Re: xorg 7.2 locks system in current

[Redirecting to x11_at_ as more appropriate]

On Fri, Jul 06, 2007 at 12:44:43PM +0800, Ganbold wrote:
> Hi,
> 
> I have todays CURRENT. My machine is Dell Latitude D620 with 945GM 
> graphics card.
> When I try to run xorg 7.2, my machine hangs and on serial console it 
> showed:
> 
> uma_zalloc_arg: zone "64" with the following non-sleepable locks held:
> exclusive sleep mutex drm device r = 0 (0xc3c06cd8) locked _at_ 
> /usr/src/sys/modules/drm/drm/../../../dev/drm/drm_drv.c:907
> KDB: enter: witness_warn
> [thread pid 739 tid 100092 ]
> Stopped at      kdb_enter+0x32: leave
> db> bt
> Tracing pid 739 tid 100092 td 0xc3fe2220
> kdb_enter(c086100b,e63ea9fc,4,1,0,...) at kdb_enter+0x32
> witness_warn(5,0,c08bd9fe,c08a71b1,66666666,...) at witness_warn+0x1b9
> uma_zalloc_arg(c1072d20,0,102,2,c09d9d64,...) at uma_zalloc_arg+0x34
> malloc(2c,c093d0c0,102,12,c4325db0,...) at malloc+0xd2
> sysctl_add_oid(c4325dcc,c09d9d64,ffffffff,c4325db0,80000001,...) at 
> sysctl_add_oid+0x95
> alloc_bounce_zone(44,c09399e0,101,1000,c3c8ec80,...) at 
> alloc_bounce_zone+0x16d
> bus_dma_tag_create(0,1000,0,ffffffff,ffffffff,...) at 
> bus_dma_tag_create+0x1a9
> drm_pci_alloc(c3c06c00,1000,1000,ffffffff,20000,...) at drm_pci_alloc+0xe1
> i915_dma_init(c3bf3800,80446440,c4325e80,3,c3fe2220,...) at 
> i915_dma_init+0x2b8
> drm_ioctl(c3bf3800,80446440,c4325e80,3,c3fe2220,...) at drm_ioctl+0x357
> giant_ioctl(c3bf3800,80446440,c4325e80,3,c3fe2220,...) at giant_ioctl+0x56
> devfs_ioctl_f(c3e70048,80446440,c4325e80,c405c500,c3fe2220,...) at 
> devfs_ioctl_f+0xc9
> kern_ioctl(c3fe2220,8,80446440,c4325e80,0,...) at kern_ioctl+0x243
> ioctl(c3fe2220,e63eacfc,c,c089e511,c0935830,...) at ioctl+0x134
> syscall(e63ead38) at syscall+0x2b3
> Xint0x80_syscall() at Xint0x80_syscall+0x20
> --- syscall (54, FreeBSD ELF32, ioctl), eip = 0x483decc3, esp = 
> 0xbfbfea5c, ebp = 0xbfbfea78 ---
> db>
> db> c
> uma_zalloc_arg: zone "16" with the following non-sleepable locks held:
> exclusive sleep mutex drm device r = 0 (0xc3c06cd8) locked _at_ 
> /usr/src/sys/modules/drm/drm/../../../dev/drm/drm_drv.c:907
> KDB: enter: witness_warn
> [thread pid 739 tid 100092 ]
> Stopped at      kdb_enter+0x32: leave
> db>
> 
> thanks,
> 
> Ganbold

Man page states explicitely that bus_dma_tag_create() (as well as
bus_dmamem_alloc()) shall not be called with non-sleepable lock held.
I am not completely sure, but it seems to be safe to drop the drm
lock around drm_pci_alloc() when the later moved to the start of the
i915_initialize().

Could you, please, test the patch below ?

diff --git a/sys/dev/drm/i915_dma.c b/sys/dev/drm/i915_dma.c
index 1d1877b..118d160 100644
--- a/sys/dev/drm/i915_dma.c
+++ b/sys/dev/drm/i915_dma.c
_at__at_ -122,7 +122,22 _at__at_ static int i915_initialize(drm_device_t * dev,
 			   drm_i915_private_t * dev_priv,
 			   drm_i915_init_t * init)
 {
+	drm_dma_handle_t *dmah;
+
+	DRM_UNLOCK();
+	dmah = drm_pci_alloc(dev, PAGE_SIZE, PAGE_SIZE, 
+	    0xffffffff);
+	if (!dmah) {
+		dev->dev_private = (void *)dev_priv;
+		i915_dma_cleanup(dev);
+		DRM_ERROR("Can not allocate hardware status page\n");
+		DRM_LOCK();
+		return DRM_ERR(ENOMEM);
+	}
+	DRM_LOCK();
+
 	memset(dev_priv, 0, sizeof(drm_i915_private_t));
+	dev_priv->status_page_dmah = dmah;
 
 	DRM_GETSAREA();
 	if (!dev_priv->sarea) {
_at__at_ -181,15 +196,6 _at__at_ static int i915_initialize(drm_device_t * dev,
 	dev_priv->allow_batchbuffer = 1;
 
 	/* Program Hardware Status Page */
-	dev_priv->status_page_dmah = drm_pci_alloc(dev, PAGE_SIZE, PAGE_SIZE, 
-	    0xffffffff);
-
-	if (!dev_priv->status_page_dmah) {
-		dev->dev_private = (void *)dev_priv;
-		i915_dma_cleanup(dev);
-		DRM_ERROR("Can not allocate hardware status page\n");
-		return DRM_ERR(ENOMEM);
-	}
 	dev_priv->hw_status_page = dev_priv->status_page_dmah->vaddr;
 	dev_priv->dma_status_page = dev_priv->status_page_dmah->busaddr;