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    <head>
      <base href="https://bugs.freedesktop.org/">
    </head>
    <body><span class="vcard"><a class="email" href="mailto:chris@chris-wilson.co.uk" title="Chris Wilson <chris@chris-wilson.co.uk>"> <span class="fn">Chris Wilson</span></a>
</span> changed
          <a class="bz_bug_link 
          bz_status_RESOLVED  bz_closed"
   title="RESOLVED FIXED - Regression in kernel 4.15-rc1, GPF and display locks up. Still in rc6"
   href="https://bugs.freedesktop.org/show_bug.cgi?id=104436">bug 104436</a>
          <br>
             <table border="1" cellspacing="0" cellpadding="8">
          <tr>
            <th>What</th>
            <th>Removed</th>
            <th>Added</th>
          </tr>

         <tr>
           <td style="text-align:right;">Resolution</td>
           <td>---
           </td>
           <td>FIXED
           </td>
         </tr>

         <tr>
           <td style="text-align:right;">Status</td>
           <td>NEEDINFO
           </td>
           <td>RESOLVED
           </td>
         </tr></table>
      <p>
        <div>
            <b><a class="bz_bug_link 
          bz_status_RESOLVED  bz_closed"
   title="RESOLVED FIXED - Regression in kernel 4.15-rc1, GPF and display locks up. Still in rc6"
   href="https://bugs.freedesktop.org/show_bug.cgi?id=104436#c4">Comment # 4</a>
              on <a class="bz_bug_link 
          bz_status_RESOLVED  bz_closed"
   title="RESOLVED FIXED - Regression in kernel 4.15-rc1, GPF and display locks up. Still in rc6"
   href="https://bugs.freedesktop.org/show_bug.cgi?id=104436">bug 104436</a>
              from <span class="vcard"><a class="email" href="mailto:chris@chris-wilson.co.uk" title="Chris Wilson <chris@chris-wilson.co.uk>"> <span class="fn">Chris Wilson</span></a>
</span></b>
        <pre>commit c218ee03b9315073ce43992792554dafa0626eb8
Author: Chris Wilson <<a href="mailto:chris@chris-wilson.co.uk">chris@chris-wilson.co.uk</a>>
Date:   Sat Jan 6 10:56:18 2018 +0000

    drm/i915: Don't adjust priority on an already signaled fence

    When we retire a signaled fence, we free the dependency tree. However,
    we skip clearing the list so that if we then try to adjust the priority
    of the signaled fence, we may walk the list of freed dependencies.

    [ 3083.156757]
==================================================================
    [ 3083.156806] BUG: KASAN: use-after-free in execlists_schedule+0x199/0x660
[i915]
    [ 3083.156810] Read of size 8 at addr ffff8806bf20f400 by task Xorg/831

