linux/kernel, branch v3.2.2

kprobes: initialize before using a hlist

2012-01-26T00:13:57Z

commit d496aab567e7e52b3e974c9192a5de6e77dce32c upstream. Commit ef53d9c5e ("kprobes: improve kretprobe scalability with hashed locking") introduced a bug where we can potentially leak kretprobe_instances since we initialize a hlist head after having used it. Initialize the hlist head before using it. Reported by: Jim Keniston Acked-by: Jim Keniston Signed-off-by: Ananth N Mavinakayanahalli Acked-by: Masami Hiramatsu Cc: Srinivasa D S Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds Signed-off-by: Greg Kroah-Hartman

tracepoints/module: Fix disabling tracepoints with taint CRAP or OOT

2012-01-26T00:13:52Z

commit c10076c4304083af15a41f6bc5e657e781c1f9a6 upstream. Tracepoints are disabled for tainted modules, which is usually because the module is either proprietary or was forced, and we don't want either of them using kernel tracepoints. But, a module can also be tainted by being in the staging directory or compiled out of tree. Either is fine for use with tracepoints, no need to punish them. I found this out when I noticed that my sample trace event module, when done out of tree, stopped working. Cc: Mathieu Desnoyers Cc: Ben Hutchings Cc: Dave Jones Cc: Greg Kroah-Hartman Cc: Rusty Russell Signed-off-by: Steven Rostedt Signed-off-by: Greg Kroah-Hartman

ftrace: Fix unregister ftrace_ops accounting

2012-01-26T00:13:29Z

commit 30fb6aa74011dcf595f306ca2727254d708b786e upstream. Multiple users of the function tracer can register their functions with the ftrace_ops structure. The accounting within ftrace will update the counter on each function record that is being traced. When the ftrace_ops filtering adds or removes functions, the function records will be updated accordingly if the ftrace_ops is still registered. When a ftrace_ops is removed, the counter of the function records, that the ftrace_ops traces, are decremented. When they reach zero the functions that they represent are modified to stop calling the mcount code. When changes are made, the code is updated via stop_machine() with a command passed to the function to tell it what to do. There is an ENABLE and DISABLE command that tells the called function to enable or disable the functions. But the ENABLE is really a misnomer as it should just update the records, as records that have been enabled and now have a count of zero should be disabled. The DISABLE command is used to disable all functions regardless of their counter values. This is the big off switch and is not the complement of the ENABLE command. To make matters worse, when a ftrace_ops is unregistered and there is another ftrace_ops registered, neither the DISABLE nor the ENABLE command are set when calling into the stop_machine() function and the records will not be updated to match their counter. A command is passed to that function that will update the mcount code to call the registered callback directly if it is the only one left. This means that the ftrace_ops that is still registered will have its callback called by all functions that have been set for it as well as the ftrace_ops that was just unregistered. Here's a way to trigger this bug. Compile the kernel with CONFIG_FUNCTION_PROFILER set and with CONFIG_FUNCTION_GRAPH not set: CONFIG_FUNCTION_PROFILER=y # CONFIG_FUNCTION_GRAPH is not set This will force the function profiler to use the function tracer instead of the function graph tracer. # cd /sys/kernel/debug/tracing # echo schedule > set_ftrace_filter # echo function > current_tracer # cat set_ftrace_filter schedule # cat trace # tracer: nop # # entries-in-buffer/entries-written: 692/68108025 #P:4 # # _-----=> irqs-off # / _----=> need-resched # | / _---=> hardirq/softirq # || / _--=> preempt-depth # ||| / delay # TASK-PID CPU# |||| TIMESTAMP FUNCTION # | | | |||| | | kworker/0:2-909 [000] .... 531.235574: schedule <-worker_thread -0 [001] .N.. 531.235575: schedule <-cpu_idle kworker/0:2-909 [000] .... 531.235597: schedule <-worker_thread sshd-2563 [001] .... 531.235647: schedule <-schedule_hrtimeout_range_clock # echo 1 > function_profile_enabled # echo 0 > function_porfile_enabled # cat set_ftrace_filter schedule # cat trace # tracer: function # # entries-in-buffer/entries-written: 159701/118821262 #P:4 # # _-----=> irqs-off # / _----=> need-resched # | / _---=> hardirq/softirq # || / _--=> preempt-depth # ||| / delay # TASK-PID CPU# |||| TIMESTAMP FUNCTION # | | | |||| | | -0 [002] ...1 604.870655: local_touch_nmi <-cpu_idle -0 [002] d..1 604.870655: enter_idle <-cpu_idle -0 [002] d..1 604.870656: atomic_notifier_call_chain <-enter_idle -0 [002] d..1 604.870656: __atomic_notifier_call_chain <-atomic_notifier_call_chain The same problem could have happened with the trace_probe_ops, but they are modified with the set_frace_filter file which does the update at closure of the file. The simple solution is to change ENABLE to UPDATE and call it every time an ftrace_ops is unregistered. Link: http://lkml.kernel.org/r/1323105776-26961-3-git-send-email-jolsa@redhat.com Signed-off-by: Jiri Olsa Signed-off-by: Steven Rostedt Signed-off-by: Greg Kroah-Hartman

