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author | Linus Torvalds <torvalds@linux-foundation.org> | 2017-04-11 23:38:16 -0700 |
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committer | Linus Torvalds <torvalds@linux-foundation.org> | 2017-04-11 23:38:16 -0700 |
commit | 06ea4c38bce80f3eb99b01d7c17419eb1a49fec2 (patch) | |
tree | 2af3797bce33f38ecfe39aa34ecec01e8ccd4b9c /kernel/cgroup/cgroup.c | |
parent | af94bdfa798b7da92cc82609acca61a287a004a4 (diff) | |
parent | bfb0b80db5f9dca5ac0a5fd0edb765ee555e5a8e (diff) | |
download | linux-stable-06ea4c38bce80f3eb99b01d7c17419eb1a49fec2.tar.gz linux-stable-06ea4c38bce80f3eb99b01d7c17419eb1a49fec2.tar.bz2 linux-stable-06ea4c38bce80f3eb99b01d7c17419eb1a49fec2.zip |
Merge branch 'for-4.11-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup
Pull cgroup fixes from Tejun Heo:
"This contains fixes for two long standing subtle bugs:
- kthread_bind() on a new kthread binds it to specific CPUs and
prevents userland from messing with the affinity or cgroup
membership. Unfortunately, for cgroup membership, there's a window
between kthread creation and kthread_bind*() invocation where the
kthread can be moved into a non-root cgroup by userland.
Depending on what controllers are in effect, this can assign the
kthread unexpected attributes. For example, in the reported case,
workqueue workers ended up in a non-root cpuset cgroups and had
their CPU affinities overridden. This broke workqueue invariants
and led to workqueue stalls.
Fixed by closing the window between kthread creation and
kthread_bind() as suggested by Oleg.
- There was a bug in cgroup mount path which could allow two
competing mount attempts to attach the same cgroup_root to two
different superblocks.
This was caused by mishandling return value from kernfs_pin_sb().
Fixed"
* 'for-4.11-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup:
cgroup: avoid attaching a cgroup root to two different superblocks
cgroup, kthread: close race window where new kthreads can be migrated to non-root cgroups
Diffstat (limited to 'kernel/cgroup/cgroup.c')
-rw-r--r-- | kernel/cgroup/cgroup.c | 9 |
1 files changed, 5 insertions, 4 deletions
diff --git a/kernel/cgroup/cgroup.c b/kernel/cgroup/cgroup.c index 48851327a15e..687f5e0194ef 100644 --- a/kernel/cgroup/cgroup.c +++ b/kernel/cgroup/cgroup.c @@ -2425,11 +2425,12 @@ ssize_t __cgroup_procs_write(struct kernfs_open_file *of, char *buf, tsk = tsk->group_leader; /* - * Workqueue threads may acquire PF_NO_SETAFFINITY and become - * trapped in a cpuset, or RT worker may be born in a cgroup - * with no rt_runtime allocated. Just say no. + * kthreads may acquire PF_NO_SETAFFINITY during initialization. + * If userland migrates such a kthread to a non-root cgroup, it can + * become trapped in a cpuset, or RT kthread may be born in a + * cgroup with no rt_runtime allocated. Just say no. */ - if (tsk == kthreadd_task || (tsk->flags & PF_NO_SETAFFINITY)) { + if (tsk->no_cgroup_migration || (tsk->flags & PF_NO_SETAFFINITY)) { ret = -EINVAL; goto out_unlock_rcu; } |