The patch titled
a fixlet for cgroups-make-cgroup_path-rcu-safe.patch
has been added to the -mm tree. Its filename is
cgroups-make-cgroup_path-rcu-safe-fixlet.patch
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Subject: a fixlet for cgroups-make-cgroup_path-rcu-safe.patch
From: Li Zefan <lizf@xxxxxxxxxxxxxx>
With cgroups-make-cgroup_path-rcu-safe.patch applied, I can trigger kernel
panic easily using this test program:
for ((; ;))
{
mount -t cgroup -o debug xxx /mnt
mkdir /mnt/0
rmdir /mnt/0
umount /mnt
}
It's caused by the deactive_super() in rcu callback.
This patch restores the original code that call deactive_super() in
cgroup_diput().
Also remove duplicated comment in cgroup.h added by the patch.
Signed-off-by: Li Zefan <lizf@xxxxxxxxxxxxxx>
Cc: Paul Menage <menage@xxxxxxxxxx>
Cc: Peter Zijlstra <a.p.zijlstra@xxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
include/linux/cgroup.h | 6 ------
include/linux/cgroup.h.orig | 6 ++++++
kernel/cgroup.c | 11 ++++++-----
3 files changed, 12 insertions(+), 11 deletions(-)
diff -puN include/linux/cgroup.h~cgroups-make-cgroup_path-rcu-safe-fixlet include/linux/cgroup.h
--- a/include/linux/cgroup.h~cgroups-make-cgroup_path-rcu-safe-fixlet
+++ a/include/linux/cgroup.h
@@ -308,12 +308,6 @@ int cgroup_add_files(struct cgroup *cgrp
int cgroup_is_removed(const struct cgroup *cgrp);
-/*
- * cgroup_path() fills in a filesystem-like path for the given cgroup
- * into "buf", up to "buflen" characters. Should be called with
- * cgroup_mutex held, or else in an RCU section with an RCU-protected
- * cgroup reference
- */
int cgroup_path(const struct cgroup *cgrp, char *buf, int buflen);
int cgroup_task_count(const struct cgroup *cgrp);
diff -puN include/linux/cgroup.h.orig~cgroups-make-cgroup_path-rcu-safe-fixlet include/linux/cgroup.h.orig
--- a/include/linux/cgroup.h.orig~cgroups-make-cgroup_path-rcu-safe-fixlet
+++ a/include/linux/cgroup.h.orig
@@ -308,6 +308,12 @@ int cgroup_add_files(struct cgroup *cgrp
int cgroup_is_removed(const struct cgroup *cgrp);
+/*
+ * cgroup_path() fills in a filesystem-like path for the given cgroup
+ * into "buf", up to "buflen" characters. Should be called with
+ * cgroup_mutex held, or else in an RCU section with an RCU-protected
+ * cgroup reference
+ */
int cgroup_path(const struct cgroup *cgrp, char *buf, int buflen);
int cgroup_task_count(const struct cgroup *cgrp);
diff -puN kernel/cgroup.c~cgroups-make-cgroup_path-rcu-safe-fixlet kernel/cgroup.c
--- a/kernel/cgroup.c~cgroups-make-cgroup_path-rcu-safe-fixlet
+++ a/kernel/cgroup.c
@@ -598,11 +598,6 @@ static void cgroup_call_pre_destroy(stru
static void free_cgroup_rcu(struct rcu_head *obj)
{
struct cgroup *cgrp = container_of(obj, struct cgroup, rcu_head);
- /*
- * Drop the active superblock reference that we took when we
- * created the cgroup
- */
- deactivate_super(cgrp->root->sb);
kfree(cgrp);
}
@@ -632,6 +627,12 @@ static void cgroup_diput(struct dentry *
cgrp->root->number_of_cgroups--;
mutex_unlock(&cgroup_mutex);
+ /*
+ * Drop the active superblock reference that we took when we
+ * created the cgroup
+ */
+ deactivate_super(cgrp->root->sb);
+
call_rcu(&cgrp->rcu_head, free_cgroup_rcu);
}
iput(inode);
_
Patches currently in -mm which might be from lizf@xxxxxxxxxxxxxx are
linux-next.patch
cpuacct-refactoring-cpuusage_read-cpuusage_write.patch
cpuacct-export-percpu-cpuacct-cgroup-stats.patch
oom-print-triggering-tasks-cpuset-and-mems-allowed-fix.patch
cgroups-documentation-updates.patch
cgroups-remove-some-redundant-null-checks.patch
ns_cgroup-remove-unused-spinlock.patch
memcg-fix-a-typo-in-kconfig.patch
cgroups-make-root_list-contains-active-hierarchies-only.patch
cgroups-add-inactive-subsystems-to-rootnodesubsys_list.patch
cgroups-add-inactive-subsystems-to-rootnodesubsys_list-fix.patch
cgroups-introduce-link_css_set-to-remove-duplicate-code.patch
cgroups-introduce-link_css_set-to-remove-duplicate-code-fix.patch
cgroups-make-cgroup_path-rcu-safe.patch
cgroups-make-cgroup_path-rcu-safe-fixlet.patch
devices-cgroup-allow-mkfifo.patch
memcg-reduce-size-of-mem_cgroup-by-using-nr_cpu_ids.patch
memcg-new-force_empty-to-free-pages-under-group.patch
memcg-new-force_empty-to-free-pages-under-group-fix.patch
memcg-new-force_empty-to-free-pages-under-group-fix-fix.patch
memcg-handle-swap-caches.patch
memcg-memswap-controller-kconfig.patch
memcg-swap-cgroup-for-remembering-usage.patch
memcg-memswap-controller-core.patch
memcg-memswap-controller-core-make-resize-limit-hold-mutex.patch
memcg-memswap-controller-core-swapcache-fixes.patch
memcg-synchronized-lru.patch
memcg-add-mem_cgroup_disabled.patch
memcg-add-mem_cgroup_disabled-fix.patch
memory-cgroup-hierarchy-documentation-v4.patch
memory-cgroup-resource-counters-for-hierarchy-v4.patch
memory-cgroup-resource-counters-for-hierarchy-v4-checkpatch-fixes.patch
memory-cgroup-hierarchical-reclaim-v4.patch
memory-cgroup-hierarchical-reclaim-v4-checkpatch-fixes.patch
memory-cgroup-hierarchical-reclaim-v4-fix-for-hierarchical-reclaim.patch
memory-cgroup-hierarchy-feature-selector-v4.patch
memory-cgroup-hierarchy-feature-selector-v4-fix.patch
memcg-avoid-unnecessary-system-wide-oom-killer.patch
memcg-avoid-unnecessary-system-wide-oom-killer-fix.patch
memcg-fix-reclaim-result-checks.patch
memcg-swapout-refcnt-fix.patch
memcg-fix-double-free-and-make-refcnt-sane.patch
memcg-use-css_tryget-in-memcg.patch
cgroups-add-a-per-subsystem-hierarchy_mutex.patch
cgroups-use-hierarchy_mutex-in-memory-controller.patch
cgroups-add-css_tryget.patch
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