The patch titled
Subject: mm/mmap: refactor mlock_future_check()
has been added to the -mm mm-unstable branch. Its filename is
mm-mmap-refactor-mlock_future_check.patch
This patch will shortly appear at
https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/mm-mmap-refactor-mlock_future_check.patch
This patch will later appear in the mm-unstable branch at
git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
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------------------------------------------------------
From: Lorenzo Stoakes <lstoakes@xxxxxxxxx>
Subject: mm/mmap: refactor mlock_future_check()
Date: Mon, 22 May 2023 09:24:12 +0100
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@xxxxxxxxx
Signed-off-by: Lorenzo Stoakes <lstoakes@xxxxxxxxx>
Cc: Liam Howlett <liam.howlett@xxxxxxxxxx>
Cc: Mike Rapoport (IBM) <rppt@xxxxxxxxxx>
Cc: Vlastimil Babka <vbabka@xxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/internal.h | 4 ++--
mm/mmap.c | 33 +++++++++++++++++----------------
mm/mremap.c | 2 +-
mm/secretmem.c | 2 +-
4 files changed, 21 insertions(+), 20 deletions(-)
--- a/mm/internal.h~mm-mmap-refactor-mlock_future_check
+++ a/mm/internal.h
@@ -576,8 +576,8 @@ 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 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,
--- a/mm/mmap.c~mm-mmap-refactor-mlock_future_check
+++ a/mm/mmap.c
@@ -182,7 +182,8 @@ 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_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_t
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,
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_a
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 */
--- a/mm/mremap.c~mm-mmap-refactor-mlock_future_check
+++ 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_check(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-mmap-refactor-mlock_future_check
+++ 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_check(vma->vm_mm, vma->vm_flags | VM_LOCKED, len))
return -EAGAIN;
vm_flags_set(vma, VM_LOCKED | VM_DONTDUMP);
_
Patches currently in -mm which might be from lstoakes@xxxxxxxxx are
mm-mmap-separate-writenotify-and-dirty-tracking-logic.patch
mm-gup-disallow-foll_longterm-gup-nonfast-writing-to-file-backed-mappings.patch
mm-gup-disallow-foll_longterm-gup-fast-writing-to-file-backed-mappings.patch
mm-gup-add-missing-gup_must_unshare-check-to-gup_huge_pgd.patch
mm-gup-remove-unused-vmas-parameter-from-get_user_pages.patch
mm-gup-remove-unused-vmas-parameter-from-pin_user_pages_remote.patch
mm-gup-remove-vmas-parameter-from-get_user_pages_remote.patch
io_uring-rsrc-delegate-vma-file-backed-check-to-gup.patch
mm-gup-remove-vmas-parameter-from-pin_user_pages.patch
mm-gup-remove-vmas-array-from-internal-gup-functions.patch
mm-mmap-refactor-mlock_future_check.patch
