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2014-10-09zbud: avoid accessing last unused freelistChao Yu
For now, there are NCHUNKS of 64 freelists in zbud_pool, the last unbuddied[63] freelist linked with all zbud pages which have free chunks of 63. Calculating according to context of num_free_chunks(), our max chunk number of unbuddied zbud page is 62, so none of zbud pages will be added/removed in last freelist, but still we will try to find an unbuddied zbud page in the last unused freelist, it is unneeded. This patch redefines NCHUNKS to 63 as free chunk number in one zbud page, hence we can decrease size of zpool and avoid accessing the last unused freelist whenever failing to allocate zbud from freelist in zbud_alloc. Signed-off-by: Chao Yu <chao2.yu@samsung.com> Cc: Seth Jennings <sjennings@variantweb.net> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2014-08-29mm/zpool: use prefixed module loadingKees Cook
To avoid potential format string expansion via module parameters, do not use the zpool type directly in request_module() without a format string. Additionally, to avoid arbitrary modules being loaded via zpool API (e.g. via the zswap_zpool_type module parameter) add a "zpool-" prefix to the requested module, as well as module aliases for the existing zpool types (zbud and zsmalloc). Signed-off-by: Kees Cook <keescook@chromium.org> Cc: Seth Jennings <sjennings@variantweb.net> Cc: Minchan Kim <minchan@kernel.org> Cc: Nitin Gupta <ngupta@vflare.org> Acked-by: Dan Streetman <ddstreet@ieee.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2014-08-06mm/zpool: zbud/zsmalloc implement zpoolDan Streetman
Update zbud and zsmalloc to implement the zpool api. [fengguang.wu@intel.com: make functions static] Signed-off-by: Dan Streetman <ddstreet@ieee.org> Tested-by: Seth Jennings <sjennings@variantweb.net> Cc: Minchan Kim <minchan@kernel.org> Cc: Nitin Gupta <ngupta@vflare.org> Cc: Weijie Yang <weijie.yang@samsung.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2014-08-06mm/zbud: change zbud_alloc size type to size_tDan Streetman
Change the type of the zbud_alloc() size param from unsigned int to size_t. Technically, this should not make any difference, as the zbud implementation already restricts the size to well within either type's limits; but as zsmalloc (and kmalloc) use size_t, and zpool will use size_t, this brings the size parameter type in line with zsmalloc/zpool. Signed-off-by: Dan Streetman <ddstreet@ieee.org> Acked-by: Seth Jennings <sjennings@variantweb.net> Tested-by: Seth Jennings <sjennings@variantweb.net> Cc: Weijie Yang <weijie.yang@samsung.com> Cc: Minchan Kim <minchan@kernel.org> Cc: Nitin Gupta <ngupta@vflare.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2014-06-04mm/zbud.c: make size unsigned like unique callsiteFabian Frederick
zbud_alloc is only called by zswap_frontswap_store with unsigned int len. Change function parameter + update >= 0 check. Signed-off-by: Fabian Frederick <fabf@skynet.be> Acked-by: Seth Jennings <sjennings@variantweb.net> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2013-09-11mm/zbud: fix some trivial typos in commentsJianguo Wu
Signed-off-by: Jianguo Wu <wujianguo@huawei.com> Cc: Seth Jennings <sjenning@linux.vnet.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2013-07-31mm: zbud: fix condition check on allocation sizeHeesub Shin
zbud_alloc() incorrectly verifies the size of allocation limit. It should deny the allocation request greater than (PAGE_SIZE - ZHDR_SIZE_ALIGNED - CHUNK_SIZE), not (PAGE_SIZE - ZHDR_SIZE_ALIGNED) which has no remaining spaces for its buddy. There is no point in spending the entire zbud page storing only a single page, since we don't have any benefits. Signed-off-by: Heesub Shin <heesub.shin@samsung.com> Acked-by: Seth Jennings <sjenning@linux.vnet.ibm.com> Cc: Bob Liu <bob.liu@oracle.com> Cc: Dongjun Shin <d.j.shin@samsung.com> Cc: Sunae Seo <sunae.seo@samsung.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2013-07-10zbud: add to mm/Seth Jennings
zbud is an special purpose allocator for storing compressed pages. It is designed to store up to two compressed pages per physical page. While this design limits storage density, it has simple and deterministic reclaim properties that make it preferable to a higher density approach when reclaim will be used. zbud works by storing compressed pages, or "zpages", together in pairs in a single memory page called a "zbud page". The first buddy is "left justifed" at the beginning of the zbud page, and the last buddy is "right justified" at the end of the zbud page. The benefit is that if either buddy is freed, the freed buddy space, coalesced with whatever slack space that existed between the buddies, results in the largest possible free region within the zbud page. zbud also provides an attractive lower bound on density. The ratio of zpages to zbud pages can not be less than 1. This ensures that zbud can never "do harm" by using more pages to store zpages than the uncompressed zpages would have used on their own. This implementation is a rewrite of the zbud allocator internally used by zcache in the driver/staging tree. The rewrite was necessary to remove some of the zcache specific elements that were ingrained throughout and provide a generic allocation interface that can later be used by zsmalloc and others. This patch adds zbud to mm/ for later use by zswap. Signed-off-by: Seth Jennings <sjenning@linux.vnet.ibm.com> Acked-by: Rik van Riel <riel@redhat.com> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: Nitin Gupta <ngupta@vflare.org> Cc: Minchan Kim <minchan@kernel.org> Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com> Cc: Dan Magenheimer <dan.magenheimer@oracle.com> Cc: Robert Jennings <rcj@linux.vnet.ibm.com> Cc: Jenifer Hopper <jhopper@us.ibm.com> Cc: Mel Gorman <mgorman@suse.de> Cc: Johannes Weiner <jweiner@redhat.com> Cc: Larry Woodman <lwoodman@redhat.com> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Dave Hansen <dave@sr71.net> Cc: Joe Perches <joe@perches.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Cody P Schafer <cody@linux.vnet.ibm.com> Cc: Hugh Dickens <hughd@google.com> Cc: Paul Mackerras <paulus@samba.org> Cc: Bob Liu <bob.liu@oracle.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>