From d6cbf35dac8a3dadb9103379820c96d7c85df3d9 Mon Sep 17 00:00:00 2001 From: Li Zefan Date: Tue, 14 May 2013 19:44:20 +0800 Subject: cgroup: initialize xattr before calling d_instantiate() cgroup_create_file() calls d_instantiate(), which may decide to look at the xattrs on the file. Smack always does this and SELinux can be configured to do so. But cgroup_add_file() didn't initialize xattrs before calling cgroup_create_file(), which finally leads to dereferencing NULL dentry->d_fsdata. This bug has been there since cgroup xattr was introduced. Cc: # 3.8.x Reported-by: Ivan Bulatovic Reported-by: Casey Schaufler Signed-off-by: Li Zefan Signed-off-by: Tejun Heo --- kernel/cgroup.c | 9 +++++---- 1 file changed, 5 insertions(+), 4 deletions(-) (limited to 'kernel') diff --git a/kernel/cgroup.c b/kernel/cgroup.c index 2a9926275f80..38b136553044 100644 --- a/kernel/cgroup.c +++ b/kernel/cgroup.c @@ -2699,13 +2699,14 @@ static int cgroup_add_file(struct cgroup *cgrp, struct cgroup_subsys *subsys, goto out; } + cfe->type = (void *)cft; + cfe->dentry = dentry; + dentry->d_fsdata = cfe; + simple_xattrs_init(&cfe->xattrs); + mode = cgroup_file_mode(cft); error = cgroup_create_file(dentry, mode | S_IFREG, cgrp->root->sb); if (!error) { - cfe->type = (void *)cft; - cfe->dentry = dentry; - dentry->d_fsdata = cfe; - simple_xattrs_init(&cfe->xattrs); list_add_tail(&cfe->node, &parent->files); cfe = NULL; } -- cgit v1.2.3 From fbe06b7bae7c9cf6ab05168fce5ee93b2f4bae7c Mon Sep 17 00:00:00 2001 From: Yinghai Lu Date: Fri, 17 May 2013 11:49:10 -0700 Subject: x86, range: fix missing merge during add range MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Christian found v3.9 does not work with E350 with EFI is enabled. [ 1.658832] Trying to unpack rootfs image as initramfs... [ 1.679935] BUG: unable to handle kernel paging request at ffff88006e3fd000 [ 1.686940] IP: [] memset+0x1f/0xb0 [ 1.692010] PGD 1f77067 PUD 1f7a067 PMD 61420067 PTE 0 but early memtest report all memory could be accessed without problem. early page table is set in following sequence: [ 0.000000] init_memory_mapping: [mem 0x00000000-0x000fffff] [ 0.000000] init_memory_mapping: [mem 0x6e600000-0x6e7fffff] [ 0.000000] init_memory_mapping: [mem 0x6c000000-0x6e5fffff] [ 0.000000] init_memory_mapping: [mem 0x00100000-0x6bffffff] [ 0.000000] init_memory_mapping: [mem 0x6e800000-0x6ea07fff] but later efi_enter_virtual_mode try set mapping again wrongly. [ 0.010644] pid_max: default: 32768 minimum: 301 [ 0.015302] init_memory_mapping: [mem 0x640c5000-0x6e3fcfff] that means it fails with pfn_range_is_mapped. It turns out that we have a bug in add_range_with_merge and it does not merge range properly when new add one fill the hole between two exsiting ranges. In the case when [mem 0x00100000-0x6bffffff] is the hole between [mem 0x00000000-0x000fffff] and [mem 0x6c000000-0x6e7fffff]. Fix the add_range_with_merge by calling itself recursively. Reported-by: "Christian König" Signed-off-by: Yinghai Lu Link: http://lkml.kernel.org/r/CAE9FiQVofGoSk7q5-0irjkBxemqK729cND4hov-1QCBJDhxpgQ@mail.gmail.com Cc: v3.9 Signed-off-by: H. Peter Anvin --- kernel/range.c | 8 +++++--- 1 file changed, 5 insertions(+), 3 deletions(-) (limited to 'kernel') diff --git a/kernel/range.c b/kernel/range.c index 071b0ab455cb..eb911dbce267 100644 --- a/kernel/range.c +++ b/kernel/range.c @@ -48,9 +48,11 @@ int add_range_with_merge(struct range *range, int az, int nr_range, final_start = min(range[i].start, start); final_end = max(range[i].end, end); - range[i].start = final_start; - range[i].end = final_end; - return nr_range; + /* clear it and add it back for further merge */ + range[i].start = 0; + range[i].end = 0; + return add_range_with_merge(range, az, nr_range, + final_start, final_end); } /* Need to add it: */ -- cgit v1.2.3 From ca1643186d3dce6171d8f171e516b02496360a9e Mon Sep 17 00:00:00 2001 From: "Steven Rostedt (Red Hat)" Date: Thu, 23 May 2013 11:51:10 -0400 Subject: tracing: Fix crash when ftrace=nop on the kernel command line If ftrace= is on the kernel command line, when that tracer is registered, it will be initiated by tracing_set_tracer() to execute that tracer. The nop tracer is just a stub tracer that is used to have no tracer enabled. It is assigned at early bootup as it is the default tracer. But if ftrace=nop is on the kernel command line, the registering of the nop tracer will call tracing_set_tracer() which will try to execute the nop tracer. But it expects tr->current_trace to be assigned something as it usually is assigned to the nop tracer. As it hasn't been assigned to anything yet, it causes the system to crash. The simple fix is to move the tr->current_trace = nop before registering the nop tracer. The functionality is still the same as the nop tracer doesn't do anything anyway. Reported-by: Peter Zijlstra Signed-off-by: Steven Rostedt --- kernel/trace/trace.c | 9 +++++++-- 1 file changed, 7 insertions(+), 2 deletions(-) (limited to 'kernel') diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c index ae6fa2d1cdf7..4d79485b3237 100644 --- a/kernel/trace/trace.c +++ b/kernel/trace/trace.c @@ -6216,10 +6216,15 @@ __init static int tracer_alloc_buffers(void) trace_init_cmdlines(); - register_tracer(&nop_trace); - + /* + * register_tracer() might reference current_trace, so it + * needs to be set before we register anything. This is + * just a bootstrap of current_trace anyway. + */ global_trace.current_trace = &nop_trace; + register_tracer(&nop_trace); + /* All seems OK, enable tracing */ tracing_disabled = 0; -- cgit v1.2.3 From 7805d000db30a3787a4c969bab6ae4d8a5fd8ce6 Mon Sep 17 00:00:00 2001 From: Tejun Heo Date: Fri, 24 May 2013 10:50:24 +0900 Subject: cgroup: fix a subtle bug in descendant pre-order walk When cgroup_next_descendant_pre() initiates a walk, it checks whether the subtree root doesn't have any children and if not returns NULL. Later code assumes that the subtree isn't empty. This is broken because the subtree may become empty inbetween, which can lead to the traversal escaping the subtree by walking to the sibling of the subtree root. There's no reason to have the early exit path. Remove it along with the later assumption that the subtree isn't empty. This simplifies the code a bit and fixes the subtle bug. While at it, fix the comment of cgroup_for_each_descendant_pre() which was incorrectly referring to ->css_offline() instead of ->css_online(). Signed-off-by: Tejun Heo Reviewed-by: Michal Hocko Cc: stable@vger.kernel.org --- include/linux/cgroup.h | 2 +- kernel/cgroup.c | 9 +++------ 2 files changed, 4 insertions(+), 7 deletions(-) (limited to 'kernel') diff --git a/include/linux/cgroup.h b/include/linux/cgroup.h index 5047355b9a0f..8bda1294c035 100644 --- a/include/linux/cgroup.h +++ b/include/linux/cgroup.h @@ -707,7 +707,7 @@ struct cgroup *cgroup_rightmost_descendant(struct cgroup *pos); * * If a subsystem synchronizes against the parent in its ->css_online() and * before starting iterating, and synchronizes against @pos on each - * iteration, any descendant cgroup which finished ->css_offline() is + * iteration, any descendant cgroup which finished ->css_online() is * guaranteed to be visible in the future iterations. * * In other words, the following guarantees that a descendant can't escape diff --git a/kernel/cgroup.c b/kernel/cgroup.c index 38b136553044..31e9ef319070 100644 --- a/kernel/cgroup.c +++ b/kernel/cgroup.c @@ -2954,11 +2954,8 @@ struct cgroup *cgroup_next_descendant_pre(struct cgroup *pos, WARN_ON_ONCE(!rcu_read_lock_held()); /* if first iteration, pretend we just visited @cgroup */ - if (!pos) { - if (list_empty(&cgroup->children)) - return NULL; + if (!pos) pos = cgroup; - } /* visit the first child if exists */ next = list_first_or_null_rcu(&pos->children, struct cgroup, sibling); @@ -2966,14 +2963,14 @@ struct cgroup *cgroup_next_descendant_pre(struct cgroup *pos, return next; /* no child, visit my or the closest ancestor's next sibling */ - do { + while (pos != cgroup) { next = list_entry_rcu(pos->sibling.next, struct cgroup, sibling); if (&next->sibling != &pos->parent->children) return next; pos = pos->parent; - } while (pos != cgroup); + } return NULL; } -- cgit v1.2.3 From 2938d2757fc99c26aa678ce4eba910c4a77c3a55 Mon Sep 17 00:00:00 2001 From: Thomas Gleixner Date: Tue, 28 May 2013 09:33:01 +0200 Subject: tick: Cure broadcast false positive pending bit warning commit 26517f3e (tick: Avoid programming the local cpu timer if broadcast pending) added a warning if the cpu enters broadcast mode again while the pending bit is still set. Meelis reported that the warning triggers. There are two corner cases which have been not considered: 1) cpuidle calls clockevents_notify(CLOCK_EVT_NOTIFY_BROADCAST_ENTER) twice. That can result in the following scenario CPU0 CPU1 cpuidle_idle_call() clockevents_notify(CLOCK_EVT_NOTIFY_BROADCAST_ENTER) set cpu in tick_broadcast_oneshot_mask broadcast interrupt event expired for cpu1 set pending bit acpi_idle_enter_simple() clockevents_notify(CLOCK_EVT_NOTIFY_BROADCAST_ENTER) WARN_ON(pending bit) Move the WARN_ON into the section where we enter broadcast mode so it wont provide false positives on the second call. 2) safe_halt() enables interrupts, so a broadcast interrupt can be delivered befor the broadcast mode is disabled. That sets the pending bit for the CPU which receives the broadcast interrupt. Though the interrupt is delivered right away from the broadcast handler and leaves the pending bit stale. Clear the pending bit for the current cpu in the broadcast handler. Reported-and-tested-by: Meelis Roos Cc: Len Brown Cc: Frederic Weisbecker Cc: Borislav Petkov Cc: Rafael J. Wysocki Link: http://lkml.kernel.org/r/alpine.LFD.2.02.1305271841130.4220@ionos Signed-off-by: Thomas