cgroup: fix to allow mounting a hierarchy by name

2012-01-12T19:29:35Z

commit 0d19ea866562e46989412a0676412fa0983c9ce7 upstream. If we mount a hierarchy with a specified name, the name is unique, and we can use it to mount the hierarchy without specifying its set of subsystem names. This feature is documented is Documentation/cgroups/cgroups.txt section 2.3 Here's an example: # mount -t cgroup -o cpuset,name=myhier xxx /cgroup1 # mount -t cgroup -o name=myhier xxx /cgroup2 But it was broken by commit 32a8cf235e2f192eb002755076994525cdbaa35a (cgroup: make the mount options parsing more accurate) This fixes the regression. Signed-off-by: Li Zefan Signed-off-by: Tejun Heo Signed-off-by: Greg Kroah-Hartman

ptrace: ensure JOBCTL_STOP_SIGMASK is not zero after detach

2012-01-04T23:01:59Z

This is the temporary simple fix for 3.2, we need more changes in this area. 1. do_signal_stop() assumes that the running untraced thread in the stopped thread group is not possible. This was our goal but it is not yet achieved: a stopped-but-resumed tracee can clone the running thread which can initiate another group-stop. Remove WARN_ON_ONCE(!current->ptrace). 2. A new thread always starts with ->jobctl = 0. If it is auto-attached and this group is stopped, __ptrace_unlink() sets JOBCTL_STOP_PENDING but JOBCTL_STOP_SIGMASK part is zero, this triggers WANR_ON(!signr) in do_jobctl_trap() if another debugger attaches. Change __ptrace_unlink() to set the artificial SIGSTOP for report. Alternatively we could change ptrace_init_task() to copy signr from current, but this means we can copy it for no reason and hide the possible similar problems. Acked-by: Tejun Heo Cc: [3.1] Signed-off-by: Oleg Nesterov Signed-off-by: Linus Torvalds

