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mm: khugepaged: make khugepaged_enter() void function

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The most callers of khugepaged_enter() don't care about the return value. 
Only dup_mmap(), anonymous THP page fault and MADV_HUGEPAGE handle the
error by returning -ENOMEM.  Actually it is not harmful for them to ignore
the error case either.  It also sounds overkilling to fail fork() and page
fault early due to khugepaged_enter() error, and MADV_HUGEPAGE does set
VM_HUGEPAGE flag regardless of the error.

Link: https://lkml.kernel.org/r/20220510203222.24246-6-shy828301@gmail.com
Signed-off-by: Yang Shi <shy828301@gmail.com>
Acked-by: Song Liu <song@kernel.org>
Acked-by: Vlastmil Babka <vbabka@suse.cz>
Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Miaohe Lin <linmiaohe@huawei.com>
Cc: Rik van Riel <riel@surriel.com>
Cc: Song Liu <songliubraving@fb.com>
Cc: Theodore Ts'o <tytso@mit.edu>
Cc: Zi Yan <ziy@nvidia.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
This commit is contained in:
Yang Shi 2022-05-19 14:08:49 -07:00 committed by akpm
parent 78d12c19e0
commit d2081b2bf8
4 changed files with 22 additions and 34 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

24
include/linux/khugepaged.h
View file

@ -12,9 +12,9 @@ extern struct attribute_group khugepaged_attr_group;
extern int khugepaged_init(void);
extern void khugepaged_destroy(void);
extern int start_stop_khugepaged(void);
extern int __khugepaged_enter(struct mm_struct *mm);
extern void __khugepaged_enter(struct mm_struct *mm);
extern void __khugepaged_exit(struct mm_struct *mm);
extern int khugepaged_enter_vma_merge(struct vm_area_struct *vma,
extern void khugepaged_enter_vma_merge(struct vm_area_struct *vma,
unsigned long vm_flags);
extern void khugepaged_min_free_kbytes_update(void);
#ifdef CONFIG_SHMEM
@ -40,11 +40,10 @@ static inline void collapse_pte_mapped_thp(struct mm_struct *mm,
(transparent_hugepage_flags & \
(1<<TRANSPARENT_HUGEPAGE_DEFRAG_KHUGEPAGED_FLAG))
static inline int khugepaged_fork(struct mm_struct *mm, struct mm_struct *oldmm)
static inline void khugepaged_fork(struct mm_struct *mm, struct mm_struct *oldmm)
{
if (test_bit(MMF_VM_HUGEPAGE, &oldmm->flags))
return __khugepaged_enter(mm);
return 0;
__khugepaged_enter(mm);
}
static inline void khugepaged_exit(struct mm_struct *mm)
@ -53,7 +52,7 @@ static inline void khugepaged_exit(struct mm_struct *mm)
__khugepaged_exit(mm);
}
static inline int khugepaged_enter(struct vm_area_struct *vma,
static inline void khugepaged_enter(struct vm_area_struct *vma,
unsigned long vm_flags)
{
if (!test_bit(MMF_VM_HUGEPAGE, &vma->vm_mm->flags))
@ -62,27 +61,22 @@ static inline int khugepaged_enter(struct vm_area_struct *vma,
(khugepaged_req_madv() && (vm_flags & VM_HUGEPAGE))) &&
!(vm_flags & VM_NOHUGEPAGE) &&
!test_bit(MMF_DISABLE_THP, &vma->vm_mm->flags))
if (__khugepaged_enter(vma->vm_mm))
return -ENOMEM;
return 0;
__khugepaged_enter(vma->vm_mm);
}
#else /* CONFIG_TRANSPARENT_HUGEPAGE */
static inline int khugepaged_fork(struct mm_struct *mm, struct mm_struct *oldmm)
static inline void khugepaged_fork(struct mm_struct *mm, struct mm_struct *oldmm)
{
return 0;
}
static inline void khugepaged_exit(struct mm_struct *mm)
{
}
static inline int khugepaged_enter(struct vm_area_struct *vma,
static inline void khugepaged_enter(struct vm_area_struct *vma,
unsigned long vm_flags)
{
return 0;
}
static inline int khugepaged_enter_vma_merge(struct vm_area_struct *vma,
static inline void khugepaged_enter_vma_merge(struct vm_area_struct *vma,
unsigned long vm_flags)
{
return 0;
}
static inline void collapse_pte_mapped_thp(struct mm_struct *mm,
unsigned long addr)

