diff options
| -rw-r--r-- | mm/mremap.c | 186 |
1 files changed, 122 insertions, 64 deletions
diff --git a/mm/mremap.c b/mm/mremap.c index af022e3b89e26..6305cb9a86f6b 100644 --- a/mm/mremap.c +++ b/mm/mremap.c @@ -68,6 +68,7 @@ struct vma_remap_struct { bool mlocked; /* Was the VMA mlock()'d? */ enum mremap_type remap_type; /* expand, shrink, etc. */ bool mmap_locked; /* Is mm currently write-locked? */ + unsigned long charged; /* If VM_ACCOUNT, # pages to account. */ }; static pud_t *get_old_pud(struct mm_struct *mm, unsigned long addr) @@ -816,35 +817,88 @@ static unsigned long vrm_set_new_addr(struct vma_remap_struct *vrm) return 0; } -static unsigned long move_vma(struct vm_area_struct *vma, - unsigned long old_addr, unsigned long old_len, - unsigned long new_len, unsigned long new_addr, - bool *mlocked, unsigned long flags, - struct vm_userfaultfd_ctx *uf, struct list_head *uf_unmap) +/* + * Keep track of pages which have been added to the memory mapping. If the VMA + * is accounted, also check to see if there is sufficient memory. + * + * Returns true on success, false if insufficient memory to charge. + */ +static bool vrm_charge(struct vma_remap_struct *vrm) { - long to_account = new_len - old_len; - struct mm_struct *mm = vma->vm_mm; - struct vm_area_struct *new_vma; - unsigned long vm_flags = vma->vm_flags; - unsigned long new_pgoff; - unsigned long moved_len; - bool account_start = false; - bool account_end = false; - unsigned long hiwater_vm; - int err = 0; - bool need_rmap_locks; - struct vma_iterator vmi; + unsigned long charged; + + if (!(vrm->vma->vm_flags & VM_ACCOUNT)) + return true; + + /* + * If we don't unmap the old mapping, then we account the entirety of + * the length of the new one. Otherwise it's just the delta in size. + */ + if (vrm->flags & MREMAP_DONTUNMAP) + charged = vrm->new_len >> PAGE_SHIFT; + else + charged = vrm->delta >> PAGE_SHIFT; + + + /* This accounts 'charged' pages of memory. */ + if (security_vm_enough_memory_mm(current->mm, charged)) + return false; + + vrm->charged = charged; + return true; +} + +/* + * an error has occurred so we will not be using vrm->charged memory. Unaccount + * this memory if the VMA is accounted. + */ +static void vrm_uncharge(struct vma_remap_struct *vrm) +{ + if (!(vrm->vma->vm_flags & VM_ACCOUNT)) + return; + + vm_unacct_memory(vrm->charged); + vrm->charged = 0; +} + +/* + * Update mm exec_vm, stack_vm, data_vm, and locked_vm fields as needed to + * account for 'bytes' memory used, and if locked, indicate this in the VRM so + * we can handle this correctly later. + */ +static void vrm_stat_account(struct vma_remap_struct *vrm, + unsigned long bytes) +{ + unsigned long pages = bytes >> PAGE_SHIFT; + struct mm_struct *mm = current->mm; + struct vm_area_struct *vma = vrm->vma; + + vm_stat_account(mm, vma->vm_flags, pages); + if (vma->vm_flags & VM_LOCKED) { + mm->locked_vm += pages; + vrm->mlocked = true; + } +} + +/* + * Perform checks before attempting to write a VMA prior to it being + * moved. + */ +static unsigned long prep_move_vma(struct vma_remap_struct *vrm, + unsigned long *vm_flags_ptr) +{ + unsigned long err = 