On 10/20/18 12:56 PM, Dennis Zhou wrote: > Hi everyone, > > It was reported in [1] that blk_get_rl() cleanup patch was causing a > null pointer dereference. After some back and forth debugging with > Valdis, it turns out I wasn't properly handling association with > recursive calls to make_request(). > > Another issue was identified with the blk_get_rl() update as it is > possible under certain circumstances that a blkg cannot be allocated > when called in blk_get_rl(). This could result in the blkcg_root being > returned. However, the blkcg_root is a special case where all blkgs > share the request_queue's request_list. > > The original series can be found at [2]. > > [1] https://lore.kernel.org/lkml/13987.1539646128@xxxxxxxxxxxxxxxxxxxxxxx/ > [2] https://lore.kernel.org/lkml/20180911184137.35897-1-dennisszhou@xxxxxxxxx/ > > This patchset contains the following 2 patches: > 0001-blkcg-fix-edge-case-for-blk_get_rl-under-memory-pres.patch > 0002-blkcg-reassociate-bios-when-make_request-is-called-r.patch > > 0001 addresses an edge case where a blkg cannot be created and can > possibly return a blkg associated with the blkcg_root. 0002 fixes the > stale association when make_request() is called recursively. Thanks Dennis, applied. -- Jens Axboe