    [ 3083.156815] CPU: 0 PID: 831 Comm: Xorg Not tainted 4.15.0-rc6-no-psn+ #1
    [ 3083.156817] Hardware name: Notebook                        
N24_25BU/N24_25BU, BIOS 5.12 02/17/2017
    [ 3083.156818] Call Trace:
    [ 3083.156823]  dump_stack+0x5c/0x7a
    [ 3083.156827]  print_address_description+0x6b/0x290
    [ 3083.156830]  kasan_report+0x28f/0x380
    [ 3083.156872]  ? execlists_schedule+0x199/0x660 [i915]
    [ 3083.156914]  execlists_schedule+0x199/0x660 [i915]
    [ 3083.156956]  ? intel_crtc_atomic_check+0x146/0x4e0 [i915]
    [ 3083.156997]  ? execlists_submit_request+0xe0/0xe0 [i915]
    [ 3083.157038]  ? i915_vma_misplaced.part.4+0x25/0xb0 [i915]
    [ 3083.157079]  ? __i915_vma_do_pin+0x7c8/0xc80 [i915]
    [ 3083.157121]  ? intel_atomic_state_alloc+0x44/0x60 [i915]
    [ 3083.157130]  ? drm_atomic_helper_page_flip+0x3e/0xb0 [drm_kms_helper]
    [ 3083.157145]  ? drm_mode_page_flip_ioctl+0x7d2/0x850 [drm]
    [ 3083.157159]  ? drm_ioctl_kernel+0xa7/0xf0 [drm]
    [ 3083.157172]  ? drm_ioctl+0x45b/0x560 [drm]
    [ 3083.157211]  i915_gem_object_wait_priority+0x14c/0x2c0 [i915]
    [ 3083.157251]  ? i915_gem_get_aperture_ioctl+0x150/0x150 [i915]
    [ 3083.157290]  ? i915_vma_pin_fence+0x1d8/0x320 [i915]
    [ 3083.157331]  ? intel_pin_and_fence_fb_obj+0x175/0x250 [i915]
    [ 3083.157372]  ? intel_rotation_info_size+0x60/0x60 [i915]
    [ 3083.157413]  ? intel_link_compute_m_n+0x80/0x80 [i915]
    [ 3083.157428]  ? drm_dev_printk+0x1b0/0x1b0 [drm]
    [ 3083.157443]  ? drm_dev_printk+0x1b0/0x1b0 [drm]
    [ 3083.157485]  intel_prepare_plane_fb+0x2f8/0x5a0 [i915]
    [ 3083.157527]  ? intel_crtc_get_vblank_counter+0x80/0x80 [i915]
    [ 3083.157536]  drm_atomic_helper_prepare_planes+0xa0/0x1c0
[drm_kms_helper]
    [ 3083.157587]  intel_atomic_commit+0x12e/0x4e0 [i915]
    [ 3083.157605]  drm_atomic_helper_page_flip+0xa2/0xb0 [drm_kms_helper]
    [ 3083.157621]  drm_mode_page_flip_ioctl+0x7d2/0x850 [drm]
    [ 3083.157638]  ? drm_mode_cursor2_ioctl+0x10/0x10 [drm]
    [ 3083.157652]  ? drm_lease_owner+0x1a/0x30 [drm]
    [ 3083.157668]  ? drm_mode_cursor2_ioctl+0x10/0x10 [drm]
    [ 3083.157681]  drm_ioctl_kernel+0xa7/0xf0 [drm]
    [ 3083.157696]  drm_ioctl+0x45b/0x560 [drm]
    [ 3083.157711]  ? drm_mode_cursor2_ioctl+0x10/0x10 [drm]
    [ 3083.157725]  ? drm_getstats+0x20/0x20 [drm]
    [ 3083.157729]  ? timerqueue_del+0x49/0x80
    [ 3083.157732]  ? __remove_hrtimer+0x62/0xb0
    [ 3083.157735]  ? hrtimer_try_to_cancel+0x173/0x210
    [ 3083.157738]  do_vfs_ioctl+0x13b/0x880
    [ 3083.157741]  ? ioctl_preallocate+0x140/0x140
    [ 3083.157744]  ? _raw_spin_unlock_irq+0xe/0x30
    [ 3083.157746]  ? do_setitimer+0x234/0x370
    [ 3083.157750]  ? SyS_setitimer+0x19e/0x1b0
    [ 3083.157752]  ? SyS_alarm+0x140/0x140
    [ 3083.157755]  ? __rcu_read_unlock+0x66/0x80
    [ 3083.157757]  ? __fget+0xc4/0x100
    [ 3083.157760]  SyS_ioctl+0x74/0x80
    [ 3083.157763]  entry_SYSCALL_64_fastpath+0x1a/0x7d
    [ 3083.157765] RIP: 0033:0x7f6135d0c6a7
    [ 3083.157767] RSP: 002b:00007fff01451888 EFLAGS: 00003246 ORIG_RAX:
0000000000000010
    [ 3083.157769] RAX: ffffffffffffffda RBX: 0000000000000004 RCX:
00007f6135d0c6a7
    [ 3083.157771] RDX: 00007fff01451950 RSI: 00000000c01864b0 RDI:
000000000000000c
    [ 3083.157772] RBP: 00007f613076f600 R08: 0000000000000001 R09:
0000000000000000
    [ 3083.157773] R10: 0000000000000060 R11: 0000000000003246 R12:
0000000000000000
    [ 3083.157774] R13: 0000000000000060 R14: 000000000000001b R15:
0000000000000060

    [ 3083.157779] Allocated by task 831:
    [ 3083.157783]  kmem_cache_alloc+0xc0/0x200
    [ 3083.157822]  i915_gem_request_await_dma_fence+0x2c4/0x5d0 [i915]
    [ 3083.157861]  i915_gem_request_await_object+0x321/0x370 [i915]
    [ 3083.157900]  i915_gem_do_execbuffer+0x1165/0x19c0 [i915]
    [ 3083.157937]  i915_gem_execbuffer2+0x1ad/0x550 [i915]
    [ 3083.157950]  drm_ioctl_kernel+0xa7/0xf0 [drm]
    [ 3083.157962]  drm_ioctl+0x45b/0x560 [drm]
    [ 3083.157964]  do_vfs_ioctl+0x13b/0x880
    [ 3083.157966]  SyS_ioctl+0x74/0x80
    [ 3083.157968]  entry_SYSCALL_64_fastpath+0x1a/0x7d

