Commit c4ea95d7 authored by Daniel Forrest's avatar Daniel Forrest Committed by Linus Torvalds
Browse files

mm: fix anon_vma_clone() error treatment

Andrew Morton noticed that the error return from anon_vma_clone() was
being dropped and replaced with -ENOMEM (which is not itself a bug
because the only error return value from anon_vma_clone() is -ENOMEM).

I did an audit of callers of anon_vma_clone() and discovered an actual
bug where the error return was being lost.  In __split_vma(), between
Linux 3.11 and 3.12 the code was changed so the err variable is used
before the call to anon_vma_clone() and the default initial value of
-ENOMEM is overwritten.  So a failure of anon_vma_clone() will return
success since err at this point is now zero.

Below is a patch which fixes this bug and also propagates the error
return value from anon_vma_clone() in all cases.

Fixes: ef0855d3

 ("mm: mempolicy: turn vma_set_policy() into vma_dup_policy()")
Signed-off-by: default avatarDaniel Forrest <>
Reviewed-by: default avatarMichal Hocko <>
Cc: Konstantin Khlebnikov <>
Cc: Andrea Arcangeli <>
Cc: Rik van Riel <>
Cc: Tim Hartrick <>
Cc: Hugh Dickins <>
Cc: Michel Lespinasse <>
Cc: Vlastimil Babka <>
Cc: <>	[3.12+]
Signed-off-by: default avatarAndrew Morton <>
Signed-off-by: default avatarLinus Torvalds <>
parent 2022b4d1
......@@ -776,8 +776,11 @@ again: remove_next = 1 + (end > next->vm_end);
* shrinking vma had, to cover any anon pages imported.
if (exporter && exporter->anon_vma && !importer->anon_vma) {
if (anon_vma_clone(importer, exporter))
return -ENOMEM;
int error;
error = anon_vma_clone(importer, exporter);
if (error)
return error;
importer->anon_vma = exporter->anon_vma;
......@@ -2469,7 +2472,8 @@ static int __split_vma(struct mm_struct *mm, struct vm_area_struct *vma,
if (err)
goto out_free_vma;
if (anon_vma_clone(new, vma))
err = anon_vma_clone(new, vma);
if (err)
goto out_free_mpol;
if (new->vm_file)
......@@ -274,6 +274,7 @@ int anon_vma_fork(struct vm_area_struct *vma, struct vm_area_struct *pvma)
struct anon_vma_chain *avc;
struct anon_vma *anon_vma;
int error;
/* Don't bother if the parent process has no anon_vma here. */
if (!pvma->anon_vma)
......@@ -283,8 +284,9 @@ int anon_vma_fork(struct vm_area_struct *vma, struct vm_area_struct *pvma)
* First, attach the new VMA to the parent VMA's anon_vmas,
* so rmap can find non-COWed pages in child processes.
if (anon_vma_clone(vma, pvma))
return -ENOMEM;
error = anon_vma_clone(vma, pvma);
if (error)
return error;
/* Then add our own anon_vma. */
anon_vma = anon_vma_alloc();
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