The patch titled Subject: mmap: fix vma_iterator in error path of vma_merge() has been added to the -mm mm-hotfixes-unstable branch. Its filename is mmap-fix-vma_iterator-in-error-path-of-vma_merge.patch

This patch will shortly appear at https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches...

This patch will later appear in the mm-hotfixes-unstable branch at git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm

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------------------------------------------------------ From: "Liam R. Howlett" Liam.Howlett@oracle.com Subject: mmap: fix vma_iterator in error path of vma_merge() Date: Fri, 29 Sep 2023 14:30:39 -0400

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... Cc: Lorenzo Stoakes lstoakes@gmail.com Cc: Matthew Wilcox (Oracle) willy@infradead.org Cc: Suren Baghdasaryan surenb@google.com Cc: Vlastimil Babka vbabka@suse.cz Cc: stable@vger.kernel.org Signed-off-by: Andrew Morton akpm@linux-foundation.org ---

mm/mmap.c | 10 ++++++++-- 1 file changed, 8 insertions(+), 2 deletions(-)

--- a/mm/mmap.c~mmap-fix-vma_iterator-in-error-path-of-vma_merge +++ a/mm/mmap.c @@ -975,7 +975,7 @@ struct vm_area_struct *vma_merge(struct

/* Error in anon_vma clone. */ if (err) - return NULL; + goto anon_vma_fail;

if (vma_start < vma->vm_start || vma_end > vma->vm_end) vma_expanded = true; @@ -988,7 +988,7 @@ struct vm_area_struct *vma_merge(struct }

if (vma_iter_prealloc(vmi, vma)) - return NULL; + goto prealloc_fail;

init_multi_vma_prep(&vp, vma, adjust, remove, remove2); VM_WARN_ON(vp.anon_vma && adjust && adjust->anon_vma && @@ -1016,6 +1016,12 @@ struct vm_area_struct *vma_merge(struct vma_complete(&vp, vmi, mm); khugepaged_enter_vma(res, vm_flags); return res; + +prealloc_fail: +anon_vma_fail: + vma_iter_set(vmi, addr); + vma_iter_load(vmi); + return NULL; }

/* _

Patches currently in -mm which might be from Liam.Howlett@oracle.com are

maple_tree-add-mas_active-to-detect-in-tree-walks.patch maple_tree-add-mas_underflow-and-mas_overflow-states.patch mm-mempolicy-fix-set_mempolicy_home_node-previous-vma-pointer.patch mmap-fix-vma_iterator-in-error-path-of-vma_merge.patch mmap-fix-error-paths-with-dup_anon_vma.patch