8cc621d2f4
Pages containing buffer_heads that are in one of the per-CPU buffer_head LRU caches will be pinned and thus cannot be migrated. This can prevent CMA allocations from succeeding, which are often used on platforms with co-processors (such as a DSP) that can only use physically contiguous memory. It can also prevent memory hot-unplugging from succeeding, which involves migrating at least MIN_MEMORY_BLOCK_SIZE bytes of memory, which ranges from 8 MiB to 1 GiB based on the architecture in use. Correspondingly, invalidate the BH LRU caches before a migration starts and stop any buffer_head from being cached in the LRU caches, until migration has finished. Link: https://lkml.kernel.org/r/20210319175127.886124-3-minchan@kernel.org Signed-off-by: Minchan Kim <minchan@kernel.org> Reported-by: Chris Goldsworthy <cgoldswo@codeaurora.org> Reported-by: Laura Abbott <labbott@kernel.org> Tested-by: Oliver Sang <oliver.sang@intel.com> Cc: David Hildenbrand <david@redhat.com> Cc: John Dias <joaodias@google.com> Cc: Matthew Wilcox <willy@infradead.org> Cc: Michal Hocko <mhocko@suse.com> Cc: Suren Baghdasaryan <surenb@google.com> Cc: Vlastimil Babka <vbabka@suse.cz> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.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.