- 21 Dec, 2018 28 commits
-
-
Will Deacon authored
commit b247be3f upstream. On x86, atomic_cond_read_relaxed will busy-wait with a cpu_relax() loop, so it is desirable to increase the number of times we spin on the qspinlock lockword when it is found to be transitioning from pending to locked. According to Waiman Long: | Ideally, the spinning times should be at least a few times the typical | cacheline load time from memory which I think can be down to 100ns or | so for each cacheline load with the newest systems or up to several | hundreds ns for older systems. which in his benchmarking corresponded to 512 iterations. Suggested-by: Waiman Long <longman@redhat.com> Signed-off-by: Will Deacon <will.deacon@arm.com> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org> Acked-by: Waiman Long <longman@redhat.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: boqun.feng@gmail.com Cc: linux-arm-kernel@lists.infradead.org Cc: paulmck@linux.vnet.ibm.com Link: http://lkml.kernel.org/r/1524738868-31318-5-git-send-email-will.deacon@arm.comSigned-off-by: Ingo Molnar <mingo@kernel.org> Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de> Signed-off-by: Sasha Levin <sashal@kernel.org>
-
Peter Zijlstra authored
commit 53bf57fa upstream. Flip the branch condition after atomic_fetch_or_acquire(_Q_PENDING_VAL) such that we loose the indent. This also result in a more natural code flow IMO. Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Acked-by: Will Deacon <will.deacon@arm.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: andrea.parri@amarulasolutions.com Cc: longman@redhat.com Link: https://lkml.kernel.org/r/20181003130257.156322446@infradead.orgSigned-off-by: Ingo Molnar <mingo@kernel.org> Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de> Signed-off-by: Sasha Levin <sashal@kernel.org>
-
Will Deacon authored
commit c61da58d upstream. When a queued locker reaches the head of the queue, it claims the lock by setting _Q_LOCKED_VAL in the lockword. If there isn't contention, it must also clear the tail as part of this operation so that subsequent lockers can avoid taking the slowpath altogether. Currently this is expressed as a cmpxchg() loop that practically only runs up to two iterations. This is confusing to the reader and unhelpful to the compiler. Rewrite the cmpxchg() loop without the loop, so that a failed cmpxchg() implies that there is contention and we just need to write to _Q_LOCKED_VAL without considering the rest of the lockword. Signed-off-by: Will Deacon <will.deacon@arm.com> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org> Acked-by: Waiman Long <longman@redhat.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: boqun.feng@gmail.com Cc: linux-arm-kernel@lists.infradead.org Cc: paulmck@linux.vnet.ibm.com Link: http://lkml.kernel.org/r/1524738868-31318-7-git-send-email-will.deacon@arm.comSigned-off-by: Ingo Molnar <mingo@kernel.org> Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de> Signed-off-by: Sasha Levin <sashal@kernel.org>
-
Will Deacon authored
commit 3bea9adc upstream. The native clear_pending() function is identical to the PV version, so the latter can simply be removed. This fixes the build for systems with >= 16K CPUs using the PV lock implementation. Reported-by: Waiman Long <longman@redhat.com> Signed-off-by: Will Deacon <will.deacon@arm.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: boqun.feng@gmail.com Cc: linux-arm-kernel@lists.infradead.org Cc: paulmck@linux.vnet.ibm.com Link: http://lkml.kernel.org/r/20180427101619.GB21705@arm.comSigned-off-by: Ingo Molnar <mingo@kernel.org> Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de> Signed-off-by: Sasha Levin <sashal@kernel.org>
-
Will Deacon authored
commit 59fb586b upstream. The qspinlock locking slowpath utilises a "pending" bit as a simple form of an embedded test-and-set lock that can avoid the overhead of explicit queuing in cases where the lock is held but uncontended. This bit is managed using a cmpxchg() loop which tries to transition the uncontended lock word from (0,0,0) -> (0,0,1) or (0,0,1) -> (0,1,1). Unfortunately, the cmpxchg() loop is unbounded and lockers can be starved indefinitely if the lock word is seen to oscillate between unlocked (0,0,0) and locked (0,0,1). This could happen if concurrent lockers are able to take the lock in the cmpxchg() loop without queuing and pass it around amongst themselves. This patch fixes the problem by unconditionally setting _Q_PENDING_VAL using atomic_fetch_or, and then inspecting the old value to see whether we need to spin on the current lock owner, or whether we now effectively hold the lock. The tricky scenario is when concurrent lockers end up queuing on the lock and the lock becomes available, causing us to see a lockword of (n,0,0). With pending now set, simply queuing could lead to deadlock as the head of the queue may not have observed the pending flag being cleared. Conversely, if the head of the queue did observe pending being cleared, then it could transition the lock from (n,0,0) -> (0,0,1) meaning that any attempt to "undo" our setting of the pending bit could race with a concurrent locker trying to set it. We handle this race by preserving the pending bit when taking the lock after reaching the head of the queue and leaving the tail entry intact if we saw pending set, because we know that the tail is going to be updated shortly. Signed-off-by: Will Deacon <will.deacon@arm.com> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org> Acked-by: Waiman Long <longman@redhat.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: boqun.feng@gmail.com Cc: linux-arm-kernel@lists.infradead.org Cc: paulmck@linux.vnet.ibm.com Link: http://lkml.kernel.org/r/1524738868-31318-6-git-send-email-will.deacon@arm.comSigned-off-by: Ingo Molnar <mingo@kernel.org> Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de> Signed-off-by: Sasha Levin <sashal@kernel.org>
-
Will Deacon authored
