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mm/mmap: refactor mlock_future_check()

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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.

Link: https://lkml.kernel.org/r/20230522082412.56685-1-lstoakes@gmail.com
Signed-off-by: Lorenzo Stoakes <lstoakes@gmail.com>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Liam Howlett <liam.howlett@oracle.com>
Cc: Mike Rapoport (IBM) <rppt@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
This commit is contained in:
Lorenzo Stoakes 2023-05-22 09:24:12 +01:00 committed by Andrew Morton
parent 89207c669b
commit 3c54a298db
4 changed files with 21 additions and 20 deletions
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4
mm/internal.h
View file

@ -576,8 +576,8 @@ extern long populate_vma_page_range(struct vm_area_struct *vma,
extern long faultin_vma_page_range(struct vm_area_struct *vma,
unsigned long start, unsigned long end,
bool write, int *locked);
extern int mlock_future_check(struct mm_struct *mm, unsigned long flags,
unsigned long len);
extern bool mlock_future_check(struct mm_struct *mm, unsigned long flags,
unsigned long bytes);
/*
* mlock_vma_folio() and munlock_vma_folio():
* should be called with vma's mmap_lock held for read or write,

33
mm/mmap.c
View file

@ -182,7 +182,8 @@ static int check_brk_limits(unsigned long addr, unsigned long len)
if (IS_ERR_VALUE(mapped_addr))
return mapped_addr;
return mlock_future_check(current->mm, current->mm->def_flags, len);
return mlock_future_check(current->mm, current->mm->def_flags, len)
? 0 : -EAGAIN;
}
static int do_brk_flags(struct vma_iterator *vmi, struct vm_area_struct *brkvma,
unsigned long addr, unsigned long request, unsigned long flags);
@ -1145,21 +1146,21 @@ static inline unsigned long round_hint_to_min(unsigned long hint)
return hint;
}
int mlock_future_check(struct mm_struct *mm, unsigned long flags,
unsigned long len)
bool mlock_future_check(struct mm_struct *mm, unsigned long flags,
unsigned long bytes)
{
unsigned long locked, lock_limit;
unsigned long locked_pages, limit_pages;
/* mlock MCL_FUTURE? */
if (flags & VM_LOCKED) {
locked = len >> PAGE_SHIFT;
locked += mm->locked_vm;
lock_limit = rlimit(RLIMIT_MEMLOCK);
lock_limit >>= PAGE_SHIFT;
if (locked > lock_limit && !capable(CAP_IPC_LOCK))
return -EAGAIN;
}
return 0;
if (!(flags & VM_LOCKED) || capable(CAP_IPC_LOCK))
return true;
locked_pages = bytes >> PAGE_SHIFT;
locked_pages += mm->locked_vm;
limit_pages = rlimit(RLIMIT_MEMLOCK);
limit_pages >>= PAGE_SHIFT;
return locked_pages <= limit_pages;
}
static inline u64 file_mmap_size_max(struct file *file, struct inode *inode)
@ -1271,7 +1272,7 @@ unsigned long do_mmap(struct file *file, unsigned long addr,
if (!can_do_mlock())
return -EPERM;
if (mlock_future_check(mm, vm_flags, len))
if (!mlock_future_check(mm, vm_flags, len))
return -EAGAIN;
if (file) {
@ -1889,7 +1890,7 @@ static int acct_stack_growth(struct vm_area_struct *vma,
return -ENOMEM;
/* mlock limit tests */
if (mlock_future_check(mm, vma->vm_flags, grow << PAGE_SHIFT))
if (!mlock_future_check(mm, vma->vm_flags, grow << PAGE_SHIFT))
return -ENOMEM;
/* Check to ensure the stack will not grow into a hugetlb-only region */

2
mm/mremap.c
View file

@ -775,7 +775,7 @@ static struct vm_area_struct *vma_to_resize(unsigned long addr,
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_check(mm, vma->vm_flags, new_len - old_len))
return ERR_PTR(-EAGAIN);
if (!may_expand_vm(mm, vma->vm_flags,

2
mm/secretmem.c
View file

@ -125,7 +125,7 @@ static int secretmem_mmap(struct file *file, struct vm_area_struct *vma)
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_check(vma->vm_mm, vma->vm_flags | VM_LOCKED, len))
return -EAGAIN;
vm_flags_set(vma, VM_LOCKED | VM_DONTDUMP);