linux-kernel - Re: [PATCH] mm: use down_read_killable for locking mmap_sem in access_remote

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Message-ID: <20190515142828.GA18892@redhat.com>
Date:   Wed, 15 May 2019 16:28:28 +0200
From:   Oleg Nesterov <oleg@...hat.com>
To:     Konstantin Khlebnikov <khlebnikov@...dex-team.ru>
Cc:     linux-mm@...ck.org, Andrew Morton <akpm@...ux-foundation.org>,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH] mm: use down_read_killable for locking mmap_sem in
 access_remote_vm

> @@ -4348,7 +4348,9 @@ int __access_remote_vm(struct task_struct *tsk, struct mm_struct *mm,
>  	void *old_buf = buf;
>  	int write = gup_flags & FOLL_WRITE;
>  
> -	down_read(&mm->mmap_sem);
> +	if (down_read_killable(&mm->mmap_sem))
> +		return 0;
> +

I too think that "return 0" looks a bit strange even if correct, to me
"return -EINTR" would look better.

But I won't insist, this is cosmetic.

Acked-by: Oleg Nesterov <oleg@...hat.com>