| Message ID | 20210225021420.2290912-2-axelrasmussen@google.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | userfaultfd: support minor fault handling for shmem | expand |
On Wed, Feb 24, 2021 at 6:14 PM Axel Rasmussen <axelrasmussen@google.com> wrote: > > Modify the userfaultfd register API to allow registering shmem VMAs in > minor mode. Modify the shmem mcopy implementation to support > UFFDIO_CONTINUE in order to resolve such faults. > > Combine the shmem mcopy handler functions into a single > shmem_mcopy_atomic_pte, which takes a mode parameter. This matches how > the hugetlbfs implementation is structured, and lets us remove a good > chunk of boilerplate. > > Signed-off-by: Axel Rasmussen <axelrasmussen@google.com> > --- > fs/userfaultfd.c | 6 +-- > include/linux/shmem_fs.h | 26 ++++------ > include/uapi/linux/userfaultfd.h | 4 +- > mm/memory.c | 8 +-- > mm/shmem.c | 88 +++++++++++++++----------------- > mm/userfaultfd.c | 27 +++++----- > 6 files changed, 77 insertions(+), 82 deletions(-) > > diff --git a/fs/userfaultfd.c b/fs/userfaultfd.c > index 0311e9b8a8fc..aa6d584ae8c7 100644 > --- a/fs/userfaultfd.c > +++ b/fs/userfaultfd.c > @@ -1267,8 +1267,7 @@ static inline bool vma_can_userfault(struct vm_area_struct *vma, > } > > if (vm_flags & VM_UFFD_MINOR) { > - /* FIXME: Add minor fault interception for shmem. */ > - if (!is_vm_hugetlb_page(vma)) > + if (!(is_vm_hugetlb_page(vma) || vma_is_shmem(vma))) > return false; > } > > @@ -1941,7 +1940,8 @@ static int userfaultfd_api(struct userfaultfd_ctx *ctx, > /* report all available features and ioctls to userland */ > uffdio_api.features = UFFD_API_FEATURES; > #ifndef CONFIG_HAVE_ARCH_USERFAULTFD_MINOR > - uffdio_api.features &= ~UFFD_FEATURE_MINOR_HUGETLBFS; > + uffdio_api.features &= > + ~(UFFD_FEATURE_MINOR_HUGETLBFS | UFFD_FEATURE_MINOR_SHMEM); > #endif > uffdio_api.ioctls = UFFD_API_IOCTLS; > ret = -EFAULT; > diff --git a/include/linux/shmem_fs.h b/include/linux/shmem_fs.h > index d82b6f396588..f0919c3722e7 100644 > --- a/include/linux/shmem_fs.h > +++ b/include/linux/shmem_fs.h > @@ -9,6 +9,7 @@ > #include <linux/percpu_counter.h> > #include <linux/xattr.h> > #include <linux/fs_parser.h> > +#include <linux/userfaultfd_k.h> > > /* inode in-kernel data */ > > @@ -122,21 +123,16 @@ 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, > - struct vm_area_struct *dst_vma, > - unsigned long dst_addr, > - unsigned long src_addr, > - 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 > +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, > + enum mcopy_atomic_mode mode, struct page **pagep); > +#else /* !CONFIG_SHMEM */ > +#define shmem_mcopy_atomic_pte(dst_mm, dst_pmd, dst_vma, dst_addr, \ > + src_addr, mode, pagep) ({ BUG(); 0; }) > +#endif /* CONFIG_SHMEM */ > +#endif /* CONFIG_USERFAULTFD */ > > #endif > diff --git a/include/uapi/linux/userfaultfd.h b/include/uapi/linux/userfaultfd.h > index bafbeb1a2624..47d9790d863d 100644 > --- a/include/uapi/linux/userfaultfd.h > +++ b/include/uapi/linux/userfaultfd.h > @@ -31,7 +31,8 @@ > UFFD_FEATURE_MISSING_SHMEM | \ > UFFD_FEATURE_SIGBUS | \ > UFFD_FEATURE_THREAD_ID | \ > - UFFD_FEATURE_MINOR_HUGETLBFS) > + UFFD_FEATURE_MINOR_HUGETLBFS | \ > + UFFD_FEATURE_MINOR_SHMEM) > #define UFFD_API_IOCTLS \ > ((__u64)1 << _UFFDIO_REGISTER | \ > (__u64)1 << _UFFDIO_UNREGISTER | \ > @@ -196,6 +197,7 @@ struct uffdio_api { > #define UFFD_FEATURE_SIGBUS (1<<7) > #define UFFD_FEATURE_THREAD_ID (1<<8) > #define UFFD_FEATURE_MINOR_HUGETLBFS (1<<9) > +#define UFFD_FEATURE_MINOR_SHMEM (1<<10) > __u64 features; > > __u64 ioctls; > diff --git a/mm/memory.c b/mm/memory.c > index c8e357627318..a1e5ff55027e 100644 > --- a/mm/memory.c > +++ b/mm/memory.c > @@ -3929,9 +3929,11 @@ static vm_fault_t do_read_fault(struct vm_fault *vmf) > * something). > */ > if (vma->vm_ops->map_pages && fault_around_bytes >> PAGE_SHIFT > 1) { > - ret = do_fault_around(vmf); > - if (ret) > - return ret; > + if (likely(!userfaultfd_minor(vmf->vma))) { > + ret = do_fault_around(vmf); > + if (ret) > + return ret; > + } > } > > ret = __do_fault(vmf); > diff --git a/mm/shmem.c b/mm/shmem.c > index 06c771d23127..d7847f6f696b 100644 > --- a/mm/shmem.c > +++ b/mm/shmem.c > @@ -77,7 +77,6 @@ static struct vfsmount *shm_mnt; > #include <linux/syscalls.h> > #include <linux/fcntl.h> > #include <uapi/linux/memfd.h> > -#include <linux/userfaultfd_k.h> > #include <linux/rmap.h> > #include <linux/uuid.h> > > @@ -1781,8 +1780,8 @@ static int shmem_swapin_page(struct inode *inode, pgoff_t index, > * vm. If we swap it in we mark it dirty since we also free the swap > * entry since a page cannot live in both the swap and page cache. > * > - * vmf and fault_type are only supplied by shmem_fault: > - * otherwise they are NULL. > + * vma, vmf, and fault_type are only supplied by shmem_fault: otherwise they > + * are NULL. > */ > static int shmem_getpage_gfp(struct inode *inode, pgoff_t index, > struct page **pagep, enum sgp_type sgp, gfp_t gfp, > @@ -1826,6 +1825,12 @@ static int shmem_getpage_gfp(struct inode *inode, pgoff_t index, > return error; > } > > + if (page && vma && userfaultfd_minor(vma)) { > + unlock_page(page); > + *fault_type = handle_userfault(vmf, VM_UFFD_MINOR); > + return 0; > + } > + > if (page) > hindex = page->index; > if (page && sgp == SGP_WRITE) > @@ -2350,14 +2355,12 @@ static struct inode *shmem_get_inode(struct super_block *sb, const struct inode > return inode; > } > > -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) > +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, > + enum mcopy_atomic_mode mode, struct page **pagep) > { > + bool is_continue = (mode == MCOPY_ATOMIC_CONTINUE); > struct inode *inode = file_inode(dst_vma->vm_file); > struct shmem_inode_info *info = SHMEM_I(inode); > struct address_space *mapping = inode->i_mapping; > @@ -2374,12 +2377,17 @@ static int shmem_mfill_atomic_pte(struct mm_struct *dst_mm, > if (!shmem_inode_acct_block(inode, 1)) > goto out; > > - if (!*pagep) { > + if (is_continue) { > + ret = -EFAULT; > + page = find_get_page(mapping, pgoff); > + if (!page) > + goto out_unacct_blocks; > + } else if (!*pagep) { > page = shmem_alloc_page(gfp, info, pgoff); > if (!page) > goto out_unacct_blocks; > > - if (!zeropage) { /* mcopy_atomic */ > + if (mode == MCOPY_ATOMIC_NORMAL) { /* mcopy_atomic */ > page_kaddr = kmap_atomic(page); > ret = copy_from_user(page_kaddr, > (const void __user *)src_addr, > @@ -2393,7 +2401,7 @@ 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 { > @@ -2401,9 +2409,12 @@ static int shmem_mfill_atomic_pte(struct mm_struct *dst_mm, > *pagep = NULL; > } > > - VM_BUG_ON(PageLocked(page) || PageSwapBacked(page)); > + if (!is_continue) > + VM_BUG_ON(PageSwapBacked(page)); > + VM_BUG_ON(PageLocked(page)); > __SetPageLocked(page); > - __SetPageSwapBacked(page); > + if (!is_continue || !PageSwapBacked(page)) > + __SetPageSwapBacked(page); > __SetPageUptodate(page); Apologies, I was testing more scenarios today and discovered this doesn't work when the shmem is backed by a tmpfs file with the huge=always mount option. I think it's more correct to lookup the page with find_lock_page, and then wrap *all* of the page flag fiddling here in an "if(!is_continue) {" block. I'll send a v2 with this fix next week. > > ret = -EFAULT; > @@ -2412,10 +2423,13 @@ static int shmem_mfill_atomic_pte(struct mm_struct *dst_mm, > if (unlikely(offset >= max_off)) > goto out_release; > > - ret = shmem_add_to_page_cache(page, mapping, pgoff, NULL, > - gfp & GFP_RECLAIM_MASK, dst_mm); > - if (ret) > - goto out_release; > + /* If page wasn't already in the page cache, add it. */ > + if (!is_continue) { > + ret = shmem_add_to_page_cache(page, mapping, pgoff, NULL, > + gfp & GFP_RECLAIM_MASK, dst_mm); > + if (ret) > + goto out_release; > + } > > _dst_pte = mk_pte(page, dst_vma->vm_page_prot); > if (dst_vma->vm_flags & VM_WRITE) > @@ -2442,13 +2456,15 @@ static int shmem_mfill_atomic_pte(struct mm_struct *dst_mm, > if (!pte_none(*dst_pte)) > goto out_release_unlock; > > - lru_cache_add(page); > + if (!is_continue) { > + lru_cache_add(page); > > - spin_lock_irq(&info->lock); > - info->alloced++; > - inode->i_blocks += BLOCKS_PER_PAGE; > - shmem_recalc_inode(inode); > - spin_unlock_irq(&info->lock); > + spin_lock_irq(&info->lock); > + info->alloced++; > + inode->i_blocks += BLOCKS_PER_PAGE; > + shmem_recalc_inode(inode); > + spin_unlock_irq(&info->lock); > + } > > inc_mm_counter(dst_mm, mm_counter_file(page)); > page_add_file_rmap(page, false); > @@ -2473,28 +2489,6 @@ static int shmem_mfill_atomic_pte(struct mm_struct *dst_mm, > 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); > -} > - > #ifdef CONFIG_TMPFS > static const struct inode_operations shmem_symlink_inode_operations; > static const struct inode_operations shmem_short_symlink_operations; > diff --git a/mm/userfaultfd.c b/mm/userfaultfd.c > index ce6cb4760d2c..6cd7ab531aec 100644 > --- a/mm/userfaultfd.c > +++ b/mm/userfaultfd.c > @@ -415,7 +415,7 @@ static __always_inline ssize_t mfill_atomic_pte(struct mm_struct *dst_mm, > unsigned long dst_addr, > unsigned long src_addr, > struct page **page, > - bool zeropage, > + enum mcopy_atomic_mode mode, > bool wp_copy) > { > ssize_t err; > @@ -431,22 +431,24 @@ static __always_inline ssize_t mfill_atomic_pte(struct mm_struct *dst_mm, > * and not in the radix tree. > */ > if (!(dst_vma->vm_flags & VM_SHARED)) { > - if (!zeropage) > + switch (mode) { > + case MCOPY_ATOMIC_NORMAL: > err = mcopy_atomic_pte(dst_mm, dst_pmd, dst_vma, > dst_addr, src_addr, page, > wp_copy); > - else > + break; > + case MCOPY_ATOMIC_ZEROPAGE: > err = mfill_zeropage_pte(dst_mm, dst_pmd, > dst_vma, dst_addr); > + break; > + case MCOPY_ATOMIC_CONTINUE: > + err = -EINVAL; > + break; > + } > } 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_mcopy_atomic_pte(dst_mm, dst_pmd, dst_vma, dst_addr, > + src_addr, mode, page); > } > > return err; > @@ -467,7 +469,6 @@ static __always_inline ssize_t __mcopy_atomic(struct mm_struct *dst_mm, > long copied; > struct page *page; > bool wp_copy; > - bool zeropage = (mcopy_mode == MCOPY_ATOMIC_ZEROPAGE); > > /* > * Sanitize the command parameters: > @@ -530,7 +531,7 @@ static __always_inline ssize_t __mcopy_atomic(struct mm_struct *dst_mm, > > if (!vma_is_anonymous(dst_vma) && !vma_is_shmem(dst_vma)) > goto out_unlock; > - if (mcopy_mode == MCOPY_ATOMIC_CONTINUE) > + if (!vma_is_shmem(dst_vma) && mcopy_mode == MCOPY_ATOMIC_CONTINUE) > goto out_unlock; > > /* > @@ -578,7 +579,7 @@ static __always_inline ssize_t __mcopy_atomic(struct mm_struct *dst_mm, > BUG_ON(pmd_trans_huge(*dst_pmd)); > > err = mfill_atomic_pte(dst_mm, dst_pmd, dst_vma, dst_addr, > - src_addr, &page, zeropage, wp_copy); > + src_addr, &page, mcopy_mode, wp_copy); > cond_resched(); > > if (unlikely(err == -ENOENT)) { > -- > 2.30.0.617.g56c4b15f3c-goog >
diff --git a/fs/userfaultfd.c b/fs/userfaultfd.c index 0311e9b8a8fc..aa6d584ae8c7 100644 --- a/fs/userfaultfd.c +++ b/fs/userfaultfd.c @@ -1267,8 +1267,7 @@ static inline bool vma_can_userfault(struct vm_area_struct *vma, } if (vm_flags & VM_UFFD_MINOR) { - /* FIXME: Add minor fault interception for shmem. */ - if (!is_vm_hugetlb_page(vma)) + if (!(is_vm_hugetlb_page(vma) || vma_is_shmem(vma))) return false; } @@ -1941,7 +1940,8 @@ static int userfaultfd_api(struct userfaultfd_ctx *ctx, /* report all available features and ioctls to userland */ uffdio_api.features = UFFD_API_FEATURES; #ifndef CONFIG_HAVE_ARCH_USERFAULTFD_MINOR - uffdio_api.features &= ~UFFD_FEATURE_MINOR_HUGETLBFS; + uffdio_api.features &= + ~(UFFD_FEATURE_MINOR_HUGETLBFS | UFFD_FEATURE_MINOR_SHMEM); #endif uffdio_api.ioctls = UFFD_API_IOCTLS; ret = -EFAULT; diff --git a/include/linux/shmem_fs.h b/include/linux/shmem_fs.h index d82b6f396588..f0919c3722e7 100644 --- a/include/linux/shmem_fs.h +++ b/include/linux/shmem_fs.h @@ -9,6 +9,7 @@ #include <linux/percpu_counter.h> #include <linux/xattr.h> #include <linux/fs_parser.h> +#include <linux/userfaultfd_k.h> /* inode in-kernel data */ @@ -122,21 +123,16 @@ 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, - struct vm_area_struct *dst_vma, - unsigned long dst_addr, - unsigned long src_addr, - 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 +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, + enum mcopy_atomic_mode mode, struct page **pagep); +#else /* !CONFIG_SHMEM */ +#define shmem_mcopy_atomic_pte(dst_mm, dst_pmd, dst_vma, dst_addr, \ + src_addr, mode, pagep) ({ BUG(); 0; }) +#endif /* CONFIG_SHMEM */ +#endif /* CONFIG_USERFAULTFD */ #endif diff --git a/include/uapi/linux/userfaultfd.h b/include/uapi/linux/userfaultfd.h index bafbeb1a2624..47d9790d863d 100644 --- a/include/uapi/linux/userfaultfd.h +++ b/include/uapi/linux/userfaultfd.h @@ -31,7 +31,8 @@ UFFD_FEATURE_MISSING_SHMEM | \ UFFD_FEATURE_SIGBUS | \ UFFD_FEATURE_THREAD_ID | \ - UFFD_FEATURE_MINOR_HUGETLBFS) + UFFD_FEATURE_MINOR_HUGETLBFS | \ + UFFD_FEATURE_MINOR_SHMEM) #define UFFD_API_IOCTLS \ ((__u64)1 << _UFFDIO_REGISTER | \ (__u64)1 << _UFFDIO_UNREGISTER | \ @@ -196,6 +197,7 @@ struct uffdio_api { #define UFFD_FEATURE_SIGBUS (1<<7) #define UFFD_FEATURE_THREAD_ID (1<<8) #define UFFD_FEATURE_MINOR_HUGETLBFS (1<<9) +#define UFFD_FEATURE_MINOR_SHMEM (1<<10) __u64 features; __u64 ioctls; diff --git a/mm/memory.c b/mm/memory.c index c8e357627318..a1e5ff55027e 100644 --- a/mm/memory.c +++ b/mm/memory.c @@ -3929,9 +3929,11 @@ static vm_fault_t do_read_fault(struct vm_fault *vmf) * something). */ if (vma->vm_ops->map_pages && fault_around_bytes >> PAGE_SHIFT > 1) { - ret = do_fault_around(vmf); - if (ret) - return ret; + if (likely(!userfaultfd_minor(vmf->vma))) { + ret = do_fault_around(vmf); + if (ret) + return ret; + } } ret = __do_fault(vmf); diff --git a/mm/shmem.c b/mm/shmem.c index 06c771d23127..d7847f6f696b 100644 --- a/mm/shmem.c +++ b/mm/shmem.c @@ -77,7 +77,6 @@ static struct vfsmount *shm_mnt; #include <linux/syscalls.h> #include <linux/fcntl.h> #include <uapi/linux/memfd.h> -#include <linux/userfaultfd_k.h> #include <linux/rmap.h> #include <linux/uuid.h> @@ -1781,8 +1780,8 @@ static int shmem_swapin_page(struct inode *inode, pgoff_t index, * vm. If we swap it in we mark it dirty since we also free the swap * entry since a page cannot live in both the swap and page cache. * - * vmf and fault_type are only supplied by shmem_fault: - * otherwise they are NULL. + * vma, vmf, and fault_type are only supplied by shmem_fault: otherwise they + * are NULL. */ static int shmem_getpage_gfp(struct inode *inode, pgoff_t index, struct page **pagep, enum sgp_type sgp, gfp_t gfp, @@ -1826,6 +1825,12 @@ static int shmem_getpage_gfp(struct inode *inode, pgoff_t index, return error; } + if (page && vma && userfaultfd_minor(vma)) { + unlock_page(page); + *fault_type = handle_userfault(vmf, VM_UFFD_MINOR); + return 0; + } + if (page) hindex = page->index; if (page && sgp == SGP_WRITE) @@ -2350,14 +2355,12 @@ static struct inode *shmem_get_inode(struct super_block *sb, const struct inode return inode; } -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) +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, + enum mcopy_atomic_mode mode, struct page **pagep) { + bool is_continue = (mode == MCOPY_ATOMIC_CONTINUE); struct inode *inode = file_inode(dst_vma->vm_file); struct shmem_inode_info *info = SHMEM_I(inode); struct address_space *mapping = inode->i_mapping; @@ -2374,12 +2377,17 @@ static int shmem_mfill_atomic_pte(struct mm_struct *dst_mm, if (!shmem_inode_acct_block(inode, 1)) goto out; - if (!*pagep) { + if (is_continue) { + ret = -EFAULT; + page = find_get_page(mapping, pgoff); + if (!page) + goto out_unacct_blocks; + } else if (!*pagep) { page = shmem_alloc_page(gfp, info, pgoff); if (!page) goto out_unacct_blocks; - if (!zeropage) { /* mcopy_atomic */ + if (mode == MCOPY_ATOMIC_NORMAL) { /* mcopy_atomic */ page_kaddr = kmap_atomic(page); ret = copy_from_user(page_kaddr, (const void __user *)src_addr, @@ -2393,7 +2401,7 @@ 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 { @@ -2401,9 +2409,12 @@ static int shmem_mfill_atomic_pte(struct mm_struct *dst_mm, *pagep = NULL; } - VM_BUG_ON(PageLocked(page) || PageSwapBacked(page)); + if (!is_continue) + VM_BUG_ON(PageSwapBacked(page)); + VM_BUG_ON(PageLocked(page)); __SetPageLocked(page); - __SetPageSwapBacked(page); + if (!is_continue || !PageSwapBacked(page)) + __SetPageSwapBacked(page); __SetPageUptodate(page); ret = -EFAULT; @@ -2412,10 +2423,13 @@ static int shmem_mfill_atomic_pte(struct mm_struct *dst_mm, if (unlikely(offset >= max_off)) goto out_release; - ret = shmem_add_to_page_cache(page, mapping, pgoff, NULL, - gfp & GFP_RECLAIM_MASK, dst_mm); - if (ret) - goto out_release; + /* If page wasn't already in the page cache, add it. */ + if (!is_continue) { + ret = shmem_add_to_page_cache(page, mapping, pgoff, NULL, + gfp & GFP_RECLAIM_MASK, dst_mm); + if (ret) + goto out_release; + } _dst_pte = mk_pte(page, dst_vma->vm_page_prot); if (dst_vma->vm_flags & VM_WRITE) @@ -2442,13 +2456,15 @@ static int shmem_mfill_atomic_pte(struct