This patch series fix a few bugs in mm/zswap based on Linux-3.11. v2 --> v3 - keep GFP_KERNEL flag v1 --> v2 - free memory in zswap_frontswap_invalidate_area(in patch 1) - fix whitespace corruption (line wrapping) Corresponding mail thread: https://lkml.org/lkml/2013/8/18/59 These issues fixed/optimized are: 1. memory leaks when re-swapon 2. memory leaks when invalidate and reclaim occur concurrently 3. avoid unnecessary page scanning Issues discussed in that mail thread NOT fixed as it happens rarely or not a big problem or controversial: 1. a "theoretical race condition" when reclaim page When a handle alloced from zbud, zbud considers this handle is used validly by upper(zswap) and can be a candidate for reclaim. But zswap has to initialize it such as setting swapentry and adding it to rbtree. so there is a race condition, such as: thread 0: obtain handle x from zbud_alloc thread 1: zbud_reclaim_page is called thread 1: callback zswap_writeback_entry to reclaim handle x thread 1: get swpentry from handle x (it is random value now) thread 1: bad thing may happen thread 0: initialize handle x with swapentry 2. frontswap_map bitmap not cleared after zswap reclaim Frontswap uses frontswap_map bitmap to track page in "backend" implementation, when zswap reclaim a page, the corresponding bitmap record is not cleared. 3. the potential that zswap store and reclaim functions called recursively mm/zswap.c | 28 ++++++++++++++++++++-------- 1 file changed, 20 insertions(+), 8 deletions(-) -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>