X-Git-Url: http://ftp.safe.ca/?a=blobdiff_plain;f=mm%2Fmremap.c;h=845190898d59f206201b4b5d60f1d4534a755913;hb=a49c65037146bfb2fe300b8277b10b4479fea5fc;hp=5572e0825d80379015cde673022d13385d10e215;hpb=2ed7c03ec17779afb4fcfa3b8c61df61bd4879ba;p=safe%2Fjmp%2Flinux-2.6 diff --git a/mm/mremap.c b/mm/mremap.c index 5572e08..8451908 100644 --- a/mm/mremap.c +++ b/mm/mremap.c @@ -11,6 +11,7 @@ #include #include #include +#include #include #include #include @@ -85,8 +86,8 @@ static void move_ptes(struct vm_area_struct *vma, pmd_t *old_pmd, if (vma->vm_file) { /* * Subtle point from Rajesh Venkatasubramanian: before - * moving file-based ptes, we must lock vmtruncate out, - * since it might clean the dst vma before the src vma, + * moving file-based ptes, we must lock truncate_pagecache + * out, since it might clean the dst vma before the src vma, * and we propagate stale pages into the dst afterward. */ mapping = vma->vm_file->f_mapping; @@ -174,6 +175,7 @@ static unsigned long move_vma(struct vm_area_struct *vma, unsigned long excess = 0; unsigned long hiwater_vm; int split = 0; + int err; /* * We'd prefer to avoid failure later on in do_munmap: @@ -182,6 +184,18 @@ static unsigned long move_vma(struct vm_area_struct *vma, if (mm->map_count >= sysctl_max_map_count - 3) return -ENOMEM; + /* + * Advise KSM to break any KSM pages in the area to be moved: + * it would be confusing if they were to turn up at the new + * location, where they happen to coincide with different KSM + * pages recently unmapped. But leave vma->vm_flags as it was, + * so KSM can come around to merge on vma and new_vma afterwards. + */ + err = ksm_madvise(vma, old_addr, old_addr + old_len, + MADV_UNMERGEABLE, &vm_flags); + if (err) + return err; + new_pgoff = vma->vm_pgoff + ((old_addr - vma->vm_start) >> PAGE_SHIFT); new_vma = copy_vma(&vma, new_addr, new_len, new_pgoff); if (!new_vma) @@ -247,6 +261,137 @@ static unsigned long move_vma(struct vm_area_struct *vma, return new_addr; } +static struct vm_area_struct *vma_to_resize(unsigned long addr, + unsigned long old_len, unsigned long new_len, unsigned long *p) +{ + struct mm_struct *mm = current->mm; + struct vm_area_struct *vma = find_vma(mm, addr); + + if (!vma || vma->vm_start > addr) + goto Efault; + + if (is_vm_hugetlb_page(vma)) + goto Einval; + + /* We can't remap across vm area boundaries */ + if (old_len > vma->vm_end - addr) + goto Efault; + + if (vma->vm_flags & (VM_DONTEXPAND | VM_PFNMAP)) { + if (new_len > old_len) + goto Efault; + } + + if (vma->vm_flags & VM_LOCKED) { + unsigned long locked, lock_limit; + locked = mm->locked_vm << PAGE_SHIFT; + lock_limit = current->signal->rlim[RLIMIT_MEMLOCK].rlim_cur; + locked += new_len - old_len; + if (locked > lock_limit && !capable(CAP_IPC_LOCK)) + goto Eagain; + } + + if (!may_expand_vm(mm, (new_len - old_len) >> PAGE_SHIFT)) + goto Enomem; + + if (vma->vm_flags & VM_ACCOUNT) { + unsigned long charged = (new_len - old_len) >> PAGE_SHIFT; + if (security_vm_enough_memory(charged)) + goto Efault; + *p = charged; + } + + return vma; + +Efault: /* very odd choice