fix #44491

0001-fixup-drm.patch

@@ -0,0 +1,70 @@
+From 8218c3f4df3bb1c637c17552405039a6dd3c1ee1 Mon Sep 17 00:00:00 2001
+From: Daniel Vetter <daniel.vetter@ffwll.ch>
+Date: Fri, 27 Feb 2015 12:58:13 +0100
+Subject: drm: Fixup racy refcounting in plane_force_disable
+
+Originally it was impossible to be dropping the last refcount in this
+function since there was always one around still from the idr. But in
+
+commit 83f45fc360c8e16a330474860ebda872d1384c8c
+Author: Daniel Vetter <daniel.vetter@ffwll.ch>
+Date:   Wed Aug 6 09:10:18 2014 +0200
+
+    drm: Don't grab an fb reference for the idr
+
+we've switched to weak references, broke that assumption but forgot to
+fix it up.
+
+Since we still force-disable planes it's only possible to hit this
+when racing multiple rmfb with fbdev restoring or similar evil things.
+As long as userspace is nice it's impossible to hit the BUG_ON.
+
+But the BUG_ON would most likely be hit from fbdev code, which usually
+invovles the console_lock besides all modeset locks. So very likely
+we'd never get the bug reports if this was hit in the wild, hence
+better be safe than sorry and backport.
+
+Spotted by Matt Roper while reviewing other patches.
+
+[airlied: pull this back into 4.0 - the oops happens there]
+
+Cc: stable@vger.kernel.org
+Cc: Matt Roper <matthew.d.roper@intel.com>
+Reviewed-by: Matt Roper <matthew.d.roper@intel.com>
+Signed-off-by: Daniel Vetter <daniel.vetter@intel.com>
+Signed-off-by: Dave Airlie <airlied@redhat.com>
+
+diff --git a/drivers/gpu/drm/drm_crtc.c b/drivers/gpu/drm/drm_crtc.c
+index f6d04c7..679b10e 100644
+--- a/drivers/gpu/drm/drm_crtc.c
++++ b/drivers/gpu/drm/drm_crtc.c
+@@ -525,17 +525,6 @@ void drm_framebuffer_reference(struct drm_framebuffer *fb)
+ }
+ EXPORT_SYMBOL(drm_framebuffer_reference);
+ 
+-static void drm_framebuffer_free_bug(struct kref *kref)
+-{
+-	BUG();
+-}
+-
+-static void __drm_framebuffer_unreference(struct drm_framebuffer *fb)
+-{
+-	DRM_DEBUG("%p: FB ID: %d (%d)\n", fb, fb->base.id, atomic_read(&fb->refcount.refcount));
+-	kref_put(&fb->refcount, drm_framebuffer_free_bug);
+-}
+-
+ /**
+  * drm_framebuffer_unregister_private - unregister a private fb from the lookup idr
+  * @fb: fb to unregister
+@@ -1320,7 +1309,7 @@ void drm_plane_force_disable(struct drm_plane *plane)
+ 		return;
+ 	}
+ 	/* disconnect the plane from the fb and crtc: */
+-	__drm_framebuffer_unreference(plane->old_fb);
++	drm_framebuffer_unreference(plane->old_fb);
+ 	plane->old_fb = NULL;
+ 	plane->fb = NULL;
+ 	plane->crtc = NULL;
+-- 
+cgit v0.10.2
+

PKGBUILD

@@ -5,7 +5,7 @@ pkgbase=linux               # Build stock -ARCH kernel
 #pkgbase=linux-custom       # Build kernel with a different name
 _srcname=linux-3.19
 pkgver=3.19.3
-pkgrel=2
+pkgrel=3
 arch=('i686' 'x86_64')
 url="http://www.kernel.org/"
 license=('GPL2')
@@ -20,7 +20,8 @@ source=("https://www.kernel.org/pub/linux/kernel/v3.x/${_srcname}.tar.xz"
         # standard config files for mkinitcpio ramdisk
         'linux.preset'
         'change-default-console-loglevel.patch'
-        '0001-fix-btrfs-mount-deadlock.patch')
+        '0001-fix-btrfs-mount-deadlock.patch'
+        '0001-fixup-drm.patch')
 sha256sums=('be42511fe5321012bb4a2009167ce56a9e5fe362b4af43e8c371b3666859806c'
             'SKIP'
             'cd9474b61b859d68f83ff0b769bafef8489d2090e0a933d2a7e5f76a23cc071a'
@@ -55,6 +56,9 @@ prepare() {
   # https://btrfs.wiki.kernel.org/index.php/Gotchas
   patch -Np1 -i "${srcdir}/0001-fix-btrfs-mount-deadlock.patch"
 
+  # fix #44491
+  patch -Np1 -i "${srcdir}/0001-fixup-drm.patch"
+
   if [ "${CARCH}" = "x86_64" ]; then
     cat "${srcdir}/config.x86_64" > ./.config
   else
@@ -301,3 +305,13 @@ for _p in ${pkgname[@]}; do
 done
 
 # vim:set ts=8 sts=2 sw=2 et:
+sha256sums=('be42511fe5321012bb4a2009167ce56a9e5fe362b4af43e8c371b3666859806c'
+            'SKIP'
+            'cd9474b61b859d68f83ff0b769bafef8489d2090e0a933d2a7e5f76a23cc071a'
+            'SKIP'
+            '704a479de77c9022e5c7a797d2cd7fd0e4ba1f52f9039ec8a80efd57f7e9f0d8'
+            '59830f47c1be39f874640d762dca55f972aca549a7a65ba2f1dac184251dabb2'
+            'f0d90e756f14533ee67afda280500511a62465b4f76adcc5effa95a40045179c'
+            '1256b241cd477b265a3c2d64bdc19ffe3c9bbcee82ea3994c590c2c76e767d99'
+            '5967cf53cb9db9f070e8f346c3d7045748e4823a7fe2ee330acd18c9d02bbb77'
+            '911872ef7000af471e649aaeb3490094a0b4c1514ca1024757ca2e90ac1d2a3d')