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TTM implements a rather extensive accounting of allocated memory. There are two reasons for this: 1. It tries to block userspace allocating a huge number of very small BOs without accounting for the kmalloced memory. 2. Make sure we don't over allocate and run into an OOM situation during swapout while trying to handle the memory shortage. This is only partially a good idea. First of all it is perfectly valid for an application to use all of system memory, limiting it to 50% is not really acceptable. What we need to take care of is that the application is held accountable for the memory it allocated. This is what control mechanisms like memcg and the normal Linux page accounting already do. Making sure that we don't run into an OOM situation while trying to cope with a memory shortage is still a good idea, but this is also not very well implemented since it means another opportunity of recursion from the driver back into TTM. So start to rework all of this by implementing a shrinker callback which allows for TT object to be swapped out if necessary. v2: Switch from limit to shrinker callback. v3: fix gfp mask handling, use atomic for swapable_pages, add debugfs v4: drop the extra gfp_mask checks Signed-off-by: Christian König <christian.koenig@amd.com> Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch> Link: https://patchwork.freedesktop.org/patch/msgid/20210208133226.36955-1-christian.koenig@amd.com
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.