6.12-stable review patch. If anyone has any objections, please let me know.
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From: T.J. Mercier tjmercier@google.com
[ Upstream commit 1bf67c8fdbda21fadd564a12dbe2b13c1ea5eda7 ]
Android has mounted the v1 cpuset controller using filesystem type "cpuset" (not "cgroup") since 2015 [1], and depends on the resulting behavior where the controller name is not added as a prefix for cgroupfs files. [2]
Later, a problem was discovered where cpu hotplug onlining did not affect the cpuset/cpus files, which Android carried an out-of-tree patch to address for a while. An attempt was made to upstream this patch, but the recommendation was to use the "cpuset_v2_mode" mount option instead. [3]
An effort was made to do so, but this fails with "cgroup: Unknown parameter 'cpuset_v2_mode'" because commit e1cba4b85daa ("cgroup: Add mount flag to enable cpuset to use v2 behavior in v1 cgroup") did not update the special cased cpuset_mount(), and only the cgroup (v1) filesystem type was updated.
Add parameter parsing to the cpuset filesystem type so that cpuset_v2_mode works like the cgroup filesystem type:
$ mkdir /dev/cpuset $ mount -t cpuset -ocpuset_v2_mode none /dev/cpuset $ mount|grep cpuset none on /dev/cpuset type cgroup (rw,relatime,cpuset,noprefix,cpuset_v2_mode,release_agent=/sbin/cpuset_release_agent)
[1] https://cs.android.com/android/_/android/platform/system/core/+/b769c8d24fd7... [2] https://cs.android.com/android/platform/superproject/main/+/main:system/core... [3] https://lore.kernel.org/lkml/f795f8be-a184-408a-0b5a-553d26061385@redhat.com...
Fixes: e1cba4b85daa ("cgroup: Add mount flag to enable cpuset to use v2 behavior in v1 cgroup") Signed-off-by: T.J. Mercier tjmercier@google.com Acked-by: Waiman Long longman@redhat.com Reviewed-by: Kamalesh Babulal kamalesh.babulal@oracle.com Acked-by: Michal Koutný mkoutny@suse.com Signed-off-by: Tejun Heo tj@kernel.org Signed-off-by: Sasha Levin sashal@kernel.org --- kernel/cgroup/cgroup.c | 29 +++++++++++++++++++++++++++++ 1 file changed, 29 insertions(+)
diff --git a/kernel/cgroup/cgroup.c b/kernel/cgroup/cgroup.c index 4378f3eff25d2..e63d6f3b00470 100644 --- a/kernel/cgroup/cgroup.c +++ b/kernel/cgroup/cgroup.c @@ -2339,9 +2339,37 @@ static struct file_system_type cgroup2_fs_type = { };
#ifdef CONFIG_CPUSETS_V1 +enum cpuset_param { + Opt_cpuset_v2_mode, +}; + +static const struct fs_parameter_spec cpuset_fs_parameters[] = { + fsparam_flag ("cpuset_v2_mode", Opt_cpuset_v2_mode), + {} +}; + +static int cpuset_parse_param(struct fs_context *fc, struct fs_parameter *param) +{ + struct cgroup_fs_context *ctx = cgroup_fc2context(fc); + struct fs_parse_result result; + int opt; + + opt = fs_parse(fc, cpuset_fs_parameters, param, &result); + if (opt < 0) + return opt; + + switch (opt) { + case Opt_cpuset_v2_mode: + ctx->flags |= CGRP_ROOT_CPUSET_V2_MODE; + return 0; + } + return -EINVAL; +} + static const struct fs_context_operations cpuset_fs_context_ops = { .get_tree = cgroup1_get_tree, .free = cgroup_fs_context_free, + .parse_param = cpuset_parse_param, };
/* @@ -2378,6 +2406,7 @@ static int cpuset_init_fs_context(struct fs_context *fc) static struct file_system_type cpuset_fs_type = { .name = "cpuset", .init_fs_context = cpuset_init_fs_context, + .parameters = cpuset_fs_parameters, .fs_flags = FS_USERNS_MOUNT, }; #endif