pm24.git/kernel/cgroup.c, branch v3.4-rc2

cgroup: cgroup_attach_task() could return -errno after success

2012-03-30T05:03:33Z

61d1d219c4 "cgroup: remove extra calls to find_existing_css_set" made cgroup_task_migrate() return void. An unfortunate side effect was that cgroup_attach_task() was depending on that function's return value to clear its @retval on the success path. On cgroup mounts without any subsystem with ->can_attach() callback, cgroup_attach_task() ended up returning @retval without initializing it on success. For some reason, gcc failed to warn about it and it didn't cause cgroup_attach_task() to return non-zero value in many cases, probably due to difference in register allocation. When the problem materializes, systemd fails to populate /systemd cgroup mount and fails to boot. Fix it by initializing @retval to zero on declaration. Signed-off-by: Tejun Heo Reported-by: Jiri Kosina LKML-Reference: Reviewed-by: Mandeep Singh Baines Acked-by: Li Zefan

Merge branch 'akpm' (Andrew's patch-bomb)

2012-03-22T16:04:48Z

Merge first batch of patches from Andrew Morton: "A few misc things and all the MM queue" * emailed from Andrew Morton : (92 commits) memcg: avoid THP split in task migration thp: add HPAGE_PMD_* definitions for !CONFIG_TRANSPARENT_HUGEPAGE memcg: clean up existing move charge code mm/memcontrol.c: remove unnecessary 'break' in mem_cgroup_read() mm/memcontrol.c: remove redundant BUG_ON() in mem_cgroup_usage_unregister_event() mm/memcontrol.c: s/stealed/stolen/ memcg: fix performance of mem_cgroup_begin_update_page_stat() memcg: remove PCG_FILE_MAPPED memcg: use new logic for page stat accounting memcg: remove PCG_MOVE_LOCK flag from page_cgroup memcg: simplify move_account() check memcg: remove EXPORT_SYMBOL(mem_cgroup_update_page_stat) memcg: kill dead prev_priority stubs memcg: remove PCG_CACHE page_cgroup flag memcg: let css_get_next() rely upon rcu_read_lock() cgroup: revert ss_id_lock to spinlock idr: make idr_get_next() good for rcu_read_lock() memcg: remove unnecessary thp check in page stat accounting memcg: remove redundant returns memcg: enum lru_list lru ...

memcg: let css_get_next() rely upon rcu_read_lock()

2012-03-22T00:55:01Z

Remove lock and unlock around css_get_next()'s call to idr_get_next(). memcg iterators (only users of css_get_next) already did rcu_read_lock(), and its comment demands that; but add a WARN_ON_ONCE to make sure of it. Signed-off-by: Hugh Dickins Acked-by: KAMEZAWA Hiroyuki Acked-by: Li Zefan Cc: Eric Dumazet Acked-by: Tejun Heo Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

cgroup: revert ss_id_lock to spinlock

2012-03-22T00:55:01Z

Commit c1e2ee2dc436 ("memcg: replace ss->id_lock with a rwlock") has now been seen to cause the unfair behavior we should have expected from converting a spinlock to an rwlock: softlockup in cgroup_mkdir(), whose get_new_cssid() is waiting for the wlock, while there are 19 tasks using the rlock in css_get_next() to get on with their memcg workload (in an artificial test, admittedly). Yet lib/idr.c was made suitable for RCU way back: revert that commit, restoring ss->id_lock to a spinlock. Signed-off-by: Hugh Dickins Acked-by: KAMEZAWA Hiroyuki Acked-by: Li Zefan Cc: Eric Dumazet Acked-by: Tejun Heo Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs

2012-03-21T20:36:41Z

Pull vfs pile 1 from Al Viro: "This is _not_ all; in particular, Miklos' and Jan's stuff is not there yet." * 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs: (64 commits) ext4: initialization of ext4_li_mtx needs to be done earlier debugfs-related mode_t whack-a-mole hfsplus: add an ioctl to bless files hfsplus: change finder_info to u32 hfsplus: initialise userflags qnx4: new helper - try_extent() qnx4: get rid of qnx4_bread/qnx4_getblk take removal of PF_FORKNOEXEC to flush_old_exec() trim includes in inode.c um: uml_dup_mmap() relies on ->mmap_sem being held, but activate_mm() doesn't hold it um: embed ->stub_pages[] into mmu_context gadgetfs: list_for_each_safe() misuse ocfs2: fix leaks on failure exits in module_init ecryptfs: make register_filesystem() the last potential failure exit ntfs: forgets to unregister sysctls on register_filesystem() failure logfs: missing cleanup on register_filesystem() failure jfs: mising cleanup on register_filesystem() failure make configfs_pin_fs() return root dentry on success configfs: configfs_create_dir() has parent dentry in dentry->d_parent configfs: sanitize configfs_create() ...

