+ mm-ksm-refer-to-special-vmas-via-vm_special-in-ksm_compatible.patch added to mm-new branch

+ mm-ksm-refer-to-special-vmas-via-vm_special-in-ksm_compatible.patch added to mm-new branch

[Andrew Morton]

The patch titled
     Subject: mm: ksm: refer to special VMAs via VM_SPECIAL in ksm_compatible()
has been added to the -mm mm-new branch.  Its filename is
     mm-ksm-refer-to-special-vmas-via-vm_special-in-ksm_compatible.patch

This patch will shortly appear at
     https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/mm-ksm-refer-to-special-vmas-via-vm_special-in-ksm_compatible.patch

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

Note, mm-new is a provisional staging ground for work-in-progress
patches, and acceptance into mm-new is a notification for others take
notice and to finish up reviews.  Please do not hesitate to respond to
review feedback and post updated versions to replace or incrementally
fixup patches in mm-new.

Before you just go and hit "reply", please:
   a) Consider who else should be cc'ed
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------------------------------------------------------
From: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Subject: mm: ksm: refer to special VMAs via VM_SPECIAL in ksm_compatible()
Date: Thu, 29 May 2025 18:15:46 +0100

There's no need to spell out all the special cases, also doing it this way
makes it absolutely clear that we preclude unmergeable VMAs in general,
and puts the other excluded flags in stark and clear contrast.

Link: https://lkml.kernel.org/r/c8be5b055163b164c8824020164076ee3b9389bd.1748537921.git.lorenzo.stoakes@oracle.com
Signed-off-by: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Acked-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Chengming Zhou <chengming.zhou@linux.dev>
Reviewed-by: Vlastimil Babka <vbabka@suse.cz>
Reviewed-by: Xu Xin <xu.xin16@zte.com.cn>
Reviewed-by: Liam R. Howlett <Liam.Howlett@oracle.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Christian Brauner <brauner@kernel.org>
Cc: Jan Kara <jack@suse.cz>
Cc: Jann Horn <jannh@google.com>
Cc: Stefan Roesch <shr@devkernel.io>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 mm/ksm.c |    5 ++---
 1 file changed, 2 insertions(+), 3 deletions(-)

--- a/mm/ksm.c~mm-ksm-refer-to-special-vmas-via-vm_special-in-ksm_compatible
+++ a/mm/ksm.c
@@ -679,9 +679,8 @@ static int break_ksm(struct vm_area_stru
 
 static bool ksm_compatible(const struct file *file, vm_flags_t vm_flags)
 {
-	if (vm_flags & (VM_SHARED   | VM_MAYSHARE   | VM_PFNMAP  |
-			VM_IO       | VM_DONTEXPAND | VM_HUGETLB |
-			VM_MIXEDMAP | VM_DROPPABLE))
+	if (vm_flags & (VM_SHARED  | VM_MAYSHARE | VM_SPECIAL |
+			VM_HUGETLB | VM_DROPPABLE))
 		return false;		/* just ignore the advice */
 
 	if (file_is_dax(file))
_

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

kvm-s390-rename-prot_none-to-prot_type_dummy.patch
mm-ksm-have-ksm-vma-checks-not-require-a-vma-pointer.patch
mm-ksm-refer-to-special-vmas-via-vm_special-in-ksm_compatible.patch
mm-prevent-ksm-from-breaking-vma-merging-for-new-vmas.patch
tools-testing-selftests-add-vma-merge-tests-for-ksm-merge.patch