commit 625e88be upstream. 'struct __qspinlock' provides a handy union of fields so that subcomponents of the lockword can be accessed by name, without having to manage shifts and masks explicitly and take endianness into account. This is useful in qspinlock.h and also potentially in arch headers, so move the 'struct __qspinlock' into 'struct qspinlock' and kill the extra definition. Signed-off-by: Will Deacon <will.deacon@arm.com> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org> Acked-by: Waiman Long <longman@redhat.com> Acked-by: Boqun Feng <boqun.feng@gmail.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: linux-arm-kernel@lists.infradead.org Cc: paulmck@linux.vnet.ibm.com Link: http://lkml.kernel.org/r/1524738868-31318-3-git-send-email-will.deacon@arm.comSigned-off-by: Ingo Molnar <mingo@kernel.org> Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de> Signed-off-by: Sasha Levin <sashal@kernel.org>
-
Will Deacon authored
commit 6512276d upstream. If a locker taking the qspinlock slowpath reads a lock value indicating that only the pending bit is set, then it will spin whilst the concurrent pending->locked transition takes effect. Unfortunately, there is no guarantee that such a transition will ever be observed since concurrent lockers could continuously set pending and hand over the lock amongst themselves, leading to starvation. Whilst this would probably resolve in practice, it means that it is not possible to prove liveness properties about the lock and means that lock acquisition time is unbounded. Rather than removing the pending->locked spinning from the slowpath altogether (which has been shown to heavily penalise a 2-threaded locking stress test on x86), this patch replaces the explicit spinning with a call to atomic_cond_read_relaxed and allows the architecture to provide a bound on the number of spins. For architectures that can respond to changes in cacheline state in their smp_cond_load implementation, it should be sufficient to use the default bound of 1. Suggested-by: Waiman Long <longman@redhat.com> Signed-off-by: Will Deacon <will.deacon@arm.com> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org> Acked-by: Waiman Long <longman@redhat.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: boqun.feng@gmail.com Cc: linux-arm-kernel@lists.infradead.org Cc: paulmck@linux.vnet.ibm.com Link: http://lkml.kernel.org/r/1524738868-31318-4-git-send-email-will.deacon@arm.comSigned-off-by: Ingo Molnar <mingo@kernel.org> Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de> Signed-off-by: Sasha Levin <sashal@kernel.org>
-
Will Deacon authored
commit 95bcade3 upstream. When a locker ends up queuing on the qspinlock locking slowpath, we initialise the relevant mcs node and publish it indirectly by updating the tail portion of the lock word using xchg_tail. If we find that there was a pre-existing locker in the queue, we subsequently update their ->next field to point at our node so that we are notified when it's our turn to take the lock. This can be roughly illustrated as follows: /* Initialise the fields in node and encode a pointer to node in tail */ tail = initialise_node(node); /* * Exchange tail into the lockword using an atomic read-modify-write * operation with release semantics */ old = xchg_tail(lock, tail); /* If there was a pre-existing waiter ... */ if (old & _Q_TAIL_MASK) { prev = decode_tail(old); smp_read_barrier_depends(); /* ... then update their ->next field to point to node. WRITE_ONCE(prev->next, node); } The conditional update of prev->next therefore relies on the address dependency from the result of xchg_tail ensuring order against the prior initialisation of node. However, since the release semantics of the xchg_tail operation apply only to the write portion of the RmW, then this ordering is not guaranteed and it is possible for the CPU to return old before the writes to node have been published, consequently allowing us to point prev->next to an uninitialised node. This patch fixes the problem by making the update of prev->next a RELEASE operation, which also removes the reliance on dependency ordering. Signed-off-by: Will Deacon <will.deacon@arm.com> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Thomas Gleixner <tglx@linutronix.de> Link: http://lkml.kernel.org/r/1518528177-19169-2-git-send-email-will.deacon@arm.comSigned-off-by: Ingo Molnar <mingo@kernel.org> Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de> Signed-off-by: Sasha Levin <sashal@kernel.org>
-
Paul E. McKenney authored
commit 548095de upstream. Queued spinlocks are not used by DEC Alpha, and furthermore operations such as READ_ONCE() and release/relaxed RMW atomics are being changed to imply smp_read_barrier_depends(). This commit therefore removes the now-redundant smp_read_barrier_depends() from queued_spin_lock_slowpath(), and adjusts the comments accordingly. Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Ingo Molnar <mingo@redhat.com> Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de> Signed-off-by: Sasha Levin <sashal@kernel.org>
-
Masahiro Yamada authored
commit 25896d07 upstream. It is troublesome to add a diagnostic like this to the Makefile parse stage because the top-level Makefile could be parsed with a stale include/config/auto.conf. Once you are hit by the error about non-retpoline compiler, the compilation still breaks even after disabling CONFIG_RETPOLINE. The easiest fix is to move this check to the "archprepare" like this commit did: 829fe4aa ("x86: Allow generating user-space headers without a compiler") Reported-by: Meelis Roos <mroos@linux.ee> Tested-by: Meelis Roos <mroos@linux.ee> Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com> Acked-by: Zhenzhong Duan <zhenzhong.duan@oracle.com> Cc: Borislav Petkov <bp@alien8.de> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Zhenzhong Duan <zhenzhong.duan@oracle.com> Fixes: 4cd24de3 ("x86/retpoline: Make CONFIG_RETPOLINE depend on compiler support") Link: http://lkml.kernel.org/r/1543991239-18476-1-git-send-email-yamada.masahiro@socionext.com Link: https://lkml.org/lkml/2018/12/4/206Signed-off-by: Ingo Molnar <mingo@kernel.org> Signed-off-by: Sasha Levin <sashal@kernel.org> Cc: Gi-Oh Kim <gi-oh.kim@cloud.ionos.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
-
Junwei Zhang authored
commit d55d8be0 upstream. Some new variants require different firmwares. Signed-off-by: Junwei Zhang <Jerry.Zhang@amd.com> Reviewed-by: Alex Deucher <alexander.deucher@amd.com> Signed-off-by: Alex Deucher <alexander.deucher@amd.com> Cc: stable@vger.kernel.org Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
-
Chris Wilson authored
