On Fri, 24 May 2019 13:50:45 -0400 Daniel Jordan <daniel.m.jor...@oracle.com>
wrote:
> locked_vm accounting is done roughly the same way in five places, so
> unify them in a helper. Standardize the debug prints, which vary
> slightly, but include the helper's caller to disambiguate between
> callsites.
>
> Error codes stay the same, so user-visible behavior does too. The one
> exception is that the -EPERM case in tce_account_locked_vm is removed
> because Alexey has never seen it triggered.
>
> ...
>
> --- a/include/linux/mm.h
> +++ b/include/linux/mm.h
> @@ -1564,6 +1564,25 @@ long get_user_pages_unlocked(unsigned long start,
> unsigned long nr_pages,
> int get_user_pages_fast(unsigned long start, int nr_pages,
> unsigned int gup_flags, struct page **pages);
>
> +int __account_locked_vm(struct mm_struct *mm, unsigned long pages, bool inc,
> + struct task_struct *task, bool bypass_rlim);
> +
> +static inline int account_locked_vm(struct mm_struct *mm, unsigned long
> pages,
> + bool inc)
> +{
> + int ret;
> +
> + if (pages == 0 || !mm)
> + return 0;
> +
> + down_write(&mm->mmap_sem);
> + ret = __account_locked_vm(mm, pages, inc, current,
> + capable(CAP_IPC_LOCK));
> + up_write(&mm->mmap_sem);
> +
> + return ret;
> +}
That's quite a mouthful for an inlined function. How about uninlining
the whole thing and fiddling drivers/vfio/vfio_iommu_type1.c to suit.
I wonder why it does down_write_killable and whether it really needs
to...
