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[ Upstream commit9fe8fec5e4] hfi1_mmu_rb_remove_unless_exact() did not move mmu_rb_node objects in mmu_rb_handler->lru_list after getting a cache hit on an mmu_rb_node. As a result, hfi1_mmu_rb_evict() was not guaranteed to evict truly least-recently used nodes. This could be a performance issue for an application when that application: - Uses some long-lived buffers frequently. - Uses a large number of buffers once. - Hits the mmu_rb_handler cache size or pinned-page limits, forcing mmu_rb_handler cache entries to be evicted. In this case, the one-time use buffers cause the long-lived buffer entries to eventually filter to the end of the LRU list where hfi1_mmu_rb_evict() will consider evicting a frequently-used long-lived entry instead of evicting one of the one-time use entries. Fix this by inserting new mmu_rb_node at the tail of mmu_rb_handler->lru_list and move mmu_rb_ndoe to the tail of mmu_rb_handler->lru_list when the mmu_rb_node is a hit in hfi1_mmu_rb_remove_unless_exact(). Change hfi1_mmu_rb_evict() to evict from the head of mmu_rb_handler->lru_list instead of the tail. Fixes:0636e9ab83("IB/hfi1: Add cache evict LRU list") Signed-off-by: Brendan Cunningham <bcunningham@cornelisnetworks.com> Signed-off-by: Patrick Kelsey <pat.kelsey@cornelisnetworks.com> Signed-off-by: Dennis Dalessandro <dennis.dalessandro@cornelisnetworks.com> Link: https://lore.kernel.org/r/168088635931.3027109.10423156330761536044.stgit@252.162.96.66.static.eigbox.net Signed-off-by: Leon Romanovsky <leon@kernel.org> Signed-off-by: Sasha Levin <sashal@kernel.org>
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.