user/sven/linux.git/kernel, branch v4.14.53

time: Make sure jiffies_to_msecs() preserves non-zero time periods

2018-07-03T09:24:56Z

commit abcbcb80cd09cd40f2089d912764e315459b71f7 upstream. For the common cases where 1000 is a multiple of HZ, or HZ is a multiple of 1000, jiffies_to_msecs() never returns zero when passed a non-zero time period. However, if HZ > 1000 and not an integer multiple of 1000 (e.g. 1024 or 1200, as used on alpha and DECstation), jiffies_to_msecs() may return zero for small non-zero time periods. This may break code that relies on receiving back a non-zero value. jiffies_to_usecs() does not need such a fix: one jiffy can only be less than one µs if HZ > 1000000, and such large values of HZ are already rejected at build time, twice: - include/linux/jiffies.h does #error if HZ >= 12288, - kernel/time/time.c has BUILD_BUG_ON(HZ > USEC_PER_SEC). Broken since forever. Signed-off-by: Geert Uytterhoeven Signed-off-by: Thomas Gleixner Reviewed-by: Arnd Bergmann Cc: John Stultz Cc: Stephen Boyd Cc: linux-alpha@vger.kernel.org Cc: linux-mips@linux-mips.org Cc: stable@vger.kernel.org Link: https://lkml.kernel.org/r/20180622143357.7495-1-geert@linux-m68k.org Signed-off-by: Greg Kroah-Hartman

printk: fix possible reuse of va_list variable

2018-07-03T09:24:49Z

commit 988a35f8da1dec5a8cd2788054d1e717be61bf25 upstream. I noticed that there is a possibility that printk_safe_log_store() causes kernel oops because "args" parameter is passed to vsnprintf() again when atomic_cmpxchg() detected that we raced. Fix this by using va_copy(). Link: http://lkml.kernel.org/r/201805112002.GIF21216.OFVHFOMLJtQFSO@I-love.SAKURA.ne.jp Cc: Peter Zijlstra Cc: Steven Rostedt Cc: dvyukov@google.com Cc: syzkaller@googlegroups.com Cc: fengguang.wu@intel.com Cc: linux-kernel@vger.kernel.org Signed-off-by: Tetsuo Handa Fixes: 42a0bb3f71383b45 ("printk/nmi: generic solution for safe printk in NMI") Cc: 4.7+ # v4.7+ Reviewed-by: Sergey Senozhatsky Signed-off-by: Petr Mladek Signed-off-by: Greg Kroah-Hartman

sched/deadline: Make the grub_reclaim() function static

2018-06-20T19:03:01Z

[ Upstream commit 3febfc8a219a036633b57a34c6678e21b6a0580d ] Since the grub_reclaim() function can be made static, make it so. Silences the following GCC warning (W=1): kernel/sched/deadline.c:1120:5: warning: no previous prototype for ‘grub_reclaim’ [-Wmissing-prototypes] Signed-off-by: Mathieu Malaterre Acked-by: Peter Zijlstra Cc: Linus Torvalds Cc: Thomas Gleixner Link: http://lkml.kernel.org/r/20180516200902.959-1-malat@debian.org Signed-off-by: Ingo Molnar Signed-off-by: Sasha Levin Signed-off-by: Greg Kroah-Hartman

sched/debug: Move the print_rt_rq() and print_dl_rq() declarations to kernel/sched/sched.h

2018-06-20T19:03:01Z

[ Upstream commit f6a3463063f42d9fb2c78f386437a822e0ad1792 ] In the following commit: 6b55c9654fcc ("sched/debug: Move print_cfs_rq() declaration to kernel/sched/sched.h") the print_cfs_rq() prototype was added to , right next to the prototypes for print_cfs_stats(), print_rt_stats() and print_dl_stats(). Finish this previous commit and also move related prototypes for print_rt_rq() and print_dl_rq(). Remove existing extern declarations now that they not needed anymore. Silences the following GCC warning, triggered by W=1: kernel/sched/debug.c:573:6: warning: no previous prototype for ‘print_rt_rq’ [-Wmissing-prototypes] kernel/sched/debug.c:603:6: warning: no previous prototype for ‘print_dl_rq’ [-Wmissing-prototypes] Signed-off-by: Mathieu Malaterre Acked-by: Peter Zijlstra Cc: Linus Torvalds Cc: Srikar Dronamraju Cc: Thomas Gleixner Link: http://lkml.kernel.org/r/20180516195348.30426-1-malat@debian.org Signed-off-by: Ingo Molnar Signed-off-by: Sasha Levin Signed-off-by: Greg Kroah-Hartman

locking/percpu-rwsem: Annotate rwsem ownership transfer by setting RWSEM_OWNER_UNKNOWN

