Lubuntu - no boot after script #6
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Thanks for updating the issue after realizing what went wrong. I'm closing this now :) |
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It was observed that a process blocked indefintely in __fscache_read_or_alloc_page(), waiting for FSCACHE_COOKIE_LOOKING_UP to be cleared via fscache_wait_for_deferred_lookup(). At this time, ->backing_objects was empty, which would normaly prevent __fscache_read_or_alloc_page() from getting to the point of waiting. This implies that ->backing_objects was cleared *after* __fscache_read_or_alloc_page was was entered. When an object is "killed" and then "dropped", FSCACHE_COOKIE_LOOKING_UP is cleared in fscache_lookup_failure(), then KILL_OBJECT and DROP_OBJECT are "called" and only in DROP_OBJECT is ->backing_objects cleared. This leaves a window where something else can set FSCACHE_COOKIE_LOOKING_UP and __fscache_read_or_alloc_page() can start waiting, before ->backing_objects is cleared There is some uncertainty in this analysis, but it seems to be fit the observations. Adding the wake in this patch will be handled correctly by __fscache_read_or_alloc_page(), as it checks if ->backing_objects is empty again, after waiting. Customer which reported the hang, also report that the hang cannot be reproduced with this fix. The backtrace for the blocked process looked like: PID: 29360 TASK: ffff881ff2ac0f80 CPU: 3 COMMAND: "zsh" #0 [ffff881ff43efbf8] schedule at ffffffff815e56f1 #1 [ffff881ff43efc58] bit_wait at ffffffff815e64ed #2 [ffff881ff43efc68] __wait_on_bit at ffffffff815e61b8 #3 [ffff881ff43efca0] out_of_line_wait_on_bit at ffffffff815e625e #4 [ffff881ff43efd08] fscache_wait_for_deferred_lookup at ffffffffa04f2e8f [fscache] #5 [ffff881ff43efd18] __fscache_read_or_alloc_page at ffffffffa04f2ffe [fscache] #6 [ffff881ff43efd58] __nfs_readpage_from_fscache at ffffffffa0679668 [nfs] #7 [ffff881ff43efd78] nfs_readpage at ffffffffa067092b [nfs] #8 [ffff881ff43efda0] generic_file_read_iter at ffffffff81187a73 #9 [ffff881ff43efe50] nfs_file_read at ffffffffa066544b [nfs] #10 [ffff881ff43efe70] __vfs_read at ffffffff811fc756 #11 [ffff881ff43efee8] vfs_read at ffffffff811fccfa #12 [ffff881ff43eff18] sys_read at ffffffff811fda62 #13 [ffff881ff43eff50] entry_SYSCALL_64_fastpath at ffffffff815e986e Signed-off-by: NeilBrown <neilb@suse.com> Signed-off-by: David Howells <dhowells@redhat.com>
heikomat
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Function graph tracing recurses into itself when stackleak is enabled, causing the ftrace graph selftest to run for up to 90 seconds and trigger the softlockup watchdog. Breakpoint 2, ftrace_graph_caller () at ../arch/arm64/kernel/entry-ftrace.S:200 200 mcount_get_lr_addr x0 // pointer to function's saved lr (gdb) bt \#0 ftrace_graph_caller () at ../arch/arm64/kernel/entry-ftrace.S:200 \#1 0xffffff80081d5280 in ftrace_caller () at ../arch/arm64/kernel/entry-ftrace.S:153 \#2 0xffffff8008555484 in stackleak_track_stack () at ../kernel/stackleak.c:106 \#3 0xffffff8008421ff8 in ftrace_ops_test (ops=0xffffff8009eaa840 <graph_ops>, ip=18446743524091297036, regs=<optimized