user/sven/linux.git/kernel, branch v3.9.7

kmsg: honor dmesg_restrict sysctl on /dev/kmsg

2013-06-20T19:01:29Z

commit 637241a900cbd982f744d44646b48a273d609b34 upstream. 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 Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds Signed-off-by: Greg Kroah-Hartman

reboot: rigrate shutdown/reboot to boot cpu

2013-06-20T19:01:29Z

commit cf7df378aa4ff7da3a44769b7ff6e9eef1a9f3db upstream. 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 Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds Signed-off-by: Greg Kroah-Hartman

CPU hotplug: provide a generic helper to disable/enable CPU hotplug

2013-06-20T19:01:29Z

commit 16e53dbf10a2d7e228709a7286310e629ede5e45 upstream. 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 Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds Signed-off-by: Greg Kroah-Hartman

audit: wait_for_auditd() should use TASK_UNINTERRUPTIBLE

2013-06-20T19:01:27Z

commit f000cfdde5de4fc15dead5ccf524359c07eadf2b upstream. 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 Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds Signed-off-by: Greg Kroah-Hartman

timekeeping: Correct run-time detection of persistent_clock.

2013-06-13T17:49:52Z

commit 0d6bd9953f739dad96d9a0de65383e479ab4e10d upstream. 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. Signed-off-by: Zoran Markovic Cc: John Stultz Cc: Thomas Gleixner Cc: Feng Tang [jstultz: Tweaked commit message and subject] Signed-off-by: John Stultz [zoran.markovic@linaro.org: reworked patch to fit 3.9-stable.] Signed-off-by: Zoran Markovic Signed-off-by: Greg Kroah-Hartman

Fix lockup related to stop_machine being stuck in __do_softirq.

2013-06-13T17:49:50Z

commit 34376a50fb1fa095b9d0636fa41ed2e73125f214 upstream. 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 Signed-off-by: Linus Torvalds Signed-off-by: Greg Kroah-Hartman

cgroup: fix a subtle bug in descendant pre-order walk

2013-06-07T19:53:07Z

commit 7805d000db30a3787a4c969bab6ae4d8a5fd8ce6 upstream. 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 Signed-off-by: Greg Kroah-Hartman

cgroup: initialize xattr before calling d_instantiate()

2013-06-07T19:53:05Z

commit d6cbf35dac8a3dadb9103379820c96d7c85df3d9 upstream. 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. Reported-by: Ivan Bulatovic Reported-by: Casey Schaufler Signed-off-by: Li Zefan Signed-off-by: Tejun Heo Signed-off-by: Greg Kroah-Hartman

module: don't unlink the module until we've removed all exposure.

2013-06-07T19:52:48Z

commit 944a1fa01266aa9ace607f29551b73c41e9440e9 upstream. Otherwise we get a race between unload and reload of the same module: the new module doesn't see the old one in the list, but then fails because it can't register over the still-extant entries in sysfs: [ 103.981925] ------------[ cut here ]------------ [ 103.986902] WARNING: at fs/sysfs/dir.c:536 sysfs_add_one+0xab/0xd0() [ 103.993606] Hardware name: CrownBay Platform [ 103.998075] sysfs: cannot create duplicate filename '/module/pch_gbe' [ 104.004784] Modules linked in: pch_gbe(+) [last unloaded: pch_gbe] [ 104.011362] Pid: 3021, comm: modprobe Tainted: G W 3.9.0-rc5+ #5 [ 104.018662] Call Trace: [ 104.021286] [] warn_slowpath_common+0x6d/0xa0 [ 104.026933] [] ? sysfs_add_one+0xab/0xd0 [ 104.031986] [] ? sysfs_add_one+0xab/0xd0 [ 104.037000] [] warn_slowpath_fmt+0x2e/0x30 [ 104.042188] [] sysfs_add_one+0xab/0xd0 [ 104.046982] [] create_dir+0x5e/0xa0 [ 104.051633] [] sysfs_create_dir+0x78/0xd0 [ 104.056774] [] kobject_add_internal+0x83/0x1f0 [ 104.062351] [] ? kvasprintf+0x46/0x60 [ 104.067231] [] kobject_add_varg+0x2d/0x50 [ 104.072450] [] kobject_init_and_add+0x27/0x30 [ 104.078075] [] mod_sysfs_setup+0x80/0x540 [ 104.083207] [] ? module_bug_finalize+0x51/0xc0 [ 104.088720] [] load_module+0x1429/0x18b0 We can teardown sysfs first, then to be sure, put the state in MODULE_STATE_UNFORMED so it's ignored while we deconstruct it. Reported-by: Veaceslav Falico Tested-by: Veaceslav Falico Signed-off-by: Rusty Russell Cc: Ben Greear Signed-off-by: Greg Kroah-Hartman

x86, range: fix missing merge during add range

2013-06-07T19:52:46Z

commit fbe06b7bae7c9cf6ab05168fce5ee93b2f4bae7c upstream. 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 Signed-off-by: H. Peter Anvin Signed-off-by: Greg Kroah-Hartman