2018-06-20T19:03:00Z

[ Upstream commit 5a817641f68a6399a5fac8b7d2da67a73698ffed ] The filesystem freezing code needs to transfer ownership of a rwsem embedded in a percpu-rwsem from the task that does the freezing to another one that does the thawing by calling percpu_rwsem_release() after freezing and percpu_rwsem_acquire() before thawing. However, the new rwsem debug code runs afoul with this scheme by warning that the task that releases the rwsem isn't the one that acquires it, as reported by Amir Goldstein: DEBUG_LOCKS_WARN_ON(sem->owner != get_current()) WARNING: CPU: 1 PID: 1401 at /home/amir/build/src/linux/kernel/locking/rwsem.c:133 up_write+0x59/0x79 Call Trace: percpu_up_write+0x1f/0x28 thaw_super_locked+0xdf/0x120 do_vfs_ioctl+0x270/0x5f1 ksys_ioctl+0x52/0x71 __x64_sys_ioctl+0x16/0x19 do_syscall_64+0x5d/0x167 entry_SYSCALL_64_after_hwframe+0x49/0xbe To work properly with the rwsem debug code, we need to annotate that the rwsem ownership is unknown during the tranfer period until a brave soul comes forward to acquire the ownership. During that period, optimistic spinning will be disabled. Reported-by: Amir Goldstein Tested-by: Amir Goldstein Signed-off-by: Waiman Long Acked-by: Peter Zijlstra Cc: Andrew Morton Cc: Davidlohr Bueso Cc: Jan Kara Cc: Linus Torvalds Cc: Matthew Wilcox Cc: Oleg Nesterov Cc: Paul E. McKenney Cc: Theodore Y. Ts'o Cc: Thomas Gleixner Cc: Will Deacon Cc: linux-fsdevel@vger.kernel.org Link: http://lkml.kernel.org/r/1526420991-21213-3-git-send-email-longman@redhat.com Signed-off-by: Ingo Molnar Signed-off-by: Sasha Levin Signed-off-by: Greg Kroah-Hartman

locking/rwsem: Add a new RWSEM_ANONYMOUSLY_OWNED flag

2018-06-20T19:03:00Z

[ Upstream commit d7d760efad70c7a030725499bf9f342f04af24dd ] There are use cases where a rwsem can be acquired by one task, but released by another task. In thess cases, optimistic spinning may need to be disabled. One example will be the filesystem freeze/thaw code where the task that freezes the filesystem will acquire a write lock on a rwsem and then un-owns it before returning to userspace. Later on, another task will come along, acquire the ownership, thaw the filesystem and release the rwsem. Bit 0 of the owner field was used to designate that it is a reader owned rwsem. It is now repurposed to mean that the owner of the rwsem is not known. If only bit 0 is set, the rwsem is reader owned. If bit 0 and other bits are set, it is writer owned with an unknown owner. One such value for the latter case is (-1L). So we can set owner to 1 for reader-owned, -1 for writer-owned. The owner is unknown in both cases. To handle transfer of rwsem ownership, the higher level code should set the owner field to -1 to indicate a write-locked rwsem with unknown owner. Optimistic spinning will be disabled in this case. Once the higher level code figures who the new owner is, it can then set the owner field accordingly. Tested-by: Amir Goldstein Signed-off-by: Waiman Long Acked-by: Peter Zijlstra Cc: Andrew Morton Cc: Davidlohr Bueso Cc: Jan Kara Cc: Linus Torvalds Cc: Matthew Wilcox Cc: Oleg Nesterov Cc: Paul E. McKenney Cc: Theodore Y. Ts'o Cc: Thomas Gleixner Cc: Will Deacon Cc: linux-fsdevel@vger.kernel.org Link: http://lkml.kernel.org/r/1526420991-21213-2-git-send-email-longman@redhat.com Signed-off-by: Ingo Molnar Signed-off-by: Sasha Levin Signed-off-by: Greg Kroah-Hartman

init: fix false positives in W+X checking

2018-06-20T19:02:57Z

[ Upstream commit ae646f0b9ca135b87bc73ff606ef996c3029780a ] load_module() creates W+X mappings via __vmalloc_node_range() (from layout_and_allocate()->move_module()->module_alloc()) by using PAGE_KERNEL_EXEC. These mappings are later cleaned up via "call_rcu_sched(&freeinit->rcu, do_free_init)" from do_init_module(). This is a problem because call_rcu_sched() queues work, which can be run after debug_checkwx() is run, resulting in a race condition. If hit, the race results in a nasty splat about insecure W+X mappings, which results in a poor user experience as these are not the mappings that debug_checkwx() is intended to catch. This issue is observed on multiple arm64 platforms, and has been artificially triggered on an x86 platform. Address the race by flushing the queued work before running the arch-defined mark_rodata_ro() which then calls debug_checkwx(). Link: http://lkml.kernel.org/r/1525103946-29526-1-git-send-email-jhugo@codeaurora.org Fixes: e1a58320a38d ("x86/mm: Warn on W^X mappings") Signed-off-by: Jeffrey Hugo Reported-by: Timur Tabi Reported-by: Jan Glauber Acked-by: Kees Cook Acked-by: Ingo Molnar Acked-by: Will Deacon Acked-by: Laura Abbott Cc: Mark Rutland Cc: Ard Biesheuvel Cc: Catalin Marinas Cc: Stephen Smalley Cc: Thomas Gleixner Cc: Peter Zijlstra Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds Signed-off-by: Sasha Levin Signed-off-by: Greg Kroah-Hartman