out>) at ../kernel/trace/ftrace.c:1507 \#4 0xffffff8008428770 in __ftrace_ops_list_func (regs=<optimized out>, ignored=<optimized out>, parent_ip=<optimized out>, ip=<optimized out>) at ../kernel/trace/ftrace.c:6286 \#5 ftrace_ops_no_ops (ip=18446743524091297036, parent_ip=18446743524091242824) at ../kernel/trace/ftrace.c:6321 \#6 0xffffff80081d5280 in ftrace_caller () at ../arch/arm64/kernel/entry-ftrace.S:153 \#7 0xffffff800832fd10 in irq_find_mapping (domain=0xffffffc03fc4bc80, hwirq=27) at ../kernel/irq/irqdomain.c:876 \#8 0xffffff800832294c in __handle_domain_irq (domain=0xffffffc03fc4bc80, hwirq=27, lookup=true, regs=0xffffff800814b840) at ../kernel/irq/irqdesc.c:650 \#9 0xffffff80081d52b4 in ftrace_graph_caller () at ../arch/arm64/kernel/entry-ftrace.S:205 Rework so we mark stackleak_track_stack as notrace Co-developed-by: Arnd Bergmann <arnd@arndb.de> Signed-off-by: Arnd Bergmann <arnd@arndb.de> Signed-off-by: Anders Roxell <anders.roxell@linaro.org> Acked-by: Steven Rostedt (VMware) <rostedt@goodmis.org> Signed-off-by: Kees Cook <keescook@chromium.org>
heikomat
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The *_frag_reasm() functions are susceptible to miscalculating the byte count of packet fragments in case the truesize of a head buffer changes. The truesize member may be changed by the call to skb_unclone(), leaving the fragment memory limit counter unbalanced even if all fragments are processed. This miscalculation goes unnoticed as long as the network namespace which holds the counter is not destroyed. Should an attempt be made to destroy a network namespace that holds an unbalanced fragment memory limit counter the cleanup of the namespace never finishes. The thread handling the cleanup gets stuck in inet_frags_exit_net() waiting for the percpu counter to reach zero. The thread is usually in running state with a stacktrace similar to: PID: 1073 TASK: ffff880626711440 CPU: 1 COMMAND: "kworker/u48:4" #5 [ffff880621563d48] _raw_spin_lock at ffffffff815f5480 #6 [ffff880621563d48] inet_evict_bucket at ffffffff8158020b #7 [ffff880621563d80] inet_frags_exit_net at ffffffff8158051c #8 [ffff880621563db0] ops_exit_list at ffffffff814f5856 #9 [ffff880621563dd8] cleanup_net at ffffffff814f67c0 #10 [ffff880621563e38] process_one_work at ffffffff81096f14 It is not possible to create new network namespaces, and processes that call unshare() end up being stuck in uninterruptible sleep state waiting to acquire the net_mutex. The bug was observed in the IPv6 netfilter code by Per Sundstrom. I thank him for his analysis of the problem. The parts of this patch that apply to IPv4 and IPv6 fragment reassembly are preemptive measures. Signed-off-by: Jiri Wiesner <jwiesner@suse.com> Reported-by: Per Sundstrom <per.sundstrom@redqube.se> Acked-by: Peter Oskolkov <posk@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>
heikomat
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ibmvnic_reset can create and schedule a reset work item from
an IRQ context, so do not use a mutex, which can sleep. Convert
the reset work item mutex to a spin lock. Locking debugger generated
the trace output below.
