linux-kernel - Re: [PATCH] mm/madvise: break reclaim when lock race

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Date:   Tue, 7 Dec 2021 09:04:47 -0800
From:   Suren Baghdasaryan <surenb@...gle.com>
To:     xf2017140389@...il.com
Cc:     akpm@...ux-foundation.org, christian@...uner.io,
        linux-mm@...ck.org, linux-kernel@...r.kernel.org,
        zhangcang@...omi.com, wangju@...omi.com, fangzhirong@...omi.com,
        xiaofeng <xiaofeng5@...omi.com>, Minchan Kim <minchan@...nel.org>
Subject: Re: [PATCH] mm/madvise: break reclaim when lock race

On Mon, Dec 6, 2021 at 7:22 PM <xf2017140389@...il.com> wrote:
>
> From: xiaofeng <xiaofeng5@...omi.com>
>
> When the process_madvise() system call is being used, it takes mmap_lock and blocks the application from allocating memory, leading to unreasonable delays. This patchset aims to fix it.

Please use checkpatch.pl script before posting (see this blog for
example: http://nickdesaulniers.github.io/blog/2017/05/16/submitting-your-first-patch-to-the-linux-kernel-and-responding-to-feedback/).

Could you please describe your usecase a bit more? Which MADV is being
used specifically (MADV_COLD or MADV_PAGEOUT)?
CC'ing Minchan as he might be interested in learning more about this.

>
> Signed-off-by: xiaofeng <xiaofeng5@...omi.com>
> ---
>  mm/madvise.c | 3 +++
>  1 file changed, 3 insertions(+)
>
> diff --git a/mm/madvise.c b/mm/madvise.c
> index 8c927202bbe6..8f1e325873e0 100644
> --- a/mm/madvise.c
> +++ b/mm/madvise.c
> @@ -322,6 +322,9 @@ static int madvise_cold_or_pageout_pte_range(pmd_t *pmd,
>         if (fatal_signal_pending(current))
>                 return -EINTR;
>
> +       if (mmap_lock_is_contended(mm))
> +               return -EINTR;
> +
>  #ifdef CONFIG_TRANSPARENT_HUGEPAGE
>         if (pmd_trans_huge(*pmd)) {
>                 pmd_t orig_pmd;
> --
> 2.17.1
>