kernel/linux.git/lib, branch v4.12.9

kernel/watchdog: Prevent false positives with turbo modes

2017-08-25T00:15:04+00:00

commit 7edaeb6841dfb27e362288ab8466ebdc4972e867 upstream. The hardlockup detector on x86 uses a performance counter based on unhalted CPU cycles and a periodic hrtimer. The hrtimer period is about 2/5 of the performance counter period, so the hrtimer should fire 2-3 times before the performance counter NMI fires. The NMI code checks whether the hrtimer fired since the last invocation. If not, it assumess a hard lockup. The calculation of those periods is based on the nominal CPU frequency. Turbo modes increase the CPU clock frequency and therefore shorten the period of the perf/NMI watchdog. With extreme Turbo-modes (3x nominal frequency) the perf/NMI period is shorter than the hrtimer period which leads to false positives. A simple fix would be to shorten the hrtimer period, but that comes with the side effect of more frequent hrtimer and softlockup thread wakeups, which is not desired. Implement a low pass filter, which checks the perf/NMI period against kernel time. If the perf/NMI fires before 4/5 of the watchdog period has elapsed then the event is ignored and postponed to the next perf/NMI. That solves the problem and avoids the overhead of shorter hrtimer periods and more frequent softlockup thread wakeups. Fixes: 58687acba592 ("lockup_detector: Combine nmi_watchdog and softlockup detector") Reported-and-tested-by: Kan Liang Signed-off-by: Thomas Gleixner Cc: dzickus@redhat.com Cc: prarit@redhat.com Cc: ak@linux.intel.com Cc: babu.moger@oracle.com Cc: peterz@infradead.org Cc: eranian@google.com Cc: acme@redhat.com Cc: atomlin@redhat.com Cc: akpm@linux-foundation.org Cc: torvalds@linux-foundation.org Link: http://lkml.kernel.org/r/alpine.DEB.2.20.1708150931310.1886@nanos Signed-off-by: Greg Kroah-Hartman

writeback: rework wb_[dec|inc]_stat family of functions

2017-07-27T22:10:23+00:00

commit 3e8f399da490e6ac20a3cfd6aa404c9aa961a9a2 upstream. Currently the writeback statistics code uses a percpu counters to hold various statistics. Furthermore we have 2 families of functions - those which disable local irq and those which doesn't and whose names begin with double underscore. However, they both end up calling __add_wb_stats which in turn calls percpu_counter_add_batch which is already irq-safe. Exploiting this fact allows to eliminated the __wb_* functions since they don't add any further protection than we already have. Furthermore, refactor the wb_* function to call __add_wb_stat directly without the irq-disabling dance. This will likely result in better runtime of code which deals with modifying the stat counters. While at it also document why percpu_counter_add_batch is in fact preempt and irq-safe since at least 3 people got confused. Link: http://lkml.kernel.org/r/1498029937-27293-1-git-send-email-nborisov@suse.com Signed-off-by: Nikolay Borisov Acked-by: Tejun Heo Reviewed-by: Jan Kara Cc: Josef Bacik Cc: Mel Gorman Cc: Jeff Layton Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds Signed-off-by: Mel Gorman Signed-off-by: Greg Kroah-Hartman

percpu_counter: Rename __percpu_counter_add to percpu_counter_add_batch

2017-07-27T22:10:23+00:00

commit 104b4e5139fe384431ac11c3b8a6cf4a529edf4a upstream. Currently, percpu_counter_add is a wrapper around __percpu_counter_add which is preempt safe due to explicit calls to preempt_disable. Given how __ prefix is used in percpu related interfaces, the naming unfortunately creates the false sense that __percpu_counter_add is less safe than percpu_counter_add. In terms of context-safety, they're equivalent. The only difference is that the __ version takes a batch parameter. Make this a bit more explicit by just renaming __percpu_counter_add to percpu_counter_add_batch. This patch doesn't cause any functional changes. tj: Minor updates to patch description for clarity. Cosmetic indentation updates. Signed-off-by: Nikolay Borisov Signed-off-by: Tejun Heo Cc: Chris Mason Cc: Josef Bacik Cc: David Sterba Cc: Darrick J. Wong Cc: Jan Kara Cc: Jens Axboe Cc: linux-mm@kvack.org Cc: "David S. Miller" Signed-off-by: Mel Gorman Signed-off-by: Greg Kroah-Hartman

sched/fair, cpumask: Export for_each_cpu_wrap()

