfaultfd.c
> index 44d1ee429eb0..365bf00dd8dd 100644
> --- a/fs/userfaultfd.c
> +++ b/fs/userfaultfd.c
> @@ -1741,9 +1741,9 @@ static int userfaultfd_copy(struct userfaultfd_ctx *ctx,
> if (uffdio_copy.mode & ~(UFFDIO_COPY_MODE_DONTWAKE|UFFDIO_COPY_MODE_WP))
> goto out;
> if (mmget_not_zero(ctx->mm)) {
> - ret = mcopy_atomic(ctx->mm, uffdio_copy.dst, uffdio_copy.src,
> - uffdio_copy.len, &ctx->mmap_changing,
> - uffdio_copy.mode);
> + ret = mfill_atomic_copy(ctx->mm, uffdio_copy.dst, uffdio_copy.src,
> + uffdio_copy.len, &ctx->mmap_changing,
> + uffdio_copy.mode);
> mmput(ctx->mm);
> } else {
> return -ESRCH;
> @@ -1793,9 +1793,9 @@ static int userfaultfd_zeropage(struct userfaultfd_ctx *ctx,
> goto out;
>
> if (mmget_not_zero(ctx->mm)) {
> - ret = mfill_zeropage(ctx->mm, uffdio_zeropage.range.start,
> - uffdio_zeropage.range.len,
> - &ctx->mmap_changing);
> + ret = mfill_atomic_zeropage(ctx->mm, uffdio_zeropage.range.start,
> + uffdio_zeropage.range.len,
> + &ctx->mmap_changing);
> mmput(ctx->mm);
> } else {
> return -ESRCH;
> @@ -1903,9 +1903,9 @@ static int userfaultfd_continue(struct userfaultfd_ctx *ctx, unsigned long arg)
> goto out;
>
> if (mmget_not_zero(ctx->mm)) {
> - ret = mcopy_continue(ctx->mm, uffdio_continue.range.start,
> - uffdio_continue.range.len,
> - &ctx->mmap_changing);
> + ret = mfill_atomic_continue(ctx->mm, uffdio_continue.range.start,
> + uffdio_continue.range.len,
> + &ctx->mmap_changing);
> mmput(ctx->mm);
> } else {
> return -ESRCH;
> diff --git a/include/linux/hugetlb.h b/include/linux/hugetlb.h
> index 7c977d234aba..8f0467bf1cbd 100644
> --- a/include/linux/hugetlb.h
> +++ b/include/linux/hugetlb.h
> @@ -158,13 +158,13 @@ unsigned long hugetlb_total_pages(void);
> vm_fault_t hugetlb_fault(struct mm_struct *mm, struct vm_area_struct *vma,
> unsigned long address, unsigned int flags);
> #ifdef CONFIG_USERFAULTFD
> -int hugetlb_mcopy_atomic_pte(struct mm_struct *dst_mm, pte_t *dst_pte,
> - struct vm_area_struct *dst_vma,
> - unsigned long dst_addr,
> - unsigned long src_addr,
> - enum mcopy_atomic_mode mode,
> - struct page **pagep,
> - bool wp_copy);
> +int hugetlb_mfill_atomic_pte(struct mm_struct *dst_mm, pte_t *dst_pte,
> + struct vm_area_struct *dst_vma,
> + unsigned long dst_addr,
> + unsigned long src_addr,
> + enum mcopy_atomic_mode mode,
> + struct page **pagep,
> + bool wp_copy);
> #endif /* CONFIG_USERFAULTFD */
> bool hugetlb_reserve_pages(struct inode *inode, long from, long to,
> struct vm_area_struct *vma,
> @@ -393,14 +393,14 @@ static inline void hugetlb_free_pgd_range(struct mmu_gather *tlb,
> }
>
> #ifdef CONFIG_USERFAULTFD
> -static inline int hugetlb_mcopy_atomic_pte(struct mm_struct *dst_mm,
> - pte_t *dst_pte,
> - struct vm_area_struct *dst_vma,
> - unsigned long dst_addr,
> - unsigned long src_addr,
> - enum mcopy_atomic_mode mode,
> - struct page **pagep,
> - bool wp_copy)
> +static inline int hugetlb_mfill_atomic_pte(struct mm_struct *dst_mm,
> + pte_t *dst_pte,
> + struct vm_area_struct *dst_vma,
> + unsigned long dst_addr,
> + unsigned long src_addr,
> + enum mcopy_atomic_mode mode,
> + struct page **pagep,
> + bool wp_copy)
> {
> BUG();
