user/sven/linux.git/kernel, branch v4.9.5

pid: fix lockdep deadlock warning due to ucount_lock

2017-01-19T19:18:03Z

commit add7c65ca426b7a37184dd3d2172394e23d585d6 upstream. ========================================================= [ INFO: possible irq lock inversion dependency detected ] 4.10.0-rc2-00024-g4aecec9-dirty #118 Tainted: G W --------------------------------------------------------- swapper/1/0 just changed the state of lock: (&(&sighand->siglock)->rlock){-.....}, at: [] __lock_task_sighand+0xb6/0x2c0 but this lock took another, HARDIRQ-unsafe lock in the past: (ucounts_lock){+.+...} and interrupts could create inverse lock ordering between them. other info that might help us debug this: Chain exists of: &(&sighand->siglock)->rlock --> &(&tty->ctrl_lock)->rlock --> ucounts_lock Possible interrupt unsafe locking scenario: CPU0 CPU1 ---- ---- lock(ucounts_lock); local_irq_disable(); lock(&(&sighand->siglock)->rlock); lock(&(&tty->ctrl_lock)->rlock); lock(&(&sighand->siglock)->rlock); *** DEADLOCK *** This patch removes a dependency between rlock and ucount_lock. Fixes: f333c700c610 ("pidns: Add a limit on the number of pid namespaces") Signed-off-by: Andrei Vagin Acked-by: Al Viro Signed-off-by: Eric W. Biederman Signed-off-by: Greg Kroah-Hartman

jump_labels: API for flushing deferred jump label updates

2017-01-19T19:17:59Z

commit b6416e61012429e0277bd15a229222fd17afc1c1 upstream. Modules that use static_key_deferred need a way to synchronize with any delayed work that is still pending when the module is unloaded. Introduce static_key_deferred_flush() which flushes any pending jump label updates. Signed-off-by: David Matlack Acked-by: Peter Zijlstra (Intel) Signed-off-by: Paolo Bonzini Signed-off-by: Greg Kroah-Hartman

mm: fix devm_memremap_pages crash, use mem_hotplug_{begin, done}

2017-01-19T19:17:58Z

commit f931ab479dd24cf7a2c6e2df19778406892591fb upstream. Both arch_add_memory() and arch_remove_memory() expect a single threaded context. For example, arch/x86/mm/init_64.c::kernel_physical_mapping_init() does not hold any locks over this check and branch: if (pgd_val(*pgd)) { pud = (pud_t *)pgd_page_vaddr(*pgd); paddr_last = phys_pud_init(pud, __pa(vaddr), __pa(vaddr_end), page_size_mask); continue; } pud = alloc_low_page(); paddr_last = phys_pud_init(pud, __pa(vaddr), __pa(vaddr_end), page_size_mask); The result is that two threads calling devm_memremap_pages() simultaneously can end up colliding on pgd initialization. This leads to crash signatures like the following where the loser of the race initializes the wrong pgd entry: BUG: unable to handle kernel paging request at ffff888ebfff0000 IP: memcpy_erms+0x6/0x10 PGD 2f8e8fc067 PUD 0 /* <---- Invalid PUD */ Oops: 0000 [#1] SMP DEBUG_PAGEALLOC CPU: 54 PID: 3818 Comm: systemd-udevd Not tainted 4.6.7+ #13 task: ffff882fac290040 ti: ffff882f887a4000 task.ti: ffff882f887a4000 RIP: memcpy_erms+0x6/0x10 [..] Call Trace: ? pmem_do_bvec+0x205/0x370 [nd_pmem] ? blk_queue_enter+0x3a/0x280 pmem_rw_page+0x38/0x80 [nd_pmem] bdev_read_page+0x84/0xb0 Hold the standard memory hotplug mutex over calls to arch_{add,remove}_memory(). Fixes: 41e94a851304 ("add devm_memremap_pages") Link: http://lkml.kernel.org/r/148357647831.9498.12606007370121652979.stgit@dwillia2-desk3.amr.corp.intel.com Signed-off-by: Dan Williams Cc: Christoph Hellwig Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds Signed-off-by: Greg Kroah-Hartman

tick/broadcast: Prevent NULL pointer dereference

2017-01-12T10:39:45Z

commit c1a9eeb938b5433947e5ea22f89baff3182e7075 upstream. When a disfunctional timer, e.g. dummy timer, is installed, the tick core tries to setup the broadcast timer. If no broadcast device is installed, the kernel crashes with a NULL pointer dereference in tick_broadcast_setup_oneshot() because the function has no sanity check. Reported-by: Mason Signed-off-by: Thomas Gleixner Cc: Mark Rutland Cc: Anna-Maria Gleixner Cc: Richard Cochran Cc: Sebastian Andrzej Siewior Cc: Daniel Lezcano Cc: Peter Zijlstra , Cc: Sebastian Frias Cc: Thibaud Cornic Cc: Robin Murphy Link: http://lkml.kernel.org/r/1147ef90-7877-e4d2-bb2b-5c4fa8d3144b@free.fr Signed-off-by: Greg Kroah-Hartman

