diff options
Diffstat (limited to 'fs/hugetlbfs/inode.c')
| -rw-r--r-- | fs/hugetlbfs/inode.c | 107 |
1 files changed, 89 insertions, 18 deletions
diff --git a/fs/hugetlbfs/inode.c b/fs/hugetlbfs/inode.c index aff8642f0c2e..b5c109703daa 100644 --- a/fs/hugetlbfs/inode.c +++ b/fs/hugetlbfs/inode.c @@ -38,6 +38,7 @@ #include <linux/uio.h> #include <linux/uaccess.h> +#include <linux/sched/mm.h> static const struct super_operations hugetlbfs_ops; static const struct address_space_operations hugetlbfs_aops; @@ -139,7 +140,7 @@ static int hugetlbfs_file_mmap(struct file *file, struct vm_area_struct *vma) * already been checked by prepare_hugepage_range. If you add * any error returns here, do so after setting VM_HUGETLB, so * is_vm_hugetlb_page tests below unmap_region go the right - * way when do_mmap_pgoff unwinds (may be important on powerpc + * way when do_mmap unwinds (may be important on powerpc * and ia64). */ vma->vm_flags |= VM_HUGETLB | VM_DONTEXPAND; @@ -186,18 +187,65 @@ out: } /* - * Called under down_write(mmap_sem). + * Called under mmap_write_lock(mm). */ #ifndef HAVE_ARCH_HUGETLB_UNMAPPED_AREA static unsigned long +hugetlb_get_unmapped_area_bottomup(struct file *file, unsigned long addr, + unsigned long len, unsigned long pgoff, unsigned long flags) +{ + struct hstate *h = hstate_file(file); + struct vm_unmapped_area_info info; + + info.flags = 0; + info.length = len; + info.low_limit = current->mm->mmap_base; + info.high_limit = TASK_SIZE; + info.align_mask = PAGE_MASK & ~huge_page_mask(h); + info.align_offset = 0; + return vm_unmapped_area(&info); +} + +static unsigned long +hugetlb_get_unmapped_area_topdown(struct file *file, unsigned long addr, + unsigned long len, unsigned long pgoff, unsigned long flags) +{ + struct hstate *h = hstate_file(file); + struct vm_unmapped_area_info info; + + info.flags = VM_UNMAPPED_AREA_TOPDOWN; + info.length = len; + info.low_limit = max(PAGE_SIZE, mmap_min_addr); + info.high_limit = current->mm->mmap_base; + info.align_mask = PAGE_MASK & ~huge_page_mask(h); + info.align_offset = 0; + addr = vm_unmapped_area(&info); + + /* + * A failed mmap() very likely causes application failure, + * so fall back to the bottom-up function here. This scenario + * can happen with large stack limits and large mmap() + * allocations. + */ + if (unlikely(offset_in_page(addr))) { + VM_BUG_ON(addr != -ENOMEM); + info.flags = 0; + info.low_limit = current->mm->mmap_base; + info.high_limit = TASK_SIZE; + addr = vm_unmapped_area(&info); + } + + return addr; +} + +static unsigned long hugetlb_get_unmapped_area(struct file *file, unsigned long addr, unsigned long len, unsigned long pgoff, unsigned long flags) { struct mm_struct *mm = current->mm; struct vm_area_struct *vma; struct hstate *h = hstate_file(file); - struct vm_unmapped_area_info info; if (len & ~huge_page_mask(h)) return -EINVAL; @@ -218,13 +266,16 @@ hugetlb_get_unmapped_area(struct file *file, unsigned long addr, return addr; } - info.flags = 0; - info.length = len; - info.low_limit = TASK_UNMAPPED_BASE; - info.high_limit = TASK_SIZE; - info.align_mask = PAGE_MASK & ~huge_page_mask(h); - info.align_offset = 0; - return vm_unmapped_area(&info); + /* + * Use mm->get_unmapped_area value as a hint to use topdown routine. + * If architectures have special needs, they should define their own + * version of hugetlb_get_unmapped_area. + */ + if (mm->get_unmapped_area == arch_get_unmapped_area_topdown) + return