There are several places in kernel/cgroup.c where task->cgroups is
accessed and modified without going through proper RCU accessors.
None is broken as they're all lock protected accesses; however, this
still triggers sparse RCU address space warnings.
* Consistently use task_css_set() for task->cgroups dereferencing.
* Use RCU_INIT_POINTER() to clear task->cgroups to &init_css_set on
exit.
* Remove unnecessary rcu_dereference_raw() from cset->subsys[]
dereference in cgroup_exit().
Signed-off-by: Tejun Heo <tj@kernel.org>
Reported-by: Fengguang Wu <fengguang.wu@intel.com>
Acked-by: Li Zefan <lizefan@huawei.com>
task->cgroups is a RCU pointer pointing to struct css_set. A task
switches to a different css_set on cgroup migration but a css_set
doesn't change once created and its pointers to cgroup_subsys_states
aren't RCU protected.
task_subsys_state[_check]() is the macro to acquire css given a task
and subsys_id pair. It RCU-dereferences task->cgroups->subsys[] not
task->cgroups, so the RCU pointer task->cgroups ends up being
dereferenced without read_barrier_depends() after it. It's broken.
Fix it by introducing task_css_set[_check]() which does
RCU-dereference on task->cgroups. task_subsys_state[_check]() is
reimplemented to directly dereference ->subsys[] of the css_set
returned from task_css_set[_check]().
This removes some of sparse RCU warnings in cgroup.
v2: Fixed unbalanced parenthsis and there's no need to use
rcu_dereference_raw() when !CONFIG_PROVE_RCU. Both spotted by Li.
Signed-off-by: Tejun Heo <tj@kernel.org>
Reported-by: Fengguang Wu <fengguang.wu@intel.com>
Acked-by: Li Zefan <lizefan@huawei.com>
Cc: stable@vger.kernel.org
This isn't strictly necessary as all subsystems specified in
@subsys_mask are guaranteed to be pinned; however, it does spuriously
trigger lockdep warning. Let's grab cgroup_mutex around it.
Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Li Zefan <lizefan@huawei.com>
cgroupfs_root used to have ->actual_subsys_mask in addition to
->subsys_mask. a8a648c4ac ("cgroup: remove
cgroup->actual_subsys_mask") removed it noting that the subsys_mask is
essentially temporary and doesn't belong in cgroupfs_root; however,
the patch made it impossible to tell whether a cgroupfs_root actually
has the subsystems bound or just have the bits set leading to the
following BUG when trying to mount with subsystems which are already
mounted elsewhere.
kernel BUG at kernel/cgroup.c:1038!
invalid opcode: 0000 [#1] PREEMPT SMP DEBUG_PAGEALLOC
...
CPU: 1 PID: 7973 Comm: mount Tainted: G W 3.10.0-rc7-next-20130625-sasha-00011-g1c1dc0e #1105
task: ffff880fc0ae8000 ti: ffff880fc0b9a000 task.ti: ffff880fc0b9a000
RIP: 0010:[<ffffffff81249b29>] [<ffffffff81249b29>] rebind_subsystems+0x409/0x5f0
...
Call Trace:
[<ffffffff8124bd4f>] cgroup_kill_sb+0xff/0x210
[<ffffffff813d21af>] deactivate_locked_super+0x4f/0x90
[<ffffffff8124f3b3>] cgroup_mount+0x673/0x6e0
[<ffffffff81257169>] cpuset_mount+0xd9/0x110
[<ffffffff813d2580>] mount_fs+0xb0/0x2d0
[<ffffffff81404afd>] vfs_kern_mount+0xbd/0x180
[<ffffffff814070b5>] do_new_mount+0x145/0x2c0
[<ffffffff814085d6>] do_mount+0x356/0x3c0
[<ffffffff8140873d>] SyS_mount+0xfd/0x140
[<ffffffff854eb600>] tracesys+0xdd/0xe2
We still want rebind_subsystems() to take added/removed masks, so
let's fix it by marking whether a cgroupfs_root has finished binding
or not. Also, document what's going on around ->subsys_mask
initialization so that similar mistakes aren't repeated.
Signed-off-by: Tejun Heo <tj@kernel.org>
Reported-by: Sasha Levin <sasha.levin@oracle.com>
Acked-by: Li Zefan <lizefan@huawei.com>
Remove dead function prototype xfs_sync_inode_grab()
from xfs_icache.h.
Signed-off-by: Jie Liu <jeff.liu@oracle.com>
Reviewed-by: Dave Chinner <dchinner@redhat.com>
Signed-off-by: Ben Myers <bpm@sgi.com>
This patch clean out the left function variable as it is
useless to xfs_ialloc_get_rec().
Signed-off-by: Jie Liu <jeff.liu@oracle.com>
Reviewed-by: Dave Chinner <dchinner@redhat.com>
Signed-off-by: Ben Myers <bpm@sgi.com>
For lockspaces with an LVB length above 64 bytes, avoid truncating
the LVB while exchanging it with another node in the cluster.
Signed-off-by: Bart Van Assche <bvanassche@acm.org>
Signed-off-by: David Teigland <teigland@redhat.com>
Delete all audit rules that were checking how the .cpuXYZ
related sections were inter-operating with other __init
like sections, now that __cpuinit is gone. Update the linker
script to not have any knowledge of .cpuinit sections.
[lds.h update courtesy of Ralf Baechle <ralf@linux-mips.org>]
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Rusty Russell <rusty@rustcorp.com.au>
Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>
The __cpuinit type of throwaway sections might have made sense
some time ago when RAM was more constrained, but now the savings
do not offset the cost and complications. For example, the fix in
commit 5e427ec2d0 ("x86: Fix bit corruption at CPU resume time")
is a good example of the nasty type of bugs that can be created
with improper use of the various __init prefixes.
After a discussion on LKML[1] it was decided that cpuinit should go
the way of devinit and be phased out. Once all the users are gone,
we can then finally remove the macros themselves from linux/init.h.
As an interim step, we can dummy out the macros to be no-ops, and
this will allow us to avoid a giant tree-wide patch, and instead
we can feed in smaller chunks mainly via the arch/ trees. This
is in keeping with commit 78d86c213f
("init.h: Remove __dev* sections from the kernel")
We don't strictly need to dummy out the macros to do this, but if
we don't then some harmless section mismatch warnings may temporarily
result. For example, notify_cpu_starting() and cpu_up() are arch
independent (kernel/cpu.c) and are flagged as __cpuinit. And hence
the calling functions in the arch specific code are also expected
to be __cpuinit -- if not, then we get the section mismatch warning.
Two of the three __CPUINIT variants are not used whatsoever, and
so they are simply removed directly at this point in time.
[1] https://lkml.org/lkml/2013/5/20/589
Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>
Commit 39c60a0948 '[SCSI] sd: fix array cache flushing bug causing
performance problems' added temp as a pointer to "temporary " and used
sizeof(temp) - 1 as its length. But sizeof(temp) is the size of the
pointer, not the size of the string constant. Change temp to a static
array so that sizeof() does what was intended.
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
Cc: stable@vger.kernel.org
Signed-off-by: James Bottomley <JBottomley@Parallels.com>
This should work with modern compilers, isn't that much of an issue if
it goes wrong and it ensures that the DT-only hardware variants don't
leave unreferenced parameters structures lying around.
Signed-off-by: Mark Brown <broonie@linaro.org>