commit cf66b8a0 upstream. Braswell is really picky about having our writes posted to memory before we execute or else the GPU may see stale values. A wmb() is insufficient as it only ensures the writes are visible to other cores, we need a full mb() to ensure the writes are in memory and visible to the GPU. The most frequent failure in flushing before execution is that we see stale PTE values and execute the wrong pages. References: 987abd5c ("drm/i915/execlists: Force write serialisation into context image vs execution") Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk> Cc: Mika Kuoppala <mika.kuoppala@linux.intel.com> Cc: Tvrtko Ursulin <tvrtko.ursulin@intel.com> Cc: Joonas Lahtinen <joonas.lahtinen@linux.intel.com> Cc: stable@vger.kernel.org Reviewed-by: Tvrtko Ursulin <tvrtko.ursulin@intel.com> Link: https://patchwork.freedesktop.org/patch/msgid/20181206084431.9805-3-chris@chris-wilson.co.uk (cherry picked from commit 490b8c65) Signed-off-by: Joonas Lahtinen <joonas.lahtinen@linux.intel.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
-
Brian Norris authored
commit 63238173 upstream. This reverts commit 7f3ef5de. It causes new warnings [1] on shutdown when running the Google Kevin or Scarlet (RK3399) boards under Chrome OS. Presumably our usage of DRM is different than what Marc and Heiko test. We're looking at a different approach (e.g., [2]) to replace this, but IMO the revert should be taken first, as it already propagated to -stable. [1] Report here: http://lkml.kernel.org/lkml/20181205030127.GA200921@google.com WARNING: CPU: 4 PID: 2035 at drivers/gpu/drm/drm_mode_config.c:477 drm_mode_config_cleanup+0x1c4/0x294 ... Call trace: drm_mode_config_cleanup+0x1c4/0x294 rockchip_drm_unbind+0x4c/0x8c component_master_del+0x88/0xb8 rockchip_drm_platform_remove+0x2c/0x44 rockchip_drm_platform_shutdown+0x20/0x2c platform_drv_shutdown+0x2c/0x38 device_shutdown+0x164/0x1b8 kernel_restart_prepare+0x40/0x48 kernel_restart+0x20/0x68 ... Memory manager not clean during takedown. WARNING: CPU: 4 PID: 2035 at drivers/gpu/drm/drm_mm.c:950 drm_mm_takedown+0x34/0x44 ... drm_mm_takedown+0x34/0x44 rockchip_drm_unbind+0x64/0x8c component_master_del+0x88/0xb8 rockchip_drm_platform_remove+0x2c/0x44 rockchip_drm_platform_shutdown+0x20/0x2c platform_drv_shutdown+0x2c/0x38 device_shutdown+0x164/0x1b8 kernel_restart_prepare+0x40/0x48 kernel_restart+0x20/0x68 ... [2] https://patchwork.kernel.org/patch/10556151/ https://www.spinics.net/lists/linux-rockchip/msg21342.html [PATCH] drm/rockchip: shutdown drm subsystem on shutdown Fixes: 7f3ef5de ("drm/rockchip: Allow driver to be shutdown on reboot/kexec") Cc: Jeffy Chen <jeffy.chen@rock-chips.com> Cc: Robin Murphy <robin.murphy@arm.com> Cc: Vicente Bergas <vicencb@gmail.com> Cc: Marc Zyngier <marc.zyngier@arm.com> Cc: Heiko Stuebner <heiko@sntech.de> Cc: stable@vger.kernel.org Signed-off-by: Brian Norris <briannorris@chromium.org> Signed-off-by: Heiko Stuebner <heiko@sntech.de> Link: https://patchwork.freedesktop.org/patch/msgid/20181205181657.177703-1-briannorris@chromium.orgSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
-
Lyude Paul authored
commit 24199c54 upstream. Noticed this while working on redoing the reference counting scheme in the DP MST helpers. Nouveau doesn't attempt to call drm_dp_mst_topology_mgr_destroy() at all, which leaves it leaking all of the resources for drm_dp_mst_topology_mgr and it's children mstbs+ports. Fixes: f479c0ba ("drm/nouveau/kms/nv50: initial support for DP 1.2 multi-stream") Signed-off-by: Lyude Paul <lyude@redhat.com> Cc: <stable@vger.kernel.org> # v4.10+ Signed-off-by: Ben Skeggs <bskeggs@redhat.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
-
Radu Rendec authored
commit 78e7b15e upstream. The arch_teardown_msi_irqs() function assumes that controller ops pointers were already checked in arch_setup_msi_irqs(), but this assumption is wrong: arch_teardown_msi_irqs() can be called even when arch_setup_msi_irqs() returns an error (-ENOSYS). This can happen in the following scenario: - msi_capability_init() calls pci_msi_setup_msi_irqs() - pci_msi_setup_msi_irqs() returns -ENOSYS - msi_capability_init() notices the error and calls free_msi_irqs() - free_msi_irqs() calls pci_msi_teardown_msi_irqs() This is easier to see when CONFIG_PCI_MSI_IRQ_DOMAIN is not set and pci_msi_setup_msi_irqs() and pci_msi_teardown_msi_irqs() are just aliases to arch_setup_msi_irqs() and arch_teardown_msi_irqs(). The call to free_msi_irqs() upon pci_msi_setup_msi_irqs() failure seems legit, as it does additional cleanup; e.g. list_del(&entry->list) and kfree(entry) inside free_msi_irqs() do happen (MSI descriptors are allocated before pci_msi_setup_msi_irqs() is called and need to be cleaned up if that fails). Fixes: 6b2fd7ef ("PCI/MSI/PPC: Remove arch_msi_check_device()") Cc: stable@vger.kernel.org # v3.18+ Signed-off-by: Radu Rendec <radu.rendec@gmail.com> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
-
Steven Rostedt (VMware) authored
commit 2840f84f upstream. The following commands will cause a memory leak: # cd /sys/kernel/tracing # mkdir instances/foo # echo schedule > instance/foo/set_ftrace_filter # rmdir instances/foo The reason is that the hashes that hold the filters to set_ftrace_filter and set_ftrace_notrace are not freed if they contain any data on the instance and the instance is removed. Found by kmemleak detector. Cc: stable@vger.kernel.org Fixes: 591dffda ("ftrace: Allow for function tracing instance to filter functions") Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
-
Steven Rostedt (VMware) authored
commit 3cec638b upstream. When create_event_filter() fails in set_trigger_filter(), the filter may still be allocated and needs to be freed. The caller expects the data->filter to be updated with the new filter, even if the new filter failed (we could add an error message by setting set_str parameter of create_event_filter(), but that's another update). But because the error would just exit, filter was left hanging and nothing could free it. Found by kmemleak detector. Cc: stable@vger.kernel.org Fixes: bac5fb97 ("tracing: Add and use generic set_trigger_filter() implementation") Reviewed-by: Tom Zanussi <tom.zanussi@linux.intel.com> Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
-
Mike Snitzer authored
