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| author | Li Xinhai <lixinhai.lxh@gmail.com> | 2021-02-24 21:04:49 +0100 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2021-02-24 22:38:30 +0100 |
| commit | ee8ab1903e3d912d8f10bedbf96c3b6a1c8cbede (patch) | |
| tree | 336052046bb2efbce056b12f6a9f2be525af6f16 /mm/rmap.c | |
| parent | mm/mprotect.c: optimize error detection in do_mprotect_pkey() (diff) | |
| download | linux-ee8ab1903e3d912d8f10bedbf96c3b6a1c8cbede.tar.xz linux-ee8ab1903e3d912d8f10bedbf96c3b6a1c8cbede.zip | |
mm: rmap: explicitly reset vma->anon_vma in unlink_anon_vmas()
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.
Link: https://lkml.kernel.org/r/20210119075126.3513154-1-lixinhai.lxh@gmail.com
Signed-off-by: Li Xinhai <lixinhai.lxh@gmail.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Brian Geffon <bgeffon@google.com>
Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Lokesh Gidra <lokeshgidra@google.com>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'mm/rmap.c')
| -rw-r--r-- | mm/rmap.c | 9 |
1 files changed, 8 insertions, 1 deletions
diff --git a/mm/rmap.c b/mm/rmap.c index 5ebf16fae4b9..e26ae119a131 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); /* |