Commit 8314c4f2 authored by Hugh Dickins's avatar Hugh Dickins Committed by Linus Torvalds
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KSM originally stood for Kernel Shared Memory: but the kernel has long
supported shared memory, and VM_SHARED and VM_MAYSHARE vmas, and KSM is
something else.  So we switched to saying "merge" instead of "share".

But Chris Wright points out that this is confusing where mmap.c merges
adjacent vmas: most especially in the name VM_MERGEABLE_FLAGS, used by
is_mergeable_vma() to let vmas be merged despite flags being different.

Call it VMA_MERGE_DESPITE_FLAGS?  Perhaps, but at present it consists
only of VM_CAN_NONLINEAR: so for now it's clearer on all sides to use
that directly, with a comment on it in is_mergeable_vma().
Signed-off-by: default avatarHugh Dickins <>
Acked-by: default avatarIzik Eidus <>
Cc: Andrea Arcangeli <>
Signed-off-by: default avatarAndrew Morton <>
Signed-off-by: default avatarLinus Torvalds <>
parent 7701c9c0
......@@ -657,9 +657,6 @@ again: remove_next = 1 + (end > next->vm_end);
/* Flags that can be inherited from an existing mapping when merging */
* If the vma has a ->close operation then the driver probably needs to release
* per-vma resources, so we don't attempt to merge those.
......@@ -667,7 +664,8 @@ again: remove_next = 1 + (end > next->vm_end);
static inline int is_mergeable_vma(struct vm_area_struct *vma,
struct file *file, unsigned long vm_flags)
if ((vma->vm_flags ^ vm_flags) & ~VM_MERGEABLE_FLAGS)
/* VM_CAN_NONLINEAR may get set later by f_op->mmap() */
if ((vma->vm_flags ^ vm_flags) & ~VM_CAN_NONLINEAR)
return 0;
if (vma->vm_file != file)
return 0;
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