commit 687cf441 upstream. Otherwise dm_bitset_cursor_begin() return -ENODATA. Other calls to dm_bitset_cursor_begin() have similar negative checks. Fixes inability to create a cache in passthrough mode (even though doing so makes no sense). Fixes: 0d963b6e ("dm cache metadata: fix metadata2 format's blocks_are_clean_separate_dirty") Cc: stable@vger.kernel.org Reported-by: David Teigland <teigland@redhat.com> Signed-off-by: Mike Snitzer <snitzer@redhat.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
-
Mike Snitzer authored
commit f6c36758 upstream. Sending a DM event before a thin-pool state change is about to happen is a bug. It wasn't realized until it became clear that userspace response to the event raced with the actual state change that the event was meant to notify about. Fix this by first updating internal thin-pool state to reflect what the DM event is being issued about. This fixes a long-standing racey/buggy userspace device-mapper-test-suite 'resize_io' test that would get an event but not find the state it was looking for -- so it would just go on to hang because no other events caused the test to reevaluate the thin-pool's state. Cc: stable@vger.kernel.org Signed-off-by: Mike Snitzer <snitzer@redhat.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
-
Lubomir Rintel authored
commit 76f4e2c3 upstream. cpu_is_mmp2() was equivalent to cpu_is_pj4(), wouldn't be correct for multiplatform kernels. Fix it by also considering mmp_chip_id, as is done for cpu_is_pxa168() and cpu_is_pxa910() above. Moreover, it is only available with CONFIG_CPU_MMP2 and thus doesn't work on DT-based MMP2 machines. Enable it on CONFIG_MACH_MMP2_DT too. Note: CONFIG_CPU_MMP2 is only used for machines that use board files instead of DT. It should perhaps be renamed. I'm not doing it now, because I don't have a better idea. Signed-off-by: Lubomir Rintel <lkundrak@v3.sk> Acked-by: Arnd Bergmann <arnd@arndb.de> Cc: stable@vger.kernel.org Signed-off-by: Olof Johansson <olof@lixom.net> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
-
Chad Austin authored
commit 2e64ff15 upstream. When FUSE_OPEN returns ENOSYS, the no_open bit is set on the connection. Because the FUSE_RELEASE and FUSE_RELEASEDIR paths share code, this incorrectly caused the FUSE_RELEASEDIR request to be dropped and never sent to userspace. Pass an isdir bool to distinguish between FUSE_RELEASE and FUSE_RELEASEDIR inside of fuse_file_put. Fixes: 7678ac50 ("fuse: support clients that don't implement 'open'") Cc: <stable@vger.kernel.org> # v3.14 Signed-off-by: Chad Austin <chadaustin@fb.com> Signed-off-by: Miklos Szeredi <mszeredi@redhat.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
-
Alek Du authored
commit b704441e upstream. We observed some premature timeouts on a virtualization platform, the log is like this: case 1: [159525.255629] mmc1: Internal clock never stabilised. [159525.255818] mmc1: sdhci: ============ SDHCI REGISTER DUMP =========== [159525.256049] mmc1: sdhci: Sys addr: 0x00000000 | Version: 0x00001002 ... [159525.257205] mmc1: sdhci: Wake-up: 0x00000000 | Clock: 0x0000fa03 From the clock control register dump, we are pretty sure the clock was stablized. case 2: [ 914.550127] mmc1: Reset 0x2 never completed. [ 914.550321] mmc1: sdhci: ============ SDHCI REGISTER DUMP =========== [ 914.550608] mmc1: sdhci: Sys addr: 0x00000010 | Version: 0x00001002 After checking the sdhci code, we found the timeout check actually has a little window that the CPU can be scheduled out and when it comes back, the original time set or check is not valid. Fixes: 5a436cc0 ("mmc: sdhci: Optimize delay loops") Cc: stable@vger.kernel.org # v4.12+ Signed-off-by: Alek Du <alek.du@intel.com> Acked-by: Adrian Hunter <adrian.hunter@intel.com> Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
-
Aaro Koskinen authored
commit e8cde625 upstream. Since v2.6.22 or so there has been reports [1] about OMAP MMC being broken on OMAP15XX based hardware (OMAP5910 and OMAP310). The breakage seems to have been caused by commit 46a6730e ("mmc-omap: Fix omap to use MMC_POWER_ON") that changed clock enabling to be done on MMC_POWER_ON. This can happen multiple times in a row, and on 15XX the hardware doesn't seem to like it and the MMC just stops responding. Fix by memorizing the power mode and do the init only when necessary. Before the patch (on Palm TE): mmc0: new SD card at address b368 mmcblk0: mmc0:b368 SDC 977 MiB mmci-omap mmci-omap.0: command timeout (CMD18) mmci-omap mmci-omap.0: command timeout (CMD13) mmci-omap mmci-omap.0: command timeout (CMD13) mmci-omap mmci-omap.0: command timeout (CMD12) [x 6] mmci-omap mmci-omap.0: command timeout (CMD13) [x 6] mmcblk0: error -110 requesting status mmci-omap mmci-omap.0: command timeout (CMD8) mmci-omap mmci-omap.0: command timeout (CMD18) mmci-omap mmci-omap.0: command timeout (CMD13) mmci-omap mmci-omap.0: command timeout (CMD13) mmci-omap mmci-omap.0: command timeout (CMD12) [x 6] mmci-omap mmci-omap.0: command timeout (CMD13) [x 6] mmcblk0: error -110 requesting status mmcblk0: recovery failed! print_req_error: I/O error, dev mmcblk0, sector 0 Buffer I/O error on dev mmcblk0, logical block 0, async page read mmcblk0: unable to read partition table After the patch: mmc0: new SD card at address b368 mmcblk0: mmc0:b368 SDC 977 MiB mmcblk0: p1 The patch is based on a fix and analysis done by Ladislav Michl. Tested on OMAP15XX/OMAP310 (Palm TE), OMAP1710 (Nokia 770) and OMAP2420 (Nokia N810). [1] https://marc.info/?t=123175197000003&r=1&w=2 Fixes: 46a6730e ("mmc-omap: Fix omap to use MMC_POWER_ON") Reported-by: Ladislav Michl <ladis@linux-mips.org> Reported-by: Andrzej Zaborowski <balrogg@gmail.com> Tested-by: Ladislav Michl <ladis@linux-mips.org> Acked-by: Tony Lindgren <tony@atomide.com> Signed-off-by: Aaro Koskinen <aaro.koskinen@iki.fi> Cc: stable@vger.kernel.org Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
-
Robin Murphy authored
commit 3238c359 upstream. We need to invalidate the caches *before* clearing the buffer via the non-cacheable alias, else in the worst case __dma_flush_area() may write back dirty lines over the top of our nice new zeros. Fixes: dd65a941 ("arm64: dma-mapping: clear buffers allocated with FORCE_CONTIGUOUS flag") Cc: <stable@vger.kernel.org> # 4.18.x- Acked-by: Will Deacon <will.deacon@arm.com> Signed-off-by: Robin Murphy <robin.murphy@arm.com> Signed-off-by: Catalin Marinas <catalin.marinas@arm.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