hugetlb_get_unmapped_area_topdown(file, addr, len, + pgoff, flags); + return hugetlb_get_unmapped_area_bottomup(file, addr, len, + pgoff, flags); } #endif @@ -393,10 +444,9 @@ hugetlb_vmdelete_list(struct rb_root_cached *root, pgoff_t start, pgoff_t end) * In this case, we first scan the range and release found pages. * After releasing pages, hugetlb_unreserve_pages cleans up region/reserv * maps and global counts. Page faults can not race with truncation - * in this routine. hugetlb_no_page() prevents page faults in the - * truncated range. It checks i_size before allocation, and again after - * with the page table lock for the page held. The same lock must be - * acquired to unmap a page. + * in this routine. hugetlb_no_page() holds i_mmap_rwsem and prevents + * page faults in the truncated range by checking i_size. i_size is + * modified while holding i_mmap_rwsem. * hole punch is indicated if end is not LLONG_MAX * In the hole punch case we scan the range and release found pages. * Only when releasing a page is the associated region/reserv map @@ -436,7 +486,15 @@ static void remove_inode_hugepages(struct inode *inode, loff_t lstart, index = page->index; hash = hugetlb_fault_mutex_hash(mapping, index); - mutex_lock(&hugetlb_fault_mutex_table[hash]); + if (!truncate_op) { + /* + * Only need to hold the fault mutex in the + * hole punch case. This prevents races with + * page faults. Races are not possible in the + * case of truncation. + */ + mutex_lock(&hugetlb_fault_mutex_table[hash]); + } /* * If page is mapped, it was faulted in after being @@ -450,7 +508,9 @@ static void remove_inode_hugepages(struct inode *inode, loff_t lstart, if (unlikely(page_mapped(page))) { BUG_ON(truncate_op); + mutex_unlock(&hugetlb_fault_mutex_table[hash]); i_mmap_lock_write(mapping); + mutex_lock(&hugetlb_fault_mutex_table[hash]); hugetlb_vmdelete_list(&mapping->i_mmap, index * pages_per_huge_page(h), (index + 1) * pages_per_huge_page(h)); @@ -477,7 +537,8 @@ static void remove_inode_hugepages(struct inode *inode, loff_t lstart, } unlock_page(page); - mutex_unlock(&hugetlb_fault_mutex_table[hash]); + if (!truncate_op) + mutex_unlock(&hugetlb_fault_mutex_table[hash]); } huge_pagevec_release(&pvec); cond_resched(); @@ -515,8 +576,8 @@ static int hugetlb_vmtruncate(struct inode *inode, loff_t offset) BUG_ON(offset & ~huge_page_mask(h)); pgoff = offset >> PAGE_SHIFT; - i_size_write(inode, offset); i_mmap_lock_write(mapping); + i_size_write(inode, offset); if (!RB_EMPTY_ROOT(&mapping->i_mmap.rb_root)) hugetlb_vmdelete_list(&mapping->i_mmap, pgoff, 0); i_mmap_unlock_write(mapping); @@ -638,7 +699,11 @@ static long hugetlbfs_fallocate(struct file *file, int mode, loff_t offset, /* addr is the offset within the file (zero based) */ addr = index * hpage_size; - /* mutex taken here, fault path and hole punch */ + /* + * fault mutex taken here, protects against fault path + * and hole punch. inode_lock previously taken protects + * against truncation. + */ hash = hugetlb_fault_mutex_hash(mapping, index); mutex_lock(&hugetlb_fault_mutex_table[hash]); @@ -1299,6 +1364,12 @@ hugetlbfs_fill_super(struct super_block *sb, struct fs_context *fc) sb->s_magic = HUGETLBFS_MAGIC; sb->s_op = &hugetlbfs_ops; sb->s_time_gran = 1; + + /* + * Due to the special and limited functionality of hugetlbfs, it does + * not work well as a stacking filesystem. + */ + sb->s_stack_depth = FILESYSTEM_MAX_STACK_DEPTH; sb->s_root = d_make_root(hugetlbfs_get_root(sb, ctx)); if (!sb->s_root) goto out_free; |