linux-kernel - Re: [PATCH RT] mm/memcontrol: Move misplaced local_unlock

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <20200203181746.htlca2aynoqidm3o@linutronix.de>
Date:   Mon, 3 Feb 2020 19:17:46 +0100
From:   Sebastian Andrzej Siewior <bigeasy@...utronix.de>
To:     Matt Fleming <matt@...eblueprint.co.uk>
Cc:     linux-kernel@...r.kernel.org, linux-rt-users@...r.kernel.org,
        Daniel Wagner <wagi@...om.org>
Subject: Re: [PATCH RT] mm/memcontrol: Move misplaced
 local_unlock_irqrestore()

On 2020-01-26 21:19:45 [+0000], Matt Fleming wrote:
> There's no need to leave interrupts disabled when calling css_put_many().

For RT the interrupts are never actually disabled and for !RT they are
disabled with or without the change.
The comment about the disable function mentions just the counters and
css_put_many()'s callback just invokes a worker so it is probably save
to move the function as suggested.

May I ask how on earth you managed to open that file on a Sunday
evening?

> Cc: Daniel Wagner <wagi@...om.org>
> Signed-off-by: Matt Fleming <matt@...eblueprint.co.uk>
> ---
>  mm/memcontrol.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/mm/memcontrol.c b/mm/memcontrol.c
> index 7b6f208c5a6b..1120b9d8dd86 100644
> --- a/mm/memcontrol.c
> +++ b/mm/memcontrol.c
> @@ -7062,10 +7062,10 @@ void mem_cgroup_swapout(struct page *page, swp_entry_t entry)
>  	mem_cgroup_charge_statistics(memcg, page, PageTransHuge(page),
>  				     -nr_entries);
>  	memcg_check_events(memcg, page);
> +	local_unlock_irqrestore(event_lock, flags);
>  
>  	if (!mem_cgroup_is_root(memcg))
>  		css_put_many(&memcg->css, nr_entries);
> -	local_unlock_irqrestore(event_lock, flags);
>  }
>  
>  /**

Sebastian