From 5f6dc078396f987bed227c1a990132c616ae16f6 Mon Sep 17 00:00:00 2001 From: Axel Rasmussen Date: Tue, 11 May 2021 15:05:57 +1000 Subject: [PATCH] BACKPORT: FROMGIT: userfaultfd/shmem: combine shmem_{mcopy_atomic,mfill_zeropage}_pte Previously, we did a dance where we had one calling path in userfaultfd.c (mfill_atomic_pte), but then we split it into two in shmem_fs.h (shmem_{mcopy_atomic,mfill_zeropage}_pte), and then rejoined into a single shared function in shmem.c (shmem_mfill_atomic_pte). This is all a bit overly complex. Just call the single combined shmem function directly, allowing us to clean up various branches, boilerplate, etc. While we're touching this function, two other small cleanup changes: - offset is equivalent to pgoff, so we can get rid of offset entirely. - Split two VM_BUG_ON cases into two statements. This means the line number reported when the BUG is hit specifies exactly which condition was true. Link: https://lkml.kernel.org/r/20210503180737.2487560-3-axelrasmussen@google.com Signed-off-by: Axel Rasmussen Reviewed-by: Peter Xu Acked-by: Hugh Dickins Cc: Alexander Viro Cc: Andrea Arcangeli Cc: Brian Geffon Cc: "Dr . David Alan Gilbert" Cc: Jerome Glisse Cc: Joe Perches Cc: Kirill A. Shutemov Cc: Lokesh Gidra Cc: Mike Kravetz Cc: Mike Rapoport Cc: Mina Almasry Cc: Oliver Upton Cc: Shaohua Li Cc: Shuah Khan Cc: Stephen Rothwell Cc: Wang Qing Signed-off-by: Andrew Morton Signed-off-by: Stephen Rothwell (cherry picked from commit 9d86e8f967c5dd2c8a31c02313be5be281b4026e https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git akpm) Link: https://lore.kernel.org/patchwork/patch/1420969/ Conflicts: mm/shmem.c (Manual rebase) Signed-off-by: Lokesh Gidra Bug: 187930641 Change-Id: I8b443809643339b407d0bc06bf96146ecfc5a9fa --- include/linux/shmem_fs.h | 19 +++++++-------- mm/shmem.c | 52 +++++++++++++--------------------------- mm/userfaultfd.c | 10 +++----- 3 files changed, 27 insertions(+), 54 deletions(-) diff --git a/include/linux/shmem_fs.h b/include/linux/shmem_fs.h index a5a5d1d4d7b1..17e9969db499 100644 --- a/include/linux/shmem_fs.h +++ b/include/linux/shmem_fs.h @@ -118,21 +118,18 @@ static inline bool shmem_file(struct file *file) extern bool shmem_charge(struct inode *inode, long pages); extern void shmem_uncharge(struct inode *inode, long pages); +#ifdef CONFIG_USERFAULTFD #ifdef CONFIG_SHMEM -extern int shmem_mcopy_atomic_pte(struct mm_struct *dst_mm, pmd_t *dst_pmd, +extern int shmem_mfill_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, + bool zeropage, struct page **pagep); -extern int shmem_mfill_zeropage_pte(struct mm_struct *dst_mm, - pmd_t *dst_pmd, - struct vm_area_struct *dst_vma, - unsigned long dst_addr); -#else -#define shmem_mcopy_atomic_pte(dst_mm, dst_pte, dst_vma, dst_addr, \ - src_addr, pagep) ({ BUG(); 0; }) -#define shmem_mfill_zeropage_pte(dst_mm, dst_pmd, dst_vma, \ - dst_addr) ({ BUG(); 0; }) -#endif +#else /* !CONFIG_SHMEM */ +#define shmem_mfill_atomic_pte(dst_mm, dst_pmd, dst_vma, dst_addr, \ + src_addr, zeropage, pagep) ({ BUG(); 0; }) +#endif /* CONFIG_SHMEM */ +#endif /* CONFIG_USERFAULTFD */ #endif diff --git a/mm/shmem.c b/mm/shmem.c index bf4e6e63fef9..78ca532c9840 100644 --- a/mm/shmem.c +++ b/mm/shmem.c @@ -2343,13 +2343,14 @@ bool