forge/linux-uconsole
1
0
Fork 0
Code Issues 1 Pull requests Projects Releases Packages Wiki Activity Actions

BACKPORT: FROMGIT: userfaultfd/shmem: combine shmem_{mcopy_atomic,mfill_zeropage}_pte

Browse source 
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 <axelrasmussen@google.com>
Reviewed-by: Peter Xu <peterx@redhat.com>
Acked-by: Hugh Dickins <hughd@google.com>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Brian Geffon <bgeffon@google.com>
Cc: "Dr . David Alan Gilbert" <dgilbert@redhat.com>
Cc: Jerome Glisse <jglisse@redhat.com>
Cc: Joe Perches <joe@perches.com>
Cc: Kirill A. Shutemov <kirill@shutemov.name>
Cc: Lokesh Gidra <lokeshgidra@google.com>
Cc: Mike Kravetz <mike.kravetz@oracle.com>
Cc: Mike Rapoport <rppt@linux.vnet.ibm.com>
Cc: Mina Almasry <almasrymina@google.com>
Cc: Oliver Upton <oupton@google.com>
Cc: Shaohua Li <shli@fb.com>
Cc: Shuah Khan <shuah@kernel.org>
Cc: Stephen Rothwell <sfr@canb.auug.org.au>
Cc: Wang Qing <wangqing@vivo.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Stephen Rothwell <sfr@canb.auug.org.au>
(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 <lokeshgidra@google.com>
Bug: 187930641
Change-Id: I8b443809643339b407d0bc06bf96146ecfc5a9fa
This commit is contained in:
Axel Rasmussen 2021-05-11 15:05:57 +10:00 • committed by Suren Baghdasaryan
commit 5f6dc07839
3 changed files with 27 additions and 54 deletions
Download patch file Download diff file Expand all files Collapse all files

19
include/linux/shmem_fs.h
View file

@ -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

52
mm/shmem.c
View file

@ -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 @@ out_unacct_blocks:
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;

10
mm/userfaultfd.c
View file

@ -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;