Gleixner --- kernel/time/tick-broadcast.c | 8 +++++++- 1 file changed, 7 insertions(+), 1 deletion(-) (limited to 'kernel') diff --git a/kernel/time/tick-broadcast.c b/kernel/time/tick-broadcast.c index 24938d577669..0c739423b0f9 100644 --- a/kernel/time/tick-broadcast.c +++ b/kernel/time/tick-broadcast.c @@ -511,6 +511,12 @@ again: } } + /* + * Remove the current cpu from the pending mask. The event is + * delivered immediately in tick_do_broadcast() ! + */ + cpumask_clear_cpu(smp_processor_id(), tick_broadcast_pending_mask); + /* Take care of enforced broadcast requests */ cpumask_or(tmpmask, tmpmask, tick_broadcast_force_mask); cpumask_clear(tick_broadcast_force_mask); @@ -575,8 +581,8 @@ void tick_broadcast_oneshot_control(unsigned long reason) raw_spin_lock_irqsave(&tick_broadcast_lock, flags); if (reason == CLOCK_EVT_NOTIFY_BROADCAST_ENTER) { - WARN_ON_ONCE(cpumask_test_cpu(cpu, tick_broadcast_pending_mask)); if (!cpumask_test_and_set_cpu(cpu, tick_broadcast_oneshot_mask)) { + WARN_ON_ONCE(cpumask_test_cpu(cpu, tick_broadcast_pending_mask)); clockevents_set_mode(dev, CLOCK_EVT_MODE_SHUTDOWN); /* * We only reprogram the broadcast timer if we -- cgit v1.2.3 From 6721cb60022629ae76365551f05d9658b8d14c55 Mon Sep 17 00:00:00 2001 From: "Steven Rostedt (Red Hat)" Date: Thu, 23 May 2013 14:21:36 -0400 Subject: ring-buffer: Do not poll non allocated cpu buffers The tracing infrastructure sets up for possible CPUs, but it uses the ring buffer polling, it is possible to call the ring buffer polling code with a CPU that hasn't been allocated. This will cause a kernel oops when it access a ring buffer cpu buffer that is part of the possible cpus but hasn't been allocated yet as the CPU has never been online. Reported-by: Mauro Carvalho Chehab Tested-by: Mauro Carvalho Chehab Signed-off-by: Steven Rostedt --- kernel/trace/ring_buffer.c | 3 +++ 1 file changed, 3 insertions(+) (limited to 'kernel') diff --git a/kernel/trace/ring_buffer.c b/kernel/trace/ring_buffer.c index b59aea2c48c2..e444ff88f0a4 100644 --- a/kernel/trace/ring_buffer.c +++ b/kernel/trace/ring_buffer.c @@ -620,6 +620,9 @@ int ring_buffer_poll_wait(struct ring_buffer *buffer, int cpu, if (cpu == RING_BUFFER_ALL_CPUS) work = &buffer->irq_work; else { + if (!cpumask_test_cpu(cpu, buffer->cpumask)) + return -EINVAL; + cpu_buffer = buffer->buffers[cpu]; work = &cpu_buffer->irq_work; } -- cgit v1.2.3 From aa848233f740abbabfa7669daca0ab94aaa37bcd Mon Sep 17 00:00:00 2001 From: Geert Uytterhoeven Date: Fri, 3 May 2013 23:27:07 +0200 Subject: ntp: Remove unused variable flags in __hardpps MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit kernel/time/ntp.c: In function ‘__hardpps’: kernel/time/ntp.c:877: warning: unused variable ‘flags’ commit a076b2146fabb0894cae5e0189a8ba3f1502d737 ("ntp: Remove ntp_lock, using the timekeeping locks to protect ntp state") removed its users, but not the actual variable. Signed-off-by: Geert Uytterhoeven Signed-off-by: John Stultz --- kernel/time/ntp.c | 1 - 1 file changed, 1 deletion(-) (limited to 'kernel') diff --git a/kernel/time/ntp.c b/kernel/time/ntp.c index 12ff13a838c6..8f5b3b98577b 100644 --- a/kernel/time/ntp.c +++ b/kernel/time/ntp.c @@ -874,7 +874,6 @@ static void hardpps_update_phase(long error) void __hardpps(const struct timespec *phase_ts, const struct timespec *raw_ts) { struct pps_normtime pts_norm, freq_norm; - unsigned long flags; pts_norm = pps_normalize_ts(*phase_ts); -- cgit v1.2.3 From 0d6bd9953f739dad96d9a0de65383e479ab4e10d Mon Sep 17 00:00:00 2001 From: Zoran Markovic Date: Fri, 17 May 2013 11:24:05 -0700 Subject: timekeeping: Correct run-time detection of persistent_clock. Since commit 31ade30692dc9680bfc95700d794818fa3f754ac, timekeeping_init() checks for presence of persistent clock by attempting to read a non-zero time value. This is an issue on platforms where persistent_clock (instead is implemented as a free-running counter (instead of an RTC) starting from zero on each boot and running during suspend. Examples are some ARM platforms (e.g. PandaBoard). An attempt to read such a clock during timekeeping_init() may return zero value and falsely declare persistent clock as missing. Additionally, in the above case suspend times may be accounted twice (once from timekeeping_resume() and once from rtc_resume()), resulting in a gradual drift of system time. This patch does a run-time correction of the issue by doing the same check during timekeeping_suspend(). A better long-term solution would have to return error when trying to read non-existing clock and zero when trying to read an uninitialized clock, but that would require changing all persistent_clock implementations. This patch addresses the immediate breakage, for now. Cc: John Stultz Cc: Thomas Gleixner Cc: Feng Tang Cc: stable@vger.kernel.org Signed-off-by: Zoran Markovic [jstultz: Tweaked commit message and subject] Signed-off-by: John Stultz --- kernel/time/timekeeping.c | 8 ++++++++ 1 file changed, 8 insertions(+) (limited to 'kernel') diff --git a/kernel/time/timekeeping.c b/kernel/time/timekeeping.c index 98cd470bbe49..baeeb5c87cf1 100644 --- a/kernel/time/timekeeping.c +++ b/kernel/time/timekeeping.c @@ -975,6 +975,14 @@ static int timekeeping_suspend(void) read_persistent_clock(&timekeeping_suspend_time); + /* + * On some systems the persistent_clock can not be detected at + * timekeeping_init by its return value, so if we see a valid + * value returned, update the persistent_clock_exists flag. + */ + if (timekeeping_suspend_time.tv_sec || timekeeping_suspend_time.tv_nsec) + persistent_clock_exist = true; + raw_spin_lock_irqsave(&timekeeper_lock, flags); write_seqcount_begin(&timekeeper_seq); timekeeping_forward_now(tk); -- cgit v1.2.3 From 2a0ff3fbe39bc93f719ff857e5a359d9780579ff Mon Sep 17 00:00:00 2001 From: Jeff Liu Date: Sun, 26 May 2013 21:33:09 +0800 Subject: cgroup: warn about mismatching options of a new mount of an existing hierarchy With the new __DEVEL__sane_behavior mount option was introduced, if the root cgroup is alive with no xattr function, to mount a new cgroup with xattr will be rejected in terms of design which just fine. However, if the root cgroup does not mounted with __DEVEL__sane_hehavior, to create a new cgroup with xattr option will succeed although after that the EA function does not works as expected but will get ENOTSUPP for setting up attributes under either cgroup. e.g. setfattr: /cgroup2/test: Operation not supported Instead of keeping silence in this case, it's better to drop a log entry in warning level. That would be helpful to understand the reason behind the scene from the user's perspective, and this is essentially an improvement does not break the backward compatibilities. With this fix, above mount attemption will keep up works as usual but the following line cound be found at the system log: [ ...] cgroup: new mount options do not match the existing superblock tj: minor formatting / message updates. Signed-off-by: Jie Liu Reported-by: Alexey Kodanev Signed-off-by: Tejun Heo Cc: stable@vger.kernel.org --- kernel/cgroup.c | 13 ++++++++----- 1 file changed, 8 insertions(+), 5 deletions(-) (limited to 'kernel') diff --git a/kernel/cgroup.c b/kernel/cgroup.c index 31e9ef319070..a7c9e6ddb979 100644 --- a/kernel/cgroup.c +++ b/kernel/cgroup.c @@ -1686,11 +1686,14 @@ static struct dentry *cgroup_mount(struct file_system_type *fs_type, */ cgroup_drop_root(opts.new_root); - if (((root->flags | opts.flags) & CGRP_ROOT_SANE_BEHAVIOR) && - root->flags != opts.flags) { - pr_err("cgroup: sane_behavior: new mount options should match the existing superblock\n"); - ret = -EINVAL; - goto drop_new_super; + if (root->flags != opts.flags) { + if ((root->flags | opts.flags) & CGRP_ROOT_SANE_BEHAVIOR) { + pr_err("cgroup: sane_behavior: new mount options should match the existing superblock\n"); + ret = -EINVAL; + goto drop_new_super; + } else { + pr_warning("cgroup: new mount options do not match the existing superblock, will be ignored\n"); + } } /* no subsys rebinding, so refcounts don't change */ -- cgit v1.2.3 From 1bb539ca36e21c2f4fce0865e11df384bc7b7656 Mon Sep 17 00:00:00 2001 From: Steven Rostedt Date: Tue, 28 May 2013 14:38:43 -0400 Subject: ftrace: Use the rcu _notrace variants for rcu_dereference_raw() and friends As rcu_dereference_raw() under RCU debug config options can add quite a bit of checks, and that tracing uses rcu_dereference_raw(), these checks happen with the function tracer. The function tracer also happens to trace these debug checks too. This added overhead can livelock the system. Have the function tracer use the new RCU _notrace equivalents that do not do the debug checks for RCU. Link: http://lkml.kernel.org/r/20130528184209.467603904@goodmis.org Acked-by: Paul E. McKenney Signed-off-by: Steven Rostedt --- kernel/trace/ftrace.c | 18 +++++++++--------- 1 file changed, 9 insertions(+), 9 deletions(-) (limited to 'kernel') diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c index b549b0f5b977..6c508ff33c62 100644 --- a/kernel/trace/ftrace.c +++ b/kernel/trace/ftrace.c @@ -120,22 +120,22 @@ static void ftrace_ops_no_ops(unsigned long ip, unsigned long parent_ip); /* * Traverse the ftrace_global_list, invoking all entries. The reason that we - * can use rcu_dereference_raw() is that elements removed from this list + * can use rcu_dereference_raw_notrace() is that elements removed from this list * are simply leaked, so there is no need to interact with a grace-period - * mechanism. The rcu_dereference_raw() calls are needed to handle + * mechanism. The rcu_dereference_raw_notrace() calls are needed to handle * concurrent insertions into the ftrace_global_list. * * Silly Alpha and silly pointer-speculation compiler optimizations! */ #define do_for_each_ftrace_op(op, list) \ - op = rcu_dereference_raw(list); \ + op = rcu_dereference_raw_notrace(list); \ do /* * Optimized for just a single item in the list (as that is the normal case). */ #define while_for_each_ftrace_op(op) \ - while (likely(op = rcu_dereference_raw((op)->next)) && \ + while (likely(op = rcu_dereference_raw_notrace((op)->next)) && \ unlikely((op) != &ftrace_list_end)) static inline void ftrace_ops_init(struct ftrace_ops *ops) @@ -779,7 +779,7 @@ ftrace_find_profiled_func(struct ftrace_profile_stat *stat, unsigned long ip) if (hlist_empty(hhd)) return NULL; - hlist_for_each_entry_rcu(rec, hhd, node) { + hlist_for_each_entry_rcu_notrace(rec, hhd, node) { if (rec->ip == ip) return rec; } @@ -1165,7 +1165,7 @@ ftrace_lookup_ip(struct ftrace_hash *hash, unsigned long ip) hhd = &hash->buckets[key]; - hlist_for_each_entry_rcu(entry, hhd, hlist) { + hlist_for_each_entry_rcu_notrace(entry, hhd, hlist) { if (entry->ip == ip) return entry; } @@ -1422,8 +1422,8 @@ ftrace_ops_test(struct ftrace_ops *ops, unsigned long ip) struct ftrace_hash *notrace_hash; int ret; - filter_hash = rcu_dereference_raw(ops->filter_hash); - notrace_hash = rcu_dereference_raw(ops->notrace_hash); + filter_hash = rcu_dereference_raw_notrace(ops->filter_hash); + notrace_hash = rcu_dereference_raw_notrace(ops->notrace_hash); if ((ftrace_hash_empty(filter_hash) || ftrace_lookup_ip(filter_hash, ip)) && @@ -2920,7 +2920,7 @@ static void function_trace_probe_call(unsigned long ip, unsigned long parent_ip, * on the hash. rcu_read_lock is too dangerous here. */ preempt_disable_notrace(); - hlist_for_each_entry_rcu(entry, hhd, node) { + hlist_for_each_entry_rcu_notrace(entry, hhd, node) { if (entry->ip == ip) entry->ops->func(ip, parent_ip, &entry->data); } -- cgit v1.2.3 From 0184d50f9fd17658c232d6ee6d465a87f989d706 Mon Sep 17 00:00:00 2001 From: "Steven Rostedt (Red Hat)" Date: Wed, 29 May 2013 15:56:49 -0400 Subject: tracing: Fix bad parameter passed in branch selftest The branch selftest calls trace_test_buffer(), but with the new code it expects the first parameter to be a pointer to a struct trace_buffer. All self tests were changed but the branch selftest was missed. This caused either a crash or failed test when the branch selftest was enabled. Link: http://lkml.kernel.org/r/20130529141333.GA24064@localhost Reported-by: Fengguang Wu Signed-off-by: Steven Rostedt --- kernel/trace/trace_selftest.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'kernel') diff --git a/kernel/trace/trace_selftest.c b/kernel/trace/trace_selftest.c index 55e2cf66967b..2901e3b88590 100644 --- a/kernel/trace/trace_selftest.c +++ b/kernel/trace/trace_selftest.c @@ -1159,7 +1159,7 @@ trace_selftest_startup_branch(struct tracer *trace, struct trace_array *tr) /* stop the tracing. */ tracing_stop(); /* check the trace buffer */ - ret = trace_test_buffer(tr, &count); + ret = trace_test_buffer(&tr->trace_buffer, &count); trace->reset(tr); tracing_start(); -- cgit v1.2.3 From f17a5194859a82afe4164e938b92035b86c55794 Mon Sep 17 00:00:00 2001 From: "Steven Rostedt (Red Hat)" Date: Thu, 30 May 2013 21:10:37 -0400 Subject: tracing: Use current_uid() for critical time tracing The irqsoff tracer records the max time that interrupts are disabled. There are hooks in the assembly code that calls back into the tracer when interrupts are disabled or enabled. When they are enabled, the tracer checks if the amount of time they were disabled is larger than the previous recorded max interrupts off time. If it is, it creates a snapshot of the currently running trace to store where the last largest interrupts off time was held and how it happened. During testing, this RCU lockdep dump appeared: [ 1257.829021] =============================== [ 1257.829021] [ INFO: suspicious RCU usage. ] [ 1257.829021] 3.10.0-rc1-test+ #171 Tainted: G W [ 1257.829021] ------------------------------- [ 1257.829021] /home/rostedt/work/git/linux-trace.git/include/linux/rcupdate.h:780 rcu_read_lock() used illegally while idle! [ 1257.829021] [ 1257.829021] other info that might help us debug this: [ 1257.829021] [ 1257.829021] [ 1257.829021] RCU used illegally from idle CPU! [ 1257.829021] rcu_scheduler_active = 1, debug_locks = 0 [ 1257.829021] RCU used illegally from extended quiescent state! [ 1257.829021] 2 locks held by trace-cmd/4831: [ 1257.829021] #0: (max_trace_lock){......}, at: [] stop_critical_timing+0x1a3/0x209 [ 1257.829021] #1: (rcu_read_lock){.+.+..}, at: [] __update_max_tr+0x88/0x1ee [ 1257.829021] [ 1257.829021] stack backtrace: [ 1257.829021] CPU: 3 PID: 4831 Comm: trace-cmd Tainted: G W 3.10.0-rc1-test+ #171 [ 1257.829021] Hardware name: To Be Filled By O.E.M. To Be Filled By O.E.M./To be filled by O.E.M., BIOS SDBLI944.86P 05/08/2007 [ 1257.829021] 0000000000000001 ffff880065f49da8 ffffffff8153dd2b ffff880065f49dd8 [ 1257.829021] ffffffff81092a00 ffff88006bd78680 ffff88007add7500 0000000000000003 [ 1257.829021] ffff88006bd78680 ffff880065f49e18 ffffffff810daebf ffffffff810dae5a [ 1257.829021] Call Trace: [ 1257.829021] [] dump_stack+0x19/0x1b [ 1257.829021] [] lockdep_rcu_suspicious+0x109/0x112 [ 1257.829021] [] __update_max_tr+0xed/0x1ee [ 1257.829021] [] ? __update_max_tr+0x88/0x1ee [ 1257.829021] [] ? user_enter+0xfd/0x107 [ 1257.829021] [] update_max_tr_single+0x11d/0x12d [ 1257.829021] [] ? user_enter+0xfd/0x107 [ 1257.829021] [] stop_critical_timing+0x141/0x209 [ 1257.829021] [] ? trace_hardirqs_on+0xd/0xf [ 1257.829021] [] ? user_enter+0xfd/0x107 [ 1257.829021] [] time_hardirqs_on+0x2a/0x2f [ 1257.829021] [] ? user_enter+0xfd/0x107 [ 1257.829021] [] trace_hardirqs_on_caller+0x16/0x197 [ 1257.829021] [] trace_hardirqs_on+0xd/0xf [ 1257.829021] [] user_enter+0xfd/0x107 [ 1257.829021] [] do_notify_resume+0x92/0x97 [ 1257.829021] [] int_signal+0x12/0x17 What happened was entering into the user code, the interrupts were enabled and a max interrupts off was recorded. The trace buffer was saved along with various information about the task: comm, pid, uid, priority, etc. The uid is recorded with task_uid(tsk). But this is a macro that uses rcu_read_lock() to retrieve the data, and this happened to happen where RCU is blind (user_enter). As only the preempt and irqs off tracers can have this happen, and they both only have the tsk == current, if tsk == current, use current_uid() instead of task_uid(), as current_uid() does not use RCU as only current can change its uid. This fixes the RCU suspicious splat. Signed-off-by: Steven Rostedt --- kernel/trace/trace.c | 10 +++++++++- 1 file changed, 9 insertions(+), 1 deletion(-) (limited to 'kernel') diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c index 4d79485b3237..1a41023a1f88 100644 --- a/kernel/trace/trace.c +++ b/kernel/trace/trace.c @@ -843,7 +843,15 @@ __update_max_tr(struct trace_array *tr, struct task_struct *tsk, int cpu) memcpy(max_data->comm, tsk->comm, TASK_COMM_LEN); max_data->pid = tsk->pid; - max_data->uid = task_uid(tsk); + /* + * If tsk == current, then use current_uid(), as that does not use + * RCU. The irq tracer can be called out of RCU scope. + */ + if (tsk == current) + max_data->uid = current_uid(); + else + max_data->uid = task_uid(tsk); + max_data->nice = tsk->static_prio - 20 - MAX_RT_PRIO; max_data->policy = tsk->policy; max_data->rt_priority = tsk->rt_priority; -- cgit v1.2.3 From 346dbb79ea0118ebb0df372b35cab9d5805216cd Mon Sep 17 00:00:00 2001 From: Arnd Bergmann Date: Thu, 25 Apr 2013 19:28:54 +0200 Subject: irqdomain: export irq_domain_add_simple All other irq_domain_add_* functions are exported already, and apparently this one got left out by mistake, which causes build errors for ARM allmodconfig kernels: ERROR: "irq_domain_add_simple" [drivers/gpio/gpio-rcar.ko] undefined! ERROR: "irq_domain_add_simple" [drivers/gpio/gpio-em.ko] undefined! Signed-off-by: Arnd Bergmann Acked-by: Simon Horman Signed-off-by: Grant Likely --- kernel/irq/irqdomain.c | 1 + 1 file changed, 1 insertion(+) (limited to 'kernel') diff --git a/kernel/irq/irqdomain.c b/kernel/irq/irqdomain.c index 5a83dde8ca0c..d1adaedb435f 100644 --- a/kernel/irq/irqdomain.c +++ b/kernel/irq/irqdomain.c @@ -191,6 +191,7 @@ struct irq_domain *irq_domain_add_simple(struct device_node *of_node, /* A linear domain is the default */ return irq_domain_add_linear(of_node, size, ops, host_data); } +EXPORT_SYMBOL_GPL(irq_domain_add_simple); /** * irq_domain_add_legacy() - Allocate and register a legacy revmap irq_domain. -- cgit v1.2.3 From 275e31b10ce20613aedceaa5160129c64b260a98 Mon Sep 17 00:00:00 2001 From: Chen Gang Date: Tue, 14 May 2013 19:02:45 +0800 Subject: kernel/irq/irqdomain.c: before use 'irq_data', need check it whether valid. Since irq_data may be NULL, if so, we WARN_ON(), and continue, 'hwirq' which related with 'irq_data' has to initialize later, or it will cause issue. Signed-off-by: Chen Gang Signed-off-by: Grant Likely --- kernel/irq/irqdomain.