87701b4b55
Inspired by Tvrtko's critique of the reaping of the stale contexts before allocating a new one, also limit the freed object reaping to the oldest stale object before allocating a fresh object. Unlike contexts, objects may have radically different sizes of backing storage, but similar to contexts, while we want to prevent starvation due to excessive freed lists, we also do not want to delay fresh allocations for too long. Only freeing the oldest on the freed object list before each allocation is a reasonable compromise. v2: Only a single consumer of llist_del_first() is allowed (although multiple llist_add are still allowed in parallel). Unlike i915_gem_context, i915_gem_flush_free_objects() is itself not serialized and so we need to add our own spinlock. Otherwise KASAN eventually spots a use-after-free for the race on *first->next. 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> #v1 Reviewed-by: Joonas Lahtinen <joonas.lahtinen@linux.intel.com> Link: https://patchwork.freedesktop.org/patch/msgid/20171013202621.7276-8-chris@chris-wilson.co.uk
Linux kernel ============ This file was moved to Documentation/admin-guide/README.rst Please notice that there are several guides for kernel developers and users. These guides can be rendered in a number of formats, like HTML and PDF. In order to build the documentation, use ``make htmldocs`` or ``make pdfdocs``. There are various text files in the Documentation/ subdirectory, several of them using the Restructured Text markup notation. See Documentation/00-INDEX for a list of what is contained in each file. 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.