From: Lorenzo Stoakes Date: Mon, 22 May 2023 08:24:12 +0000 (+0100) Subject: mm/mmap: refactor mlock_future_check() X-Git-Url: http://git.maquefel.me/?a=commitdiff_plain;h=3c54a298db4c6b38bbd5f86216ce0f5ad4596ccf;p=linux.git mm/mmap: refactor mlock_future_check() 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 Acked-by: Vlastimil Babka Cc: Liam Howlett Cc: Mike Rapoport (IBM) Signed-off-by: Andrew Morton --- diff --git a/mm/internal.h b/mm/internal.h index bb65422795993..66dd214b302a6 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 44be7fdfaac91..28d2c489a7e5f 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); @@ -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 */ diff --git a/mm/mremap.c b/mm/mremap.c index b11ce6c920996..bcfcb8df58750 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 974b32ba8b9d4..58d2af12df4fa 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);