linux-kernel - Re: [PATCH 1/4] mm/vmalloc: allow to call vfree() in atomic context

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Message-ID: <6b390234-71e7-e379-201c-0fb4a05399c2@vmware.com>
Date:   Thu, 30 Mar 2017 17:04:17 +0200
From:   Thomas Hellstrom <thellstrom@...are.com>
To:     Andrey Ryabinin <aryabinin@...tuozzo.com>,
        <akpm@...ux-foundation.org>
CC:     <penguin-kernel@...ove.SAKURA.ne.jp>,
        <linux-kernel@...r.kernel.org>, <mhocko@...nel.org>,
        <linux-mm@...ck.org>, <hpa@...or.com>, <chris@...is-wilson.co.uk>,
        <hch@....de>, <mingo@...e.hu>, <jszhang@...vell.com>,
        <joelaf@...gle.com>, <joaodias@...gle.com>, <willy@...radead.org>,
        <tglx@...utronix.de>, <stable@...r.kernel.org>
Subject: Re: [PATCH 1/4] mm/vmalloc: allow to call vfree() in atomic context

On 03/30/2017 04:48 PM, Andrey Ryabinin wrote:
> On 03/30/2017 03:00 PM, Thomas Hellstrom wrote:
>
>>>  
>>>  	if (unlikely(nr_lazy > lazy_max_pages()))
>>> -		try_purge_vmap_area_lazy();
>> Perhaps a slight optimization would be to schedule work iff
>> !mutex_locked(&vmap_purge_lock) below?
>>
> Makes sense, we don't need to spawn workers if we already purging.
>
>
>
> From: Andrey Ryabinin <aryabinin@...tuozzo.com>
> Subject: mm/vmalloc: allow to call vfree() in atomic context fix
>
> Don't spawn worker if we already purging.
>
> Signed-off-by: Andrey Ryabinin <aryabinin@...tuozzo.com>
> ---
>  mm/vmalloc.c | 3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)
>
> diff --git a/mm/vmalloc.c b/mm/vmalloc.c
> index ea1b4ab..88168b8 100644
> --- a/mm/vmalloc.c
> +++ b/mm/vmalloc.c
> @@ -737,7 +737,8 @@ static void free_vmap_area_noflush(struct vmap_area *va)
>  	/* After this point, we may free va at any time */
>  	llist_add(&va->purge_list, &vmap_purge_list);
>  
> -	if (unlikely(nr_lazy > lazy_max_pages()))
> +	if (unlikely(nr_lazy > lazy_max_pages()) &&
> +	    !mutex_is_locked(&vmap_purge_lock))
>  		schedule_work(&purge_vmap_work);
>  }
>  

For both patches,

Reviewed-by: Thomas Hellstrom <thellstrom@...are.com>

Thanks,

Thomas