On Fri, Aug 23, 2013 at 07:26:01PM +0800, Weijie Yang wrote: > This patch series fix a few bugs in zswap based on Linux-3.11-rc6. > > Corresponding mail thread see: lkml.org/lkml/2013/8/18/59 . > > These issues fixed are: > 1. memory leaks when re-swapon > 2. potential problem which store and reclaim functions is called recursively > 3. memory leaks when invalidate and reclaim occur simultaneously > 4. unnecessary page scanning Thanks for the patches! Patches 2-4 have whitespace corruption (line wrapping) probably caused by your mail agent. You might check Documentation/email-clients.txt on how to prevent this. Seth > > Issues discussed in that mail thread NOT fixed as it happens rarely or > not a big problem: > 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. > > mm/zswap.c | 35 ++++++++++++++++++++++++----------- > 1 files changed, 24 insertions(+), 11 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>