switch open-coded instances of d_make_root() to new helper

2012-03-21T01:29:35Z

Signed-off-by: Al Viro

cgroup: Walk task list under tasklist_lock in cgroup_enable_task_cg_list

2012-02-21T17:46:47Z

Walking through the tasklist in cgroup_enable_task_cg_list() inside an RCU read side critical section is not enough because: - RCU is not (yet) safe against while_each_thread() - If we use only RCU, a forking task that has passed cgroup_post_fork() without seeing use_task_css_set_links == 1 is not guaranteed to have its child immediately visible in the tasklist if we walk through it remotely with RCU. In this case it will be missing in its css_set's task list. Thus we need to traverse the list (unfortunately) under the tasklist_lock. It makes us safe against while_each_thread() and also make sure we see all forked task that have been added to the tasklist. As a secondary effect, reading and writing use_task_css_set_links are now well ordered against tasklist traversing and modification. The new layout is: CPU 0 CPU 1 use_task_css_set_links = 1 write_lock(tasklist_lock) read_lock(tasklist_lock) add task to tasklist do_each_thread() { write_unlock(tasklist_lock) add thread to css set links if (use_task_css_set_links) } while_each_thread() add thread to css set links read_unlock(tasklist_lock) If CPU 0 traverse the list after the task has been added to the tasklist then it is correctly added to the css set links. OTOH if CPU 0 traverse the tasklist before the new task had the opportunity to be added to the tasklist because it was too early in the fork process, then CPU 1 catches up and add the task to the css set links after it added the task to the tasklist. The right value of use_task_css_set_links is guaranteed to be visible from CPU 1 due to the LOCK/UNLOCK implicit barrier properties: the read_unlock on CPU 0 makes the write on use_task_css_set_links happening and the write_lock on CPU 1 make the read of use_task_css_set_links that comes afterward to return the correct value. Signed-off-by: Frederic Weisbecker Acked-by: Li Zefan Signed-off-by: Tejun Heo Cc: Mandeep Singh Baines Cc: Oleg Nesterov Cc: Andrew Morton Cc: Paul E. McKenney

cgroup: Remove wrong comment on cgroup_enable_task_cg_list()

2012-02-21T17:46:43Z

Remove the stale comment about RCU protection. Many callers (all of them?) of cgroup_enable_task_cg_list() don't seem to be in an RCU read side critical section. Besides, RCU is not helpful to protect against while_each_thread(). Signed-off-by: Frederic Weisbecker Acked-by: Li Zefan Signed-off-by: Tejun Heo Cc: Mandeep Singh Baines Cc: Oleg Nesterov Cc: Andrew Morton Cc: Paul E. McKenney

cgroup: remove cgroup_subsys argument from callbacks

2012-02-02T17:20:22Z

The argument is not used at all, and it's not necessary, because a specific callback handler of course knows which subsys it belongs to. Now only ->pupulate() takes this argument, because the handlers of this callback always call cgroup_add_file()/cgroup_add_files(). So we reduce a few lines of code, though the shrinking of object size is minimal. 16 files changed, 113 insertions(+), 162 deletions(-) text data bss dec hex filename 5486240 656987 7039960 13183187 c928d3 vmlinux.o.orig 5486170 656987 7039960 13183117 c9288d vmlinux.o Signed-off-by: Li Zefan Signed-off-by: Tejun Heo

cgroup: remove extra calls to find_existing_css_set

2012-01-30T21:01:39Z

In cgroup_attach_proc, we indirectly call find_existing_css_set 3 times. It is an expensive call so we want to call it a minimum of times. This patch only calls it once and stores the result so that it can be used later on when we call cgroup_task_migrate. This required modifying cgroup_task_migrate to take the new css_set (which we obtained from find_css_set) as a parameter. The nice side effect of this is that cgroup_task_migrate is now identical for cgroup_attach_task and cgroup_attach_proc. It also now returns a void since it can never fail. Changes in V5: * https://lkml.org/lkml/2012/1/20/344 (Tejun Heo) * Remove css_set_refs Changes in V4: * https://lkml.org/lkml/2011/12/22/421 (Li Zefan) * Avoid GFP_KERNEL (sleep) in rcu_read_lock by getting css_set in a separate loop not under an rcu_read_lock Changes in V3: * https://lkml.org/lkml/2011/12/22/13 (Li Zefan) * Fixed earlier bug by creating a seperate patch to remove tasklist_lock Changes in V2: * https://lkml.org/lkml/2011/12/20/372 (Tejun Heo) * Move find_css_set call into loop which creates the flex array * Author * Kill css_set_refs and use group_size instead * Fix an off-by-one error in counting css_set refs * Add a retval check in out_list_teardown Signed-off-by: Mandeep Singh Baines Acked-by: Li Zefan Signed-off-by: Tejun Heo Cc: containers@lists.linux-foundation.org Cc: cgroups@vger.kernel.org Cc: KAMEZAWA Hiroyuki Cc: Frederic Weisbecker Cc: Oleg Nesterov Cc: Andrew Morton Cc: Paul Menage