    [ 3083.157971] Freed by task 831:
    [ 3083.157973]  kmem_cache_free+0x77/0x220
    [ 3083.158012]  i915_gem_request_retire+0x72c/0xa70 [i915]
    [ 3083.158051]  i915_gem_request_alloc+0x1e9/0x8b0 [i915]
    [ 3083.158089]  i915_gem_do_execbuffer+0xa96/0x19c0 [i915]
    [ 3083.158127]  i915_gem_execbuffer2+0x1ad/0x550 [i915]
    [ 3083.158140]  drm_ioctl_kernel+0xa7/0xf0 [drm]
    [ 3083.158153]  drm_ioctl+0x45b/0x560 [drm]
    [ 3083.158155]  do_vfs_ioctl+0x13b/0x880
    [ 3083.158156]  SyS_ioctl+0x74/0x80
    [ 3083.158158]  entry_SYSCALL_64_fastpath+0x1a/0x7d

    [ 3083.158162] The buggy address belongs to the object at ffff8806bf20f400
                    which belongs to the cache i915_dependency of size 64
    [ 3083.158166] The buggy address is located 0 bytes inside of
                    64-byte region [ffff8806bf20f400, ffff8806bf20f440)
    [ 3083.158168] The buggy address belongs to the page:
    [ 3083.158171] page:00000000d43decc4 count:1 mapcount:0 mapping:         
(null) index:0x0
    [ 3083.158174] flags: 0x17ffe0000000100(slab)
    [ 3083.158179] raw: 017ffe0000000100 0000000000000000 0000000000000000
0000000180200020
    [ 3083.158182] raw: ffffea001afc16c0 0000000500000005 ffff880731b881c0
0000000000000000
    [ 3083.158184] page dumped because: kasan: bad access detected

    [ 3083.158187] Memory state around the buggy address:
    [ 3083.158190]  ffff8806bf20f300: fb fb fb fb fb fb fb fb fc fc fc fc fc fc
fc fc
    [ 3083.158192]  ffff8806bf20f380: fb fb fb fb fb fb fb fb fc fc fc fc fc fc
fc fc
    [ 3083.158195] >ffff8806bf20f400: fb fb fb fb fb fb fb fb fc fc fc fc fc fc
fc fc
    [ 3083.158196]                    ^
    [ 3083.158199]  ffff8806bf20f480: fb fb fb fb fb fb fb fb fc fc fc fc fc fc
fc fc
    [ 3083.158201]  ffff8806bf20f500: fb fb fb fb fb fb fb fb fc fc fc fc fc fc
fc fc
    [ 3083.158203]
==================================================================

    Reported-by: Alexandru Chirvasitu <<a href="mailto:achirvasub@gmail.com">achirvasub@gmail.com</a>>
    Reported-by: Mike Keehan <<a href="mailto:mike@keehan.net">mike@keehan.net</a>>
    Bugzilla: <a class="bz_bug_link 
          bz_status_RESOLVED  bz_closed"
   title="RESOLVED FIXED - Regression in kernel 4.15-rc1, GPF and display locks up. Still in rc6"
   href="show_bug.cgi?id=104436">https://bugs.freedesktop.org/show_bug.cgi?id=104436</a>
    Fixes: 1f181225f8ec ("drm/i915/execlists: Keep request->priority for its
lifetime")
    Signed-off-by: Chris Wilson <<a href="mailto:chris@chris-wilson.co.uk">chris@chris-wilson.co.uk</a>>
    Cc: Alexandru Chirvasitu <<a href="mailto:achirvasub@gmail.com">achirvasub@gmail.com</a>>
    Cc: Michał Winiarski <<a href="mailto:michal.winiarski@intel.com">michal.winiarski@intel.com</a>>
    Cc: Joonas Lahtinen <<a href="mailto:joonas.lahtinen@linux.intel.com">joonas.lahtinen@linux.intel.com</a>>
    Cc: Tvrtko Ursulin <<a href="mailto:tvrtko.ursulin@intel.com">tvrtko.ursulin@intel.com</a>>
    Tested-by: Alexandru Chirvasitu <<a href="mailto:achirvasub@gmail.com">achirvasub@gmail.com</a>>
    Reviewed-by: Michał Winiarski <<a href="mailto:michal.winiarski@intel.com">michal.winiarski@intel.com</a>>
    Link:
<a href="https://patchwork.freedesktop.org/patch/msgid/20180106105618.13532-1-chris@chris-wilson.co.uk">https://patchwork.freedesktop.org/patch/msgid/20180106105618.13532-1-chris@chris-wilson.co.uk</a></pre>
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