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) (limited to 'kernel') diff --git a/kernel/irq/irqdomain.c b/kernel/irq/irqdomain.c index d1adaedb435f..8c4c8ea6a205 100644 --- a/kernel/irq/irqdomain.c +++ b/kernel/irq/irqdomain.c @@ -398,11 +398,12 @@ static void irq_domain_disassociate_many(struct irq_domain *domain, while (count--) { int irq = irq_base + count; struct irq_data *irq_data = irq_get_irq_data(irq); - irq_hw_number_t hwirq = irq_data->hwirq; + irq_hw_number_t hwirq; if (WARN_ON(!irq_data || irq_data->domain != domain)) continue; + hwirq = irq_data->hwirq; irq_set_status_flags(irq, IRQ_NOREQUEST); /* remove chip and handler */ -- cgit v1.2.3 From 94a63da0ac1a67bfb8b30aec1086523c5031ea5a Mon Sep 17 00:00:00 2001 From: Linus Walleij Date: Thu, 6 Jun 2013 12:10:23 +0100 Subject: irqdomain: document the simple domain first_irq The first_irq needs to be zero to get a linear domain and that comes with special semantics. We want to simplify this going forward but some documentation never hurts. Signed-off-by: Linus Walleij Signed-off-by: Grant Likely --- kernel/irq/irqdomain.c | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-) (limited to 'kernel') diff --git a/kernel/irq/irqdomain.c b/kernel/irq/irqdomain.c index 8c4c8ea6a205..54a4d5223238 100644 --- a/kernel/irq/irqdomain.c +++ b/kernel/irq/irqdomain.c @@ -143,7 +143,10 @@ static unsigned int irq_domain_legacy_revmap(struct irq_domain *domain, * irq_domain_add_simple() - Allocate and register a simple irq_domain. * @of_node: pointer to interrupt controller's device tree node. * @size: total number of irqs in mapping - * @first_irq: first number of irq block assigned to the domain + * @first_irq: first number of irq block assigned to the domain, + * pass zero to assign irqs on-the-fly. This will result in a + * linear IRQ domain so it is important to use irq_create_mapping() + * for each used IRQ, especially when SPARSE_IRQ is enabled. * @ops: map/unmap domain callbacks * @host_data: Controller private data pointer * -- cgit v1.2.3 From 016a8d5be6ddcc72ef0432d82d9f6fa34f61b907 Mon Sep 17 00:00:00 2001 From: Steven Rostedt Date: Tue, 28 May 2013 17:32:53 -0400 Subject: rcu: Don't call wakeup() with rcu_node structure ->lock held This commit fixes a lockdep-detected deadlock by moving a wake_up() call out from a rnp->lock critical section. Please see below for the long version of this story. On Tue, 2013-05-28 at 16:13 -0400, Dave Jones wrote: > [12572.705832] ====================================================== > [12572.750317] [ INFO: possible circular locking dependency detected ] > [12572.796978] 3.10.0-rc3+ #39 Not tainted > [12572.833381] ------------------------------------------------------- > [12572.862233] trinity-child17/31341 is trying to acquire lock: > [12572.870390] (rcu_node_0){..-.-.}, at: [] rcu_read_unlock_special+0x9f/0x4c0 > [12572.878859] > but task is already holding lock: > [12572.894894] (&ctx->lock){-.-...}, at: [] perf_lock_task_context+0x7d/0x2d0 > [12572.903381] > which lock already depends on the new lock. > > [12572.927541] > the existing dependency chain (in reverse order) is: > [12572.943736] > -> #4 (&ctx->lock){-.-...}: > [12572.960032] [] lock_acquire+0x91/0x1f0 > [12572.968337] [] _raw_spin_lock+0x40/0x80 > [12572.976633] [] __perf_event_task_sched_out+0x2e7/0x5e0 > [12572.984969] [] perf_event_task_sched_out+0x93/0xa0 > [12572.993326] [] __schedule+0x2cf/0x9c0 > [12573.001652] [] schedule_user+0x2e/0x70 > [12573.009998] [] retint_careful+0x12/0x2e > [12573.018321] > -> #3 (&rq->lock){-.-.-.}: > [12573.034628] [] lock_acquire+0x91/0x1f0 > [12573.042930] [] _raw_spin_lock+0x40/0x80 > [12573.051248] [] wake_up_new_task+0xb7/0x260 > [12573.059579] [] do_fork+0x105/0x470 > [12573.067880] [] kernel_thread+0x26/0x30 > [12573.076202] [] rest_init+0x23/0x140 > [12573.084508] [] start_kernel+0x3f1/0x3fe > [12573.092852] [] x86_64_start_reservations+0x2a/0x2c > [12573.101233] [] x86_64_start_kernel+0xcc/0xcf > [12573.109528] > -> #2 (&p->pi_lock){-.-.-.}: > [12573.125675] [] lock_acquire+0x91/0x1f0 > [12573.133829] [] _raw_spin_lock_irqsave+0x4b/0x90 > [12573.141964] [] try_to_wake_up+0x31/0x320 > [12573.150065] [] default_wake_function+0x12/0x20 > [12573.158151] [] autoremove_wake_function+0x18/0x40 > [12573.166195] [] __wake_up_common+0x58/0x90 > [12573.174215] [] __wake_up+0x39/0x50 > [12573.182146] [] rcu_start_gp_advanced.isra.11+0x4a/0x50 > [12573.190119] [] rcu_start_future_gp+0x1c9/0x1f0 > [12573.198023] [] rcu_nocb_kthread+0x114/0x930 > [12573.205860] [] kthread+0xed/0x100 > [12573.213656] [] ret_from_fork+0x7c/0xb0 > [12573.221379] > -> #1 (&rsp->gp_wq){..-.-.}: > [12573.236329] [] lock_acquire+0x91/0x1f0 > [12573.243783] [] _raw_spin_lock_irqsave+0x4b/0x90 > [12573.251178] [] __wake_up+0x23/0x50 > [12573.258505] [] rcu_start_gp_advanced.isra.11+0x4a/0x50 > [12573.265891] [] rcu_start_future_gp+0x1c9/0x1f0 > [12573.273248] [] rcu_nocb_kthread+0x114/0x930 > [12573.280564] [] kthread+0xed/0x100 > [12573.287807] [] ret_from_fork+0x7c/0xb0 Notice the above call chain. rcu_start_future_gp() is called with the rnp->lock held. Then it calls rcu_start_gp_advance, which does a wakeup. You can't do wakeups while holding the rnp->lock, as that would mean that you could not do a rcu_read_unlock() while holding the rq lock, or any lock that was taken while holding the rq lock. This is because... (See below). > [12573.295067] > -> #0 (rcu_node_0){..-.-.}: > [12573.309293] [] __lock_acquire+0x1786/0x1af0 > [12573.316568] [] lock_acquire+0x91/0x1f0 > [12573.323825] [] _raw_spin_lock+0x40/0x80 > [12573.331081] [] rcu_read_unlock_special+0x9f/0x4c0 > [12573.338377] [] __rcu_read_unlock+0x96/0xa0 > [12573.345648] [] perf_lock_task_context+0x143/0x2d0 > [12573.352942] [] find_get_context+0x4e/0x1f0 > [12573.360211] [] SYSC_perf_event_open+0x514/0xbd0 > [12573.367514] [] SyS_perf_event_open+0x9/0x10 > [12573.374816] [] tracesys+0xdd/0xe2 Notice the above trace. perf took its own ctx->lock, which can be taken while holding the rq lock. While holding this lock, it did a rcu_read_unlock(). The perf_lock_task_context() basically looks like: rcu_read_lock(); raw_spin_lock(ctx->lock); rcu_read_unlock(); Now, what looks to have happened, is that we scheduled after taking that first rcu_read_lock() but before taking the spin lock. When we scheduled back in and took the ctx->lock, the following rcu_read_unlock() triggered the "special" code. The rcu_read_unlock_special() takes the rnp->lock, which gives us a possible deadlock scenario. CPU0 CPU1 CPU2 ---- ---- ---- rcu_nocb_kthread() lock(rq->lock); lock(ctx->lock); lock(rnp->lock); wake_up(); lock(rq->lock); rcu_read_unlock(); rcu_read_unlock_special(); lock(rnp->lock); lock(ctx->lock); **** DEADLOCK **** > [12573.382068] > other info that might help us debug this: > > [12573.403229] Chain exists of: > rcu_node_0 --> &rq->lock --> &ctx->lock > > [12573.424471] Possible unsafe locking scenario: > > [12573.438499] CPU0 CPU1 > [12573.445599] ---- ---- > [12573.452691] lock(&ctx->lock); > [12573.459799] lock(&rq->lock); > [12573.467010] lock(&ctx->lock); > [12573.474192] lock(rcu_node_0); > [12573.481262] > *** DEADLOCK *** > > [12573.501931] 1 lock held by trinity-child17/31341: > [12573.508990] #0: (&ctx->lock){-.-...}, at: [] perf_lock_task_context+0x7d/0x2d0 > [12573.516475] > stack backtrace: > [12573.530395] CPU: 1 PID: 31341 Comm: trinity-child17 Not tainted 3.10.0-rc3+ #39 > [12573.545357] ffffffff825b4f90 ffff880219f1dbc0 ffffffff816e375b ffff880219f1dc00 > [12573.552868] ffffffff816dfa5d ffff880219f1dc50 ffff88023ce4d1f8 ffff88023ce4ca40 > [12573.560353] 0000000000000001 0000000000000001 ffff88023ce4d1f8 ffff880219f1dcc0 > [12573.567856] Call Trace: > [12573.575011] [] dump_stack+0x19/0x1b > [12573.582284] [] print_circular_bug+0x200/0x20f > [12573.589637] [] __lock_acquire+0x1786/0x1af0 > [12573.596982] [] ? sched_clock_cpu+0xb5/0x100 > [12573.604344] [] lock_acquire+0x91/0x1f0 > [12573.611652] [] ? rcu_read_unlock_special+0x9f/0x4c0 > [12573.619030] [] _raw_spin_lock+0x40/0x80 > [12573.626331] [] ? rcu_read_unlock_special+0x9f/0x4c0 > [12573.633671] [] rcu_read_unlock_special+0x9f/0x4c0 > [12573.640992] [] ? perf_lock_task_context+0x7d/0x2d0 > [12573.648330] [] ? put_lock_stats.isra.29+0xe/0x40 > [12573.655662] [] ? delay_tsc+0x90/0xe0 > [12573.662964] [] __rcu_read_unlock+0x96/0xa0 > [12573.670276] [] perf_lock_task_context+0x143/0x2d0 > [12573.677622] [] ? __perf_event_enable+0x370/0x370 > [12573.684981] [] find_get_context+0x4e/0x1f0 > [12573.692358] [] SYSC_perf_event_open+0x514/0xbd0 > [12573.699753] [] ? get_parent_ip+0xd/0x50 > [12573.707135] [] ? trace_hardirqs_on_caller+0xfd/0x1c0 > [12573.714599] [] SyS_perf_event_open+0x9/0x10 > [12573.721996] [] tracesys+0xdd/0xe2 This commit delays the wakeup via irq_work(), which is what perf and ftrace use to perform wakeups in critical sections. Reported-by: Dave Jones Signed-off-by: Steven Rostedt Signed-off-by: Paul E. McKenney --- init/Kconfig | 1 + kernel/rcutree.c | 17 +++++++++++++++-- kernel/rcutree.h | 2 ++ 3 files changed, 18 insertions(+), 2 deletions(-) (limited to 'kernel') diff --git a/init/Kconfig b/init/Kconfig index 9d3a7887a6d3..2d9b83104dcf 100644 --- a/init/Kconfig +++ b/init/Kconfig @@ -431,6 +431,7 @@ choice config TREE_RCU bool "Tree-based hierarchical RCU" depends on !PREEMPT && SMP + select IRQ_WORK help This option selects the RCU implementation that is designed for very large SMP system with hundreds or diff --git a/kernel/rcutree.c b/kernel/rcutree.c index 16ea67925015..b61d20c5ee7b 100644 --- a/kernel/rcutree.c +++ b/kernel/rcutree.c @@ -1613,6 +1613,14 @@ static int __noreturn rcu_gp_kthread(void *arg) } } +static void rsp_wakeup(struct irq_work *work) +{ + struct rcu_state *rsp = container_of(work, struct rcu_state, wakeup_work); + + /* Wake up rcu_gp_kthread() to start the grace period. */ + wake_up(&rsp->gp_wq); +} + /* * Start a new RCU grace period if warranted, re-initializing the hierarchy * in preparation for detecting the next grace period. The caller must hold @@ -1637,8 +1645,12 @@ rcu_start_gp_advanced(struct rcu_state *rsp, struct rcu_node *rnp, } rsp->gp_flags = RCU_GP_FLAG_INIT; - /* Wake up rcu_gp_kthread() to start the grace period. */ - wake_up(&rsp->gp_wq); + /* + * We can't do wakeups while holding the rnp->lock, as that + * could cause possible deadlocks with the rq->lock. Deter + * the wakeup to interrupt context. + */ + irq_work_queue(&rsp->wakeup_work); } /* @@ -3235,6 +3247,7 @@ static void __init rcu_init_one(struct rcu_state *rsp, rsp->rda = rda; init_waitqueue_head(&rsp->gp_wq); + init_irq_work(&rsp->wakeup_work, rsp_wakeup); rnp = rsp->level[rcu_num_lvls - 1]; for_each_possible_cpu(i) { while (i > rnp->grphi) diff --git a/kernel/rcutree.h b/kernel/rcutree.h index da77a8f57ff9..4df503470e42 100644 --- a/kernel/rcutree.h +++ b/kernel/rcutree.h @@ -27,6 +27,7 @@ #include #include #include +#include /* * Define shape of hierarchy based on NR_CPUS, CONFIG_RCU_FANOUT, and @@ -442,6 +443,7 @@ struct rcu_state { char *name; /* Name of structure. */ char abbr; /* Abbreviated name. */ struct list_head flavors; /* List of RCU flavors. */ + struct irq_work wakeup_work; /* Postponed wakeups */ }; /* Values for rcu_state structure's gp_flags field. */ -- cgit v1.2.3 From 971394f389992f8462c4e5ae0e3b49a10a9534a3 Mon Sep 17 00:00:00 2001 From: "Paul E. McKenney" Date: Sun, 2 Jun 2013 07:13:57 -0700 Subject: rcu: Fix deadlock with CPU hotplug, RCU GP init, and timer migration In Steven Rostedt's words: > I've been debugging the last couple of days why my tests have been > locking up. One of my tracing tests, runs all available tracers. The > lockup always happened with the mmiotrace, which is used to trace > interactions between priority drivers and the kernel. But to do this > easily, when the tracer gets registered, it disables all but the boot > CPUs. The lockup always happened after it got done disabling the CPUs. > > Then I decided to try this: > > while :; do > for i in 1 2 3; do > echo 0 > /sys/devices/system/cpu/cpu$i/online > done > for i in 1 2 3; do > echo 1 > /sys/devices/system/cpu/cpu$i/online > done > done > > Well, sure enough, that locked up too, with the same users. Doing a > sysrq-w (showing all blocked tasks): > > [ 2991.344562] task PC stack pid father > [ 2991.344562] rcu_preempt D ffff88007986fdf8 0 10 2 0x00000000 > [ 2991.344562] ffff88007986fc98 0000000000000002 ffff88007986fc48 0000000000000908 > [ 2991.344562] ffff88007986c280 ffff88007986ffd8 ffff88007986ffd8 00000000001d3c80 > [ 2991.344562] ffff880079248a40 ffff88007986c280 0000000000000000 00000000fffd4295 > [ 2991.344562] Call Trace: > [ 2991.344562] [] schedule+0x64/0x66 > [ 2991.344562] [] schedule_timeout+0xbc/0xf9 > [ 2991.344562] [] ? ftrace_call+0x5/0x2f > [ 2991.344562] [] ? cascade+0xa8/0xa8 > [ 2991.344562] [] schedule_timeout_uninterruptible+0x1e/0x20 > [ 2991.344562] [] rcu_gp_kthread+0x502/0x94b > [ 2991.344562] [] ? __init_waitqueue_head+0x50/0x50 > [ 2991.344562] [] ? rcu_gp_fqs+0x64/0x64 > [ 2991.344562] [] kthread+0xb1/0xb9 > [ 2991.344562] [] ? lock_release_holdtime.part.23+0x4e/0x55 > [ 2991.344562] [] ? __init_kthread_worker+0x58/0x58 > [ 2991.344562] [] ret_from_fork+0x7c/0xb0 > [ 2991.344562] [] ? __init_kthread_worker+0x58/0x58 > [ 2991.344562] kworker/0:1 D ffffffff81a30680 0 47 2 0x00000000 > [ 2991.344562] Workqueue: events cpuset_hotplug_workfn > [ 2991.344562] ffff880078dbbb58 0000000000000002 0000000000000006 00000000000000d8 > [ 2991.344562] ffff880078db8100 ffff880078dbbfd8 ffff880078dbbfd8 00000000001d3c80 > [ 2991.344562] ffff8800779ca5c0 ffff880078db8100 ffffffff81541fcf 0000000000000000 > [ 2991.344562] Call Trace: > [ 2991.344562] [] ? __mutex_lock_common+0x3d4/0x609 > [ 2991.344562] [] schedule+0x64/0x66 > [ 2991.344562] [] schedule_preempt_disabled+0x18/0x24 > [ 2991.344562] [] __mutex_lock_common+0x3d4/0x609 > [ 2991.344562] [] ? get_online_cpus+0x3c/0x50 > [ 2991.344562] [] ? get_online_cpus+0x3c/0x50 > [ 2991.344562] [] mutex_lock_nested+0x3b/0x40 > [ 2991.344562] [] get_online_cpus+0x3c/0x50 > [ 2991.344562] [] rebuild_sched_domains_locked+0x6e/0x3a8 > [ 2991.344562] [] rebuild_sched_domains+0x1c/0x2a > [ 2991.344562] [] cpuset_hotplug_workfn+0x1c7/0x1d3 > [ 2991.344562] [] ? cpuset_hotplug_workfn+0x5/0x1d3 > [ 2991.344562] [] process_one_work+0x2d4/0x4d1 > [ 2991.344562] [] ? process_one_work+0x207/0x4d1 > [ 2991.344562] [] worker_thread+0x2e7/0x3b5 > [ 2991.344562] [] ? rescuer_thread+0x332/0x332 > [ 2991.344562] [] kthread+0xb1/0xb9 > [ 2991.344562] [] ? __init_kthread_worker+0x58/0x58 > [ 2991.344562] [] ret_from_fork+0x7c/0xb0 > [ 2991.344562] [] ? __init_kthread_worker+0x58/0x58 > [ 2991.344562] bash D ffffffff81a4aa80 0 2618 2612 0x10000000 > [ 2991.344562] ffff8800379abb58 0000000000000002 0000000000000006 0000000000000c2c > [ 2991.344562] ffff880077fea140 ffff8800379abfd8 ffff8800379abfd8 00000000001d3c80 > [ 2991.344562] ffff8800779ca5c0 ffff880077fea140 ffffffff81541fcf 0000000000000000 > [ 2991.344562] Call Trace: > [ 2991.344562] [] ? __mutex_lock_common+0x3d4/0x609 > [ 2991.344562] [] schedule+0x64/0x66 > [ 2991.344562] [] schedule_preempt_disabled+0x18/0x24 > [ 2991.344562] [] __mutex_lock_common+0x3d4/0x609 > [ 2991.344562] [] ? rcu_cpu_notify+0x2f5/0x86e > [ 2991.344562] [] ? rcu_cpu_notify+0x2f5/0x86e > [ 2991.344562] [] mutex_lock_nested+0x3b/0x40 > [ 2991.344562] [] rcu_cpu_notify+0x2f5/0x86e > [ 2991.344562] [] ? __lock_is_held+0x32/0x53 > [ 2991.344562] [] notifier_call_chain+0x6b/0x98 > [ 2991.344562] [] __raw_notifier_call_chain+0xe/0x10 > [ 2991.344562] [] __cpu_notify+0x20/0x32 > [ 2991.344562] [] cpu_notify_nofail+0x17/0x36 > [ 2991.344562] [] _cpu_down+0x154/0x259 > [ 2991.344562] [] cpu_down+0x2d/0x3a > [ 2991.344562] [] store_online+0x4e/0xe7 > [ 2991.344562] [] dev_attr_store+0x20/0x22 > [ 2991.344562] [] sysfs_write_file+0x108/0x144 > [ 2991.344562] [] vfs_write+0xfd/0x158 > [ 2991.344562] [] SyS_write+0x5c/0x83 > [ 2991.344562] [] tracesys+0xdd/0xe2 > > As well as held locks: > > [ 3034.728033] Showing all locks held in the system: > [ 3034.728033] 1 lock held by rcu_preempt/10: > [ 3034.728033] #0: (rcu_preempt_state.onoff_mutex){+.+...}, at: [] rcu_gp_kthread+0x167/0x94b > [ 3034.728033] 4 locks held by kworker/0:1/47: > [ 3034.728033] #0: (events){.+.+.+}, at: [] process_one_work+0x207/0x4d1 > [ 3034.728033] #1: (cpuset_hotplug_work){+.+.+.}, at: [] process_one_work+0x207/0x4d1 > [ 3034.728033] #2: (cpuset_mutex){+.+.+.}, at: [] rebuild_sched_domains+0x17/0x2a > [ 3034.728033] #3: (cpu_hotplug.lock){+.+.+.}, at: [] get_online_cpus+0x3c/0x50 > [ 3034.728033] 1 lock held by mingetty/2563: > [ 3034.728033] #0: (&ldata->atomic_read_lock){+.+...}, at: [] n_tty_read+0x252/0x7e8 > [ 3034.728033] 1 lock held by mingetty/2565: > [ 3034.728033] #0: (&ldata->atomic_read_lock){+.+...}, at: [] n_tty_read+0x252/0x7e8 > [ 3034.728033] 1 lock held by mingetty/2569: > [ 3034.728033] #0: (&ldata->atomic_read_lock){+.+...}, at: [] n_tty_read+0x252/0x7e8 > [ 3034.728033] 1 lock held by mingetty/2572: > [ 3034.728033] #0: (&ldata->atomic_read_lock){+.+...}, at: [] n_tty_read+0x252/0x7e8 > [ 3034.728033] 1 lock held by mingetty/2575: > [ 3034.728033] #0: (&ldata->atomic_read_lock){+.+...}, at: [] n_tty_read+0x252/0x7e8 > [ 3034.728033] 7 locks held by bash/2618: > [ 3034.728033] #0: (sb_writers#5){.+.+.+}, at: [] file_start_write+0x2a/0x2c > [ 3034.728033] #1: (&buffer->mutex#2){+.+.+.}, at: [] sysfs_write_file+0x3c/0x144 > [ 3034.728033] #2: (s_active#54){.+.+.+}, at: [] sysfs_write_file+0xe7/0x144 > [ 3034.728033] #3: (x86_cpu_hotplug_driver_mutex){+.+.+.}, at: [] cpu_hotplug_driver_lock+0x17/0x19 > [ 3034.728033] #4: (cpu_add_remove_lock){+.+.+.}, at: [] cpu_maps_update_begin+0x17/0x19 > [ 3034.728033] #5: (cpu_hotplug.lock){+.+.+.}, at: [] cpu_hotplug_begin+0x2c/0x6d > [ 3034.728033] #6: (rcu_preempt_state.onoff_mutex){+.+...}, at: [] rcu_cpu_notify+0x2f5/0x86e > [ 3034.728033] 1 lock held by bash/2980: > [ 3034.728033] #0: (&ldata->atomic_read_lock){+.+...}, at: [] n_tty_read+0x252/0x7e8 > > Things looked a little weird. Also, this is a deadlock that lockdep did > not catch. But what we have here does not look like a circular lock > issue: > > Bash is blocked in rcu_cpu_notify(): > > 1961 /* Exclude any attempts to start a new grace period. */ > 1962 mutex_lock(&rsp->onoff_mutex); > > > kworker is blocked in get_online_cpus(), which makes sense as we are > currently taking down a CPU. > > But rcu_preempt is not blocked on anything. It is simply sleeping in > rcu_gp_kthread (really rcu_gp_init) here: > > 1453 #ifdef CONFIG_PROVE_RCU_DELAY > 1454 if ((prandom_u32() % (rcu_num_nodes * 8)) == 0 && > 1455 system_state == SYSTEM_RUNNING) > 1456 schedule_timeout_uninterruptible(2); > 1457 #endif /* #ifdef CONFIG_PROVE_RCU_DELAY */ > > And it does this while holding the onoff_mutex that bash is waiting for. > > Doing a function trace, it showed me where it happened: > > [ 125.940066] rcu_pree-10 3.... 28384115273: schedule_timeout_uninterruptible <-rcu_gp_kthread > [...] > [ 125.940066] rcu_pree-10 3d..3 28384202439: sched_switch: prev_comm=rcu_preempt prev_pid=10 prev_prio=120 prev_state=D ==> next_comm=watchdog/3 next_pid=38 next_prio=120 > > The watchdog ran, and then: > > [ 125.940066] watchdog-38 3d..3 28384692863: sched_switch: prev_comm=watchdog/3 prev_pid=38 prev_prio=120 prev_state=P ==> next_comm=modprobe next_pid=2848 next_prio=118 > > Not sure what modprobe was doing, but shortly after that: > > [ 125.940066] modprobe-2848 3d..3 28385041749: sched_switch: prev_comm=modprobe prev_pid=2848 prev_prio=118 prev_state=R+ ==> next_comm=migration/3 next_pid=40 next_prio=0 > > Where the migration thread took down the CPU: > > [ 125.940066] migratio-40 3d..3 28389148276: sched_switch: prev_comm=migration/3 prev_pid=40 prev_prio=0 prev_state=P ==> next_comm=swapper/3 next_pid=0 next_prio=120 > > which finally did: > > [ 125.940066] -0 3...1 28389282142: arch_cpu_idle_dead <-cpu_startup_entry > [ 125.940066] -0 3...1 28389282548: native_play_dead <-arch_cpu_idle_dead > [ 125.940066] -0 3...1 28389282924: play_dead_common <-native_play_dead > [ 125.940066] -0 3...1 28389283468: idle_task_exit <-play_dead_common > [ 125.940066] -0 3...1 28389284644: amd_e400_remove_cpu <-play_dead_common > > > CPU 3 is now offline, the rcu_preempt thread that ran on CPU 3 is still > doing a schedule_timeout_uninterruptible() and it registered it's > timeout to the timer base for CPU 3. You would think that it would get > migrated right? The issue here is that the timer migration happens at > the CPU notifier for CPU_DEAD. The problem is that the rcu notifier for > CPU_DOWN is blocked waiting for the onoff_mutex to be released, which is > held by the thread that just put itself into a uninterruptible sleep, > that wont wake up until the CPU_DEAD notifier of the timer > infrastructure is called, which wont happen until the rcu notifier > finishes. Here's our deadlock! This commit breaks this deadlock cycle by substituting a shorter udelay() for the previous schedule_timeout_uninterruptible(), while at the same time increasing the probability of the delay. This maintains the intensity of the testing. Reported-by: Steven Rostedt Signed-off-by: Paul E. McKenney Tested-by: Steven Rostedt --- kernel/rcutree.