The patch titled cgroup: introduce cancel_attach() has been added to the -mm tree. Its filename is cgroup-introduce-cancel_attach.patch Before you just go and hit "reply", please: a) Consider who else should be cc'ed b) Prefer to cc a suitable mailing list as well c) Ideally: find the original patch on the mailing list and do a reply-to-all to that, adding suitable additional cc's *** Remember to use Documentation/SubmitChecklist when testing your code *** See http://userweb.kernel.org/~akpm/stuff/added-to-mm.txt to find out what to do about this The current -mm tree may be found at http://userweb.kernel.org/~akpm/mmotm/ ------------------------------------------------------ Subject: cgroup: introduce cancel_attach() From: Daisuke Nishimura <nishimura@xxxxxxxxxxxxxxxxx> Add cancel_attach() operation to struct cgroup_subsys. cancel_attach() can be used when can_attach() operation prepares something for the subsys, but we should rollback what can_attach() operation has prepared if attach task fails after we've succeeded in can_attach(). Signed-off-by: Daisuke Nishimura <nishimura@xxxxxxxxxxxxxxxxx> Acked-by: Li Zefan <lizf@xxxxxxxxxxxxxx> Reviewed-by: Paul Menage <menage@xxxxxxxxxx> Cc: Balbir Singh <balbir@xxxxxxxxxxxxxxxxxx> Acked-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@xxxxxxxxxxxxxx> Cc: Daisuke Nishimura <nishimura@xxxxxxxxxxxxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- Documentation/cgroups/cgroups.txt | 13 ++++++++- include/linux/cgroup.h | 2 + kernel/cgroup.c | 40 +++++++++++++++++++++++----- 3 files changed, 47 insertions(+), 8 deletions(-) diff -puN Documentation/cgroups/cgroups.txt~cgroup-introduce-cancel_attach Documentation/cgroups/cgroups.txt --- a/Documentation/cgroups/cgroups.txt~cgroup-introduce-cancel_attach +++ a/Documentation/cgroups/cgroups.txt @@ -536,10 +536,21 @@ returns an error, this will abort the at task is passed, then a successful result indicates that *any* unspecified task can be moved into the cgroup. Note that this isn't called on a fork. If this method returns 0 (success) then this should -remain valid while the caller holds cgroup_mutex. If threadgroup is +remain valid while the caller holds cgroup_mutex and it is ensured that either +attach() or cancel_attach() will be called in future. If threadgroup is true, then a successful result indicates that all threads in the given thread's threadgroup can be moved together. +void cancel_attach(struct cgroup_subsys *ss, struct cgroup *cgrp, + struct task_struct *task, bool threadgroup) +(cgroup_mutex held by caller) + +Called when a task attach operation has failed after can_attach() has succeeded. +A subsystem whose can_attach() has some side-effects should provide this +function, so that the subsytem can implement a rollback. If not, not necessary. +This will be called only about subsystems whose can_attach() operation have +succeeded. + void attach(struct cgroup_subsys *ss, struct cgroup *cgrp, struct cgroup *old_cgrp, struct task_struct *task, bool threadgroup) diff -puN include/linux/cgroup.h~cgroup-introduce-cancel_attach include/linux/cgroup.h --- a/include/linux/cgroup.h~cgroup-introduce-cancel_attach +++ a/include/linux/cgroup.h @@ -427,6 +427,8 @@ struct cgroup_subsys { void (*destroy)(struct cgroup_subsys *ss, struct cgroup *cgrp); int (*can_attach)(struct cgroup_subsys *ss, struct cgroup *cgrp, struct task_struct *tsk, bool threadgroup); + void (*cancel_attach)(struct cgroup_subsys *ss, struct cgroup *cgrp, + struct task_struct *tsk, bool threadgroup); void (*attach)(struct cgroup_subsys *ss, struct cgroup *cgrp, struct cgroup *old_cgrp, struct task_struct *tsk, bool threadgroup); diff -puN kernel/cgroup.c~cgroup-introduce-cancel_attach kernel/cgroup.c --- a/kernel/cgroup.c~cgroup-introduce-cancel_attach +++ a/kernel/cgroup.c @@ -1539,7 +1539,7 @@ int cgroup_path(const struct cgroup *cgr int cgroup_attach_task(struct cgroup *cgrp, struct task_struct *tsk) { int retval = 0; - struct cgroup_subsys *ss; + struct cgroup_subsys *ss, *failed_ss = NULL; struct cgroup *oldcgrp; struct css_set *cg; struct css_set *newcg; @@ -1553,8 +1553,16 @@ int cgroup_attach_task(struct cgroup *cg for_each_subsys(root, ss) { if (ss->can_attach) { retval = ss->can_attach(ss, cgrp, tsk, false); - if (retval) - return retval; + if (retval) { + /* + * Remember on which subsystem the can_attach() + * failed, so that we only call cancel_attach() + * against the subsystems whose can_attach() + * succeeded. (See below) + */ + failed_ss = ss; + goto out; + } } } @@ -1568,14 +1576,17 @@ int cgroup_attach_task(struct cgroup *cg */ newcg = find_css_set(cg, cgrp); put_css_set(cg); - if (!newcg) - return -ENOMEM; + if (!newcg) { + retval = -ENOMEM; + goto out; + } task_lock(tsk); if (tsk->flags & PF_EXITING) { task_unlock(tsk); put_css_set(newcg); - return -ESRCH; + retval = -ESRCH; + goto out; } rcu_assign_pointer(tsk->cgroups, newcg); task_unlock(tsk); @@ -1601,7 +1612,22 @@ int cgroup_attach_task(struct cgroup *cg * is no longer empty. */ cgroup_wakeup_rmdir_waiter(cgrp); - return 0; +out: + if (retval) { + for_each_subsys(root, ss) { + if (ss == failed_ss) + /* + * This subsystem was the one that failed the + * can_attach() check earlier, so we don't need + * to call cancel_attach() against it or any + * remaining subsystems. + */ + break; + if (ss->cancel_attach) + ss->cancel_attach(ss, cgrp, tsk, false); + } + } + return retval; } /* _ Patches currently in -mm which might be from nishimura@xxxxxxxxxxxxxxxxx are cgroup-introduce-cancel_attach.patch cgroup-introduce-coalesce-css_get-and-css_put.patch memcg-add-interface-to-move-charge-at-task-migration.patch memcg-move-charges-of-anonymous-page.patch memcg-move-charges-of-anonymous-page-cleanup.patch memcg-improve-performance-in-moving-charge.patch memcg-avoid-oom-during-moving-charge.patch memcg-move-charges-of-anonymous-swap.patch memcg-improve-performance-in-moving-swap-charge.patch -- To unsubscribe from this list: send the line "unsubscribe mm-commits" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html