From: Luigi Rizzo Date: Mon, 23 Aug 2021 23:59:21 +0000 (+1000) Subject: mm/pagemap: add mmap_assert_locked() annotations to find_vma*() X-Git-Url: https://www.infradead.org/git/?a=commitdiff_plain;h=78ed3bb6526904930fc6344dcb728f06b4091812;p=users%2Fjedix%2Flinux-maple.git 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@google.com Signed-off-by: Luigi Rizzo Cc: David Rientjes Signed-off-by: Andrew Morton Signed-off-by: Stephen Rothwell --- diff --git a/fs/exec.c b/fs/exec.c index eb2a99793018d..816c7e347c9c1 100644 --- a/fs/exec.c +++ b/fs/exec.c @@ -217,8 +217,10 @@ static struct page *get_arg_page(struct linux_binprm *bprm, unsigned long pos, * 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; diff --git a/mm/mmap.c b/mm/mmap.c index ca54d36d203ae..79f4f8ae43ecd 100644 --- a/mm/mmap.c +++ b/mm/mmap.c @@ -534,6 +534,7 @@ static int find_vma_links(struct mm_struct *mm, unsigned long addr, { 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 mm_struct *mm, unsigned long addr) 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))