> return 0;
> diff --git a/include/linux/userfaultfd_k.h b/include/linux/userfaultfd_k.h
> index 3767f18114ef..468080125612 100644
> --- a/include/linux/userfaultfd_k.h
> +++ b/include/linux/userfaultfd_k.h
> @@ -61,15 +61,15 @@ extern int mfill_atomic_install_pte(struct mm_struct *dst_mm, pmd_t *dst_pmd,
> unsigned long dst_addr, struct page *page,
> bool newly_allocated, bool wp_copy);
>
> -extern ssize_t mcopy_atomic(struct mm_struct *dst_mm, unsigned long dst_start,
> - unsigned long src_start, unsigned long len,
> - atomic_t *mmap_changing, __u64 mode);
> -extern ssize_t mfill_zeropage(struct mm_struct *dst_mm,
> - unsigned long dst_start,
> - unsigned long len,
> - atomic_t *mmap_changing);
> -extern ssize_t mcopy_continue(struct mm_struct *dst_mm, unsigned long dst_start,
> - unsigned long len, atomic_t *mmap_changing);
> +extern ssize_t mfill_atomic_copy(struct mm_struct *dst_mm, unsigned long dst_start,
> + unsigned long src_start, unsigned long len,
> + atomic_t *mmap_changing, __u64 mode);
> +extern ssize_t mfill_atomic_zeropage(struct mm_struct *dst_mm,
> + unsigned long dst_start,
> + unsigned long len,
> + atomic_t *mmap_changing);
> +extern ssize_t mfill_atomic_continue(struct mm_struct *dst_mm, unsigned long dst_start,
> + unsigned long len, atomic_t *mmap_changing);
> extern int mwriteprotect_range(struct mm_struct *dst_mm,
> unsigned long start, unsigned long len,
> bool enable_wp, atomic_t *mmap_changing);
> diff --git a/mm/hugetlb.c b/mm/hugetlb.c
> index 07abcb6eb203..4c9276549394 100644
> --- a/mm/hugetlb.c
> +++ b/mm/hugetlb.c
> @@ -6154,17 +6154,17 @@ vm_fault_t hugetlb_fault(struct mm_struct *mm, struct vm_area_struct *vma,
>
> #ifdef CONFIG_USERFAULTFD
> /*
> - * Used by userfaultfd UFFDIO_COPY. Based on mcopy_atomic_pte with
> - * modifications for huge pages.
> + * Used by userfaultfd UFFDIO_* ioctls. Based on userfaultfd's mfill_atomic_pte
> + * with modifications for hugetlb pages.
> */
> -int hugetlb_mcopy_atomic_pte(struct mm_struct *dst_mm,
> - pte_t *dst_pte,
> - struct vm_area_struct *dst_vma,
> - unsigned long dst_addr,
> - unsigned long src_addr,
> - enum mcopy_atomic_mode mode,
> - struct page **pagep,
> - bool wp_copy)
> +int hugetlb_mfill_atomic_pte(struct mm_struct *dst_mm,
> + pte_t *dst_pte,
> + struct vm_area_struct *dst_vma,
> + unsigned long dst_addr,
> + unsigned long src_addr,
> + enum mcopy_atomic_mode mode,
> + struct page **pagep,
> + bool wp_copy)
> {
> bool is_continue = (mode == MCOPY_ATOMIC_CONTINUE);
> struct hstate *h = hstate_vma(dst_vma);
> diff --git a/mm/userfaultfd.c b/mm/userfaultfd.c
> index 53c3d916ff66..84db5b2fad3a 100644
> --- a/mm/userfaultfd.c
> +++ b/mm/userfaultfd.c
> @@ -127,13 +127,13 @@ int mfill_atomic_install_pte(struct mm_struct *dst_mm, pmd_t *dst_pmd,
> return ret;
> }
>
> -static int mcopy_atomic_pte(struct mm_struct *dst_mm,
> - pmd_t *dst_pmd,
> - struct vm_area_struct *dst_vma,
> - unsigned long dst_addr,
> - unsigned long src_addr,
> - struct page **pagep,
> - bool wp_copy)
> +static int mfill_atomic_pte_copy(struct mm_struct *dst_mm,
> + pmd_t *dst_pmd,
> + struct vm_area_struct *dst_vma,
> + unsigned long dst_addr,
