The patch titled
cgroups: forbid noprefix if mounting more than just cpuset subsystem
has been added to the -mm tree. Its filename is
cgroups-forbid-noprefix-if-mounting-more-than-just-cpuset-subsystem.patch
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Subject: cgroups: forbid noprefix if mounting more than just cpuset subsystem
From: Li Zefan <lizf@xxxxxxxxxxxxxx>
The 'noprefix' option was introduced for backwards-compatibility of
cpuset, but actually it can be used when mounting other subsystems.
This results in possibility of name collision, and now the collision can
really happen, because we have 'stat' file in both memory and cpuacct
subsystem:
# mount -t cgroup -o noprefix,memory,cpuacct xxx /mnt
Cgroup will happily mount the 2 subsystems, but only 'stat' file of memory
subsys can be seen.
We don't want users to use nopreifx, and also want to avoid name
collision, so we change to allow noprefix only if mounting just the cpuset
subsystem.
Signed-off-by: Li Zefan <lizf@xxxxxxxxxxxxxx>
Cc: Paul Menage <menage@xxxxxxxxxx>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@xxxxxxxxxxxxxx>
Cc: Balbir Singh <balbir@xxxxxxxxxxxxxxxxxx>
Cc: Dhaval Giani <dhaval@xxxxxxxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
kernel/cgroup.c | 10 ++++++++++
1 file changed, 10 insertions(+)
diff -puN kernel/cgroup.c~cgroups-forbid-noprefix-if-mounting-more-than-just-cpuset-subsystem kernel/cgroup.c
--- a/kernel/cgroup.c~cgroups-forbid-noprefix-if-mounting-more-than-just-cpuset-subsystem
+++ a/kernel/cgroup.c
@@ -842,6 +842,11 @@ static int parse_cgroupfs_options(char *
struct cgroup_sb_opts *opts)
{
char *token, *o = data ?: "all";
+ unsigned long mask = (unsigned long)-1;
+
+#ifdef CONFIG_CPUSETS
+ mask = ~(1 << cpuset_subsys_id);
+#endif
opts->subsys_bits = 0;
opts->flags = 0;
@@ -886,6 +891,11 @@ static int parse_cgroupfs_options(char *
}
}
+ /* We allow noprefix only if mounting just the cpuset subsystem */
+ if (test_bit(ROOT_NOPREFIX, &opts->flags) &&
+ (opts->subsys_bits & mask))
+ return -EINVAL;
+
/* We can't have an empty hierarchy */
if (!opts->subsys_bits)
return -EINVAL;
_
Patches currently in -mm which might be from lizf@xxxxxxxxxxxxxx are
origin.patch
linux-next.patch
mm-add-swap-cache-interface-for-swap-reference.patch
mm-modify-swap_map-and-add-swap_has_cache-flag.patch
mm-reuse-unused-swap-entry-if-necessary.patch
hexdump-remove-the-trailing-space.patch
cgroups-make-messages-more-readable.patch
cgroups-forbid-noprefix-if-mounting-more-than-just-cpuset-subsystem.patch
devcgroup-skip-superfluous-checks-when-found-the-dev_all-elem.patch
memcg-remove-some-redundant-checks.patch
memcg-remove-unneeded-forward-declaration-from-schedh.patch
memcg-fix-swap-accounting.patch
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