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) (limited to 'kernel') diff --git a/kernel/rcutree.c b/kernel/rcutree.c index b61d20c5ee7b..35380019f0fc 100644 --- a/kernel/rcutree.c +++ b/kernel/rcutree.c @@ -1451,9 +1451,9 @@ static int rcu_gp_init(struct rcu_state *rsp) rnp->grphi, rnp->qsmask); raw_spin_unlock_irq(&rnp->lock); #ifdef CONFIG_PROVE_RCU_DELAY - if ((prandom_u32() % (rcu_num_nodes * 8)) == 0 && + if ((prandom_u32() % (rcu_num_nodes + 1)) == 0 && system_state == SYSTEM_RUNNING) - schedule_timeout_uninterruptible(2); + udelay(200); #endif /* #ifdef CONFIG_PROVE_RCU_DELAY */ cond_resched(); } -- cgit v1.2.3 From 34376a50fb1fa095b9d0636fa41ed2e73125f214 Mon Sep 17 00:00:00 2001 From: Ben Greear Date: Thu, 6 Jun 2013 14:29:49 -0700 Subject: Fix lockup related to stop_machine being stuck in __do_softirq. The stop machine logic can lock up if all but one of the migration threads make it through the disable-irq step and the one remaining thread gets stuck in __do_softirq. The reason __do_softirq can hang is that it has a bail-out based on jiffies timeout, but in the lockup case, jiffies itself is not incremented. To work around this, re-add the max_restart counter in __do_irq and stop processing irqs after 10 restarts. Thanks to Tejun Heo and Rusty Russell and others for helping me track this down. This was introduced in 3.9 by commit c10d73671ad3 ("softirq: reduce latencies"). It may be worth looking into ath9k to see if it has issues with its irq handler at a later date. The hang stack traces look something like this: ------------[ cut here ]------------ WARNING: at kernel/watchdog.c:245 watchdog_overflow_callback+0x9c/0xa7() Watchdog detected hard LOCKUP on cpu 2 Modules linked in: ath9k ath9k_common ath9k_hw ath mac80211 cfg80211 nfsv4 auth_rpcgss nfs fscache nf_nat_ipv4 nf_nat veth 8021q garp stp mrp llc pktgen lockd sunrpc] Pid: 23, comm: migration/2 Tainted: G C 3.9.4+ #11 Call Trace: warn_slowpath_common+0x85/0x9f warn_slowpath_fmt+0x46/0x48 watchdog_overflow_callback+0x9c/0xa7 __perf_event_overflow+0x137/0x1cb perf_event_overflow+0x14/0x16 intel_pmu_handle_irq+0x2dc/0x359 perf_event_nmi_handler+0x19/0x1b nmi_handle+0x7f/0xc2 do_nmi+0xbc/0x304 end_repeat_nmi+0x1e/0x2e <> cpu_stopper_thread+0xae/0x162 smpboot_thread_fn+0x258/0x260 kthread+0xc7/0xcf ret_from_fork+0x7c/0xb0 ---[ end trace 4947dfa9b0a4cec3 ]--- BUG: soft lockup - CPU#1 stuck for 22s! [migration/1:17] Modules linked in: ath9k ath9k_common ath9k_hw ath mac80211 cfg80211 nfsv4 auth_rpcgss nfs fscache nf_nat_ipv4 nf_nat veth 8021q garp stp mrp llc pktgen lockd sunrpc] irq event stamp: 835637905 hardirqs last enabled at (835637904): __do_softirq+0x9f/0x257 hardirqs last disabled at (835637905): apic_timer_interrupt+0x6d/0x80 softirqs last enabled at (5654720): __do_softirq+0x1ff/0x257 softirqs last disabled at (5654725): irq_exit+0x5f/0xbb CPU 1 Pid: 17, comm: migration/1 Tainted: G WC 3.9.4+ #11 To be filled by O.E.M. To be filled by O.E.M./To be filled by O.E.M. RIP: tasklet_hi_action+0xf0/0xf0 Process migration/1 Call Trace: __do_softirq+0x117/0x257 irq_exit+0x5f/0xbb smp_apic_timer_interrupt+0x8a/0x98 apic_timer_interrupt+0x72/0x80 printk+0x4d/0x4f stop_machine_cpu_stop+0x22c/0x274 cpu_stopper_thread+0xae/0x162 smpboot_thread_fn+0x258/0x260 kthread+0xc7/0xcf ret_from_fork+0x7c/0xb0 Signed-off-by: Ben Greear Acked-by: Tejun Heo Acked-by: Pekka Riikonen Cc: Eric Dumazet Cc: stable@kernel.org Signed-off-by: Linus Torvalds --- kernel/softirq.c | 13 ++++++++++--- 1 file changed, 10 insertions(+), 3 deletions(-) (limited to 'kernel') diff --git a/kernel/softirq.c b/kernel/softirq.c index b5197dcb0dad..3d6833f125d3 100644 --- a/kernel/softirq.c +++ b/kernel/softirq.c @@ -195,8 +195,12 @@ void local_bh_enable_ip(unsigned long ip) EXPORT_SYMBOL(local_bh_enable_ip); /* - * We restart softirq processing for at most 2 ms, - * and if need_resched() is not set. + * We restart softirq processing for at most MAX_SOFTIRQ_RESTART times, + * but break the loop if need_resched() is set or after 2 ms. + * The MAX_SOFTIRQ_TIME provides a nice upper bound in most cases, but in + * certain cases, such as stop_machine(), jiffies may cease to + * increment and so we need the MAX_SOFTIRQ_RESTART limit as + * well to make sure we eventually return from this method. * * These limits have been established via experimentation. * The two things to balance is latency against fairness - @@ -204,6 +208,7 @@ EXPORT_SYMBOL(local_bh_enable_ip); * should not be able to lock up the box. */ #define MAX_SOFTIRQ_TIME msecs_to_jiffies(2) +#define MAX_SOFTIRQ_RESTART 10 asmlinkage void __do_softirq(void) { @@ -212,6 +217,7 @@ asmlinkage void __do_softirq(void) unsigned long end = jiffies + MAX_SOFTIRQ_TIME; int cpu; unsigned long old_flags = current->flags; + int max_restart = MAX_SOFTIRQ_RESTART; /* * Mask out PF_MEMALLOC s current task context is borrowed for the @@ -265,7 +271,8 @@ restart: pending = local_softirq_pending(); if (pending) { - if (time_before(jiffies, end) && !need_resched()) + if (time_before(jiffies, end) && !need_resched() && + --max_restart) goto restart; wakeup_softirqd(); -- cgit v1.2.3 From 58e8eedf18577c7eac722d5d1f190507ea263d1b Mon Sep 17 00:00:00 2001 From: Yoshihiro YUNOMAE Date: Tue, 23 Apr 2013 10:32:39 +0900 Subject: tracing: Fix outputting formats of x86-tsc and counter when use trace_clock Outputting formats of x86-tsc and counter should be a raw format, but after applying the patch(2b6080f28c7cc3efc8625ab71495aae89aeb63a0), the format was changed to nanosec. This is because the global variable trace_clock_id was used. When we use multiple buffers, clock_id of each sub-buffer should be used. Then, this patch uses tr->clock_id instead of the global variable trace_clock_id. [ Basically, this fixes a regression where the multibuffer code changed the trace_clock file to update tr->clock_id but the traces still use the old global trace_clock_id variable, negating the file's effect. The global trace_clock_id variable is obsolete and removed. - SR ] Link: http://lkml.kernel.org/r/20130423013239.22334.7394.stgit@yunodevel Signed-off-by: Yoshihiro YUNOMAE Signed-off-by: Steven Rostedt --- kernel/trace/trace.c | 8 +++----- kernel/trace/trace.h | 2 -- 2 files changed, 3 insertions(+), 7 deletions(-) (limited to 'kernel') diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c index 1a41023a1f88..e71a8be4a6ee 100644 --- a/kernel/trace/trace.c +++ b/kernel/trace/trace.c @@ -652,8 +652,6 @@ static struct { ARCH_TRACE_CLOCKS }; -int trace_clock_id; - /* * trace_parser_get_init - gets the buffer for trace parser */ @@ -2826,7 +2824,7 @@ __tracing_open(struct inode *inode, struct file *file, bool snapshot) iter->iter_flags |= TRACE_FILE_ANNOTATE; /* Output in nanoseconds only if we are using a clock in nanoseconds. */ - if (trace_clocks[trace_clock_id].in_ns) + if (trace_clocks[tr->clock_id].in_ns) iter->iter_flags |= TRACE_FILE_TIME_IN_NS; /* stop the trace while dumping if we are not opening "snapshot" */ @@ -3825,7 +3823,7 @@ static int tracing_open_pipe(struct inode *inode, struct file *filp) iter->iter_flags |= TRACE_FILE_LAT_FMT; /* Output in nanoseconds only if we are using a clock in nanoseconds. */ - if (trace_clocks[trace_clock_id].in_ns) + if (trace_clocks[tr->clock_id].in_ns) iter->iter_flags |= TRACE_FILE_TIME_IN_NS; iter->cpu_file = tc->cpu; @@ -5095,7 +5093,7 @@ tracing_stats_read(struct file *filp, char __user *ubuf, cnt = ring_buffer_bytes_cpu(trace_buf->buffer, cpu); trace_seq_printf(s, "bytes: %ld\n", cnt); - if (trace_clocks[trace_clock_id].in_ns) { + if (trace_clocks[tr->clock_id].in_ns) { /* local or global for trace_clock */ t = ns2usecs(ring_buffer_oldest_event_ts(trace_buf->buffer, cpu)); usec_rem = do_div(t, USEC_PER_SEC); diff --git a/kernel/trace/trace.h b/kernel/trace/trace.h index 711ca7d3e7f1..20572ed88c5c 100644 --- a/kernel/trace/trace.h +++ b/kernel/trace/trace.h @@ -700,8 +700,6 @@ enum print_line_t print_trace_line(struct trace_iterator *iter); extern unsigned long trace_flags; -extern int trace_clock_id; - /* Standard output formatting function used for function return traces */ #ifdef CONFIG_FUNCTION_GRAPH_TRACER -- cgit v1.2.3 From 16e53dbf10a2d7e228709a7286310e629ede5e45 Mon Sep 17 00:00:00 2001 From: "Srivatsa S. Bhat" Date: Wed, 12 Jun 2013 14:04:36 -0700 Subject: CPU hotplug: provide a generic helper to disable/enable CPU hotplug There are instances in the kernel where we would like to disable CPU hotplug (from sysfs) during some important operation. Today the freezer code depends on this and the code to do it was kinda tailor-made for that. Restructure the code and make it generic enough to be useful for other usecases too. Signed-off-by: Srivatsa S. Bhat Signed-off-by: Robin Holt Cc: H. Peter Anvin Cc: Thomas Gleixner Cc: Ingo Molnar Cc: Russ Anderson Cc: Robin Holt Cc: Russell King Cc: Guan Xuetao Cc: Shawn Guo