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| author | Chris Wilson <chris@chris-wilson.co.uk> | 2016-04-05 17:00:00 +0300 |
|---|---|---|
| committer | Chris Wilson <chris@chris-wilson.co.uk> | 2016-04-11 22:39:01 +0300 |
| commit | 40313f0cd0b711a7a5905e5182422799e157d8aa (patch) | |
| tree | 348c8ad14d42c1b12903b26560351b3062b422d5 /drivers/gpu/drm/i915/i915_gem_userptr.c | |
| parent | 393afc2c3fda670ff392725ca618e956d625b964 (diff) | |
| download | linux-40313f0cd0b711a7a5905e5182422799e157d8aa.tar.xz | |
drm/i915/userptr: Hold mmref whilst calling get-user-pages
Holding a reference to the containing task_struct is not sufficient to
prevent the mm_struct from being reaped under memory pressure. If this
happens whilst we are calling get_user_pages(), explosions erupt -
sometimes an immediate GPF, sometimes page flag corruption. To prevent
the target mm from being reaped as we are reading from it, acquire a
reference before we begin.
Testcase: igt/gem_shrink/*userptr
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Cc: Michał Winiarski <michal.winiarski@intel.com>
Cc: stable@vger.kernel.org
Reviewed-by: Michał Winiarski <michal.winiarski@intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1459864801-28606-2-git-send-email-chris@chris-wilson.co.uk
Diffstat (limited to 'drivers/gpu/drm/i915/i915_gem_userptr.c')
| -rw-r--r-- | drivers/gpu/drm/i915/i915_gem_userptr.c | 29 |
1 files changed, 17 insertions, 12 deletions
diff --git a/drivers/gpu/drm/i915/i915_gem_userptr.c b/drivers/gpu/drm/i915/i915_gem_userptr.c index d76847e7b636..3e31f59c6203 100644 --- a/drivers/gpu/drm/i915/i915_gem_userptr.c +++ b/drivers/gpu/drm/i915/i915_gem_userptr.c @@ -544,19 +544,24 @@ __i915_gem_userptr_get_pages_worker(struct work_struct *_work) if (pvec != NULL) { struct mm_struct *mm = obj->userptr.mm->mm; - down_read(&mm->mmap_sem); - while (pinned < npages) { - ret = get_user_pages_remote(work->task, mm, - obj->userptr.ptr + pinned * PAGE_SIZE, - npages - pinned, - !obj->userptr.read_only, 0, - pvec + pinned, NULL); - if (ret < 0) - break; - - pinned += ret; + ret = -EFAULT; + if (atomic_inc_not_zero(&mm->mm_users)) { + down_read(&mm->mmap_sem); + while (pinned < npages) { + ret = get_user_pages_remote + (work->task, mm, + obj->userptr.ptr + pinned * PAGE_SIZE, + npages - pinned, + !obj->userptr.read_only, 0, + pvec + pinned, NULL); + if (ret < 0) + break; + + pinned += ret; + } + up_read(&mm->mmap_sem); + mmput(mm); } - up_read(&mm->mmap_sem); } mutex_lock(&dev->struct_mutex); |