linux-kernel - Re: [PATCH 17/18] drm/radeon: make radeon_mn_get wait for mmap

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Message-ID: <56D4493B.7010004@amd.com>
Date:	Mon, 29 Feb 2016 14:35:55 +0100
From:	Christian König <christian.koenig@....com>
To:	Michal Hocko <mhocko@...nel.org>,
	LKML <linux-kernel@...r.kernel.org>
CC:	"dri-devel@...ts.freedesktop.org" <dri-devel@...ts.freedesktop.org>,
	<linux-mm@...ck.org>, <linux-arch@...r.kernel.org>
Subject: Re: [PATCH 17/18] drm/radeon: make radeon_mn_get wait for mmap_sem
 killable

[Dropping CCing the individual people, but adding the dri-devel mailing 
list as well instead].

Am 29.02.2016 um 14:26 schrieb Michal Hocko:
> From: Michal Hocko <mhocko@...e.com>
>
> radeon_mn_get which is called during ioct path relies on mmap_sem for
> write. If the waiting task gets killed by the oom killer it would block
> oom_reaper from asynchronous address space reclaim and reduce the
> chances of timely OOM resolving. Wait for the lock in the killable mode
> and return with EINTR if the task got killed while waiting.
>
> Cc: Alex Deucher <alexander.deucher@....com>
> Cc: "Christian König" <christian.koenig@....com>
> Cc: David Airlie <airlied@...ux.ie>
> Signed-off-by: Michal Hocko <mhocko@...e.com>

This one and patch #18 in this series are Reviewed-by: Christian König 
<christian.koenig@....com>.

Nice to see some improvements on this side,
Christian.

> ---
>   drivers/gpu/drm/radeon/radeon_mn.c | 4 +++-
>   1 file changed, 3 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/gpu/drm/radeon/radeon_mn.c b/drivers/gpu/drm/radeon/radeon_mn.c
> index eef006c48584..896f2cf51e4e 100644
> --- a/drivers/gpu/drm/radeon/radeon_mn.c
> +++ b/drivers/gpu/drm/radeon/radeon_mn.c
> @@ -186,7 +186,9 @@ static struct radeon_mn *radeon_mn_get(struct radeon_device *rdev)
>   	struct radeon_mn *rmn;
>   	int r;
>   
> -	down_write(&mm->mmap_sem);
> +	if (down_write_killable(&mm->mmap_sem))
> +		return ERR_PTR(-EINTR);
> +
>   	mutex_lock(&rdev->mn_lock);
>   
>   	hash_for_each_possible(rdev->mn_hash, rmn, node, (unsigned long)mm)