> + unsigned long src_addr,
> + struct page **pagep,
> + bool wp_copy)
> {
> void *page_kaddr;
> int ret;
> @@ -204,10 +204,10 @@ static int mcopy_atomic_pte(struct mm_struct *dst_mm,
> goto out;
> }
>
> -static int mfill_zeropage_pte(struct mm_struct *dst_mm,
> - pmd_t *dst_pmd,
> - struct vm_area_struct *dst_vma,
> - unsigned long dst_addr)
> +static int mfill_atomic_pte_zeropage(struct mm_struct *dst_mm,
> + pmd_t *dst_pmd,
> + struct vm_area_struct *dst_vma,
> + unsigned long dst_addr)
> {
> pte_t _dst_pte, *dst_pte;
> spinlock_t *ptl;
> @@ -240,11 +240,11 @@ static int mfill_zeropage_pte(struct mm_struct *dst_mm,
> }
>
> /* Handles UFFDIO_CONTINUE for all shmem VMAs (shared or private). */
> -static int mcontinue_atomic_pte(struct mm_struct *dst_mm,
> - pmd_t *dst_pmd,
> - struct vm_area_struct *dst_vma,
> - unsigned long dst_addr,
> - bool wp_copy)
> +static int mfill_atomic_pte_continue(struct mm_struct *dst_mm,
> + pmd_t *dst_pmd,
> + struct vm_area_struct *dst_vma,
> + unsigned long dst_addr,
> + bool wp_copy)
> {
> struct inode *inode = file_inode(dst_vma->vm_file);
> pgoff_t pgoff = linear_page_index(dst_vma, dst_addr);
> @@ -307,10 +307,10 @@ static pmd_t *mm_alloc_pmd(struct mm_struct *mm, unsigned long address)
>
> #ifdef CONFIG_HUGETLB_PAGE
> /*
> - * __mcopy_atomic processing for HUGETLB vmas. Note that this routine is
> + * mfill_atomic processing for HUGETLB vmas. Note that this routine is
> * called with mmap_lock held, it will release mmap_lock before returning.
> */
> -static __always_inline ssize_t __mcopy_atomic_hugetlb(struct mm_struct *dst_mm,
> +static __always_inline ssize_t mfill_atomic_hugetlb(struct mm_struct *dst_mm,
> struct vm_area_struct *dst_vma,
> unsigned long dst_start,
> unsigned long src_start,
> @@ -411,7 +411,7 @@ static __always_inline ssize_t __mcopy_atomic_hugetlb(struct mm_struct *dst_mm,
> goto out_unlock;
> }
>
> - err = hugetlb_mcopy_atomic_pte(dst_mm, dst_pte, dst_vma,
> + err = hugetlb_mfill_atomic_pte(dst_mm, dst_pte, dst_vma,
> dst_addr, src_addr, mode, &page,
> wp_copy);
>
> @@ -463,7 +463,7 @@ static __always_inline ssize_t __mcopy_atomic_hugetlb(struct mm_struct *dst_mm,
> }
> #else /* !CONFIG_HUGETLB_PAGE */
> /* fail at build time if gcc attempts to use this */
> -extern ssize_t __mcopy_atomic_hugetlb(struct mm_struct *dst_mm,
> +extern ssize_t mfill_atomic_hugetlb(struct mm_struct *dst_mm,
> struct vm_area_struct *dst_vma,
> unsigned long dst_start,
> unsigned long src_start,
> @@ -484,8 +484,8 @@ static __always_inline ssize_t mfill_atomic_pte(struct mm_struct *dst_mm,
> ssize_t err;
>
> if (mode == MCOPY_ATOMIC_CONTINUE) {
> - return mcontinue_atomic_pte(dst_mm, dst_pmd, dst_vma, dst_addr,
> - wp_copy);
> + return mfill_atomic_pte_continue(dst_mm, dst_pmd, dst_vma,
> + dst_addr, wp_copy);
> }
>
> /*
> @@ -500,11 +500,11 @@ static __always_inline ssize_t mfill_atomic_pte(struct mm_struct *dst_mm,
> */
> if (!(dst_vma->vm_flags & VM_SHARED)) {
> if (mode == MCOPY_ATOMIC_NORMAL)
> - err = mcopy_atomic_pte(dst_mm, dst_pmd, dst_vma,
> - dst_addr, src_addr, page,
> - wp_copy);
> + err = mfill_atomic_pte_copy(dst_mm, dst_pmd, dst_vma,