2017-07-12T14:55:25+00:00

commit c743f0a5c50f2fcbc628526279cfa24f3dabe182 upstream. More users for for_each_cpu_wrap() have appeared. Promote the construct to generic cpumask interface. The implementation is slightly modified to reduce arguments. Signed-off-by: Peter Zijlstra (Intel) Cc: Lauro Ramos Venancio Cc: Linus Torvalds Cc: Mike Galbraith Cc: Peter Zijlstra Cc: Rik van Riel Cc: Thomas Gleixner Cc: lwang@redhat.com Link: http://lkml.kernel.org/r/20170414122005.o35me2h5nowqkxbv@hirez.programming.kicks-ass.net Signed-off-by: Ingo Molnar Signed-off-by: Mel Gorman Signed-off-by: Greg Kroah-Hartman

lib/cmdline.c: fix get_options() overflow while parsing ranges

2017-06-23T23:15:55+00:00

When using get_options() it's possible to specify a range of numbers, like 1-100500. The problem is that it doesn't track array size while calling internally to get_range() which iterates over the range and fills the memory with numbers. Link: http://lkml.kernel.org/r/2613C75C-B04D-4BFF-82A6-12F97BA0F620@gmail.com Signed-off-by: Ilya V. Matveychikov Cc: Jonathan Corbet Cc: Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

Merge branch 'linus' of git://git.kernel.org/pub/scm/linux/kernel/git/herbert/crypto-2.6

2017-06-15T08:54:51+00:00

Pull crypto fix from Herbert Xu: "This fixes a bug on sparc where we may dereference freed stack memory" * 'linus' of git://git.kernel.org/pub/scm/linux/kernel/git/herbert/crypto-2.6: crypto: Work around deallocated stack frame reference gcc bug on sparc.

crypto: Work around deallocated stack frame reference gcc bug on sparc.

2017-06-08T09:36:03+00:00

On sparc, if we have an alloca() like situation, as is the case with SHASH_DESC_ON_STACK(), we can end up referencing deallocated stack memory. The result can be that the value is clobbered if a trap or interrupt arrives at just the right instruction. It only occurs if the function ends returning a value from that alloca() area and that value can be placed into the return value register using a single instruction. For example, in lib/libcrc32c.c:crc32c() we end up with a return sequence like: return %i7+8 lduw [%o5+16], %o0 ! MEM[(u32 *)__shash_desc.1_10 + 16B], %o5 holds the base of the on-stack area allocated for the shash descriptor. But the return released the stack frame and the register window. So if an intererupt arrives between 'return' and 'lduw', then the value read at %o5+16 can be corrupted. Add a data compiler barrier to work around this problem. This is exactly what the gcc fix will end up doing as well, and it absolutely should not change the code generated for other cpus (unless gcc on them has the same bug :-) With crucial insight from Eric Sandeen. Cc: Reported-by: Anatoly Pugachev Signed-off-by: David S. Miller Signed-off-by: Herbert Xu

test_bpf: Add a couple of tests for BPF_JSGE.

2017-05-25T18:37:56+00:00

Some JITs can optimize comparisons with zero. Add a couple of BPF_JSGE tests against immediate zero. Signed-off-by: David Daney Acked-by: Daniel Borkmann Signed-off-by: David S. Miller

Merge tag 'dmaengine-4.12-rc1' of git://git.infradead.org/users/vkoul/slave-dma

2017-05-09T22:40:28+00:00

Pull dmaengine updates from Vinod Koul: "This time again a smaller update consisting of: - support for TI DA8xx dma controller and updates to the cppi driver - updates on bunch of drivers like xilinx, pl08x, stm32-dma, mv_xor, ioat, dmatest" * tag 'dmaengine-4.12-rc1' of git://git.infradead.org/users/vkoul/slave-dma: (35 commits) dmaengine: pl08x: remove lock documentation dmaengine: pl08x: fix pl08x_dma_chan_state documentation dmaengine: pl08x: Use the BIT() macro consistently dmaengine: pl080: Fix some missing kerneldoc dmaengine: pl080: Cut some unused defines dmaengine: dmatest: Add check for supported buffer count (sg_buffers) dmaengine: dmatest: Select DMA_ENGINE_RAID as its needed for the slave_sg test dmaengine: virt-dma: Convert to use list_for_each_entry_safe() dma-debug: use offset_in_page() macro dmaengine: mv_xor: use offset_in_page() macro dmaengine: dmatest: use offset_in_page() macro dmaengine: sun4i: fix invalid argument dmaengine: ioat: use setup_timer dmaengine: cppi41: Fix an Oops happening in cppi41_dma_probe() dmaengine: pl330: remove pdata based initialization dmaengine: cppi: fix build error due to bad variable dmaengine: imx-sdma: add 1ms delay to ensure SDMA channel is stopped dmaengine: cppi41: use managed functions devm_*() dmaengine: cppi41: fix cppi41_dma_tx_status() logic dmaengine: qcom_hidma: pause the channel on shutdown ...

Merge branch 'work.iov_iter' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs

2017-05-09T16:01:21+00:00

Pull vfs fix from Al Viro: "Braino fix for iov_iter_revert() misuse" * 'work.iov_iter' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs: fix braino in generic_file_read_iter()