BUG: sleeping function called from invalid context at kernel/locking/mutex.c:908
in_atomic(): 1, irqs_disabled(): 1, pid: 120, name: kworker/8:1
4 locks held by kworker/8:1/120:
#0: 0000000017c05720 ((wq_completion)"events"){+.+.}, at: process_one_work+0x188/0x710
#1: 00000000ace90706 ((linkwatch_work).work){+.+.}, at: process_one_work+0x188/0x710
#2: 000000007632871f (rtnl_mutex){+.+.}, at: rtnl_lock+0x30/0x50
#3: 00000000fc36813a (&(&crq->lock)->rlock){..-.}, at: ibmvnic_tasklet+0x88/0x2010 [ibmvnic]
irq event stamp: 26293
hardirqs last enabled at (26292): [<c000000000122468>] tasklet_action_common.isra.12+0x78/0x1c0
hardirqs last disabled at (26293): [<c000000000befce8>] _raw_spin_lock_irqsave+0x48/0xf0
softirqs last enabled at (26288): [<c000000000a8ac78>] dev_deactivate_queue.constprop.28+0xc8/0x160
softirqs last disabled at (26289): [<c0000000000306e0>] call_do_softirq+0x14/0x24
CPU: 8 PID: 120 Comm: kworker/8:1 Kdump: loaded Not tainted 4.20.0-rc6 #6
Workqueue: events linkwatch_event
Call Trace:
[c0000003fffa7a50] [c000000000bc83e4] dump_stack+0xe8/0x164 (unreliable)
[c0000003fffa7aa0] [c00000000015ba0c] ___might_sleep+0x2dc/0x320
[c0000003fffa7b20] [c000000000be960c] __mutex_lock+0x8c/0xb40
[c0000003fffa7c30] [d000000006202ac8] ibmvnic_reset+0x78/0x330 [ibmvnic]
[c0000003fffa7cc0] [d0000000062097f4] ibmvnic_tasklet+0x1054/0x2010 [ibmvnic]
[c0000003fffa7e00] [c0000000001224c8] tasklet_action_common.isra.12+0xd8/0x1c0
[c0000003fffa7e60] [c000000000bf1238] __do_softirq+0x1a8/0x64c
[c0000003fffa7f90] [c0000000000306e0] call_do_softirq+0x14/0x24
[c0000003f3f87980] [c00000000001ba50] do_softirq_own_stack+0x60/0xb0
[c0000003f3f879c0] [c0000000001218a8] do_softirq+0xa8/0x100
[c0000003f3f879f0] [c000000000121a74] __local_bh_enable_ip+0x174/0x180
[c0000003f3f87a60] [c000000000bf003c] _raw_spin_unlock_bh+0x5c/0x80
[c0000003f3f87a90] [c000000000a8ac78] dev_deactivate_queue.constprop.28+0xc8/0x160
[c0000003f3f87ad0] [c000000000a8c8b0] dev_deactivate_many+0xd0/0x520
[c0000003f3f87b70] [c000000000a8cd40] dev_deactivate+0x40/0x60
[c0000003f3f87ba0] [c000000000a5e0c4] linkwatch_do_dev+0x74/0xd0
[c0000003f3f87bd0] [c000000000a5e694] __linkwatch_run_queue+0x1a4/0x1f0
[c0000003f3f87c30] [c000000000a5e728] linkwatch_event+0x48/0x60
[c0000003f3f87c50] [c0000000001444e8] process_one_work+0x238/0x710
[c0000003f3f87d20] [c000000000144a48] worker_thread+0x88/0x4e0
[c0000003f3f87db0] [c00000000014e3a8] kthread+0x178/0x1c0
[c0000003f3f87e20] [c00000000000bfd0] ret_from_kernel_thread+0x5c/0x6c
Signed-off-by: Thomas Falcon <tlfalcon@linux.ibm.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
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Commit 9b6f7e1 ("mm: rework memcg kernel stack accounting") will result in fork failing if allocating a kernel stack for a task in dup_task_struct exceeds the kernel memory allowance for that cgroup. Unfortunately, it also results in a crash. This is due to the code jumping to free_stack and calling free_thread_stack when the memcg kernel stack charge fails, but without tsk->stack pointing at the freshly allocated stack. This in turn results in the vfree_atomic in free_thread_stack oopsing with a backtrace like this: #5 [ffffc900244efc88] die at ffffffff8101f0ab #6 [ffffc900244efcb8] do_general_protection at ffffffff8101cb86 #7 [ffffc900244efce0] general_protection at ffffffff818ff082 [exception RIP: llist_add_batch+7] RIP: ffffffff8150d487 RSP: ffffc900244efd98 RFLAGS: 00010282 RAX: 