for most of the cases, but... */ + return ERR_PTR(-EFAULT); +Einval: + return ERR_PTR(-EINVAL); +Enomem: + return ERR_PTR(-ENOMEM); +Eagain: + return ERR_PTR(-EAGAIN); +} + +static unsigned long mremap_to(unsigned long addr, + unsigned long old_len, unsigned long new_addr, + unsigned long new_len) +{ + struct mm_struct *mm = current->mm; + struct vm_area_struct *vma; + unsigned long ret = -EINVAL; + unsigned long charged = 0; + unsigned long map_flags; + + if (new_addr & ~PAGE_MASK) + goto out; + + if (new_len > TASK_SIZE || new_addr > TASK_SIZE - new_len) + goto out; + + /* Check if the location we're moving into overlaps the + * old location at all, and fail if it does. + */ + if ((new_addr <= addr) && (new_addr+new_len) > addr) + goto out; + + if ((addr <= new_addr) && (addr+old_len) > new_addr) + goto out; + + ret = security_file_mmap(NULL, 0, 0, 0, new_addr, 1); + if (ret) + goto out; + + ret = do_munmap(mm, new_addr, new_len); + if (ret) + goto out; + + if (old_len >= new_len) { + ret = do_munmap(mm, addr+new_len, old_len - new_len); + if (ret && old_len != new_len) + goto out; + old_len = new_len; + } + + vma = vma_to_resize(addr, old_len, new_len, &charged); + if (IS_ERR(vma)) { + ret = PTR_ERR(vma); + goto out; + } + + map_flags = MAP_FIXED; + if (vma->vm_flags & VM_MAYSHARE) + map_flags |= MAP_SHARED; + + ret = get_unmapped_area(vma->vm_file, new_addr, new_len, vma->vm_pgoff + + ((addr - vma->vm_start) >> PAGE_SHIFT), + map_flags); + if (ret & ~PAGE_MASK) + goto out1; + + ret = move_vma(vma, addr, old_len, new_len, new_addr); + if (!(ret & ~PAGE_MASK)) + goto out; +out1: + vm_unacct_memory(charged); + +out: + return ret; +} + +static int vma_expandable(struct vm_area_struct *vma, unsigned long delta) +{ + unsigned long end = vma->vm_end + delta; + if (end < vma->vm_end) /* overflow */ + return 0; + if (vma->vm_next && vma->vm_next->vm_start < end) /* intersection */ + return 0; + if (get_unmapped_area(NULL, vma->vm_start, end - vma->vm_start, + 0, MAP_FIXED) & ~PAGE_MASK) + return 0; + return 1; +} + /* * Expand (or shrink) an existing mapping, potentially moving it at the * same time (controlled by the MREMAP_MAYMOVE flag and available VM space) @@ -280,32 +425,10 @@ unsigned long do_mremap(unsigned long addr, if (!new_len) goto out; - /* new_addr is only valid if MREMAP_FIXED is specified */ if (flags & MREMAP_FIXED) { - if (new_addr & ~PAGE_MASK) - goto out; - if (!(flags & MREMAP_MAYMOVE)) - goto out; - - if (new_len > TASK_SIZE || new_addr > TASK_SIZE - new_len) - goto out; - - /* Check if the location we're moving into overlaps the - * old location at all, and fail if it does. - */ - if ((new_addr <= addr) && (new_addr+new_len) > addr) - goto out; - - if ((addr <= new_addr) && (addr+old_len) > new_addr) - goto out; - - ret = security_file_mmap(NULL, 0, 0, 0, new_addr, 1); - if (ret) - goto out; - - ret = do_munmap(mm, new_addr, new_len); - if (ret) - goto out; + if (flags & MREMAP_MAYMOVE) + ret = mremap_to(addr, old_len, new_addr, new_len); + goto out; } /* @@ -318,60 +441,23 @@ unsigned long do_mremap(unsigned long addr, if (ret && old_len != new_len) goto out; ret = addr; - if (!