-
Andrea Arcangeli authored
commit 01e881f5 upstream. Calling UFFDIO_UNREGISTER on virtual ranges not yet registered in uffd could trigger an harmless false positive WARN_ON. Check the vma is already registered before checking VM_MAYWRITE to shut off the false positive warning. Link: http://lkml.kernel.org/r/20181206212028.18726-2-aarcange@redhat.com Cc: <stable@vger.kernel.org> Fixes: 29ec9066 ("userfaultfd: shmem/hugetlbfs: only allow to register VM_MAYWRITE vmas") Signed-off-by: Andrea Arcangeli <aarcange@redhat.com> Reported-by: syzbot+06c7092e7d71218a2c16@syzkaller.appspotmail.com Acked-by: Mike Rapoport <rppt@linux.ibm.com> Acked-by: Hugh Dickins <hughd@google.com> Acked-by: Peter Xu <peterx@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
-
Jeff Moyer authored
commit a538e3ff upstream. Matthew pointed out that the ioctx_table is susceptible to spectre v1, because the index can be controlled by an attacker. The below patch should mitigate the attack for all of the aio system calls. Cc: stable@vger.kernel.org Reported-by: Matthew Wilcox <willy@infradead.org> Reported-by: Dan Carpenter <dan.carpenter@oracle.com> Signed-off-by: Jeff Moyer <jmoyer@redhat.com> Signed-off-by: Jens Axboe <axboe@kernel.dk> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
-
Chen-Yu Tsai authored
commit 478b6767 upstream. Pin PH11 is used on various A83T board to detect a change in the OTG port's ID pin, as in when an OTG host cable is plugged in. The incorrect offset meant the gpiochip/irqchip was activating the wrong pin for interrupts. Fixes: 4730f33f ("pinctrl: sunxi: add allwinner A83T PIO controller support") Cc: <stable@vger.kernel.org> Signed-off-by: Chen-Yu Tsai <wens@csie.org> Acked-by: Maxime Ripard <maxime.ripard@bootlin.com> Signed-off-by: Linus Walleij <linus.walleij@linaro.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
-
Ingo Molnar authored
[ Upstream commit 8e7df2b5 ] While it uses %pK, there's still few reasons to read this file as non-root. Suggested-by: Linus Torvalds <torvalds@linux-foundation.org> Acked-by: Thomas Gleixner <tglx@linutronix.de> Cc: Peter Zijlstra <peterz@infradead.org> Cc: linux-kernel@vger.kernel.org Signed-off-by: Ingo Molnar <mingo@kernel.org> Signed-off-by: Sasha Levin <sashal@kernel.org>
-
- 17 Dec, 2018 12 commits
-
-
Greg Kroah-Hartman authored
-
Eric Dumazet authored
commit f9bfe4e6 upstream. tcp_tso_should_defer() can return true in three different cases : 1) We are cwnd-limited 2) We are rwnd-limited 3) We are application limited. Neal pointed out that my recent fix went too far, since it assumed that if we were not in 1) case, we must be rwnd-limited Fix this by properly populating the is_cwnd_limited and is_rwnd_limited booleans. After this change, we can finally move the silly check for FIN flag only for the application-limited case. The same move for EOR bit will be handled in net-next, since commit 1c09f7d0 ("tcp: do not try to defer skbs with eor mark (MSG_EOR)") is scheduled for linux-4.21 Tested by running 200 concurrent netperf -t TCP_RR -- -r 60000,100 and checking none of them was rwnd_limited in the chrono_stat output from "ss -ti" command. Fixes: 41727549 ("tcp: Do not underestimate rwnd_limited") Signed-off-by: Eric Dumazet <edumazet@google.com> Suggested-by: Neal Cardwell <ncardwell@google.com> Reviewed-by: Neal Cardwell <ncardwell@google.com> Acked-by: Soheil Hassas Yeganeh <soheil@google.com> Reviewed-by: Yuchung Cheng <ycheng@google.com> Signed-off-by: David S. Miller <davem@davemloft.net> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
-
Piotr Stankiewicz authored
commit 36d84219 upstream. When running with KASAN, the following trace is produced: [ 62.535888] ================================================================== [ 62.544930] BUG: KASAN: slab-out-of-bounds in gut_hw_stats+0x122/0x230 [hfi1] [ 62.553856] Write of size 8 at addr ffff88080e8d6330 by task kworker/0:1/14 [ 62.565333] CPU: 0 PID: 14 Comm: kworker/0:1 Not tainted 4.19.0-test-build-kasan+ #8 [ 62.575087] Hardware name: Intel Corporation S2600KPR/S2600KPR, BIOS SE5C610.86B.01.01.0019.101220160604 10/12/2016 [ 62.587951] Workqueue: events work_for_cpu_fn [ 62.594050] Call Trace: [ 62.598023] dump_stack+0xc6/0x14c [ 62.603089] ? dump_stack_print_info.cold.1+0x2f/0x2f [ 62.610041] ? kmsg_dump_rewind_nolock+0x59/0x59 [ 62.616615] ? get_hw_stats+0x122/0x230 [hfi1] [ 62.622985] print_address_description+0x6c/0x23c [ 62.629744] ? get_hw_stats+0x122/0x230 [hfi1] [ 62.636108] kasan_report.cold.6+0x241/0x308 [ 62.642365] get_hw_stats+0x122/0x230 [hfi1] [ 62.648703] ? hfi1_alloc_rn+0x40/0x40 [hfi1] [ 62.655088] ? __kmalloc+0x110/0x240 [ 62.660695] ? hfi1_alloc_rn+0x40/0x40 [hfi1] [ 62.667142] setup_hw_stats+0xd8/0x430 [ib_core] [ 62.673972] ? show_hfi+0x50/0x50 [hfi1] [ 62.680026] ib_device_register_sysfs+0x165/0x180 [ib_core] [ 62.687995] ib_register_device+0x5a2/0xa10 [ib_core] [ 62.695340] ? show_hfi+0x50/0x50 [hfi1] [ 62.701421] ? ib_unregister_device+0x2e0/0x2e0 [ib_core] [ 62.709222] ? __vmalloc_node_range+0x2d0/0x380 [ 62.716131] ? rvt_driver_mr_init+0x11f/0x2d0 [rdmavt] [ 62.723735] ? vmalloc_node+0x5c/0x70 [ 62.729697] ? rvt_driver_mr_init+0x11f/0x2d0 [rdmavt] [ 62.737347] ? rvt_driver_mr_init+0x1f5/0x2d0 [rdmavt] [ 62.744998] ? __rvt_alloc_mr+0x110/0x110 [rdmavt] [ 62.752315] ? rvt_rc_error+0x140/0x140 [rdmavt] [ 62.759434] ? rvt_vma_open+0x30/0x30 [rdmavt] [ 62.766364] ? mutex_unlock+0x1d/0x40 [ 62.772445] ? kmem_cache_create_usercopy+0x15d/0x230 [ 62.780115] rvt_register_device+0x1f6/0x360 [rdmavt] [ 62.787823] ? rvt_get_port_immutable+0x180/0x180 [rdmavt] [ 62.796058] ? __get_txreq+0x400/0x400 [hfi1] [ 62.802969] ? memcpy+0x34/0x50 [ 62.808611] hfi1_register_ib_device+0xde6/0xeb0 [hfi1] [ 62.816601] ? hfi1_get_npkeys+0x10/0x10 [hfi1] [ 62.823760] ? hfi1_init+0x89f/0x9a0 [hfi1] [ 62.830469] ? hfi1_setup_eagerbufs+0xad0/0xad0 [hfi1] [ 62.838204] ? pcie_capability_clear_and_set_word+0xcd/0xe0 [ 62.846429] ? pcie_capability_read_word+0xd0/0xd0 [ 62.853791] ? hfi1_pcie_init+0x187/0x4b0 [hfi1] [ 62.860958] init_one+0x67f/0xae0 [hfi1] [ 62.867301] ? hfi1_init+0x9a0/0x9a0 [hfi1] [ 62.873876] ? wait_woken+0x130/0x130 [ 62.879860] ? read_word_at_a_time+0xe/0x20 [ 