diff options
| -rw-r--r-- | include/linux/mm_types.h | 13 | ||||
| -rw-r--r-- | kernel/fork.c | 7 |
2 files changed, 15 insertions, 5 deletions
diff --git a/include/linux/mm_types.h b/include/linux/mm_types.h index de09ae2a0de6..69ce407b4343 100644 --- a/include/linux/mm_types.h +++ b/include/linux/mm_types.h @@ -1831,16 +1831,23 @@ enum { #define MMF_TOPDOWN 31 /* mm searches top down by default */ #define MMF_TOPDOWN_MASK BIT(MMF_TOPDOWN) -#define MMF_INIT_MASK (MMF_DUMPABLE_MASK | MMF_DUMP_FILTER_MASK |\ +#define MMF_INIT_LEGACY_MASK (MMF_DUMPABLE_MASK | MMF_DUMP_FILTER_MASK |\ MMF_DISABLE_THP_MASK | MMF_HAS_MDWE_MASK |\ MMF_VM_MERGE_ANY_MASK | MMF_TOPDOWN_MASK) -static inline unsigned long mmf_init_flags(unsigned long flags) +/* Legacy flags must fit within 32 bits. */ +static_assert((u64)MMF_INIT_LEGACY_MASK <= (u64)UINT_MAX); + +/* + * Initialise legacy flags according to masks, propagating selected flags on + * fork. Further flag manipulation can be performed by the caller. + */ +static inline unsigned long mmf_init_legacy_flags(unsigned long flags) { if (flags & (1UL << MMF_HAS_MDWE_NO_INHERIT)) flags &= ~((1UL << MMF_HAS_MDWE) | (1UL << MMF_HAS_MDWE_NO_INHERIT)); - return flags & MMF_INIT_MASK; + return flags & MMF_INIT_LEGACY_MASK; } #endif /* _LINUX_MM_TYPES_H */ diff --git a/kernel/fork.c b/kernel/fork.c index af673856499d..b04ecba4a709 100644 --- a/kernel/fork.c +++ b/kernel/fork.c @@ -1057,11 +1057,14 @@ static struct mm_struct *mm_init(struct mm_struct *mm, struct task_struct *p, mm_init_uprobes_state(mm); hugetlb_count_init(mm); + mm_flags_clear_all(mm); if (current->mm) { - mm->flags = mmf_init_flags(current->mm->flags); + unsigned long flags = __mm_flags_get_word(current->mm); + + __mm_flags_set_word(mm, mmf_init_legacy_flags(flags)); mm->def_flags = current->mm->def_flags & VM_INIT_DEF_MASK; } else { - mm->flags = default_dump_filter; + __mm_flags_set_word(mm, default_dump_filter); mm->def_flags = 0; } |