+ mm-mremap-do-not-set-vrm-vma-null-immediately-prior-to-checking-it.patch added to mm-unstable branch

+ mm-mremap-do-not-set-vrm-vma-null-immediately-prior-to-checking-it.patch added to mm-unstable branch

[Andrew Morton]

The patch titled
     Subject: mm/mremap: do not set vrm->vma NULL immediately prior to checking it
has been added to the -mm mm-unstable branch.  Its filename is
     mm-mremap-do-not-set-vrm-vma-null-immediately-prior-to-checking-it.patch

This patch will shortly appear at
     https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/mm-mremap-do-not-set-vrm-vma-null-immediately-prior-to-checking-it.patch

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

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------------------------------------------------------
From: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Subject: mm/mremap: do not set vrm->vma NULL immediately prior to checking it
Date: Sun, 30 Mar 2025 17:20:48 +0100

This seems rather unwise.  If we cannot merge, extend, then we need to
recall the original VMA to see if we need to uncharge.

If we do need to, do so.

Link: https://lkml.kernel.org/r/b2fb6b9c-376d-4e9b-905e-26d847fd3865@lucifer.local
Fixes: d5c8aec0542e ("mm/mremap: initial refactor of move_vma()")
Signed-off-by: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Reported-=by: "Lai, Yi" <yi1.lai@linux.intel.com>
Closes: https://lore.kernel.org/linux-mm/Z+lcvEIHMLiKVR1i@ly-workstation/
Cc: Liam R. Howlett <Liam.Howlett@Oracle.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Harry Yoo <harry.yoo@oracle.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 mm/mremap.c |    3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

--- a/mm/mremap.c~mm-mremap-do-not-set-vrm-vma-null-immediately-prior-to-checking-it
+++ a/mm/mremap.c
@@ -1561,11 +1561,12 @@ static unsigned long expand_vma_in_place
 	 * adjacent to the expanded vma and otherwise
 	 * compatible.
 	 */
-	vma = vrm->vma = vma_merge_extend(&vmi, vma, vrm->delta);
+	vma = vma_merge_extend(&vmi, vma, vrm->delta);
 	if (!vma) {
 		vrm_uncharge(vrm);
 		return -ENOMEM;
 	}
+	vrm->vma = vma;
 
 	vrm_stat_account(vrm, vrm->delta);
 
_

Patches currently in -mm which might be from lorenzo.stoakes@oracle.com are

mm-mremap-do-not-set-vrm-vma-null-immediately-prior-to-checking-it.patch