The patch titled
Subject: mm/pagemap: add mmap_assert_locked() annotations to find_vma*()
has been added to the -mm tree. Its filename is
add-mmap_assert_locked-annotations-to-find_vma.patch
This patch should soon appear at
https://ozlabs.org/~akpm/mmots/broken-out/add-mmap_assert_locked-annotations-to-find_vma.patch
and later at
https://ozlabs.org/~akpm/mmotm/broken-out/add-mmap_assert_locked-annotations-to-find_vma.patch
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------------------------------------------------------
From: Luigi Rizzo <lrizzo@xxxxxxxxxx>
Subject: mm/pagemap: add mmap_assert_locked() annotations to find_vma*()
find_vma() and variants need protection when used. This patch adds
mmap_assert_lock() calls in the functions.
To make sure the invariant is satisfied, we also need to add a
mmap_read_loc() around the get_user_pages_remote() call in get_arg_page().
The lock is not strictly necessary because the mm has been newly created,
but the extra cost is limited because the same mutex was also acquired
shortly before in __bprm_mm_init(), so it is hot and uncontended.
Link: https://lkml.kernel.org/r/20210731175341.3458608-1-lrizzo@xxxxxxxxxx
Signed-off-by: Luigi Rizzo <lrizzo@xxxxxxxxxx>
Cc: David Rientjes <rientjes@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
fs/exec.c | 2 ++
mm/mmap.c | 2 ++
2 files changed, 4 insertions(+)
--- a/fs/exec.c~add-mmap_assert_locked-annotations-to-find_vma
+++ a/fs/exec.c
@@ -217,8 +217,10 @@ static struct page *get_arg_page(struct
* We are doing an exec(). 'current' is the process
* doing the exec and bprm->mm is the new process's mm.
*/
+ mmap_read_lock(bprm->mm);
ret = get_user_pages_remote(bprm->mm, pos, 1, gup_flags,
&page, NULL, NULL);
+ mmap_read_unlock(bprm->mm);
if (ret <= 0)
return NULL;
--- a/mm/mmap.c~add-mmap_assert_locked-annotations-to-find_vma
+++ a/mm/mmap.c
@@ -534,6 +534,7 @@ static int find_vma_links(struct mm_stru
{
struct rb_node **__rb_link, *__rb_parent, *rb_prev;
+ mmap_assert_locked(mm);
__rb_link = &mm->mm_rb.rb_node;
rb_prev = __rb_parent = NULL;
@@ -2303,6 +2304,7 @@ struct vm_area_struct *find_vma(struct m
struct rb_node *rb_node;
struct vm_area_struct *vma;
+ mmap_assert_locked(mm);
/* Check the cache first. */
vma = vmacache_find(mm, addr);
if (likely(vma))
_
Patches currently in -mm which might be from lrizzo@xxxxxxxxxx are
add-mmap_assert_locked-annotations-to-find_vma.patch
