6.5-stable review patch. If anyone has any objections, please let me know.
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From: Liam R. Howlett Liam.Howlett@oracle.com
commit 1419430c8abb5a00590169068590dd54d86590ba upstream.
During the error path, the vma iterator may not be correctly positioned or set to the correct range. Undo the vma_prev() call by resetting to the passed in address. Re-walking to the same range will fix the range to the area previously passed in.
Users would notice increased cycles as vma_merge() would be called an extra time with vma == prev, and thus would fail to merge and return.
Link: https://lore.kernel.org/linux-mm/CAG48ez12VN1JAOtTNMY+Y2YnsU45yL5giS-Qn=ejti... Link: https://lkml.kernel.org/r/20230929183041.2835469-2-Liam.Howlett@oracle.com Fixes: 18b098af2890 ("vma_merge: set vma iterator to correct position.") Signed-off-by: Liam R. Howlett Liam.Howlett@oracle.com Reported-by: Jann Horn jannh@google.com Closes: https://lore.kernel.org/linux-mm/CAG48ez12VN1JAOtTNMY+Y2YnsU45yL5giS-Qn=ejti... Reviewed-by: Lorenzo Stoakes lstoakes@gmail.com Acked-by: Vlastimil Babka vbabka@suse.cz Cc: Matthew Wilcox (Oracle) willy@infradead.org Cc: Suren Baghdasaryan surenb@google.com Cc: stable@vger.kernel.org Signed-off-by: Andrew Morton akpm@linux-foundation.org Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- mm/mmap.c | 10 ++++++++-- 1 file changed, 8 insertions(+), 2 deletions(-)
--- a/mm/mmap.c +++ b/mm/mmap.c @@ -988,10 +988,10 @@ struct vm_area_struct *vma_merge(struct
/* Error in anon_vma clone. */ if (err) - return NULL; + goto anon_vma_fail;
if (vma_iter_prealloc(vmi)) - return NULL; + goto prealloc_fail;
init_multi_vma_prep(&vp, vma, adjust, remove, remove2); VM_WARN_ON(vp.anon_vma && adjust && adjust->anon_vma && @@ -1024,6 +1024,12 @@ struct vm_area_struct *vma_merge(struct khugepaged_enter_vma(res, vm_flags);
return res; + +prealloc_fail: +anon_vma_fail: + vma_iter_set(vmi, addr); + vma_iter_load(vmi); + return NULL; }
/*