f9c32a5a90
Currently the bcache internal btree node occupies a whole bucket. When loading the btree node from cache device into memory, mca_data_alloc() will call bch_btree_keys_alloc() to allocate memory for the whole bucket size, ilog2(b->c->btree_pages) is send to bch_btree_keys_alloc() as the parameter 'page_order'. c->btree_pages is set as bucket_pages() in bch_cache_set_alloc(), for bucket size > 8MB, ilog2(b->c->btree_pages) is 12 for 4KB page size. By default the maximum page order __get_free_pages() accepts is MAX_ORDER (11), in this condition bch_btree_keys_alloc() will always fail. Because of other over-page-order allocation failure fails the cache device registration, such btree node allocation failure wasn't observed during runtime. After other blocking page allocation failures for bucket size > 8MB, this btree node allocation issue may trigger potentical risk e.g. infinite dead-loop to retry btree node allocation after failure. This patch fixes the potential problem by setting c->btree_pages to meta_bucket_pages() in bch_cache_set_alloc(). In the condition that bucket size > 8MB, meta_bucket_pages() will always return a number which won't exceed the maximum page order of the buddy allocator. Signed-off-by: Coly Li <colyli@suse.de> Reviewed-by: Hannes Reinecke <hare@suse.de> Signed-off-by: Jens Axboe <axboe@kernel.dk>
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.