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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: David Hildenbrand <david@redhat.com>
Acked-by: Janosch Frank <frankja@linux.ibm.com>
Acked-by: Stefan 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: Andrew Morton <akpm@linux-foundation.org>
This commit is contained in:
David Hildenbrand 2023-04-22 23:01:56 +02:00 committed by Andrew Morton
parent 1150ea9338
commit 2c281f54f5
3 changed files with 18 additions and 19 deletions
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20
arch/s390/mm/gmap.c
View File

@ -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);

6
include/linux/ksm.h
View File

@ -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;

11
mm/ksm.c
View File

@ -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)
{