Commit 2c281f54 authored by David Hildenbrand's avatar David Hildenbrand Committed by Andrew Morton
Browse files

mm/ksm: move disabling KSM from s390/gmap code to KSM code 

Let's factor out actual disabling of KSM.  The existing "mm->def_flags &=
~VM_MERGEABLE;" was essentially a NOP and can be dropped, because
def_flags should never include VM_MERGEABLE.  Note that we don't currently
prevent re-enabling KSM.

This should now be faster in case KSM was never enabled, because we only
conditionally iterate all VMAs.  Further, it certainly looks cleaner.

Link: https://lkml.kernel.org/r/20230422210156.33630-1-david@redhat.com


Signed-off-by: default avatarDavid Hildenbrand <david@redhat.com>
Acked-by: default avatarJanosch Frank <frankja@linux.ibm.com>
Acked-by: default avatarStefan Roesch <shr@devkernel.io>
Cc: Christian Borntraeger <borntraeger@linux.ibm.com>
Cc: Claudio Imbrenda <imbrenda@linux.ibm.com>
Cc: Heiko Carstens <hca@linux.ibm.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Rik van Riel <riel@surriel.com>
Cc: Shuah Khan <shuah@kernel.org>
Cc: Sven Schnelle <svens@linux.ibm.com>
Cc: Vasily Gorbik <gor@linux.ibm.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
parent 1150ea93

arch/s390/mm/gmap.c

+1 −19
Original line number Diff line number Diff line
@@ -2585,30 +2585,12 @@ EXPORT_SYMBOL_GPL(s390_enable_sie); 


int gmap_mark_unmergeable(void)

{

	struct mm_struct *mm = current->mm;

	struct vm_area_struct *vma;

	unsigned long vm_flags;

	int ret;

	VMA_ITERATOR(vmi, mm, 0);



	/*

	 * Make sure to disable KSM (if enabled for the whole process or

	 * individual VMAs). Note that nothing currently hinders user space

	 * from re-enabling it.

	 */

	clear_bit(MMF_VM_MERGE_ANY, &mm->flags);



	for_each_vma(vmi, vma) {

		/* Copy vm_flags to avoid partial modifications in ksm_madvise */

		vm_flags = vma->vm_flags;

		ret = ksm_madvise(vma, vma->vm_start, vma->vm_end,

				  MADV_UNMERGEABLE, &vm_flags);

		if (ret)

			return ret;

		vm_flags_reset(vma, vm_flags);

	}

	mm->def_flags &= ~VM_MERGEABLE;

	return 0;

	return ksm_disable(current->mm);

}

EXPORT_SYMBOL_GPL(gmap_mark_unmergeable);

include/linux/ksm.h

+6 −0
Original line number Diff line number Diff line
@@ -22,6 +22,7 @@ int ksm_madvise(struct vm_area_struct *vma, unsigned long start, 
void ksm_add_vma(struct vm_area_struct *vma);

int ksm_enable_merge_any(struct mm_struct *mm);

int ksm_disable_merge_any(struct mm_struct *mm);

int ksm_disable(struct mm_struct *mm);



int __ksm_enter(struct mm_struct *mm);

void __ksm_exit(struct mm_struct *mm);
@@ -80,6 +81,11 @@ static inline void ksm_add_vma(struct vm_area_struct *vma) 
{

}



static inline int ksm_disable(struct mm_struct *mm)

{

	return 0;

}



static inline int ksm_fork(struct mm_struct *mm, struct mm_struct *oldmm)

{

	return 0;

mm/ksm.c

+11 −0
Original line number Diff line number Diff line
@@ -2628,6 +2628,17 @@ int ksm_disable_merge_any(struct mm_struct *mm) 
	return 0;

}



int ksm_disable(struct mm_struct *mm)

{

	mmap_assert_write_locked(mm);



	if (!test_bit(MMF_VM_MERGEABLE, &mm->flags))

		return 0;

	if (test_bit(MMF_VM_MERGE_ANY, &mm->flags))

		return ksm_disable_merge_any(mm);

	return ksm_del_vmas(mm);

}



int ksm_madvise(struct vm_area_struct *vma, unsigned long start,

		unsigned long end, int advice, unsigned long *vm_flags)

{