> + dst_addr, src_addr, page,
> + wp_copy);
> else
> - err = mfill_zeropage_pte(dst_mm, dst_pmd,
> + err = mfill_atomic_pte_zeropage(dst_mm, dst_pmd,
> dst_vma, dst_addr);
> } else {
> err = shmem_mfill_atomic_pte(dst_mm, dst_pmd, dst_vma,
> @@ -516,13 +516,13 @@ static __always_inline ssize_t mfill_atomic_pte(struct mm_struct *dst_mm,
> return err;
> }
>
> -static __always_inline ssize_t __mcopy_atomic(struct mm_struct *dst_mm,
> - unsigned long dst_start,
> - unsigned long src_start,
> - unsigned long len,
> - enum mcopy_atomic_mode mcopy_mode,
> - atomic_t *mmap_changing,
> - __u64 mode)
> +static __always_inline ssize_t mfill_atomic(struct mm_struct *dst_mm,
> + unsigned long dst_start,
> + unsigned long src_start,
> + unsigned long len,
> + enum mcopy_atomic_mode mcopy_mode,
> + atomic_t *mmap_changing,
> + __u64 mode)
> {
> struct vm_area_struct *dst_vma;
> ssize_t err;
> @@ -588,9 +588,9 @@ static __always_inline ssize_t __mcopy_atomic(struct mm_struct *dst_mm,
> * If this is a HUGETLB vma, pass off to appropriate routine
> */
> if (is_vm_hugetlb_page(dst_vma))
> - return __mcopy_atomic_hugetlb(dst_mm, dst_vma, dst_start,
> - src_start, len, mcopy_mode,
> - wp_copy);
> + return mfill_atomic_hugetlb(dst_mm, dst_vma, dst_start,
> + src_start, len, mcopy_mode,
> + wp_copy);
>
> if (!vma_is_anonymous(dst_vma) && !vma_is_shmem(dst_vma))
> goto out_unlock;
> @@ -688,26 +688,26 @@ static __always_inline ssize_t __mcopy_atomic(struct mm_struct *dst_mm,
> return copied ? copied : err;
> }
>
> -ssize_t mcopy_atomic(struct mm_struct *dst_mm, unsigned long dst_start,
> - unsigned long src_start, unsigned long len,
> - atomic_t *mmap_changing, __u64 mode)
> +ssize_t mfill_atomic_copy(struct mm_struct *dst_mm, unsigned long dst_start,
> + unsigned long src_start, unsigned long len,
> + atomic_t *mmap_changing, __u64 mode)
> {
> - return __mcopy_atomic(dst_mm, dst_start, src_start, len,
> - MCOPY_ATOMIC_NORMAL, mmap_changing, mode);
> + return mfill_atomic(dst_mm, dst_start, src_start, len,
> + MCOPY_ATOMIC_NORMAL, mmap_changing, mode);
> }
>
> -ssize_t mfill_zeropage(struct mm_struct *dst_mm, unsigned long start,
> - unsigned long len, atomic_t *mmap_changing)
> +ssize_t mfill_atomic_zeropage(struct mm_struct *dst_mm, unsigned long start,
> + unsigned long len, atomic_t *mmap_changing)
> {
> - return __mcopy_atomic(dst_mm, start, 0, len, MCOPY_ATOMIC_ZEROPAGE,
> - mmap_changing, 0);
> + return mfill_atomic(dst_mm, start, 0, len, MCOPY_ATOMIC_ZEROPAGE,
> + mmap_changing, 0);
> }
>
> -ssize_t mcopy_continue(struct mm_struct *dst_mm, unsigned long start,
> - unsigned long len, atomic_t *mmap_changing)
> +ssize_t mfill_atomic_continue(struct mm_struct *dst_mm, unsigned long start,
> + unsigned long len, atomic_t *mmap_changing)
> {
> - return __mcopy_atomic(dst_mm, start, 0, len, MCOPY_ATOMIC_CONTINUE,
> - mmap_changing, 0);
> + return mfill_atomic(dst_mm, start, 0, len, MCOPY_ATOMIC_CONTINUE,
> + mmap_changing, 0);
> }
>
> long uffd_wp_range(struct mm_struct *dst_mm, struct vm_area_struct *dst_vma,
> --
> 2.40.0.rc1.284.g88254d51c5-goog
>
--
Sincerely yours,
Mike.
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