0000000000000000 RBX: ffff88085ef55980 RCX: 0000000000000000 RDX: ffff88085ef55980 RSI: 343834343531203a RDI: 343834343531203a RBP: ffffc900244efd98 R8: 0000000000000001 R9: ffff8808578c3600 R10: 0000000000000000 R11: 0000000000000001 R12: ffff88029f6c21c0 R13: 0000000000000286 R14: ffff880147759b00 R15: 0000000000000000 ORIG_RAX: ffffffffffffffff CS: 0010 SS: 0018 #8 [ffffc900244efda0] vfree_atomic at ffffffff811df2c7 #9 [ffffc900244efdb8] copy_process at ffffffff81086e37 #10 [ffffc900244efe98] _do_fork at ffffffff810884e0 #11 [ffffc900244eff10] sys_vfork at ffffffff810887ff #12 [ffffc900244eff20] do_syscall_64 at ffffffff81002a43 RIP: 000000000049b948 RSP: 00007ffcdb307830 RFLAGS: 00000246 RAX: ffffffffffffffda RBX: 0000000000896030 RCX: 000000000049b948 RDX: 0000000000000000 RSI: 00007ffcdb307790 RDI: 00000000005d7421 RBP: 000000000067370f R8: 00007ffcdb3077b0 R9: 000000000001ed00 R10: 0000000000000008 R11: 0000000000000246 R12: 0000000000000040 R13: 000000000000000f R14: 0000000000000000 R15: 000000000088d018 ORIG_RAX: 000000000000003a CS: 0033 SS: 002b The simplest fix is to assign tsk->stack right where it is allocated. Link: http://lkml.kernel.org/r/20181214231726.7ee4843c@imladris.surriel.com Fixes: 9b6f7e1 ("mm: rework memcg kernel stack accounting") Signed-off-by: Rik van Riel <riel@surriel.com> Acked-by: Roman Gushchin <guro@fb.com> Acked-by: Michal Hocko <mhocko@suse.com> Cc: Shakeel Butt <shakeelb@google.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Tejun Heo <tj@kernel.org> Cc: <stable@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
heikomat
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Ido Schimmel says: ==================== mlxsw: Various fixes This patchset contains various small fixes for mlxsw. Patch #1 fixes a warning generated by switchdev core when the driver fails to insert an MDB entry in the commit phase. Patches #2-#4 fix a warning in check_flush_dependency() that can be triggered when a work item in a WQ_MEM_RECLAIM workqueue tries to flush a non-WQ_MEM_RECLAIM workqueue. It seems that the semantics of the WQ_MEM_RECLAIM flag are not very clear [1] and that various patches have been sent to remove it from various workqueues throughout the kernel [2][3][4] in order to silence the warning. These patches do the same for the workqueues created by mlxsw that probably should not have been created with this flag in the first place. Patch #5 fixes a regression where an IP address cannot be assigned to a VRF upper due to erroneous MAC validation check. Patch #6 adds a test case. Patch #7 adjusts Spectrum-2 shared buffer configuration to be compatible with Spectrum-1. The problem and fix are described in detail in the commit message. Please consider patches #1-#5 for 5.0.y. I verified they apply cleanly. [1] https://patchwork.kernel.org/patch/10791315/ [2] Commit ce162bf ("mac80211_hwsim: don't use WQ_MEM_RECLAIM") [3] Commit 39baf10 ("IB/core: Fix use workqueue without WQ_MEM_RECLAIM") [4] Commit 75215e5 ("iwcm: Don't allocate iwcm workqueue with WQ_MEM_RECLAIM") ==================== Signed-off-by: David S. Miller <davem@davemloft.net>
heikomat