shmem_mapping(struct address_space *mapping) return mapping->a_ops == &shmem_aops; } -static int shmem_mfill_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, - bool zeropage, - struct page **pagep) +#ifdef CONFIG_USERFAULTFD +int shmem_mfill_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, + bool zeropage, + struct page **pagep) { struct inode *inode = file_inode(dst_vma->vm_file); struct shmem_inode_info *info = SHMEM_I(inode); @@ -2361,7 +2362,7 @@ static int shmem_mfill_atomic_pte(struct mm_struct *dst_mm, struct page *page; pte_t _dst_pte, *dst_pte; int ret; - pgoff_t offset, max_off; + pgoff_t max_off; ret = -ENOMEM; if (!shmem_inode_acct_block(inode, 1)) { @@ -2382,7 +2383,7 @@ static int shmem_mfill_atomic_pte(struct mm_struct *dst_mm, if (!page) goto out_unacct_blocks; - if (!zeropage) { /* mcopy_atomic */ + if (!zeropage) { /* COPY */ page_kaddr = kmap_atomic(page); ret = copy_from_user(page_kaddr, (const void __user *)src_addr, @@ -2396,7 +2397,7 @@ static int shmem_mfill_atomic_pte(struct mm_struct *dst_mm, /* don't free the page */ return -ENOENT; } - } else { /* mfill_zeropage_atomic */ + } else { /* ZEROPAGE */ clear_highpage(page); } } else { @@ -2404,15 +2405,15 @@ static int shmem_mfill_atomic_pte(struct mm_struct *dst_mm, *pagep = NULL; } - VM_BUG_ON(PageLocked(page) || PageSwapBacked(page)); + VM_BUG_ON(PageLocked(page)); + VM_BUG_ON(PageSwapBacked(page)); __SetPageLocked(page); __SetPageSwapBacked(page); __SetPageUptodate(page); ret = -EFAULT; - offset = linear_page_index(dst_vma, dst_addr); max_off = DIV_ROUND_UP(i_size_read(inode), PAGE_SIZE); - if (unlikely(offset >= max_off)) + if (unlikely(pgoff >= max_off)) goto out_release; ret = shmem_add_to_page_cache(page, mapping, pgoff, NULL, @@ -2438,7 +2439,7 @@ static int shmem_mfill_atomic_pte(struct mm_struct *dst_mm, ret = -EFAULT; max_off = DIV_ROUND_UP(i_size_read(inode), PAGE_SIZE); - if (unlikely(offset >= max_off)) + if (unlikely(pgoff >= max_off)) goto out_release_unlock; ret = -EEXIST; @@ -2475,28 +2476,7 @@ static int shmem_mfill_atomic_pte(struct mm_struct *dst_mm, shmem_inode_unacct_blocks(inode, 1); goto out; } - -int shmem_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) -{ - return shmem_mfill_atomic_pte(dst_mm, dst_pmd, dst_vma, - dst_addr, src_addr, false, pagep); -} - -int shmem_mfill_zeropage_pte(struct mm_struct *dst_mm, - pmd_t *dst_pmd, - struct vm_area_struct *dst_vma, - unsigned long dst_addr) -{ - struct page *page = NULL; - - return shmem_mfill_atomic_pte(dst_mm, dst_pmd, dst_vma, - dst_addr, 0, true, &page); -} +#endif /* CONFIG_USERFAULTFD */ #ifdef CONFIG_TMPFS static const struct inode_operations shmem_symlink_inode_operations; diff --git a/mm/userfaultfd.c b/mm/userfaultfd.c index e14b3820c6a8..242b7a04c16d 100644 --- a/mm/userfaultfd.c +++ b/mm/userfaultfd.c @@ -440,13 +440,9 @@ static __always_inline ssize_t mfill_atomic_pte(struct mm_struct *dst_mm, dst_vma, dst_addr); } else { VM_WARN_ON_ONCE(wp_copy); - if (!zeropage) - err = shmem_mcopy_atomic_pte(dst_mm, dst_pmd, - dst_vma, dst_addr, - src_addr, page); - else - err = shmem_mfill_zeropage_pte(dst_mm, dst_pmd, - dst_vma, dst_addr); + err = shmem_mfill_atomic_pte(dst_mm, dst_pmd, dst_vma, + dst_addr, src_addr, zeropage, + page); } return err;