mm_struct *dst_mm, if (!pte_none(*dst_pte)) goto out_release_unlock; - lru_cache_add(page); + if (!is_continue) { + lru_cache_add(page); - spin_lock_irq(&info->lock); - info->alloced++; - inode->i_blocks += BLOCKS_PER_PAGE; - shmem_recalc_inode(inode); - spin_unlock_irq(&info->lock); + spin_lock_irq(&info->lock); + info->alloced++; + inode->i_blocks += BLOCKS_PER_PAGE; + shmem_recalc_inode(inode); + spin_unlock_irq(&info->lock); + } inc_mm_counter(dst_mm, mm_counter_file(page)); page_add_file_rmap(page, false); @@ -2473,28 +2489,6 @@ static int shmem_mfill_atomic_pte(struct mm_struct *dst_mm, 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); -} - #ifdef CONFIG_TMPFS static const struct inode_operations shmem_symlink_inode_operations; static const struct inode_operations shmem_short_symlink_operations; diff --git a/mm/userfaultfd.c b/mm/userfaultfd.c index ce6cb4760d2c..6cd7ab531aec 100644 --- a/mm/userfaultfd.c +++ b/mm/userfaultfd.c @@ -415,7 +415,7 @@ static __always_inline ssize_t mfill_atomic_pte(struct mm_struct *dst_mm, unsigned long dst_addr, unsigned long src_addr, struct page **page, - bool zeropage, + enum mcopy_atomic_mode mode, bool wp_copy) { ssize_t err; @@ -431,22 +431,24 @@ static __always_inline ssize_t mfill_atomic_pte(struct mm_struct *dst_mm, * and not in the radix tree. */ if (!(dst_vma->vm_flags & VM_SHARED)) { - if (!zeropage) + switch (mode) { + case MCOPY_ATOMIC_NORMAL: err = mcopy_atomic_pte(dst_mm, dst_pmd, dst_vma, dst_addr, src_addr, page, wp_copy); - else + break; + case MCOPY_ATOMIC_ZEROPAGE: err = mfill_zeropage_pte(dst_mm, dst_pmd, dst_vma, dst_addr); + break; + case MCOPY_ATOMIC_CONTINUE: + err = -EINVAL; + break; + } } 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_mcopy_atomic_pte(dst_mm, dst_pmd, dst_vma, dst_addr, + src_addr, mode, page); } return err; @@ -467,7 +469,6 @@ static __always_inline ssize_t __mcopy_atomic(struct mm_struct *dst_mm, long copied; struct page *page; bool wp_copy; - bool zeropage = (mcopy_mode == MCOPY_ATOMIC_ZEROPAGE); /* * Sanitize the command parameters: @@ -530,7 +531,7 @@ static __always_inline ssize_t __mcopy_atomic(struct mm_struct *dst_mm, if (!vma_is_anonymous(dst_vma) && !vma_is_shmem(dst_vma)) goto out_unlock; - if (mcopy_mode == MCOPY_ATOMIC_CONTINUE) + if (!vma_is_shmem(dst_vma) && mcopy_mode == MCOPY_ATOMIC_CONTINUE) goto out_unlock; /* @@ -578,7 +579,7 @@ static __always_inline ssize_t __mcopy_atomic(struct mm_struct *dst_mm, BUG_ON(pmd_trans_huge(*dst_pmd)); err = mfill_atomic_pte(dst_mm, dst_pmd, dst_vma, dst_addr, - src_addr, &page, zeropage, wp_copy); + src_addr, &page, mcopy_mode, wp_copy); cond_resched(); if (unlikely(err == -ENOENT)) {
Modify the userfaultfd register API to allow registering shmem VMAs in minor mode. Modify the shmem mcopy implementation to support UFFDIO_CONTINUE in order to resolve such faults. Combine the shmem mcopy handler functions into a single shmem_mcopy_atomic_pte, which takes a mode parameter. This matches how the hugetlbfs implementation is structured, and lets us remove a good chunk of boilerplate. Signed-off-by: Axel Rasmussen <axelrasmussen@google.com> --- fs/userfaultfd.c | 6 +-- include/linux/shmem_fs.h | 26 ++++------ include/uapi/linux/userfaultfd.h | 4 +- mm/memory.c | 8 +-- mm/shmem.c | 88 +++++++++++++++----------------- mm/userfaultfd.c | 27 +++++----- 6 files changed, 77 insertions(+), 82 deletions(-)