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By calling maps__insert() we assume to get 2 references on the map, which we relese within maps__remove call. However if there's already same map name, we currently don't bump the reference and can crash, like: Program received signal SIGABRT, Aborted. 0x00007ffff75e60f5 in raise () from /lib64/libc.so.6 (gdb) bt #0 0x00007ffff75e60f5 in raise () from /lib64/libc.so.6 #1 0x00007ffff75d0895 in abort () from /lib64/libc.so.6 #2 0x00007ffff75d0769 in __assert_fail_base.cold () from /lib64/libc.so.6 #3 0x00007ffff75de596 in __assert_fail () from /lib64/libc.so.6 #4 0x00000000004fc006 in refcount_sub_and_test (i=1, r=0x1224e88) at tools/include/linux/refcount.h:131 #5 refcount_dec_and_test (r=0x1224e88) at tools/include/linux/refcount.h:148 #6 map__put (map=0x1224df0) at util/map.c:299 #7 0x00000000004fdb95 in __maps__remove (map=0x1224df0, maps=0xb17d80) at util/map.c:953 #8 maps__remove (maps=0xb17d80, map=0x1224df0) at util/map.c:959 #9 0x00000000004f7d8a in map_groups__remove (map=<optimized out>, mg=<optimized out>) at util/map_groups.h:65 #10 machine__process_ksymbol_unregister (sample=<optimized out>, event=0x7ffff7279670, machine=<optimized out>) at util/machine.c:728 #11 machine__process_ksymbol (machine=<optimized out>, event=0x7ffff7279670, sample=<optimized out>) at util/machine.c:741 #12 0x00000000004fffbb in perf_session__deliver_event (session=0xb11390, event=0x7ffff7279670, tool=0x7fffffffc7b0, file_offset=13936) at util/session.c:1362 #13 0x00000000005039bb in do_flush (show_progress=false, oe=0xb17e80) at util/ordered-events.c:243 #14 __ordered_events__flush (oe=0xb17e80, how=OE_FLUSH__ROUND, timestamp=<optimized out>) at util/ordered-events.c:322 torvalds#15 0x00000000005005e4 in perf_session__process_user_event (session=session@entry=0xb11390, event=event@entry=0x7ffff72a4af8, ... Add the map to the list and getting the reference event if we find the map with same name. Signed-off-by: Jiri Olsa <jolsa@kernel.org> Cc: Adrian Hunter <adrian.hunter@intel.com> Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com> Cc: Alexei Starovoitov <ast@kernel.org> Cc: Andi Kleen <ak@linux.intel.com> Cc: Daniel Borkmann <daniel@iogearbox.net> Cc: Eric Saint-Etienne <eric.saint.etienne@oracle.com> Cc: Namhyung Kim <namhyung@kernel.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Song Liu <songliubraving@fb.com> Fixes: 1e62856 ("perf symbols: Fix slowness due to -ffunction-section") Link: http://lkml.kernel.org/r/20190416160127.30203-10-jolsa@kernel.org Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
heikomat
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This patch addresses below two issues and prepares the code to address
3rd issue listed below.
1. mdev device is placed on the mdev bus before it is created in the
vendor driver. Once a device is placed on the mdev bus without creating
its supporting underlying vendor device, mdev driver's probe() gets
triggered. However there isn't a stable mdev available to work on.
create_store()
mdev_create_device()
device_register()
...
vfio_mdev_probe()
[...]
parent->ops->create()
vfio_ap_mdev_create()
mdev_set_drvdata(mdev, matrix_mdev);
/* Valid pointer set above */
Due to this way of initialization, mdev driver who wants to use the mdev,
doesn't have a valid mdev to work on.
2. Current creation sequence is,
parent->ops_create()
groups_register()
Remove sequence is,
parent->ops->remove()
groups_unregister()
However, remove sequence should be exact mirror of creation sequence.
Once this is achieved, all users of the mdev will be terminated first
before removing underlying vendor device.
(Follow standard linux driver model).
At that point vendor's remove() ops shouldn't fail because taking the
device off the bus should terminate any usage.
