Messages in this thread Patch in this message | | | Date | Thu, 8 Apr 2010 07:11:11 -0700 (PDT) | From | Linus Torvalds <> | Subject | Re: [PATCH -v2] rmap: make anon_vma_prepare link in all the anon_vmas of a mergeable VMA |
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On Thu, 8 Apr 2010, Borislav Petkov wrote: > > There are still issues: vma_adjust() grabs mapping->i_mmap_lock for file > mappings while we might sleep in anon_vma_prepare():
Ahh. Good catch. So I can't actually do that anon_vma_prepare() thing in __insert_vm_struct.
It should be simple enough to just move it into the caller, just after it releases that lock. There's only one user of that __insert_vm_struct() anyway. You can do it yourself, or you can replace my previous patch with this..
[ The patch below also makes it warn once and return SIGBUS for the case where there is no anon_vma. I decided I still want to hear about it if there might be some path that tries to insert a vma on its own ]
Linus
--- mm/memory.c | 12 +++--------- mm/mmap.c | 17 ++++------------- 2 files changed, 7 insertions(+), 22 deletions(-)
diff --git a/mm/memory.c b/mm/memory.c index 833952d..08d4423 100644 --- a/mm/memory.c +++ b/mm/memory.c @@ -2223,9 +2223,6 @@ reuse: gotten: pte_unmap_unlock(page_table, ptl); - if (unlikely(anon_vma_prepare(vma))) - goto oom; - if (is_zero_pfn(pte_pfn(orig_pte))) { new_page = alloc_zeroed_user_highpage_movable(vma, address); if (!new_page) @@ -2766,8 +2763,6 @@ static int do_anonymous_page(struct mm_struct *mm, struct vm_area_struct *vma, /* Allocate our own private page. */ pte_unmap(page_table); - if (unlikely(anon_vma_prepare(vma))) - goto oom; page = alloc_zeroed_user_highpage_movable(vma, address); if (!page) goto oom; @@ -2863,10 +2858,6 @@ static int __do_fault(struct mm_struct *mm, struct vm_area_struct *vma, if (flags & FAULT_FLAG_WRITE) { if (!(vma->vm_flags & VM_SHARED)) { anon = 1; - if (unlikely(anon_vma_prepare(vma))) { - ret = VM_FAULT_OOM; - goto out; - } page = alloc_page_vma(GFP_HIGHUSER_MOVABLE, vma, address); if (!page) { @@ -3115,6 +3106,9 @@ int handle_mm_fault(struct mm_struct *mm, struct vm_area_struct *vma, pmd_t *pmd; pte_t *pte; + if (WARN_ONCE(!vma->anon_vma, "Mapping with no anon_vma")) + return VM_FAULT_SIGBUS; + __set_current_state(TASK_RUNNING); count_vm_event(PGFAULT); diff --git a/mm/mmap.c b/mm/mmap.c index 75557c6..82392c2 100644 --- a/mm/mmap.c +++ b/mm/mmap.c @@ -463,6 +463,8 @@ static void vma_link(struct mm_struct *mm, struct vm_area_struct *vma, mm->map_count++; validate_mm(mm); + + anon_vma_prepare(vma); } /* @@ -628,6 +630,8 @@ again: remove_next = 1 + (end > next->vm_end); if (mapping) spin_unlock(&mapping->i_mmap_lock); + anon_vma_prepare(vma); + if (remove_next) { if (file) { fput(file); @@ -1674,12 +1678,6 @@ int expand_upwards(struct vm_area_struct *vma, unsigned long address) if (!(vma->vm_flags & VM_GROWSUP)) return -EFAULT; - /* - * We must make sure the anon_vma is allocated - * so that the anon_vma locking is not a noop. - */ - if (unlikely(anon_vma_prepare(vma))) - return -ENOMEM; anon_vma_lock(vma); /* @@ -1720,13 +1718,6 @@ static int expand_downwards(struct vm_area_struct *vma, { int error; - /* - * We must make sure the anon_vma is allocated - * so that the anon_vma locking is not a noop. - */ - if (unlikely(anon_vma_prepare(vma))) - return -ENOMEM; - address &= PAGE_MASK; error = security_file_mmap(NULL, 0, 0, 0, address, 1); if (error)
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