From 771fa5a4e91d95bd49f007c2853eaaedd47a93f7 Mon Sep 17 00:00:00 2001
From: Chris Wilson <chris@chris-wilson.co.uk>
Date: Wed, 11 Mar 2020 09:26:24 +0000
Subject: drm/i915/gem: Mark up the racy read of the mmap_singleton
Git-commit: 4aea5a9e6521c1ad484992d490f1cefa7d73d1ec
Patch-mainline: v5.7-rc1
References: jsc#SLE-12680, jsc#SLE-12880, jsc#SLE-12882, jsc#SLE-12883, jsc#SLE-13496, jsc#SLE-15322
[11057.642683] BUG: KCSAN: data-race in i915_gem_mmap [i915] / singleton_release [i915]
[11057.642717]
[11057.642740] write (marked) to 0xffff8881f24471a0 of 8 bytes by task 44668 on cpu 2:
[11057.643162] singleton_release+0x38/0x60 [i915]
[11057.643192] __fput+0x160/0x3c0
[11057.643217] ____fput+0x16/0x20
[11057.643241] task_work_run+0xba/0x100
[11057.643263] exit_to_usermode_loop+0xe4/0xf0
[11057.643286] do_syscall_64+0x27e/0x2c0
[11057.643314] entry_SYSCALL_64_after_hwframe+0x44/0xa9
[11057.643339]
[11057.643359] read to 0xffff8881f24471a0 of 8 bytes by task 44667 on cpu 3:
[11057.643774] i915_gem_mmap+0x295/0x670 [i915]
[11057.643802] mmap_region+0x62b/0xac0
[11057.643825] do_mmap+0x414/0x6b0
[11057.643848] vm_mmap_pgoff+0xa9/0xf0
[11057.643875] ksys_mmap_pgoff+0x1ac/0x2f0
[11057.643900] do_syscall_64+0x6e/0x2c0
[11057.643924] entry_SYSCALL_64_after_hwframe+0x44/0xa9
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: Mika Kuoppala <mika.kuoppala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20200311092624.10012-3-chris@chris-wilson.co.uk
Signed-off-by: Patrik Jakobsson <pjakobsson@suse.de>
---
drivers/gpu/drm/i915/gem/i915_gem_mman.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/drivers/gpu/drm/i915/gem/i915_gem_mman.c b/drivers/gpu/drm/i915/gem/i915_gem_mman.c
index e8cccc131c40..b39c24dae64e 100644
--- a/drivers/gpu/drm/i915/gem/i915_gem_mman.c
+++ b/drivers/gpu/drm/i915/gem/i915_gem_mman.c
@@ -775,7 +775,7 @@ static struct file *mmap_singleton(struct drm_i915_private *i915)
struct file *file;
rcu_read_lock();
- file = i915->gem.mmap_singleton;
+ file = READ_ONCE(i915->gem.mmap_singleton);
if (file && !get_file_rcu(file))
file = NULL;
rcu_read_unlock();
--
2.28.0