When inserting a VMA, we restrict the placement to the low 4G unless the caller opts into using the full range. This was done to allow usersapce the opportunity to transition slowly from a 32b address space, and to avoid breaking inherent 32b assumptions of some commands. However, for insert we limited ourselves to 4G-4K, but on verification we allowed the full 4G. This causes some attempts to bind a new buffer to sporadically fail with -ENOSPC, but at other times be bound successfully. commit 48ea1e32c39d ("drm/i915/gen9: Set PIN_ZONE_4G end to 4GB - 1 page") suggests that there is a genuine problem with stateless addressing that cannot utilize the last page in 4G and so we purposefully excluded it. This means that the quick pin pass may cause us to utilize a buggy placement. Reported-by: CQ Tang <cq.tang@intel.com> Testcase: igt/gem_exec_params/larger-than-life-batch Fixes: 48ea1e32c39d ("drm/i915/gen9: Set PIN_ZONE_4G end to 4GB - 1 page") Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk> Cc: CQ Tang <cq.tang@intel.com> Reviewed-by: CQ Tang <cq.tang@intel.com> Reviewed-by: Matthew Auld <matthew.auld@intel.com> Cc: <stable@vger.kernel.org> # v4.5+ Link: https://patchwork.freedesktop.org/patch/msgid/20201216092951.7124-1-chris@chris-wilson.co.uk
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.
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