62.886329] ? strscpy+0x14b/0x280 [ 62.891998] ? hfi1_init+0x9a0/0x9a0 [hfi1] [ 62.898405] local_pci_probe+0x70/0xd0 [ 62.904295] ? pci_device_shutdown+0x90/0x90 [ 62.910833] work_for_cpu_fn+0x29/0x40 [ 62.916750] process_one_work+0x584/0x960 [ 62.922974] ? rcu_work_rcufn+0x40/0x40 [ 62.928991] ? __schedule+0x396/0xdc0 [ 62.934806] ? __sched_text_start+0x8/0x8 [ 62.941020] ? pick_next_task_fair+0x68b/0xc60 [ 62.947674] ? run_rebalance_domains+0x260/0x260 [ 62.954471] ? __list_add_valid+0x29/0xa0 [ 62.960607] ? move_linked_works+0x1c7/0x230 [ 62.967077] ? trace_event_raw_event_workqueue_execute_start+0x140/0x140 [ 62.976248] ? mutex_lock+0xa6/0x100 [ 62.982029] ? __mutex_lock_slowpath+0x10/0x10 [ 62.988795] ? __switch_to+0x37a/0x710 [ 62.994731] worker_thread+0x62e/0x9d0 [ 63.000602] ? max_active_store+0xf0/0xf0 [ 63.006828] ? __switch_to_asm+0x40/0x70 [ 63.012932] ? __switch_to_asm+0x34/0x70 [ 63.019013] ? __switch_to_asm+0x40/0x70 [ 63.025042] ? __switch_to_asm+0x34/0x70 [ 63.031030] ? __switch_to_asm+0x40/0x70 [ 63.037006] ? __schedule+0x396/0xdc0 [ 63.042660] ? kmem_cache_alloc_trace+0xf3/0x1f0 [ 63.049323] ? kthread+0x59/0x1d0 [ 63.054594] ? ret_from_fork+0x35/0x40 [ 63.060257] ? __sched_text_start+0x8/0x8 [ 63.066212] ? schedule+0xcf/0x250 [ 63.071529] ? __wake_up_common+0x110/0x350 [ 63.077794] ? __schedule+0xdc0/0xdc0 [ 63.083348] ? wait_woken+0x130/0x130 [ 63.088963] ? finish_task_switch+0x1f1/0x520 [ 63.095258] ? kasan_unpoison_shadow+0x30/0x40 [ 63.101792] ? __init_waitqueue_head+0xa0/0xd0 [ 63.108183] ? replenish_dl_entity.cold.60+0x18/0x18 [ 63.115151] ? _raw_spin_lock_irqsave+0x25/0x50 [ 63.121754] ? max_active_store+0xf0/0xf0 [ 63.127753] kthread+0x1ae/0x1d0 [ 63.132894] ? kthread_bind+0x30/0x30 [ 63.138422] ret_from_fork+0x35/0x40 [ 63.146973] Allocated by task 14: [ 63.152077] kasan_kmalloc+0xbf/0xe0 [ 63.157471] __kmalloc+0x110/0x240 [ 63.162804] init_cntrs+0x34d/0xdf0 [hfi1] [ 63.168883] hfi1_init_dd+0x29a3/0x2f90 [hfi1] [ 63.175244] init_one+0x551/0xae0 [hfi1] [ 63.181065] local_pci_probe+0x70/0xd0 [ 63.186759] work_for_cpu_fn+0x29/0x40 [ 63.192310] process_one_work+0x584/0x960 [ 63.198163] worker_thread+0x62e/0x9d0 [ 63.203843] kthread+0x1ae/0x1d0 [ 63.208874] ret_from_fork+0x35/0x40 [ 63.217203] Freed by task 1: [ 63.221844] __kasan_slab_free+0x12e/0x180 [ 63.227844] kfree+0x92/0x1a0 [ 63.232570] single_release+0x3a/0x60 [ 63.238024] __fput+0x1d9/0x480 [ 63.242911] task_work_run+0x139/0x190 [ 63.248440] exit_to_usermode_loop+0x191/0x1a0 [ 63.254814] do_syscall_64+0x301/0x330 [ 63.260283] entry_SYSCALL_64_after_hwframe+0x44/0xa9 [ 63.270199] The buggy address belongs to the object at ffff88080e8d5500 which belongs to the cache kmalloc-4096 of size 4096 [ 63.287247] The buggy address is located 3632 bytes inside of 4096-byte region [ffff88080e8d5500, ffff88080e8d6500) [ 63.303564] The buggy address belongs to the page: [ 63.310447] page:ffffea00203a3400 count:1 mapcount:0 mapping:ffff88081380e840 index:0x0 compound_mapcount: 0 [ 63.323102] flags: 0x2fffff80008100(slab|head) [ 63.329775] raw: 002fffff80008100 0000000000000000 0000000100000001 ffff88081380e840 [ 63.340175] raw: 0000000000000000 0000000000070007 00000001ffffffff 0000000000000000 [ 63.350564] page dumped because: kasan: bad access detected [ 63.361974] Memory state around the buggy address: [ 63.369137] ffff88080e8d6200: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 [ 63.379082] ffff88080e8d6280: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 [ 63.389032] >ffff88080e8d6300: 00 00 00 00 00 00 fc fc fc fc fc fc fc fc fc fc [ 63.398944] ^ [ 63.406141] ffff88080e8d6380: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc [ 63.416109] ffff88080e8d6400: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc [ 63.426099] ================================================================== The trace happens because get_hw_stats() assumes there is room in the memory allocated in init_cntrs() to accommodate the driver counters. Unfortunately, that routine only allocated space for the device counters. Fix by insuring the allocation has room for the additional driver counters. Cc: <Stable@vger.kernel.org> # v4.14+ Fixes: b7481944 ("IB/hfi1: Show statistics counters under IB stats interface") Reviewed-by: Mike Marciniczyn <mike.marciniszyn@intel.com> Reviewed-by: Mike Ruhl <michael.j.ruhl@intel.com> Signed-off-by: Piotr Stankiewicz <piotr.stankiewicz@intel.com> Signed-off-by: Dennis Dalessandro <dennis.dalessandro@intel.com> Signed-off-by: Doug Ledford <dledford@redhat.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
-
Kailang Yang authored
commit bde1a745 upstream. If it plugged headphone or headset into the jack, then do the reboot, it will have a chance to cause headphone no sound. It just need to run the headphone mode procedure after boot time. The issue will be fixed. It also suitable for ALC234 ALC274 and ALC294. Signed-off-by: Kailang Yang <kailang@realtek.com> Cc: <stable@vger.kernel.org> Signed-off-by: Takashi Iwai <tiwai@suse.de> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
-
Takashi Sakamoto authored
commit fa9c98e4 upstream. In an initial commit, 'SYNC_STATUS' register is referred to get clock configuration, however this is wrong, according to my local note at hand for reverse-engineering about packet dump. It should be 'CLOCK_CONFIG' register. Actually, ff400_dump_clock_config() is correctly programmed. This commit fixes the bug. Cc: <stable@vger.kernel.org> # v4.12+ Fixes: 76fdb3a9 ('ALSA: fireface: add support for Fireface 400') Signed-off-by: Takashi Sakamoto <o-takashi@sakamocchi.jp> Signed-off-by: Takashi Iwai <tiwai@suse.de> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
-
Guenter Roeck authored
commit fd29edc7 upstream. gcc 8.1.0 generates the following warnings. drivers/staging/speakup/kobjects.c: In function 'punc_store': drivers/staging/speakup/kobjects.c:522:2: warning: 'strncpy' output truncated before terminating nul copying as many bytes from a string as its length drivers/staging/speakup/kobjects.c:504:6: note: length computed here drivers/staging/speakup/kobjects.c: In function 'synth_store': drivers/staging/speakup/kobjects.c:391:2: warning: 'strncpy' output truncated before terminating nul copying as many bytes from a string as its length drivers/staging/speakup/kobjects.c:388:8: note: length computed here Using strncpy() is indeed less than perfect since the length of data to be copied has already been determined with strlen(). Replace strncpy() with memcpy() to address the warning and optimize the code a little. Signed-off-by: Guenter Roeck <linux@roeck-us.net> Reviewed-by: Samuel Thibault <samuel.thibault@ens-lyon.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