ptrace: partially fix the do_wait(WEXITED) vs EXIT_DEAD->EXIT_ZOMBIE race

2012-01-04T23:01:59Z

Test-case: int main(void) { int pid, status; pid = fork(); if (!pid) { for (;;) { if (!fork()) return 0; if (waitpid(-1, &status, 0) < 0) { printf("ERR!! wait: %m\n"); return 0; } } } assert(ptrace(PTRACE_ATTACH, pid, 0,0) == 0); assert(waitpid(-1, NULL, 0) == pid); assert(ptrace(PTRACE_SETOPTIONS, pid, 0, PTRACE_O_TRACEFORK) == 0); do { ptrace(PTRACE_CONT, pid, 0, 0); pid = waitpid(-1, NULL, 0); } while (pid > 0); return 1; } It fails because ->real_parent sees its child in EXIT_DEAD state while the tracer is going to change the state back to EXIT_ZOMBIE in wait_task_zombie(). The offending commit is 823b018e which moved the EXIT_DEAD check, but in fact we should not blame it. The original code was not correct as well because it didn't take ptrace_reparented() into account and because we can't really trust ->ptrace. This patch adds the additional check to close this particular race but it doesn't solve the whole problem. We simply can't rely on ->ptrace in this case, it can be cleared if the tracer is multithreaded by the exiting ->parent. I think we should kill EXIT_DEAD altogether, we should always remove the soon-to-be-reaped child from ->children or at least we should never do the DEAD->ZOMBIE transition. But this is too complex for 3.2. Reported-and-tested-by: Denys Vlasenko Tested-by: Lukasz Michalik Acked-by: Tejun Heo Cc: [3.0+] Signed-off-by: Oleg Nesterov Signed-off-by: Linus Torvalds

hung_task: fix false positive during vfork

2012-01-04T00:14:32Z

vfork parent uninterruptibly and unkillably waits for its child to exec/exit. This wait is of unbounded length. Ignore such waits in the hung_task detector. Signed-off-by: Mandeep Singh Baines Reported-by: Sasha Levin LKML-Reference: <1325344394.28904.43.camel@lappy> Cc: Linus Torvalds Cc: Ingo Molnar Cc: Peter Zijlstra Cc: Andrew Morton Cc: John Kacur Cc: stable@kernel.org Signed-off-by: Linus Torvalds

futex: Fix uninterruptible loop due to gate_area

2011-12-31T19:48:28Z

It was found (by Sasha) that if you use a futex located in the gate area we get stuck in an uninterruptible infinite loop, much like the ZERO_PAGE issue. While looking at this problem, PeterZ realized you'll get into similar trouble when hitting any install_special_pages() mapping. And are there still drivers setting up their own special mmaps without page->mapping, and without special VM or pte flags to make get_user_pages fail? In most cases, if page->mapping is NULL, we do not need to retry at all: Linus points out that even /proc/sys/vm/drop_caches poses no problem, because it ends up using remove_mapping(), which takes care not to interfere when the page reference count is raised. But there is still one case which does need a retry: if memory pressure called shmem_writepage in between get_user_pages_fast dropping page table lock and our acquiring page lock, then the page gets switched from filecache to swapcache (and ->mapping set to NULL) whatever the refcount. Fault it back in to get the page->mapping needed for key->shared.inode. Reported-by: Sasha Levin Signed-off-by: Hugh Dickins Cc: stable@vger.kernel.org Signed-off-by: Linus Torvalds

Revert "clockevents: Set noop handler in clockevents_exchange_device()"

2011-12-30T21:24:40Z

This reverts commit de28f25e8244c7353abed8de0c7792f5f883588c. It results in resume problems for various people. See for example http://thread.gmane.org/gmane.linux.kernel/1233033 http://thread.gmane.org/gmane.linux.kernel/1233389 http://thread.gmane.org/gmane.linux.kernel/1233159 http://thread.gmane.org/gmane.linux.kernel/1227868/focus=1230877 and the fedora and ubuntu bug reports https://bugzilla.redhat.com/show_bug.cgi?id=767248 https://bugs.launchpad.net/ubuntu/+source/linux/+bug/904569 which got bisected down to the stable version of this commit. Reported-by: Jonathan Nieder Reported-by: Phil Miller Reported-by: Philip Langdale Reported-by: Tim Gardner Cc: Thomas Gleixner Cc: Greg KH Cc: stable@kernel.org # for stable kernels that applied the original Signed-off-by: Linus Torvalds

Merge branch 'for-3.2-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup

2011-12-20T19:44:18Z

* 'for-3.2-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup: cgroups: fix a css_set not found bug in cgroup_attach_proc