The patch below does not apply to the 6.5-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to stable@vger.kernel.org.

To reproduce the conflict and resubmit, you may use the following commands:

git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-6.5.y git checkout FETCH_HEAD git cherry-pick -x 1419430c8abb5a00590169068590dd54d86590ba # <resolve conflicts, build, test, etc.> git commit -s git send-email --to 'stable@vger.kernel.org' --in-reply-to '2023102731-olympics-bullpen-6897@gregkh' --subject-prefix 'PATCH 6.5.y' HEAD^..

Possible dependencies:

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From 1419430c8abb5a00590169068590dd54d86590ba Mon Sep 17 00:00:00 2001 From: "Liam R. Howlett" Liam.Howlett@oracle.com Date: Fri, 29 Sep 2023 14:30:39 -0400 Subject: [PATCH] mmap: fix vma_iterator in error path of vma_merge()

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

diff --git a/mm/mmap.c b/mm/mmap.c index 7ed286662839..a0917ed26057 100644 --- a/mm/mmap.c +++ b/mm/mmap.c @@ -975,7 +975,7 @@ struct vm_area_struct *vma_merge(struct vma_iterator *vmi, struct mm_struct *mm,

/* 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 vma_iterator *vmi, struct mm_struct *mm, }

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_iterator *vmi, struct mm_struct *mm, 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; }

/*