linux-kernel - Re: [PATCH 3/5] proc: use down_read

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Message-ID: <20190517124648.GC1825@dhcp22.suse.cz>
Date:   Fri, 17 May 2019 14:46:48 +0200
From:   Michal Hocko <mhocko@...nel.org>
To:     Konstantin Khlebnikov <khlebnikov@...dex-team.ru>
Cc:     linux-mm@...ck.org, Andrew Morton <akpm@...ux-foundation.org>,
        linux-kernel@...r.kernel.org, Cyrill Gorcunov <gorcunov@...il.com>,
        Kirill Tkhai <ktkhai@...tuozzo.com>,
        Al Viro <viro@...iv.linux.org.uk>
Subject: Re: [PATCH 3/5] proc: use down_read_killable for /proc/pid/pagemap

On Wed 15-05-19 11:41:19, Konstantin Khlebnikov wrote:
> Ditto.

ditto to the previous patch, including -EINTR.

> 
> Signed-off-by: Konstantin Khlebnikov <khlebnikov@...dex-team.ru>
> ---
>  fs/proc/task_mmu.c |    4 +++-
>  1 file changed, 3 insertions(+), 1 deletion(-)
> 
> diff --git a/fs/proc/task_mmu.c b/fs/proc/task_mmu.c
> index 781879a91e3b..78bed6adc62d 100644
> --- a/fs/proc/task_mmu.c
> +++ b/fs/proc/task_mmu.c
> @@ -1547,7 +1547,9 @@ static ssize_t pagemap_read(struct file *file, char __user *buf,
>  		/* overflow ? */
>  		if (end < start_vaddr || end > end_vaddr)
>  			end = end_vaddr;
> -		down_read(&mm->mmap_sem);
> +		ret = down_read_killable(&mm->mmap_sem);
> +		if (ret)
> +			goto out_free;
>  		ret = walk_page_range(start_vaddr, end, &pagemap_walk);
>  		up_read(&mm->mmap_sem);
>  		start_vaddr = end;

-- 
Michal Hocko
SUSE Labs