(flags & MREMAP_FIXED) || (new_addr == addr)) - goto out; - old_len = new_len; + goto out; } /* - * Ok, we need to grow.. or relocate. + * Ok, we need to grow.. */ - ret = -EFAULT; - vma = find_vma(mm, addr); - if (!vma || vma->vm_start > addr) + vma = vma_to_resize(addr, old_len, new_len, &charged); + if (IS_ERR(vma)) { + ret = PTR_ERR(vma); goto out; - if (is_vm_hugetlb_page(vma)) { - ret = -EINVAL; - goto out; - } - /* We can't remap across vm area boundaries */ - if (old_len > vma->vm_end - addr) - goto out; - if (vma->vm_flags & (VM_DONTEXPAND | VM_PFNMAP)) { - if (new_len > old_len) - goto out; - } - if (vma->vm_flags & VM_LOCKED) { - unsigned long locked, lock_limit; - locked = mm->locked_vm << PAGE_SHIFT; - lock_limit = current->signal->rlim[RLIMIT_MEMLOCK].rlim_cur; - locked += new_len - old_len; - ret = -EAGAIN; - if (locked > lock_limit && !capable(CAP_IPC_LOCK)) - goto out; - } - if (!may_expand_vm(mm, (new_len - old_len) >> PAGE_SHIFT)) { - ret = -ENOMEM; - goto out; - } - - if (vma->vm_flags & VM_ACCOUNT) { - charged = (new_len - old_len) >> PAGE_SHIFT; - if (security_vm_enough_memory(charged)) - goto out_nc; } /* old_len exactly to the end of the area.. - * And we're not relocating the area. */ - if (old_len == vma->vm_end - addr && - !((flags & MREMAP_FIXED) && (addr != new_addr)) && - (old_len != new_len || !(flags & MREMAP_MAYMOVE))) { - unsigned long max_addr = TASK_SIZE; - if (vma->vm_next) - max_addr = vma->vm_next->vm_start; + if (old_len == vma->vm_end - addr) { /* can we just expand the current mapping? */ - if (max_addr - addr >= new_len) { + if (vma_expandable(vma, new_len - old_len)) { int pages = (new_len - old_len) >> PAGE_SHIFT; vma_adjust(vma, vma->vm_start, @@ -395,34 +481,33 @@ unsigned long do_mremap(unsigned long addr, */ ret = -ENOMEM; if (flags & MREMAP_MAYMOVE) { - if (!(flags & MREMAP_FIXED)) { - unsigned long map_flags = 0; - if (vma->vm_flags & VM_MAYSHARE) - map_flags |= MAP_SHARED; - - new_addr = get_unmapped_area(vma->vm_file, 0, new_len, - vma->vm_pgoff, map_flags); - if (new_addr & ~PAGE_MASK) { - ret = new_addr; - goto out; - } - - ret = security_file_mmap(NULL, 0, 0, 0, new_addr, 1); - if (ret) - goto out; + unsigned long map_flags = 0; + if (vma->vm_flags & VM_MAYSHARE) + map_flags |= MAP_SHARED; + + new_addr = get_unmapped_area(vma->vm_file, 0, new_len, + vma->vm_pgoff + + ((addr - vma->vm_start) >> PAGE_SHIFT), + map_flags); + if (new_addr & ~PAGE_MASK) { + ret = new_addr; + goto out; } + + ret = security_file_mmap(NULL, 0, 0, 0, new_addr, 1); + if (ret) + goto out; ret = move_vma(vma, addr, old_len, new_len, new_addr); } out: if (ret & ~PAGE_MASK) vm_unacct_memory(charged); -out_nc: return ret; } -asmlinkage long sys_mremap(unsigned long addr, - unsigned long old_len, unsigned long new_len, - unsigned long flags, unsigned long new_addr) +SYSCALL_DEFINE5(mremap, unsigned long, addr, unsigned long, old_len, + unsigned long, new_len, unsigned long, flags, + unsigned long, new_addr) { unsigned long ret;