feat(mm): 实现 VM_DONTCOPY 标志支持#1349
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fslongjin merged 1 commit intoDragonOS-Community:masterfrom Nov 6, 2025
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- 在地址空间克隆时跳过标记为 VM_DONTCOPY 的 VMA - 移除已拷贝的 VM_DONTCOPY 区域的页面映射 - 更新测试用例以验证 MADV_DONTFORK 功能 Signed-off-by: longjin <longjin@DragonOS.org>
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Pull Request Overview
This PR implements support for the MADV_DONTFORK system call flag, which prevents virtual memory areas (VMAs) from being copied to child processes during fork operations. The implementation adds logic to skip VM_DONTCOPY-flagged VMAs during address space cloning and unmaps any pages that were inadvertently copied.
- Added collection and handling of VM_DONTCOPY VMAs during address space cloning
- Skip VMA copying for regions marked with VM_DONTCOPY flag
- Unmap pages from VM_DONTCOPY regions in the new address space
Reviewed Changes
Copilot reviewed 2 out of 2 changed files in this pull request and generated 2 comments.
| File | Description |
|---|---|
| user/apps/tests/syscall/gvisor/blocklists/madvise_test | Removed MadviseDontforkTest.DontforkAnonPrivate test from blocklist, indicating it now passes |
| kernel/src/mm/ucontext.rs | Implemented VM_DONTCOPY (MADV_DONTFORK) support in the address space cloning logic |
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TODO: 支持文件映射页面的VM_DONTCOPY (当前实现过不了文件映射的DONTCOPY测例）