On Mon, 22 May 2023 21:34:31 +0100 Lorenzo Stoakes <lstoakes@xxxxxxxxx> wrote:
> On Mon, May 22, 2023 at 01:28:51PM -0700, Andrew Morton wrote:
> > On Mon, 22 May 2023 09:24:12 +0100 Lorenzo Stoakes <lstoakes@xxxxxxxxx> wrote:
> >
> > > In all but one instance, mlock_future_check() is treated as a boolean
> > > function despite returning an error code. In one instance, this error code
> > > is ignored and replaced with -ENOMEM.
> > >
> > > This is confusing, and the inversion of true -> failure, false -> success
> > > is not warranted. Convert the function to a bool, lightly refactor and
> > > return true if the check passes, false if not.
> >
> > Yup.
> >
> > I don't think the name does a good job of conveying the
> > function's use.
> >
> > > - if (mlock_future_check(mm, vm_flags, len))
> > > + if (!mlock_future_check(mm, vm_flags, len))
> > > return -EAGAIN;
> >
> > if (!may_mlock_future(...))
> >
> > or
> >
> > if (!mlock_future_ok(...))
> >
> > ?
> >
> >
>
> Yeah I struggled with this, because the check only triggers if VM_LOCKED. I was
> originally toying with can_mlock_future() but of course, it also returns true if
> !VM_LOCKED...
>
> I think your suggestion of mlock_future_ok() works well, could you change it to
> that? Thanks!
Sure. I'll make it a separate patch.
From: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Subject: mm/mlock: rename mlock_future_check() to mlock_future_ok()
Date: Mon May 22 01:52:10 PM PDT 2023
It is felt that the name mlock_future_check() is vague - it doesn't
particularly convey the function's operation. mlock_future_ok() is a
clearer name for a predicate function.
Cc: Liam Howlett <liam.howlett@xxxxxxxxxx>
Cc: Lorenzo Stoakes <lstoakes@xxxxxxxxx>
Cc: Mike Rapoport (IBM) <rppt@xxxxxxxxxx>
Cc: Vlastimil Babka <vbabka@xxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/internal.h | 2 +-
mm/mmap.c | 8 ++++----
mm/mremap.c | 2 +-
mm/secretmem.c | 2 +-
4 files changed, 7 insertions(+), 7 deletions(-)
--- a/mm/internal.h~mm-mlock-rename-mlock_future_check-to-mlock_future_ok
+++ a/mm/internal.h
@@ -576,7 +576,7 @@ extern long populate_vma_page_range(stru
extern long faultin_vma_page_range(struct vm_area_struct *vma,
unsigned long start, unsigned long end,
bool write, int *locked);
-extern bool mlock_future_check(struct mm_struct *mm, unsigned long flags,
+extern bool mlock_future_ok(struct mm_struct *mm, unsigned long flags,
unsigned long bytes);
/*
* mlock_vma_folio() and munlock_vma_folio():
--- a/mm/mmap.c~mm-mlock-rename-mlock_future_check-to-mlock_future_ok
+++ a/mm/mmap.c
@@ -182,7 +182,7 @@ static int check_brk_limits(unsigned lon
if (IS_ERR_VALUE(mapped_addr))
return mapped_addr;
- return mlock_future_check(current->mm, current->mm->def_flags, len)
+ return mlock_future_ok(current->mm, current->mm->def_flags, len)
? 0 : -EAGAIN;
}
static int do_brk_flags(struct vma_iterator *vmi, struct vm_area_struct *brkvma,
@@ -1149,7 +1149,7 @@ static inline unsigned long round_hint_t
return hint;
}
-bool mlock_future_check(struct mm_struct *mm, unsigned long flags,
+bool mlock_future_ok(struct mm_struct *mm, unsigned long flags,
unsigned long bytes)
{
unsigned long locked_pages, limit_pages;
@@ -1275,7 +1275,7 @@ unsigned long do_mmap(struct file *file,
if (!can_do_mlock())
return -EPERM;
- if (!mlock_future_check(mm, vm_flags, len))
+ if (!mlock_future_ok(mm, vm_flags, len))
return -EAGAIN;
if (file) {
@@ -1927,7 +1927,7 @@ static int acct_stack_growth(struct vm_a
return -ENOMEM;
/* mlock limit tests */
- if (!mlock_future_check(mm, vma->vm_flags, grow << PAGE_SHIFT))
+ if (!mlock_future_ok(mm, vma->vm_flags, grow << PAGE_SHIFT))
return -ENOMEM;
/* Check to ensure the stack will not grow into a hugetlb-only region */
--- a/mm/mremap.c~mm-mlock-rename-mlock_future_check-to-mlock_future_ok
+++ a/mm/mremap.c
@@ -775,7 +775,7 @@ static struct vm_area_struct *vma_to_res
if (vma->vm_flags & (VM_DONTEXPAND | VM_PFNMAP))
return ERR_PTR(-EFAULT);
- if (!mlock_future_check(mm, vma->vm_flags, new_len - old_len))
+ if (!mlock_future_ok(mm, vma->vm_flags, new_len - old_len))
return ERR_PTR(-EAGAIN);
if (!may_expand_vm(mm, vma->vm_flags,
--- a/mm/secretmem.c~mm-mlock-rename-mlock_future_check-to-mlock_future_ok
+++ a/mm/secretmem.c
@@ -125,7 +125,7 @@ static int secretmem_mmap(struct file *f
if ((vma->vm_flags & (VM_SHARED | VM_MAYSHARE)) == 0)
return -EINVAL;
- if (!mlock_future_check(vma->vm_mm, vma->vm_flags | VM_LOCKED, len))
+ if (!mlock_future_ok(vma->vm_mm, vma->vm_flags | VM_LOCKED, len))
return -EAGAIN;
vm_flags_set(vma, VM_LOCKED | VM_DONTDUMP);
_
