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.
Signed-off-by: Lorenzo Stoakes <lstoakes@xxxxxxxxx>
---
mm/internal.h | 4 ++--
mm/mmap.c | 33 +++++++++++++++++----------------
mm/mremap.c | 2 +-
mm/secretmem.c | 2 +-
4 files changed, 21 insertions(+), 20 deletions(-)
diff --git a/mm/internal.h b/mm/internal.h
index bb6542279599..66dd214b302a 100644
--- a/mm/internal.h
+++ b/mm/internal.h
@@ -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,
diff --git a/mm/mmap.c b/mm/mmap.c
index 877696464c09..10f2d5d689da 100644
--- a/mm/mmap.c
+++ b/mm/mmap.c
@@ -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);
@@ -1148,21 +1149,21 @@ 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)
@@ -1274,7 +1275,7 @@ 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) {
@@ -1926,7 +1927,7 @@ 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 */
diff --git a/mm/mremap.c b/mm/mremap.c
index b11ce6c92099..bcfcb8df5875 100644
--- a/mm/mremap.c
+++ b/mm/mremap.c
@@ -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,
diff --git a/mm/secretmem.c b/mm/secretmem.c
index 974b32ba8b9d..58d2af12df4f 100644
--- a/mm/secretmem.c
+++ b/mm/secretmem.c
@@ -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);
--
2.40.1
