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Message-Id: <20220228235741.102941-6-shy828301@gmail.com>
Date: Mon, 28 Feb 2022 15:57:38 -0800
From: Yang Shi <shy828301@...il.com>
To: vbabka@...e.cz, kirill.shutemov@...ux.intel.com,
songliubraving@...com, linmiaohe@...wei.com, riel@...riel.com,
willy@...radead.org, ziy@...dia.com, akpm@...ux-foundation.org,
tytso@....edu, adilger.kernel@...ger.ca, darrick.wong@...cle.com
Cc: linux-mm@...ck.org, linux-fsdevel@...r.kernel.org,
linux-ext4@...r.kernel.org, linux-xfs@...r.kernel.org,
linux-kernel@...r.kernel.org
Subject: [PATCH 5/8] mm: khugepaged: make khugepaged_enter() void function
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.
Signed-off-by: Yang Shi <shy828301@...il.com>
---
include/linux/khugepaged.h | 30 ++++++++++++------------------
kernel/fork.c | 4 +---
mm/huge_memory.c | 4 ++--
mm/khugepaged.c | 18 +++++++-----------
4 files changed, 22 insertions(+), 34 deletions(-)
diff --git a/include/linux/khugepaged.h b/include/linux/khugepaged.h
index 2fcc01891b47..0423d3619f26 100644
--- a/include/linux/khugepaged.h
+++ b/include/linux/khugepaged.h
@@ -12,10 +12,10 @@ 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,
- unsigned long vm_flags);
+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
extern void collapse_pte_mapped_thp(struct mm_struct *mm, unsigned long addr);
@@ -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,
- unsigned long vm_flags)
+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,
- unsigned long vm_flags)
+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)
diff --git a/kernel/fork.c b/kernel/fork.c
index a024bf6254df..dc85418c426a 100644
--- a/kernel/fork.c
+++ b/kernel/fork.c
@@ -523,9 +523,7 @@ 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) {
diff --git a/mm/huge_memory.c b/mm/huge_memory.c
index a87b3df63209..ec2490d6af09 100644
--- a/mm/huge_memory.c
+++ b/mm/huge_memory.c
@@ -725,8 +725,8 @@ 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()) {
diff --git a/mm/khugepaged.c b/mm/khugepaged.c
index 3dbac3e23f43..b87af297e652 100644
--- a/mm/khugepaged.c
+++ b/mm/khugepaged.c
@@ -366,8 +366,7 @@ 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;
@@ -476,20 +475,20 @@ 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);
@@ -505,11 +504,9 @@ 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;
@@ -520,13 +517,12 @@ 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)
--
2.26.3
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