sched/core: Introduce set_special_state()

2018-06-20T19:02:54Z

[ Upstream commit b5bf9a90bbebffba888c9144c5a8a10317b04064 ] Gaurav reported a perceived problem with TASK_PARKED, which turned out to be a broken wait-loop pattern in __kthread_parkme(), but the reported issue can (and does) in fact happen for states that do not do condition based sleeps. When the 'current->state = TASK_RUNNING' store of a previous (concurrent) try_to_wake_up() collides with the setting of a 'special' sleep state, we can loose the sleep state. Normal condition based wait-loops are immune to this problem, but for sleep states that are not condition based are subject to this problem. There already is a fix for TASK_DEAD. Abstract that and also apply it to TASK_STOPPED and TASK_TRACED, both of which are also without condition based wait-loop. Reported-by: Gaurav Kohli Signed-off-by: Peter Zijlstra (Intel) Reviewed-by: Oleg Nesterov Cc: Linus Torvalds Cc: Peter Zijlstra Cc: Thomas Gleixner Signed-off-by: Ingo Molnar Signed-off-by: Sasha Levin Signed-off-by: Greg Kroah-Hartman

kthread, sched/wait: Fix kthread_parkme() wait-loop

2018-06-20T19:02:53Z

[ Upstream commit 741a76b350897604c48fb12beff1c9b77724dc96 ] Gaurav reported a problem with __kthread_parkme() where a concurrent try_to_wake_up() could result in competing stores to ->state which, when the TASK_PARKED store got lost bad things would happen. The comment near set_current_state() actually mentions this competing store, but only mentions the case against TASK_RUNNING. This same store, with different timing, can happen against a subsequent !RUNNING store. This normally is not a problem, because as per that same comment, the !RUNNING state store is inside a condition based wait-loop: for (;;) { set_current_state(TASK_UNINTERRUPTIBLE); if (!need_sleep) break; schedule(); } __set_current_state(TASK_RUNNING); If we loose the (first) TASK_UNINTERRUPTIBLE store to a previous (concurrent) wakeup, the schedule() will NO-OP and we'll go around the loop once more. The problem here is that the TASK_PARKED store is not inside the KTHREAD_SHOULD_PARK condition wait-loop. There is a genuine issue with sleeps that do not have a condition; this is addressed in a subsequent patch. Reported-by: Gaurav Kohli Signed-off-by: Peter Zijlstra (Intel) Reviewed-by: Oleg Nesterov Cc: Linus Torvalds Cc: Peter Zijlstra Cc: Thomas Gleixner Signed-off-by: Ingo Molnar Signed-off-by: Sasha Levin Signed-off-by: Greg Kroah-Hartman

stop_machine, sched: Fix migrate_swap() vs. active_balance() deadlock

2018-06-20T19:02:53Z

[ Upstream commit 0b26351b910fb8fe6a056f8a1bbccabe50c0e19f ] Matt reported the following deadlock: CPU0 CPU1 schedule(.prev=migrate/0) pick_next_task() ... idle_balance() migrate_swap() active_balance() stop_two_cpus() spin_lock(stopper0->lock) spin_lock(stopper1->lock) ttwu(migrate/0) smp_cond_load_acquire() -- waits for schedule() stop_one_cpu(1) spin_lock(stopper1->lock) -- waits for stopper lock Fix this deadlock by taking the wakeups out from under stopper->lock. This allows the active_balance() to queue the stop work and finish the context switch, which in turn allows the wakeup from migrate_swap() to observe the context and complete the wakeup. Signed-off-by: Peter Zijlstra (Intel) Reported-by: Matt Fleming Signed-off-by: Peter Zijlstra (Intel) Acked-by: Matt Fleming Cc: Linus Torvalds Cc: Michal Hocko Cc: Mike Galbraith Cc: Peter Zijlstra Cc: Thomas Gleixner Link: http://lkml.kernel.org/r/20180420095005.GH4064@hirez.programming.kicks-ass.net Signed-off-by: Ingo Molnar Signed-off-by: Sasha Levin Signed-off-by: Greg Kroah-Hartman