genirq/affinity: Fix node generation from cpumask

2017-01-12T10:39:31Z

commit c0af52437254fda8b0cdbaae5a9b6d9327f1fcd5 upstream. Commit 34c3d9819fda ("genirq/affinity: Provide smarter irq spreading infrastructure") introduced a better IRQ spreading mechanism, taking account of the available NUMA nodes in the machine. Problem is that the algorithm of retrieving the nodemask iterates "linearly" based on the number of online nodes - some architectures present non-linear node distribution among the nodemask, like PowerPC. If this is the case, the algorithm lead to a wrong node count number and therefore to a bad/incomplete IRQ affinity distribution. For example, this problem were found in a machine with 128 CPUs and two nodes, namely nodes 0 and 8 (instead of 0 and 1, if it was linearly distributed). This led to a wrong affinity distribution which then led to a bad mq allocation for nvme driver. Finally, we take the opportunity to fix a comment regarding the affinity distribution when we have _more_ nodes than vectors. Fixes: 34c3d9819fda ("genirq/affinity: Provide smarter irq spreading infrastructure") Reported-by: Gabriel Krisman Bertazi Signed-off-by: Guilherme G. Piccoli Reviewed-by: Christoph Hellwig Reviewed-by: Gabriel Krisman Bertazi Reviewed-by: Gavin Shan Cc: linux-pci@vger.kernel.org Cc: linuxppc-dev@lists.ozlabs.org Cc: hch@lst.de Link: http://lkml.kernel.org/r/1481738472-2671-1-git-send-email-gpiccoli@linux.vnet.ibm.com Signed-off-by: Thomas Gleixner Signed-off-by: Greg Kroah-Hartman

relay: check array offset before using it

2017-01-12T10:39:30Z

commit 9a29d0fbc2d9ad99fb8a981ab72548cc360e9d4c upstream. Smatch complains that we started using the array offset before we checked that it was valid. Fixes: 017c59c042d0 ('relay: Use per CPU constructs for the relay channel buffer pointers') Link: http://lkml.kernel.org/r/20161013084947.GC16198@mwanda Signed-off-by: Dan Carpenter Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds Signed-off-by: Greg Kroah-Hartman

fgraph: Handle a case where a tracer ignores set_graph_notrace

2017-01-09T07:32:23Z

commit 794de08a16cf1fc1bf785dc48f66d36218cf6d88 upstream. Both the wakeup and irqsoff tracers can use the function graph tracer when the display-graph option is set. The problem is that they ignore the notrace file, and record the entry of functions that would be ignored by the function_graph tracer. This causes the trace->depth to be recorded into the ring buffer. The set_graph_notrace uses a trick by adding a large negative number to the trace->depth when a graph function is to be ignored. On trace output, the graph function uses the depth to record a stack of functions. But since the depth is negative, it accesses the array with a negative number and causes an out of bounds access that can cause a kernel oops or corrupt data. Have the print functions handle cases where a tracer still records functions even when they are in set_graph_notrace. Also add warnings if the depth is below zero before accessing the array. Note, the function graph logic will still prevent the return of these functions from being recorded, which means that they will be left hanging without a return. For example: # echo '*spin*' > set_graph_notrace # echo 1 > options/display-graph # echo wakeup > current_tracer # cat trace [...] _raw_spin_lock() { preempt_count_add() { do_raw_spin_lock() { update_rq_clock(); Where it should look like: _raw_spin_lock() { preempt_count_add(); do_raw_spin_lock(); } update_rq_clock(); Cc: Namhyung Kim Fixes: 29ad23b00474 ("ftrace: Add set_graph_notrace filter") Signed-off-by: Steven Rostedt Signed-off-by: Greg Kroah-Hartman