Cc: Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- include/linux/cpu.h | 4 ++++ kernel/cpu.c | 55 ++++++++++++++++++++++------------------------------- 2 files changed, 27 insertions(+), 32 deletions(-) (limited to 'kernel') diff --git a/include/linux/cpu.h b/include/linux/cpu.h index c6f6e0839b61..9f3c7e81270a 100644 --- a/include/linux/cpu.h +++ b/include/linux/cpu.h @@ -175,6 +175,8 @@ extern struct bus_type cpu_subsys; extern void get_online_cpus(void); extern void put_online_cpus(void); +extern void cpu_hotplug_disable(void); +extern void cpu_hotplug_enable(void); #define hotcpu_notifier(fn, pri) cpu_notifier(fn, pri) #define register_hotcpu_notifier(nb) register_cpu_notifier(nb) #define unregister_hotcpu_notifier(nb) unregister_cpu_notifier(nb) @@ -198,6 +200,8 @@ static inline void cpu_hotplug_driver_unlock(void) #define get_online_cpus() do { } while (0) #define put_online_cpus() do { } while (0) +#define cpu_hotplug_disable() do { } while (0) +#define cpu_hotplug_enable() do { } while (0) #define hotcpu_notifier(fn, pri) do { (void)(fn); } while (0) /* These aren't inline functions due to a GCC bug. */ #define register_hotcpu_notifier(nb) ({ (void)(nb); 0; }) diff --git a/kernel/cpu.c b/kernel/cpu.c index b5e4ab2d427e..198a38883e64 100644 --- a/kernel/cpu.c +++ b/kernel/cpu.c @@ -133,6 +133,27 @@ static void cpu_hotplug_done(void) mutex_unlock(&cpu_hotplug.lock); } +/* + * Wait for currently running CPU hotplug operations to complete (if any) and + * disable future CPU hotplug (from sysfs). The 'cpu_add_remove_lock' protects + * the 'cpu_hotplug_disabled' flag. The same lock is also acquired by the + * hotplug path before performing hotplug operations. So acquiring that lock + * guarantees mutual exclusion from any currently running hotplug operations. + */ +void cpu_hotplug_disable(void) +{ + cpu_maps_update_begin(); + cpu_hotplug_disabled = 1; + cpu_maps_update_done(); +} + +void cpu_hotplug_enable(void) +{ + cpu_maps_update_begin(); + cpu_hotplug_disabled = 0; + cpu_maps_update_done(); +} + #else /* #if CONFIG_HOTPLUG_CPU */ static void cpu_hotplug_begin(void) {} static void cpu_hotplug_done(void) {} @@ -540,36 +561,6 @@ static int __init alloc_frozen_cpus(void) } core_initcall(alloc_frozen_cpus); -/* - * Prevent regular CPU hotplug from racing with the freezer, by disabling CPU - * hotplug when tasks are about to be frozen. Also, don't allow the freezer - * to continue until any currently running CPU hotplug operation gets - * completed. - * To modify the 'cpu_hotplug_disabled' flag, we need to acquire the - * 'cpu_add_remove_lock'. And this same lock is also taken by the regular - * CPU hotplug path and released only after it is complete. Thus, we - * (and hence the freezer) will block here until any currently running CPU - * hotplug operation gets completed. - */ -void cpu_hotplug_disable_before_freeze(void) -{ - cpu_maps_update_begin(); - cpu_hotplug_disabled = 1; - cpu_maps_update_done(); -} - - -/* - * When tasks have been thawed, re-enable regular CPU hotplug (which had been - * disabled while beginning to freeze tasks). - */ -void cpu_hotplug_enable_after_thaw(void) -{ - cpu_maps_update_begin(); - cpu_hotplug_disabled = 0; - cpu_maps_update_done(); -} - /* * When callbacks for CPU hotplug notifications are being executed, we must * ensure that the state of the system with respect to the tasks being frozen @@ -589,12 +580,12 @@ cpu_hotplug_pm_callback(struct notifier_block *nb, case PM_SUSPEND_PREPARE: case PM_HIBERNATION_PREPARE: - cpu_hotplug_disable_before_freeze(); + cpu_hotplug_disable(); break; case PM_POST_SUSPEND: case PM_POST_HIBERNATION: - cpu_hotplug_enable_after_thaw(); + cpu_hotplug_enable(); break; default: -- cgit v1.2.3 From cf7df378aa4ff7da3a44769b7ff6e9eef1a9f3db Mon Sep 17 00:00:00 2001 From: Robin Holt Date: Wed, 12 Jun 2013 14:04:37 -0700 Subject: reboot: rigrate shutdown/reboot to boot cpu We recently noticed that reboot of a 1024 cpu machine takes approx 16 minutes of just stopping the cpus. The slowdown was tracked to commit f96972f2dc63 ("kernel/sys.c: call disable_nonboot_cpus() in kernel_restart()"). The current implementation does all the work of hot removing the cpus before halting the system. We are switching to just migrating to the boot cpu and then continuing with shutdown/reboot. This also has the effect of not breaking x86's command line parameter for specifying the reboot cpu. Note, this code was shamelessly copied from arch/x86/kernel/reboot.c with bits removed pertaining to the reboot_cpu command line parameter. Signed-off-by: Robin Holt Tested-by: Shawn Guo Cc: "Srivatsa S. Bhat" Cc: H. Peter Anvin Cc: Thomas Gleixner Cc: Ingo Molnar Cc: Russ Anderson Cc: Robin Holt Cc: Russell King Cc: Guan Xuetao Cc: Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- kernel/sys.c | 29 ++++++++++++++++++++++++++--- 1 file changed, 26 insertions(+), 3 deletions(-) (limited to 'kernel') diff --git a/kernel/sys.c b/kernel/sys.c index b95d3c72ba21..2bbd9a73b54c 100644 --- a/kernel/sys.c +++ b/kernel/sys.c @@ -362,6 +362,29 @@ int unregister_reboot_notifier(struct notifier_block *nb) } EXPORT_SYMBOL(unregister_reboot_notifier); +/* Add backwards compatibility for stable trees. */ +#ifndef PF_NO_SETAFFINITY +#define PF_NO_SETAFFINITY PF_THREAD_BOUND +#endif + +static void migrate_to_reboot_cpu(void) +{ + /* The boot cpu is always logical cpu 0 */ + int cpu = 0; + + cpu_hotplug_disable(); + + /* Make certain the cpu I'm about to reboot on is online */ + if (!cpu_online(cpu)) + cpu = cpumask_first(cpu_online_mask); + + /* Prevent races with other tasks migrating this task */ + current->flags |= PF_NO_SETAFFINITY; + + /* Make certain I only run on the appropriate processor */ + set_cpus_allowed_ptr(current, cpumask_of(cpu)); +} + /** * kernel_restart - reboot the system * @cmd: pointer to buffer containing command to execute for restart @@ -373,7 +396,7 @@ EXPORT_SYMBOL(unregister_reboot_notifier); void kernel_restart(char *cmd) { kernel_restart_prepare(cmd); - disable_nonboot_cpus(); + migrate_to_reboot_cpu(); syscore_shutdown(); if (!cmd) printk(KERN_EMERG "Restarting system.\n"); @@ -400,7 +423,7 @@ static void kernel_shutdown_prepare(enum system_states state) void kernel_halt(void) { kernel_shutdown_prepare(SYSTEM_HALT); - disable_nonboot_cpus(); + migrate_to_reboot_cpu(); syscore_shutdown(); printk(KERN_EMERG "System halted.\n"); kmsg_dump(KMSG_DUMP_HALT); @@ -419,7 +442,7 @@ void kernel_power_off(void) kernel_shutdown_prepare(SYSTEM_POWER_OFF); if (pm_power_off_prepare) pm_power_off_prepare(); - disable_nonboot_cpus(); + migrate_to_reboot_cpu(); syscore_shutdown(); printk(KERN_EMERG "Power down.\n"); kmsg_dump(KMSG_DUMP_POWEROFF); -- cgit v1.2.3 From 637241a900cbd982f744d44646b48a273d609b34 Mon Sep 17 00:00:00 2001 From: Kees Cook Date: Wed, 12 Jun 2013 14:04:39 -0700 Subject: kmsg: honor dmesg_restrict sysctl on /dev/kmsg The dmesg_restrict sysctl currently covers the syslog method for access dmesg, however /dev/kmsg isn't covered by the same protections. Most people haven't noticed because util-linux dmesg(1) defaults to using the syslog method for access in older versions. With util-linux dmesg(1) defaults to reading directly from /dev/kmsg. To fix /dev/kmsg, let's compare the existing interfaces and what they allow: - /proc/kmsg allows: - open (SYSLOG_ACTION_OPEN) if CAP_SYSLOG since it uses a destructive single-reader interface (SYSLOG_ACTION_READ). - everything, after an open. - syslog syscall allows: - anything, if CAP_SYSLOG. - SYSLOG_ACTION_READ_ALL and SYSLOG_ACTION_SIZE_BUFFER, if dmesg_restrict==0. - nothing else (EPERM). The use-cases were: - dmesg(1) needs to do non-destructive SYSLOG_ACTION_READ_ALLs. - sysklog(1) needs to open /proc/kmsg, drop privs, and still issue the destructive SYSLOG_ACTION_READs. AIUI, dmesg(1) is moving to /dev/kmsg, and systemd-journald doesn't clear the ring buffer. Based on the comments in devkmsg_llseek, it sounds like actions besides reading aren't going to be supported by /dev/kmsg (i.e. SYSLOG_ACTION_CLEAR), so we have a strict subset of the non-destructive syslog syscall actions. To this end, move the check as Josh had done, but also rename the constants to reflect their new uses (SYSLOG_FROM_CALL becomes SYSLOG_FROM_READER, and SYSLOG_FROM_FILE becomes SYSLOG_FROM_PROC). SYSLOG_FROM_READER allows non-destructive actions, and SYSLOG_FROM_PROC allows destructive actions after a capabilities-constrained SYSLOG_ACTION_OPEN check. - /dev/kmsg allows: - open if CAP_SYSLOG or dmesg_restrict==0 - reading/polling, after open Addresses https://bugzilla.redhat.com/show_bug.cgi?id=903192 [akpm@linux-foundation.org: use pr_warn_once()] Signed-off-by: Kees Cook Reported-by: Christian Kujau Tested-by: Josh Boyer Cc: Kay Sievers Cc: Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- fs/proc/kmsg.c | 10 +++--- include/linux/syslog.h | 4 +-- kernel/printk.c | 91 +++++++++++++++++++++++++++----------------------- 3 files changed, 57 insertions(+), 48 deletions(-) (limited to 'kernel') diff --git a/fs/proc/kmsg.c b/fs/proc/kmsg.c index bd4b5a740ff1..bdfabdaefdce 100644 --- a/fs/proc/kmsg.c +++ b/fs/proc/kmsg.c @@ -21,12 +21,12 @@ extern wait_queue_head_t log_wait; static int kmsg_open(struct inode * inode, struct file * file) { - return do_syslog(SYSLOG_ACTION_OPEN, NULL, 0, SYSLOG_FROM_FILE); + return do_syslog(SYSLOG_ACTION_OPEN, NULL, 0, SYSLOG_FROM_PROC); } static int kmsg_release(struct inode * inode, struct file * file) { - (void) do_syslog(SYSLOG_ACTION_CLOSE, NULL, 0, SYSLOG_FROM_FILE); + (void) do_syslog(SYSLOG_ACTION_CLOSE, NULL, 0, SYSLOG_FROM_PROC); return 0; } @@ -34,15 +34,15 @@ static ssize_t kmsg_read(struct file *file, char __user *buf, size_t count, loff_t *ppos) { if ((file->f_flags & O_NONBLOCK) && - !do_syslog(SYSLOG_ACTION_SIZE_UNREAD, NULL, 0, SYSLOG_FROM_FILE)) + !do_syslog(SYSLOG_ACTION_SIZE_UNREAD, NULL, 0, SYSLOG_FROM_PROC)) return -EAGAIN; - return do_syslog(SYSLOG_ACTION_READ, buf, count, SYSLOG_FROM_FILE); + return do_syslog(SYSLOG_ACTION_READ, buf, count, SYSLOG_FROM_PROC); } static unsigned int kmsg_poll(struct file *file, poll_table *wait) { poll_wait(file, &log_wait, wait); - if (do_syslog(SYSLOG_ACTION_SIZE_UNREAD, NULL, 0, SYSLOG_FROM_FILE)) + if (do_syslog(SYSLOG_ACTION_SIZE_UNREAD, NULL, 0, SYSLOG_FROM_PROC)) return POLLIN | POLLRDNORM; return 0; } diff --git a/include/linux/syslog.h b/include/linux/syslog.h index 38911391a139..98a3153c0f96 100644 --- a/include/linux/syslog.h +++ b/include/linux/syslog.h @@ -44,8 +44,8 @@ /* Return size of the log buffer */ #define SYSLOG_ACTION_SIZE_BUFFER 10 -#define SYSLOG_FROM_CALL 0 -#define SYSLOG_FROM_FILE 1 +#define SYSLOG_FROM_READER 0 +#define SYSLOG_FROM_PROC 1 int do_syslog(int type, char __user *buf, int count, bool from_file); diff --git a/kernel/printk.c b/kernel/printk.c index fa36e1494420..8212c1aef125 100644 --- a/kernel/printk.c +++ b/kernel/printk.c @@ -363,6 +363,53 @@ static void log_store(int facility, int level, log_next_seq++; } +#ifdef CONFIG_SECURITY_DMESG_RESTRICT +int dmesg_restrict = 1; +#else +int dmesg_restrict; +#endif + +static int syslog_action_restricted(int type) +{ + if (dmesg_restrict) + return 1; + /* + * Unless restricted, we allow "read all" and "get buffer size" + * for everybody. + */ + return type != SYSLOG_ACTION_READ_ALL && + type != SYSLOG_ACTION_SIZE_BUFFER; +} + +static int check_syslog_permissions(int type, bool from_file) +{ + /* + * If this is from /proc/kmsg and we've already opened it, then we've + * already done the capabilities checks at open time. + */ + if (from_file && type != SYSLOG_ACTION_OPEN) + return 0; + + if (syslog_action_restricted(type)) { + if (capable(CAP_SYSLOG)) + return 0; + /* + * For historical reasons, accept CAP_SYS_ADMIN too, with + * a warning. + */ + if (capable(CAP_SYS_ADMIN)) { + pr_warn_once("%s (%d): Attempt to access syslog with " + "CAP_SYS_ADMIN but no CAP_SYSLOG " + "(deprecated).\n", + current->comm, task_pid_nr(current)); + return 0; + } + return -EPERM; + } + return security_syslog(type); +} + + /* /dev/kmsg - userspace message inject/listen interface */ struct devkmsg_user { u64 seq; @@ -620,7 +667,8 @@ static int devkmsg_open(struct inode *inode, struct file *file) if ((file->f_flags & O_ACCMODE) == O_WRONLY) return 0; - err = security_syslog(SYSLOG_ACTION_READ_ALL); + err = check_syslog_permissions(SYSLOG_ACTION_READ_ALL, + SYSLOG_FROM_READER); if (err) return err; @@ -813,45 +861,6 @@ static inline void boot_delay_msec(int level) } #endif -#ifdef CONFIG_SECURITY_DMESG_RESTRICT -int dmesg_restrict = 1; -#else -int dmesg_restrict; -#endif - -static int syslog_action_restricted(int type) -{ - if (dmesg_restrict) - return 1; - /* Unless restricted, we allow "read all" and "get buffer size" for everybody */ - return type != SYSLOG_ACTION_READ_ALL && type != SYSLOG_ACTION_SIZE_BUFFER; -} - -static int check_syslog_permissions(int type, bool from_file) -{ - /* - * If this is from /proc/kmsg and we've already opened it, then we've - * already done the capabilities checks at open time. - */ - if (from_file && type != SYSLOG_ACTION_OPEN) - return 0; - - if (syslog_action_restricted(type)) { - if (capable(CAP_SYSLOG)) - return 0; - /* For historical reasons, accept CAP_SYS_ADMIN too, with a warning */ - if (capable(CAP_SYS_ADMIN)) { - printk_once(KERN_WARNING "%s (%d): " - "Attempt to access syslog with CAP_SYS_ADMIN " - "but no CAP_SYSLOG (deprecated).\n", - current->comm, task_pid_nr(current)); - return 0; - } - return -EPERM; - } - return 0; -} - #if defined(CONFIG_PRINTK_TIME) static bool printk_time = 1; #else @@ -1249,7 +1258,7 @@ out: SYSCALL_DEFINE3(syslog, int, type, char __user *, buf, int, len) { - return do_syslog(type, buf, len, SYSLOG_FROM_CALL); + return do_syslog(type, buf, len, SYSLOG_FROM_READER); } /* -- cgit v1.2.3 From f000cfdde5de4fc15dead5ccf524359c07eadf2b Mon Sep 17 00:00:00 2001 From: Oleg Nesterov Date: Wed, 12 Jun 2013 14:04:46 -0700 Subject: audit: wait_for_auditd() should use TASK_UNINTERRUPTIBLE audit_log_start() does wait_for_auditd() in a loop until audit_backlog_wait_time passes or audit_skb_queue has a room. If signal_pending() is true this becomes a busy-wait loop, schedule() in TASK_INTERRUPTIBLE won't block. Thanks to Guy for fully investigating and explaining the problem. (akpm: that'll cause the system to lock up on a non-preemptible uniprocessor kernel) (Guy: "Our customer was in fact running a uniprocessor machine, and they reported a system hang.") Signed-off-by: Oleg Nesterov Reported-by: Guy Streeter Cc: Eric Paris Cc: Al Viro Cc: Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- kernel/audit.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'kernel') diff --git a/kernel/audit.c b/kernel/audit.c index 21c7fa615bd3..91e53d04b6a9 100644 --- a/kernel/audit.c +++ b/kernel/audit.c @@ -1056,7 +1056,7 @@ static inline void audit_get_stamp(struct audit_context *ctx, static void wait_for_auditd(unsigned long sleep_time) { DECLARE_WAITQUEUE(wait, current); - set_current_state(TASK_INTERRUPTIBLE); + set_current_state(TASK_UNINTERRUPTIBLE); add_wait_queue(&audit_backlog_wait, &wait); if (audit_backlog_limit && -- cgit v1.2.3 From 736f3203a06eafd0944103775a98584082744c6b Mon Sep 17 00:00:00 2001 From: Chen Gang Date: Wed, 12 Jun 2013 14:05:07 -0700 Subject: kernel/audit_tree.c:audit_add_tree_rule(): protect `rule' from kill_rules() audit_add_tree_rule() must set 'rule->tree = NULL;' firstly, to protect the rule itself freed in kill_rules(). The reason is when it is killed, the 'rule' itself may have already released, we should not access it. one example: we add a rule to an inode, just at the same time the other task is deleting this inode. The work flow for adding a rule: audit_receive() -> (need audit_cmd_mutex lock) audit_receive_skb() -> audit_receive_msg() -> audit_receive_filter() -> audit_add_rule() -> audit_add_tree_rule() -> (need audit_filter_mutex lock) ... unlock audit_filter_mutex get_tree() ... iterate_mounts() -> (iterate all related inodes) tag_mount() -> tag_trunk() -> create_trunk() -> (assume it is 1st rule) fsnotify_add_mark() -> fsnotify_add_inode_mark() -> (add mark to inode->i_fsnotify_marks) ... get_tree(); (each inode will get one) ... lock audit_filter_mutex The work flow for deleting an inode: __destroy_inode() -> fsnotify_inode_delete() -> __fsnotify_inode_delete() -> fsnotify_clear_marks_by_inode() -> (get mark from inode->i_fsnotify_marks) fsnotify_destroy_mark() -> fsnotify_destroy_mark_locked() -> audit_tree_freeing_mark() -> evict_chunk() -> ... tree->goner = 1 ... kill_rules() -> (assume current->audit_context == NULL) call_rcu() -> (rule->tree != NULL) audit_free_rule_rcu() -> audit_free_rule() ... audit_schedule_prune() -> (assume current->audit_context == NULL) kthread_run() -> (need audit_cmd_mutex and audit_filter_mutex lock) prune_one() -> (delete it from prue_list) put_tree(); (match the original get_tree above) Signed-off-by: Chen Gang Cc: Eric Paris Cc: Al Viro Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- kernel/audit_tree.c | 1 + 1 file changed, 1 insertion(+) (limited to 'kernel') diff --git a/kernel/audit_tree.c b/kernel/audit_tree.c index a291aa23fb3f..43c307dc9453 100644 --- a/kernel/audit_tree.c +++ b/kernel/audit_tree.c @@ -658,6 +658,7 @@ int audit_add_tree_rule(struct audit_krule *rule) struct vfsmount *mnt; int err; + rule->tree = NULL; list_for_each_entry(tree, &tree_list, list) { if (!strcmp(seed->pathname, tree->pathname)) { put_tree(seed); -- cgit v1.2.3 From 8aac62706adaaf0fab02c4327761561c8bda9448 Mon Sep 17 00:00:00 2001 From: Oleg Nesterov Date: Fri, 14 Jun 2013 21:09:49 +0200 Subject: move exit_task_namespaces() outside of exit_notify() exit_notify() does exit_task_namespaces() after forget_original_parent(). This was needed to ensure that ->nsproxy can't be cleared prematurely, an exiting child we are going to reparent can do do_notify_parent() and use the parent's (ours) pid_ns. However, after 32084504 "pidns: use task_active_pid_ns in do_notify_parent" ->nsproxy != NULL is no longer needed, we rely on task_active_pid_ns(). Move exit_task_namespaces() from exit_notify() to do_exit(), after exit_fs() and before exit_task_work(). This solves the problem reported by Andrey, free_ipc_ns()->shm_destroy() does fput() which needs task_work_add(). Note: this particular problem can be fixed if we change fput(), and that change makes sense anyway. But there is another reason to move the callsite. The original reason for exit_task_namespaces() from the middle of exit_notify() was subtle and it has already gone away, now this looks confusing. And this allows us do simplify exit_notify(), we can avoid unlock/lock(tasklist) and we can use ->exit_state instead of PF_EXITING in forget_original_parent(). Reported-by: Andrey Vagin Signed-off-by: Oleg Nesterov Acked-by: "Eric W. Biederman" Acked-by: Andrey Vagin Signed-off-by: Al Viro --- kernel/exit.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'kernel') diff --git a/kernel/exit.c b/kernel/exit.c index af2eb3cbd499..7bb73f9d09db 100644 --- a/kernel/exit.c +++ b/kernel/exit.c @@ -649,7 +649,6 @@ static void exit_notify(struct task_struct *tsk, int group_dead) * jobs, send them a SIGHUP and then a SIGCONT. (POSIX 3.2.2.2) */ forget_original_parent(tsk); - exit_task_namespaces(tsk); write_lock_irq(&tasklist_lock); if (group_dead) @@ -795,6 +794,7 @@ void do_exit(long code) exit_shm(tsk); exit_files(tsk); exit_fs(tsk); + exit_task_namespaces(tsk); exit_task_work(tsk); check_stack_usage(); exit_thread(); -- cgit v1.2.3