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Chris Wilson e5429340bf drm/i915/gt: Acquire ce->active before ce->pin_count/ce->pin_mutex
Similar to commit ac0e331a62 ("drm/i915: Tighten atomicity of
i915_active_acquire vs i915_active_release") we have the same race of
trying to pin the context underneath a mutex while allowing the
decrement to be atomic outside of that mutex. This leads to the problem
where two threads may simultaneously try to pin the context and the
second not notice that they needed to repin the context.

<2> [198.669621] kernel BUG at drivers/gpu/drm/i915/gt/intel_timeline.c:387!
<4> [198.669703] invalid opcode: 0000 [#1] PREEMPT SMP PTI
<4> [198.669712] CPU: 0 PID: 1246 Comm: gem_exec_create Tainted: G     U  W         5.5.0-rc6-CI-CI_DRM_7755+ #1
<4> [198.669723] Hardware name:  /NUC7i5BNB, BIOS BNKBL357.86A.0054.2017.1025.1822 10/25/2017
<4> [198.669776] RIP: 0010:timeline_advance+0x7b/0xe0 [i915]
<4> [198.669785] Code: 00 48 c7 c2 10 f1 46 a0 48 c7 c7 70 1b 32 a0 e8 bb dd e7 e0 bf 01 00 00 00 e8 d1 af e7 e0 31 f6 bf 09 00 00 00 e8 35 ef d8 e0 <0f> 0b 48 c7 c1 48 fa 49 a0 ba 84 01 00 00 48 c7 c6 10 f1 46 a0 48
<4> [198.669803] RSP: 0018:ffffc900004c3a38 EFLAGS: 00010296
<4> [198.669810] RAX: ffff888270b35140 RBX: ffff88826f32ee00 RCX: 0000000000000006
<4> [198.669818] RDX: 00000000000017c5 RSI: 0000000000000000 RDI: 0000000000000009
<4> [198.669826] RBP: ffffc900004c3a64 R08: 0000000000000000 R09: 0000000000000000
<4> [198.669834] R10: 0000000000000000 R11: 0000000000000000 R12: ffff88826f9b5980
<4> [198.669841] R13: 0000000000000cc0 R14: ffffc900004c3dc0 R15: ffff888253610068
<4> [198.669849] FS:  00007f63e663fe40(0000) GS:ffff888276c00000(0000) knlGS:0000000000000000
<4> [198.669857] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
<4> [198.669864] CR2: 00007f171f8e39a8 CR3: 000000026b1f6005 CR4: 00000000003606f0
<4> [198.669872] Call Trace:
<4> [198.669924]  intel_timeline_get_seqno+0x12/0x40 [i915]
<4> [198.669977]  __i915_request_create+0x76/0x5a0 [i915]
<4> [198.670024]  i915_request_create+0x86/0x1c0 [i915]
<4> [198.670068]  i915_gem_do_execbuffer+0xbf2/0x2500 [i915]
<4> [198.670082]  ? __lock_acquire+0x460/0x15d0
<4> [198.670128]  i915_gem_execbuffer2_ioctl+0x11f/0x470 [i915]
<4> [198.670171]  ? i915_gem_execbuffer_ioctl+0x300/0x300 [i915]
<4> [198.670181]  drm_ioctl_kernel+0xa7/0xf0
<4> [198.670188]  drm_ioctl+0x2e1/0x390
<4> [198.670233]  ? i915_gem_execbuffer_ioctl+0x300/0x300 [i915]

Fixes: 8413502238 ("drm/i915/gt: Drop mutex serialisation between context pin/unpin")
References: ac0e331a62 ("drm/i915: Tighten atomicity of i915_active_acquire vs i915_active_release")
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Reviewed-by: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20200127152829.2842149-1-chris@chris-wilson.co.uk
2020-01-27 21:11:59 +00:00
Documentation dt-bindings: fix warnings in xinpeng,xpp055c272.yaml 2020-01-06 19:43:40 +01:00
LICENSES LICENSES: Rename other to deprecated 2019-05-03 06:34:32 -06:00
arch Merge drm/drm-next into drm-intel-next-queued 2020-01-09 17:19:12 +02:00
block for-linus-20191212 2019-12-13 14:27:19 -08:00
certs certs: Add wrapper function to check blacklisted binary hash 2019-11-12 12:25:50 +11:00
crypto treewide: Use sizeof_field() macro 2019-12-09 10:36:44 -08:00
drivers drm/i915/gt: Acquire ce->active before ce->pin_count/ce->pin_mutex 2020-01-27 21:11:59 +00:00
fs Merge branch 'remove-ksys-mount-dup' of git://git.kernel.org/pub/scm/linux/kernel/git/brodo/linux 2019-12-15 11:36:12 -08:00
include Merge tag 'topic/drm-warn-2020-01-22' of git://anongit.freedesktop.org/drm/drm-intel into drm-intel-next-queued 2020-01-22 17:26:19 +02:00
init fs: remove ksys_dup() 2019-12-12 19:00:36 +01:00
ipc treewide: Use sizeof_field() macro 2019-12-09 10:36:44 -08:00
kernel treewide conversion from FIELD_SIZEOF() to sizeof_field() 2019-12-13 14:02:12 -08:00
lib lib: raid6: fix awk build warnings 2019-12-09 18:55:03 +01:00
mm Merge branch 'akpm' (patches from Andrew) 2019-12-05 09:46:26 -08:00
net io_uring-5.5-20191212 2019-12-13 14:24:54 -08:00
samples drm-misc-next for v5.6: 2019-12-17 13:57:54 +01:00
scripts pr_warning() removal for 5.5 2019-12-09 11:48:21 -08:00
security treewide: Use sizeof_field() macro 2019-12-09 10:36:44 -08:00
sound sound fixes for 5.5-rc2 2019-12-13 14:40:38 -08:00
tools drm-misc-next for v5.6: 2020-01-03 11:43:44 +10:00
usr arch: sembuf.h: make uapi asm/sembuf.h self-contained 2019-12-04 19:44:14 -08:00
virt KVM: Fix jump label out_free_* in kvm_init() 2019-11-23 11:29:17 +01:00
.clang-format clang-format: Update with the latest for_each macro list 2019-08-31 10:00:51 +02:00
.cocciconfig
.get_maintainer.ignore Opt out of scripts/get_maintainer.pl 2019-05-16 10:53:40 -07:00
.gitattributes .gitattributes: use 'dts' diff driver for dts files 2019-12-04 19:44:11 -08:00
.gitignore modpost: dump missing namespaces into a single modules.nsdeps file 2019-11-11 20:10:01 +09:00
.mailmap Update mailmap info for Steve Wise 2019-12-09 13:49:25 -05:00
COPYING
CREDITS Linux 5.4-rc4 2019-10-29 04:43:29 -06:00
Kbuild kbuild: do not descend to ./Kbuild when cleaning 2019-08-21 21:03:58 +09:00
Kconfig docs: kbuild: convert docs to ReST and rename to *.rst 2019-06-14 14:21:21 -06:00
MAINTAINERS drm-misc-next for v5.6: 2019-12-17 13:57:54 +01:00
Makefile Linux 5.5-rc2 2019-12-15 15:16:08 -08:00
README Drop all 00-INDEX files from Documentation/ 2018-09-09 15:08:58 -06:00

README

Linux kernel
============

There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.

In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``.  The formatted documentation can also be read online at:

    https://www.kernel.org/doc/html/latest/

There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.

Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.