4
kernel/fork.c
View file

@ -612,9 +612,7 @@ static __latent_entropy int dup_mmap(struct mm_struct *mm,
retval = ksm_fork(mm, oldmm);
if (retval)
goto out;
retval = khugepaged_fork(mm, oldmm);
if (retval)
goto out;
khugepaged_fork(mm, oldmm);
prev = NULL;
for (mpnt = oldmm->mmap; mpnt; mpnt = mpnt->vm_next) {

4
mm/huge_memory.c
View file

@ -726,8 +726,8 @@ vm_fault_t do_huge_pmd_anonymous_page(struct vm_fault *vmf)
return VM_FAULT_FALLBACK;
if (unlikely(anon_vma_prepare(vma)))
return VM_FAULT_OOM;
if (unlikely(khugepaged_enter(vma, vma->vm_flags)))
return VM_FAULT_OOM;
khugepaged_enter(vma, vma->vm_flags);
if (!(vmf->flags & FAULT_FLAG_WRITE) &&
!mm_forbids_zeropage(vma->vm_mm) &&
transparent_hugepage_use_zero_page()) {

18
mm/khugepaged.c
View file

@ -365,8 +365,7 @@ int hugepage_madvise(struct vm_area_struct *vma,
* register it here without waiting a page fault that
* may not happen any time soon.
*/
if (khugepaged_enter_vma_merge(vma, *vm_flags))
return -ENOMEM;
khugepaged_enter_vma_merge(vma, *vm_flags);
break;
case MADV_NOHUGEPAGE:
*vm_flags &= ~VM_HUGEPAGE;
@ -475,20 +474,20 @@ static bool hugepage_vma_check(struct vm_area_struct *vma,
return true;
}
int __khugepaged_enter(struct mm_struct *mm)
void __khugepaged_enter(struct mm_struct *mm)
{
struct mm_slot *mm_slot;
int wakeup;
mm_slot = alloc_mm_slot();
if (!mm_slot)
return -ENOMEM;
return;
/* __khugepaged_exit() must not run from under us */
VM_BUG_ON_MM(khugepaged_test_exit(mm), mm);
if (unlikely(test_and_set_bit(MMF_VM_HUGEPAGE, &mm->flags))) {
free_mm_slot(mm_slot);
return 0;
return;
}
spin_lock(&khugepaged_mm_lock);
@ -504,11 +503,9 @@ int __khugepaged_enter(struct mm_struct *mm)
mmgrab(mm);
if (wakeup)
wake_up_interruptible(&khugepaged_wait);
return 0;
}
int khugepaged_enter_vma_merge(struct vm_area_struct *vma,
void khugepaged_enter_vma_merge(struct vm_area_struct *vma,
unsigned long vm_flags)
{
unsigned long hstart, hend;
@ -519,13 +516,12 @@ int khugepaged_enter_vma_merge(struct vm_area_struct *vma,
* file-private shmem THP is not supported.
*/
if (!hugepage_vma_check(vma, vm_flags))
return 0;
return;
hstart = (vma->vm_start + ~HPAGE_PMD_MASK) & HPAGE_PMD_MASK;
hend = vma->vm_end & HPAGE_PMD_MASK;
if (hstart < hend)
return khugepaged_enter(vma, vm_flags);
return 0;
khugepaged_enter(vma, vm_flags);
}
void __khugepaged_exit(struct mm_struct *mm)