0; + struct vm_area_struct *vma = vrm->vma; + unsigned long old_addr = vrm->addr; + unsigned long old_len = vrm->old_len; /* * We'd prefer to avoid failure later on in do_munmap: * which may split one vma into three before unmapping. */ - if (mm->map_count >= sysctl_max_map_count - 3) + if (current->mm->map_count >= sysctl_max_map_count - 3) return -ENOMEM; - if (unlikely(flags & MREMAP_DONTUNMAP)) - to_account = new_len; - if (vma->vm_ops && vma->vm_ops->may_split) { if (vma->vm_start != old_addr) err = vma->vm_ops->may_split(vma, old_addr); @@ -862,22 +916,46 @@ static unsigned long move_vma(struct vm_area_struct *vma, * 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); + MADV_UNMERGEABLE, vm_flags_ptr); if (err) return err; - if (vm_flags & VM_ACCOUNT) { - if (security_vm_enough_memory_mm(mm, to_account >> PAGE_SHIFT)) - return -ENOMEM; - } + return 0; +} + +static unsigned long move_vma(struct vma_remap_struct *vrm) +{ + struct mm_struct *mm = current->mm; + struct vm_area_struct *vma = vrm->vma; + struct vm_area_struct *new_vma; + unsigned long vm_flags = vma->vm_flags; + unsigned long old_addr = vrm->addr, new_addr = vrm->new_addr; + unsigned long old_len = vrm->old_len, new_len = vrm->new_len; + unsigned long new_pgoff; + unsigned long moved_len; + unsigned long account_start = false; + unsigned long account_end = false; + unsigned long hiwater_vm; + int err; + bool need_rmap_locks; + struct vma_iterator vmi; + + err = prep_move_vma(vrm, &vm_flags); + if (err) + return err; + + /* If accounted, charge the number of bytes the operation will use. */ + if (!vrm_charge(vrm)) + return -ENOMEM; vma_start_write(vma); new_pgoff = vma->vm_pgoff + ((old_addr - vma->vm_start) >> PAGE_SHIFT); - new_vma = copy_vma(&vma, new_addr, new_len, new_pgoff, + new_vma = copy_vma(&vrm->vma, new_addr, new_len, new_pgoff, &need_rmap_locks); + /* This may have been updated. */ + vma = vrm->vma; if (!new_vma) { - if (vm_flags & VM_ACCOUNT) - vm_unacct_memory(to_account >> PAGE_SHIFT); + vrm_uncharge(vrm); return -ENOMEM; } @@ -902,7 +980,7 @@ static unsigned long move_vma(struct vm_area_struct *vma, old_addr = new_addr; new_addr = err; } else { - mremap_userfaultfd_prep(new_vma, uf); + mremap_userfaultfd_prep(new_vma, vrm->uf); } if (is_vm_hugetlb_page(vma)) { @@ -910,7 +988,7 @@ static unsigned long move_vma(struct vm_area_struct *vma, } /* Conceal VM_ACCOUNT so old reservation is not undone */ - if (vm_flags & VM_ACCOUNT && !(flags & MREMAP_DONTUNMAP)) { + if (vm_flags & VM_ACCOUNT && !(vrm->flags & MREMAP_DONTUNMAP)) { vm_flags_clear(vma, VM_ACCOUNT); if (vma->vm_start < old_addr) account_start = true; @@ -928,13 +1006,12 @@ static unsigned long move_vma(struct vm_area_struct *vma, * If this were a serious issue, we'd add a flag to do_munmap(). */ hiwater_vm = mm->hiwater_vm; - vm_stat_account(mm, vma->vm_flags, new_len >> PAGE_SHIFT); /* Tell pfnmap has moved from this vma */ if (unlikely(vma->vm_flags & VM_PFNMAP)) untrack_pfn_clear(vma); - if (unlikely(!err && (flags & MREMAP_DONTUNMAP))) { + if (unlikely(!err && (vrm->flags & MREMAP_DONTUNMAP))) { /* We always clear VM_LOCKED[ONFAULT] on the old vma */ vm_flags_clear(vma, VM_LOCKED_MASK); @@ -947,22 +1024,20 @@ static unsigned long move_vma(struct vm_area_struct *vma, unlink_anon_vmas(vma); /* Because we won't unmap we don't need to touch locked_vm */ + vrm_stat_account(vrm, new_len); return new_addr; } + vrm_stat_account(vrm, new_len); + vma_iter_init(&vmi, mm, old_addr); - if (do_vmi_munmap(&vmi, mm, old_addr, old_len, uf_unmap, false) < 0) { + if (do_vmi_munmap(&vmi, mm, old_addr, old_len, vrm->uf_unmap, false) < 0) { /* OOM: unable to split vma, just get accounts right */ - if (vm_flags & VM_ACCOUNT && !(flags & MREMAP_DONTUNMAP)) + if (vm_flags & VM_ACCOUNT && !(vrm->flags & MREMAP_DONTUNMAP)) vm_acct_memory(old_len >> PAGE_SHIFT); account_start = account_end = false; } - if (vm_flags & VM_LOCKED) { - mm->locked_vm += new_len >> PAGE_SHIFT; - *mlocked = true; - } - mm->hiwater_vm = hiwater_vm; /* Restore VM_ACCOUNT if one or two pieces of vma left */ @@ -1141,9 +1216,7 @@ static unsigned long mremap_to(struct vma_remap_struct *vrm) if (err) return err; - return move_vma(vrm->vma, vrm->addr, vrm->old_len, vrm->new_len, - vrm->new_addr, &vrm->mlocked, vrm->flags, - vrm->uf, vrm->uf_unmap); + return move_vma(vrm); } static int vma_expandable(struct vm_area_struct *vma, unsigned long delta) @@ -1248,17 +1321,11 @@ static unsigned long check_mremap_params(struct vma_remap_struct *vrm) static unsigned long expand_vma_in_place(struct vma_remap_struct *vrm) { struct mm_struct *mm = current->mm; - long pages = vrm->delta >> PAGE_SHIFT; struct vm_area_struct *vma = vrm->vma; VMA_ITERATOR(vmi, mm, vma->vm_end); - long charged = 0; - - if (vma->vm_flags & VM_ACCOUNT) { - if (security_vm_enough_memory_mm(mm, pages)) - return -ENOMEM; - charged = pages; - } + if (!vrm_charge(vrm)) + return -ENOMEM; /* * Function vma_merge_extend() is called on the @@ -1271,15 +1338,11 @@ static unsigned long expand_vma_in_place(struct vma_remap_struct *vrm) */ vma = vrm->vma = vma_merge_extend(&vmi, vma, vrm->delta); if (!vma) { - vm_unacct_memory(charged); + vrm_uncharge(vrm); return -ENOMEM; } - vm_stat_account(mm, vma->vm_flags, pages); - if (vma->vm_flags & VM_LOCKED) { - mm->locked_vm += pages; - vrm->mlocked = true; - } + vrm_stat_account(vrm, vrm->delta); return 0; } @@ -1319,11 +1382,7 @@ static bool align_hugetlb(struct vma_remap_struct *vrm) static unsigned long expand_vma(struct vma_remap_struct *vrm) { unsigned long err; - struct vm_area_struct *vma = vrm->vma; unsigned long addr = vrm->addr; - unsigned long old_len = vrm->old_len; - unsigned long new_len = vrm->new_len; - unsigned long flags = vrm->flags; err = resize_is_valid(vrm); if (err) @@ -1356,7 +1415,7 @@ static unsigned long expand_vma(struct vma_remap_struct *vrm) */ /* We're not allowed to move the VMA, so error out. */ - if (!(flags & MREMAP_MAYMOVE)) + if (!(vrm->flags & MREMAP_MAYMOVE)) return -ENOMEM; /* Find a new location to move the VMA to. */ @@ -1364,8 +1423,7 @@ static unsigned long expand_vma(struct vma_remap_struct *vrm) if (err) return err; - return move_vma(vma, addr, old_len, new_len, vrm->new_addr, - &vrm->mlocked, flags, vrm->uf, vrm->uf_unmap); + return move_vma(vrm); } /* |