-
Tigran Mkrtchyan authored
commit 320f35b7 upstream. Since commit bb21ce0a we always enforce per-mirror stateid. However, this makes sense only for v4+ servers. Signed-off-by: Tigran Mkrtchyan <tigran.mkrtchyan@desy.de> Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
-
Davidlohr Bueso authored
commit 0b548e33 upstream. Fengguang reported soft lockups while running the rbtree and interval tree test modules. The logic for these tests all occur in init phase, and we currently are pounding with the default values for number of nodes and number of iterations of each test. Reduce the latter by two orders of magnitude. This does not influence the value of the tests in that one thousand times by default is enough to get the picture. Link: http://lkml.kernel.org/r/20171109161715.xai2dtwqw2frhkcm@linux-n805Signed-off-by: Davidlohr Bueso <dbueso@suse.de> Reported-by: Fengguang Wu <fengguang.wu@intel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> Cc: Guenter Roeck <linux@roeck-us.net> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
-
Petr Mladek authored
[ Upstream commit c14376de ] wake_klogd is a local variable in console_unlock(). The information is lost when the console_lock owner using the busy wait added by the commit dbdda842 ("printk: Add console owner and waiter logic to load balance console writes"). The following race is possible: CPU0 CPU1 console_unlock() for (;;) /* calling console for last message */ printk() log_store() log_next_seq++; /* see new message */ if (seen_seq != log_next_seq) { wake_klogd = true; seen_seq = log_next_seq; } console_lock_spinning_enable(); if (console_trylock_spinning()) /* spinning */ if (console_lock_spinning_disable_and_check()) { printk_safe_exit_irqrestore(flags); return; console_unlock() if (seen_seq != log_next_seq) { /* already seen */ /* nothing to do */ Result: Nobody would wakeup klogd. One solution would be to make a global variable from wake_klogd. But then we would need to manipulate it under a lock or so. This patch wakes klogd also when console_lock is passed to the spinning waiter. It looks like the right way to go. Also userspace should have a chance to see and store any "flood" of messages. Note that the very late klogd wake up was a historic solution. It made sense on single CPU systems or when sys_syslog() operations were synchronized using the big kernel lock like in v2.1.113. But it is questionable these days. Fixes: dbdda842 ("printk: Add console owner and waiter logic to load balance console writes") Link: http://lkml.kernel.org/r/20180226155734.dzwg3aovqnwtvkoy@pathway.suse.cz Cc: Steven Rostedt <rostedt@goodmis.org> Cc: linux-kernel@vger.kernel.org Cc: Tejun Heo <tj@kernel.org> Suggested-by: Sergey Senozhatsky <sergey.senozhatsky@gmail.com> Reviewed-by: Sergey Senozhatsky <sergey.senozhatsky@gmail.com> Signed-off-by: Petr Mladek <pmladek@suse.com> Signed-off-by: Sasha Levin <sashal@kernel.org>
-
Sergey Senozhatsky authored
[ Upstream commit fd5f7cde ] This patch, basically, reverts commit 6b97a20d ("printk: set may_schedule for some of console_trylock() callers"). That commit was a mistake, it introduced a big dependency on the scheduler, by enabling preemption under console_sem in printk()->console_unlock() path, which is rather too critical. The patch did not significantly reduce the possibilities of printk() lockups, but made it possible to stall printk(), as has been reported by Tetsuo Handa [1]. Another issues is that preemption under console_sem also messes up with Steven Rostedt's hand off scheme, by making it possible to sleep with console_sem both in console_unlock() and in vprintk_emit(), after acquiring the console_sem ownership (anywhere between printk_safe_exit_irqrestore() in console_trylock_spinning() and printk_safe_enter_irqsave() in console_unlock()). This makes hand off less likely and, at the same time, may result in a significant amount of pending logbuf messages. Preempted console_sem owner makes it impossible for other CPUs to emit logbuf messages, but does not make it impossible for other CPUs to append new messages to the logbuf. Reinstate the old behavior and make printk() non-preemptible. Should any printk() lockup reports arrive they must be handled in a different way. [1] http://lkml.kernel.org/r/201603022101.CAH73907.OVOOMFHFFtQJSL%20()%20I-love%20!%20SAKURA%20!%20ne%20!%20jp Fixes: 6b97a20d ("printk: set may_schedule for some of console_trylock() callers") Link: http://lkml.kernel.org/r/20180116044716.GE6607@jagdpanzerIV To: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp> Cc: Sergey Senozhatsky <sergey.senozhatsky@gmail.com> Cc: Tejun Heo <tj@kernel.org> Cc: akpm@linux-foundation.org Cc: linux-mm@kvack.org Cc: Cong Wang <xiyou.wangcong@gmail.com> Cc: Dave Hansen <dave.hansen@intel.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Mel Gorman <mgorman@suse.de> Cc: Michal Hocko <mhocko@kernel.org> Cc: Vlastimil Babka <vbabka@suse.cz> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Jan Kara <jack@suse.cz> Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com> Cc: Byungchul Park <byungchul.park@lge.com> Cc: Pavel Machek <pavel@ucw.cz> Cc: linux-kernel@vger.kernel.org Signed-off-by: Sergey Senozhatsky <sergey.senozhatsky@gmail.com> Reported-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp> Reviewed-by: Steven Rostedt (VMware) <rostedt@goodmis.org> Signed-off-by: Petr Mladek <pmladek@suse.com> Signed-off-by: Sasha Levin <sashal@kernel.org>
-
Petr Mladek authored
