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Merge branch 'for-5.17-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup

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Pull cgroup fixes from Tejun Heo:

 - Fix for a subtle bug in the recent release_agent permission check
   update

 - Fix for a long-standing race condition between cpuset and cpu hotplug

 - Comment updates

* 'for-5.17-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup:
  cpuset: Fix kernel-doc
  cgroup-v1: Correct privileges check in release_agent writes
  cgroup: clarify cgroup_css_set_fork()
  cgroup/cpuset: Fix a race between cpuset_attach() and cpu hotplug
This commit is contained in:
Linus Torvalds 2022-02-22 16:14:35 -08:00
commit 5c1ee56966
3 changed files with 25 additions and 7 deletions
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6
kernel/cgroup/cgroup-v1.c
View File

@ -546,6 +546,7 @@ static ssize_t cgroup_release_agent_write(struct kernfs_open_file *of,
char *buf, size_t nbytes, loff_t off)
{
struct cgroup *cgrp;
struct cgroup_file_ctx *ctx;
BUILD_BUG_ON(sizeof(cgrp->root->release_agent_path) < PATH_MAX);
@ -553,8 +554,9 @@ static ssize_t cgroup_release_agent_write(struct kernfs_open_file *of,
* Release agent gets called with all capabilities,
* require capabilities to set release agent.
*/
if ((of->file->f_cred->user_ns != &init_user_ns) ||
!capable(CAP_SYS_ADMIN))
ctx = of->priv;
if ((ctx->ns->user_ns != &init_user_ns) ||
!file_ns_capable(of->file, &init_user_ns, CAP_SYS_ADMIN))
return -EPERM;
cgrp = cgroup_kn_lock_live(of->kn, false);

14
kernel/cgroup/cgroup.c
View File

@ -6166,6 +6166,20 @@ static int cgroup_css_set_fork(struct kernel_clone_args *kargs)
if (ret)
goto err;
/*
* Spawning a task directly into a cgroup works by passing a file
* descriptor to the target cgroup directory. This can even be an O_PATH
* file descriptor. But it can never be a cgroup.procs file descriptor.
* This was done on purpose so spawning into a cgroup could be
* conceptualized as an atomic
*
* fd = openat(dfd_cgroup, "cgroup.procs", ...);
* write(fd, <child-pid>, ...);
*
* sequence, i.e. it's a shorthand for the caller opening and writing
* cgroup.procs of the cgroup indicated by @dfd_cgroup. This allows us
* to always use the caller's credentials.
*/
ret = cgroup_attach_permissions(cset->dfl_cgrp, dst_cgrp, sb,
!(kargs->flags & CLONE_THREAD),
current->nsproxy->cgroup_ns);

12
kernel/cgroup/cpuset.c
View File

@ -2289,6 +2289,7 @@ static void cpuset_attach(struct cgroup_taskset *tset)
cgroup_taskset_first(tset, &css);
cs = css_cs(css);
cpus_read_lock();
percpu_down_write(&cpuset_rwsem);
guarantee_online_mems(cs, &cpuset_attach_nodemask_to);
@ -2342,6 +2343,7 @@ static void cpuset_attach(struct cgroup_taskset *tset)
wake_up(&cpuset_attach_wq);
percpu_up_write(&cpuset_rwsem);
cpus_read_unlock();
}
/* The various types of files and directories in a cpuset file system */
@ -3522,8 +3524,8 @@ static struct cpuset *nearest_hardwall_ancestor(struct cpuset *cs)
return cs;
}
/**
* cpuset_node_allowed - Can we allocate on a memory node?
/*
* __cpuset_node_allowed - Can we allocate on a memory node?
* @node: is this an allowed node?
* @gfp_mask: memory allocation flags
*
@ -3694,8 +3696,8 @@ void cpuset_print_current_mems_allowed(void)
int cpuset_memory_pressure_enabled __read_mostly;
/**
* cpuset_memory_pressure_bump - keep stats of per-cpuset reclaims.
/*
* __cpuset_memory_pressure_bump - keep stats of per-cpuset reclaims.
*
* Keep a running average of the rate of synchronous (direct)
* page reclaim efforts initiated by tasks in each cpuset.
@ -3710,7 +3712,7 @@ int cpuset_memory_pressure_enabled __read_mostly;
* "memory_pressure". Value displayed is an integer
* representing the recent rate of entry into the synchronous
* (direct) page reclaim by any task attached to the cpuset.
**/
*/
void __cpuset_memory_pressure_bump(void)
{