timekeeping_Force_unsigned_clocksource_to_nanoseconds_conversion

2017-01-09T07:32:17Z

commit 9c1645727b8fa90d07256fdfcc45bf831242a3ab upstream. The clocksource delta to nanoseconds conversion is using signed math, but the delta is unsigned. This makes the conversion space smaller than necessary and in case of a multiplication overflow the conversion can become negative. The conversion is done with scaled math: s64 nsec_delta = ((s64)clkdelta * clk->mult) >> clk->shift; Shifting a signed integer right obvioulsy preserves the sign, which has interesting consequences: - Time jumps backwards - __iter_div_u64_rem() which is used in one of the calling code pathes will take forever to piecewise calculate the seconds/nanoseconds part. This has been reported by several people with different scenarios: David observed that when stopping a VM with a debugger: "It was essentially the stopped by debugger case. I forget exactly why, but the guest was being explicitly stopped from outside, it wasn't just scheduling lag. I think it was something in the vicinity of 10 minutes stopped." When lifting the stop the machine went dead. The stopped by debugger case is not really interesting, but nevertheless it would be a good thing not to die completely. But this was also observed on a live system by Liav: "When the OS is too overloaded, delta will get a high enough value for the msb of the sum delta * tkr->mult + tkr->xtime_nsec to be set, and so after the shift the nsec variable will gain a value similar to 0xffffffffff000000." Unfortunately this has been reintroduced recently with commit 6bd58f09e1d8 ("time: Add cycles to nanoseconds translation"). It had been fixed a year ago already in commit 35a4933a8959 ("time: Avoid signed overflow in timekeeping_get_ns()"). Though it's not surprising that the issue has been reintroduced because the function itself and the whole call chain uses s64 for the result and the propagation of it. The change in this recent commit is subtle: s64 nsec; - nsec = (d * m + n) >> s: + nsec = d * m + n; + nsec >>= s; d being type of cycle_t adds another level of obfuscation. This wouldn't have happened if the previous change to unsigned computation would have made the 'nsec' variable u64 right away and a follow up patch had cleaned up the whole call chain. There have been patches submitted which basically did a revert of the above patch leaving everything else unchanged as signed. Back to square one. This spawned a admittedly pointless discussion about potential users which rely on the unsigned behaviour until someone pointed out that it had been fixed before. The changelogs of said patches added further confusion as they made finally false claims about the consequences for eventual users which expect signed results. Despite delta being cycle_t, aka. u64, it's very well possible to hand in a signed negative value and the signed computation will happily return the correct result. But nobody actually sat down and analyzed the code which was added as user after the propably unintended signed conversion. Though in sensitive code like this it's better to analyze it proper and make sure that nothing relies on this than hunting the subtle wreckage half a year later. After analyzing all call chains it stands that no caller can hand in a negative value (which actually would work due to the s64 cast) and rely on the signed math to do the right thing. Change the conversion function to unsigned math. The conversion of all call chains is done in a follow up patch. This solves the starvation issue, which was caused by the negative result, but it does not solve the underlying problem. It merily procrastinates it. When the timekeeper update is deferred long enough that the unsigned multiplication overflows, then time going backwards is observable again. It does neither solve the issue of clocksources with a small counter width which will wrap around possibly several times and cause random time stamps to be generated. But those are usually not found on systems used for virtualization, so this is likely a non issue. I took the liberty to claim authorship for this simply because analyzing all callsites and writing the changelog took substantially more time than just making the simple s/s64/u64/ change and ignore the rest. Fixes: 6bd58f09e1d8 ("time: Add cycles to nanoseconds translation") Reported-by: David Gibson Reported-by: Liav Rehana Signed-off-by: Thomas Gleixner Reviewed-by: David Gibson Acked-by: Peter Zijlstra (Intel) Cc: Parit Bhargava Cc: Laurent Vivier Cc: "Christopher S. Hall" Cc: Chris Metcalf Cc: Richard Cochran Cc: John Stultz Link: http://lkml.kernel.org/r/20161208204228.688545601@linutronix.de Signed-off-by: Thomas Gleixner Signed-off-by: Greg Kroah-Hartman

kernel/debug/debug_core.c: more properly delay for secondary CPUs

2017-01-06T09:40:17Z

commit 2d13bb6494c807bcf3f78af0e96c0b8615a94385 upstream. We've got a delay loop waiting for secondary CPUs. That loop uses loops_per_jiffy. However, loops_per_jiffy doesn't actually mean how many tight loops make up a jiffy on all architectures. It is quite common to see things like this in the boot log: Calibrating delay loop (skipped), value calculated using timer frequency.. 48.00 BogoMIPS (lpj=24000) In my case I was seeing lots of cases where other CPUs timed out entering the debugger only to print their stack crawls shortly after the kdb> prompt was written. Elsewhere in kgdb we already use udelay(), so that should be safe enough to use to implement our timeout. We'll delay 1 ms for 1000 times, which should give us a full second of delay (just like the old code wanted) but allow us to notice that we're done every 1 ms. [akpm@linux-foundation.org: simplifications, per Daniel] Link: http://lkml.kernel.org/r/1477091361-2039-1-git-send-email-dianders@chromium.org Signed-off-by: Douglas Anderson Reviewed-by: Daniel Thompson Cc: Jason Wessel Cc: Brian Norris Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds Signed-off-by: Greg Kroah-Hartman

kernel/watchdog: use nmi registers snapshot in hardlockup handler

2017-01-06T09:40:16Z

commit 4d1f0fb096aedea7bb5489af93498a82e467c480 upstream. NMI handler doesn't call set_irq_regs(), it's set only by normal IRQ. Thus get_irq_regs() returns NULL or stale registers snapshot with IP/SP pointing to the code interrupted by IRQ which was interrupted by NMI. NULL isn't a problem: in this case watchdog calls dump_stack() and prints full stack trace including NMI. But if we're stuck in IRQ handler then NMI watchlog will print stack trace without IRQ part at all. This patch uses registers snapshot passed into NMI handler as arguments: these registers point exactly to the instruction interrupted by NMI. Fixes: 55537871ef66 ("kernel/watchdog.c: perform all-CPU backtrace in case of hard lockup") Link: http://lkml.kernel.org/r/146771764784.86724.6006627197118544150.stgit@buzz Signed-off-by: Konstantin Khlebnikov Cc: Jiri Kosina Cc: Ulrich Obergfell Cc: Aaron Tomlin Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds Signed-off-by: Greg Kroah-Hartman