[ Upstream commit c162d5b4 ] The commit ("printk: Add console owner and waiter logic to load balance console writes") made vprintk_emit() and console_unlock() even more complicated. This patch extracts the new code into 3 helper functions. They should help to keep it rather self-contained. It will be easier to use and maintain. This patch just shuffles the existing code. It does not change the functionality. Link: http://lkml.kernel.org/r/20180112160837.GD24497@linux.suse Cc: akpm@linux-foundation.org Cc: linux-mm@kvack.org Cc: Cong Wang <xiyou.wangcong@gmail.com> Cc: Dave Hansen <dave.hansen@intel.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Mel Gorman <mgorman@suse.de> Cc: Michal Hocko <mhocko@kernel.org> Cc: Vlastimil Babka <vbabka@suse.cz> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Jan Kara <jack@suse.cz> Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com> Cc: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp> Cc: rostedt@home.goodmis.org Cc: Byungchul Park <byungchul.park@lge.com> Cc: Tejun Heo <tj@kernel.org> Cc: Pavel Machek <pavel@ucw.cz> Cc: linux-kernel@vger.kernel.org Reviewed-by: Steven Rostedt (VMware) <rostedt@goodmis.org> Acked-by: Sergey Senozhatsky <sergey.senozhatsky@gmail.com> Signed-off-by: Petr Mladek <pmladek@suse.com> Signed-off-by: Sasha Levin <sashal@kernel.org>
-
Steven Rostedt (VMware) authored
[ Upstream commit dbdda842 ] This patch implements what I discussed in Kernel Summit. I added lockdep annotation (hopefully correctly), and it hasn't had any splats (since I fixed some bugs in the first iterations). It did catch problems when I had the owner covering too much. But now that the owner is only set when actively calling the consoles, lockdep has stayed quiet. Here's the design again: I added a "console_owner" which is set to a task that is actively writing to the consoles. It is *not* the same as the owner of the console_lock. It is only set when doing the calls to the console functions. It is protected by a console_owner_lock which is a raw spin lock. There is a console_waiter. This is set when there is an active console owner that is not current, and waiter is not set. This too is protected by console_owner_lock. In printk() when it tries to write to the consoles, we have: if (console_trylock()) console_unlock(); Now I added an else, which will check if there is an active owner, and no current waiter. If that is the case, then console_waiter is set, and the task goes into a spin until it is no longer set. When the active console owner finishes writing the current message to the consoles, it grabs the console_owner_lock and sees if there is a waiter, and clears console_owner. If there is a waiter, then it breaks out of the loop, clears the waiter flag (because that will release the waiter from its spin), and exits. Note, it does *not* release the console semaphore. Because it is a semaphore, there is no owner. Another task may release it. This means that the waiter is guaranteed to be the new console owner! Which it becomes. Then the waiter calls console_unlock() and continues to write to the consoles. If another task comes along and does a printk() it too can become the new waiter, and we wash rinse and repeat! By Petr Mladek about possible new deadlocks: The thing is that we move console_sem only to printk() call that normally calls console_unlock() as well. It means that the transferred owner should not bring new type of dependencies. As Steven said somewhere: "If there is a deadlock, it was there even before." We could look at it from this side. The possible deadlock would look like: CPU0 CPU1 console_unlock() console_owner = current; spin_lockA() printk() spin = true; while (...) call_console_drivers() spin_lockA() This would be a deadlock. CPU0 would wait for the lock A. While CPU1 would own the lockA and would wait for CPU0 to finish calling the console drivers and pass the console_sem owner. But if the above is true than the following scenario was already possible before: CPU0 spin_lockA() printk() console_unlock() call_console_drivers() spin_lockA() By other words, this deadlock was there even before. Such deadlocks are prevented by using printk_deferred() in the sections guarded by the lock A. By Steven Rostedt: To demonstrate the issue, this module has been shown to lock up a system with 4 CPUs and a slow console (like a serial console). It is also able to lock up a 8 CPU system with only a fast (VGA) console, by passing in "loops=100". The changes in this commit prevent this module from locking up the system. #include <linux/module.h> #include <linux/delay.h> #include <linux/sched.h> #include <linux/mutex.h> #include <linux/workqueue.h> #include <linux/hrtimer.h> static bool stop_testing; static unsigned int loops = 1; static void preempt_printk_workfn(struct work_struct *work) { int i; while (!READ_ONCE(stop_testing)) { for (i = 0; i < loops && !READ_ONCE(stop_testing); i++) { preempt_disable(); pr_emerg("%5d%-75s\n", smp_processor_id(), " XXX NOPREEMPT"); preempt_enable(); } msleep(1); } } static struct work_struct __percpu *works; static void finish(void) { int cpu; WRITE_ONCE(stop_testing, true); for_each_online_cpu(cpu) flush_work(per_cpu_ptr(works, cpu)); free_percpu(works); } static int __init test_init(void) { int cpu; works = alloc_percpu(struct work_struct); if (!works) return -ENOMEM; /* * This is just a test module. This will break if you * do any CPU hot plugging between loading and * unloading the module. */ for_each_online_cpu(cpu) { struct work_struct *work = per_cpu_ptr(works, cpu); INIT_WORK(work, &preempt_printk_workfn); schedule_work_on(cpu, work); } return 0; } static void __exit test_exit(void) { finish(); } module_param(loops, uint, 0); module_init(test_init); module_exit(test_exit); MODULE_LICENSE("GPL"); Link: http://lkml.kernel.org/r/20180110132418.7080-2-pmladek@suse.com Cc: akpm@linux-foundation.org Cc: linux-mm@kvack.org Cc: Cong Wang <xiyou.wangcong@gmail.com> Cc: Dave Hansen <dave.hansen@intel.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Mel Gorman <mgorman@suse.de> Cc: Michal Hocko <mhocko@kernel.org> Cc: Vlastimil Babka <vbabka@suse.cz> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Jan Kara <jack@suse.cz> Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com> Cc: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp> Cc: Byungchul Park <byungchul.park@lge.com> Cc: Tejun Heo <tj@kernel.org> Cc: Pavel Machek <pavel@ucw.cz> Cc: linux-kernel@vger.kernel.org Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org> [pmladek@suse.com: Commit message about possible deadlocks] Acked-by: Sergey Senozhatsky <sergey.senozhatsky@gmail.com> Signed-off-by: Petr Mladek <pmladek@suse.com> Signed-off-by: Sasha Levin <sashal@kernel.org>
-