Groups | Search | Server Info | Keyboard shortcuts | Login | Register [http] [https] [nntp] [nntps]

Groups > linux.kernel > #1504883 > unrolled thread

Re: [PATCH] drm/fb-helper: Fix race between deferred_io worker and dirty updater

Back to article view | Back to linux.kernel

This discussion starts older than the indexed window; earlier articles aren't shown. The article labeled Started by below is the oldest one visible, not the original post.

Contents

  Re: [PATCH] drm/fb-helper: Fix race between deferred_io worker and dirty updater Takashi Iwai <tiwai@suse.de> - 2016-10-20 15:30 +0200

#1504883 — Re: [PATCH] drm/fb-helper: Fix race between deferred_io worker and dirty updater

On Thu, 20 Oct 2016 15:20:55 +0200,
Takashi Iwai wrote:
> 
> Since 4.7 kernel, we've seen the error messages like
> 
>  kernel: [TTM] Buffer eviction failed
>  kernel: qxl 0000:00:02.0: object_init failed for (4026540032, 0x00000001)
>  kernel: [drm:qxl_alloc_bo_reserved [qxl]] *ERROR* failed to allocate VRAM BO
> 
> on QXL when switching and accessing on VT.  The culprit was the generic
> deferred_io code (qxl driver switched to it since 4.7).  There is a
> race between the dirty clip update and the call of callback.
> 
> In drm_fb_helper_dirty(), the dirty clip is updated in the spinlock,
> while it kicks off the update worker outside the spinlock.  Meanwhile
> the update worker clears the dirty clip in the spinlock, too.  Thus,
> when drm_fb_helper_dirty() is called concurrently, schedule_work() is
> called after the clip is cleared in the first worker call.
> 
> The fix is simply moving schedule_work() inside the spinlock.
> 
> Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=98322
> Bugzilla: https://bugzilla.suse.com/show_bug.cgi?id=1003298
> Fixes: eaa434defaca ('drm/fb-helper: Add fb_deferred_io support')
> Signed-off-by: Takashi Iwai <tiwai@suse.de>

I forgot to put Cc to stable.  Feel free to add it once if it's
accepted.


thanks,

Takashi

> ---
>  drivers/gpu/drm/drm_fb_helper.c | 3 +--
>  1 file changed, 1 insertion(+), 2 deletions(-)
> 
> diff --git a/drivers/gpu/drm/drm_fb_helper.c b/drivers/gpu/drm/drm_fb_helper.c
> index 03414bde1f15..bae392dea2cc 100644
> --- a/drivers/gpu/drm/drm_fb_helper.c
> +++ b/drivers/gpu/drm/drm_fb_helper.c
> @@ -861,9 +861,8 @@ static void drm_fb_helper_dirty(struct fb_info *info, u32 x, u32 y,
>  	clip->y1 = min_t(u32, clip->y1, y);
>  	clip->x2 = max_t(u32, clip->x2, x + width);
>  	clip->y2 = max_t(u32, clip->y2, y + height);
> -	spin_unlock_irqrestore(&helper->dirty_lock, flags);
> -
>  	schedule_work(&helper->dirty_work);
> +	spin_unlock_irqrestore(&helper->dirty_lock, flags);
>  }
>  
>  /**
> -- 
> 2.10.1
> 

[toc] | [standalone]

Back to top | Article view | linux.kernel

csiph-web