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>>> + mmgrab(mm); >>> + lock_limit = rlimit(RLIMIT_MEMLOCK) >> PAGE_SHIFT; >>> + new_pinned = atomic64_add_return(userptr->npages, &mm->pinned_vm); >>> + if (new_pinned < 0 || >>> + (new_pinned > lock_limit && !capable(CAP_IPC_LOCK))) { >>> + atomic64_sub(userptr->npages, &mm->pinned_vm) >> >> At a quick glance over other kernel code touching pinned_vm, nobody else >> check for new_pinned < 0 and then doing atomic64_sub() for the negative >> value will be incorrect. > Though no, negative will restore pinned_vm. Still neg looks confusing > and shouldn't be needed as such overflow shouldn't be possible. > Got it will remove this check in next version Regards, Honglei