linux-kernel - Re: [PATCH] mm: remove remnants of SPLIT_RSS

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Message-ID: <CAGudoHGveDS3rjLv90eAZQjroFRTOuyVj=mG=s-Z7OKjOGkFNg@mail.gmail.com>
Date:   Fri, 25 Aug 2023 21:58:33 +0200
From:   Mateusz Guzik <mjguzik@...il.com>
To:     akpm@...ux-foundation.org
Cc:     shakeelb@...gle.com, linux-kernel@...r.kernel.org,
        linux-mm@...ck.org, Mateusz Guzik <mjguzik@...il.com>
Subject: Re: [PATCH] mm: remove remnants of SPLIT_RSS_COUNTING

anyone in particular I should cc to get this reviewed?

this finishes a removal from an earlier commit, there is not much to
think about ;)

On 8/23/23, Mateusz Guzik <mjguzik@...il.com> wrote:
> The feature got retired in f1a7941243c1 ("mm: convert mm's rss stats
> into percpu_counter"), but the patch failed to fully clean it up.
>
> Signed-off-by: Mateusz Guzik <mjguzik@...il.com>
> ---
>  fs/exec.c          | 2 --
>  include/linux/mm.h | 8 --------
>  kernel/exit.c      | 4 ----
>  kernel/fork.c      | 4 ----
>  kernel/kthread.c   | 1 -
>  mm/madvise.c       | 5 +----
>  mm/memory.c        | 2 --
>  7 files changed, 1 insertion(+), 25 deletions(-)
>
> diff --git a/fs/exec.c b/fs/exec.c
> index 1a827d55ba94..8d31d5fc658f 100644
> --- a/fs/exec.c
> +++ b/fs/exec.c
> @@ -985,8 +985,6 @@ static int exec_mmap(struct mm_struct *mm)
>  	tsk = current;
>  	old_mm = current->mm;
>  	exec_mm_release(tsk, old_mm);
> -	if (old_mm)
> -		sync_mm_rss(old_mm);
>
>  	ret = down_write_killable(&tsk->signal->exec_update_lock);
>  	if (ret)
> diff --git a/include/linux/mm.h b/include/linux/mm.h
> index 406ab9ea818f..08402054767a 100644
> --- a/include/linux/mm.h
> +++ b/include/linux/mm.h
> @@ -2606,14 +2606,6 @@ static inline void setmax_mm_hiwater_rss(unsigned
> long *maxrss,
>  		*maxrss = hiwater_rss;
>  }
>
> -#if defined(SPLIT_RSS_COUNTING)
> -void sync_mm_rss(struct mm_struct *mm);
> -#else
> -static inline void sync_mm_rss(struct mm_struct *mm)
> -{
> -}
> -#endif
> -
>  #ifndef CONFIG_ARCH_HAS_PTE_SPECIAL
>  static inline int pte_special(pte_t pte)
>  {
> diff --git a/kernel/exit.c b/kernel/exit.c
> index edb50b4c9972..3cdbe797008f 100644
> --- a/kernel/exit.c
> +++ b/kernel/exit.c
> @@ -539,7 +539,6 @@ static void exit_mm(void)
>  	exit_mm_release(current, mm);
>  	if (!mm)
>  		return;
> -	sync_mm_rss(mm);
>  	mmap_read_lock(mm);
>  	mmgrab_lazy_tlb(mm);
>  	BUG_ON(mm != current->active_mm);
> @@ -829,9 +828,6 @@ void __noreturn do_exit(long code)
>  	io_uring_files_cancel();
>  	exit_signals(tsk);  /* sets PF_EXITING */
>
> -	/* sync mm's RSS info before statistics gathering */
> -	if (tsk->mm)
> -		sync_mm_rss(tsk->mm);
>  	acct_update_integrals(tsk);
>  	group_dead = atomic_dec_and_test(&tsk->signal->live);
>  	if (group_dead) {
> diff --git a/kernel/fork.c b/kernel/fork.c
> index d2e12b6d2b18..1ac1d850f7ab 100644
> --- a/kernel/fork.c
> +++ b/kernel/fork.c
> @@ -2409,10 +2409,6 @@ __latent_entropy struct task_struct *copy_process(
>  	p->io_uring = NULL;
>  #endif
>
> -#if defined(SPLIT_RSS_COUNTING)
> -	memset(&p->rss_stat, 0, sizeof(p->rss_stat));
> -#endif
> -
>  	p->default_timer_slack_ns = current->timer_slack_ns;
>
>  #ifdef CONFIG_PSI
> diff --git a/kernel/kthread.c b/kernel/kthread.c
> index 4fff7df17a68..0cf5582122b3 100644
> --- a/kernel/kthread.c
> +++ b/kernel/kthread.c
> @@ -1470,7 +1470,6 @@ void kthread_unuse_mm(struct mm_struct *mm)
>  	 * clearing tsk->mm.
>  	 */
>  	smp_mb__after_spinlock();
> -	sync_mm_rss(mm);
>  	local_irq_disable();
>  	tsk->mm = NULL;
>  	membarrier_update_current_mm(NULL);
> diff --git a/mm/madvise.c b/mm/madvise.c
> index 886f06066622..39bed9e4b08b 100644
> --- a/mm/madvise.c
> +++ b/mm/madvise.c
> @@ -741,11 +741,8 @@ static int madvise_free_pte_range(pmd_t *pmd, unsigned
> long addr,
>  		folio_mark_lazyfree(folio);
>  	}
>
> -	if (nr_swap) {
> -		if (current->mm == mm)
> -			sync_mm_rss(mm);
> +	if (nr_swap)
>  		add_mm_counter(mm, MM_SWAPENTS, nr_swap);
> -	}
>  	if (start_pte) {
>  		arch_leave_lazy_mmu_mode();
>  		pte_unmap_unlock(start_pte, ptl);
> diff --git a/mm/memory.c b/mm/memory.c
> index cdc4d4c1c858..b72d90ece7fe 100644
> --- a/mm/memory.c
> +++ b/mm/memory.c
> @@ -474,8 +474,6 @@ static inline void add_mm_rss_vec(struct mm_struct *mm,
> int *rss)
>  {
>  	int i;
>
> -	if (current->mm == mm)
> -		sync_mm_rss(mm);
>  	for (i = 0; i < NR_MM_COUNTERS; i++)
>  		if (rss[i])
>  			add_mm_counter(mm, i, rss[i]);
> --
> 2.39.2
>
>


-- 
Mateusz Guzik <mjguzik gmail.com>