| Message ID | 20210127083917.309264-1-lixinhai.lxh@gmail.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | [v2,1/2] mm: rmap: explicitly reset vma->anon_vma in unlink_anon_vmas() | expand |
diff --git a/mm/rmap.c b/mm/rmap.c index 08c56aaf72eb..31ef76180c53 100644 --- a/mm/rmap.c +++ b/mm/rmap.c @@ -413,8 +413,15 @@ void unlink_anon_vmas(struct vm_area_struct *vma) list_del(&avc->same_vma); anon_vma_chain_free(avc); } - if (vma->anon_vma) + if (vma->anon_vma) { vma->anon_vma->degree--; + + /* + * vma would still be needed after unlink, and anon_vma will be prepared + * when handle fault. + */ + vma->anon_vma = NULL; + } unlock_anon_vma_root(root); /*
In case the vma will continue to be used after unlink its relevant anon_vma, we need to reset the vma->anon_vma pointer to NULL. So, later when fault happen within this vma again, a new anon_vma will be prepared. By this way, the vma will only be checked for reverse mapping of pages which been fault in after the unlink_anon_vmas call. Currently, the mremap with MREMAP_DONTUNMAP scenario will continue use the vma after moved its page table entries to a new vma. For other scenarios, the vma itself will be freed after call unlink_anon_vmas. Signed-off-by: Li Xinhai <lixinhai.lxh@gmail.com> --- v1->v2: No chnages. mm/rmap.c | 9 ++++++++- 1 file changed, 8 insertions(+), 1 deletion(-)