3. When remove operation fails, mdev sysfs removal attempts to add the
file back on already removed device. Following call trace [1] is observed.
[1] call trace:
kernel: WARNING: CPU: 2 PID: 9348 at fs/sysfs/file.c:327 sysfs_create_file_ns+0x7f/0x90
kernel: CPU: 2 PID: 9348 Comm: bash Kdump: loaded Not tainted 5.1.0-rc6-vdevbus+ #6
kernel: Hardware name: Supermicro SYS-6028U-TR4+/X10DRU-i+, BIOS 2.0b 08/09/2016
kernel: RIP: 0010:sysfs_create_file_ns+0x7f/0x90
kernel: Call Trace:
kernel: remove_store+0xdc/0x100 [mdev]
kernel: kernfs_fop_write+0x113/0x1a0
kernel: vfs_write+0xad/0x1b0
kernel: ksys_write+0x5a/0xe0
kernel: do_syscall_64+0x5a/0x210
kernel: entry_SYSCALL_64_after_hwframe+0x49/0xbe
Therefore, mdev core is improved in following ways.
1. Split the device registration/deregistration sequence so that some
things can be done between initialization of the device and hooking it
up to the bus respectively after deregistering it from the bus but
before giving up our final reference.
In particular, this means invoking the ->create() and ->remove()
callbacks in those new windows. This gives the vendor driver an
initialized mdev device to work with during creation.
At the same time, a bus driver who wish to bind to mdev driver also
gets initialized mdev device.
This follows standard Linux kernel bus and device model.
2. During remove flow, first remove the device from the bus. This
ensures that any bus specific devices are removed.
Once device is taken off the mdev bus, invoke remove() of mdev
from the vendor driver.
3. The driver core device model provides way to register and auto
unregister the device sysfs attribute groups at dev->groups.
Make use of dev->groups to let core create the groups and eliminate
code to avoid explicit groups creation and removal.
To ensure, that new sequence is solid, a below stack dump of a
process is taken who attempts to remove the device while device is in
use by vfio driver and user application.
This stack dump validates that vfio driver guards against such device
removal when device is in use.
cat /proc/21962/stack
[<0>] vfio_del_group_dev+0x216/0x3c0 [vfio]
[<0>] mdev_remove+0x21/0x40 [mdev]
[<0>] device_release_driver_internal+0xe8/0x1b0
[<0>] bus_remove_device+0xf9/0x170
[<0>] device_del+0x168/0x350
[<0>] mdev_device_remove_common+0x1d/0x50 [mdev]
[<0>] mdev_device_remove+0x8c/0xd0 [mdev]
[<0>] remove_store+0x71/0x90 [mdev]
[<0>] kernfs_fop_write+0x113/0x1a0
[<0>] vfs_write+0xad/0x1b0
[<0>] ksys_write+0x5a/0xe0
[<0>] do_syscall_64+0x5a/0x210
[<0>] entry_SYSCALL_64_after_hwframe+0x49/0xbe
[<0>] 0xffffffffffffffff
This prepares the code to eliminate calling device_create_file() in
subsequent patch.
Reviewed-by: Cornelia Huck <cohuck@redhat.com>
Signed-off-by: Parav Pandit <parav@mellanox.com>
Signed-off-by: Alex Williamson <alex.williamson@redhat.com>
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If device is removal is initiated by two threads as below, mdev core
attempts to create a syfs remove file on stale device.
During this flow, below [1] call trace is observed.
cpu-0 cpu-1
----- -----
mdev_unregister_device()
device_for_each_child
mdev_device_remove_cb
mdev_device_remove
user_syscall
remove_store()
mdev_device_remove()
[..]
unregister device();
/* not found in list or
* active=false.
*/
sysfs_create_file()
..Call trace
Now that mdev core follows correct device removal sequence of the linux
bus model, remove shouldn't fail in normal cases. If it fails, there is
no point of creating a stale file or checking for specific error status.
kernel: WARNING: CPU: 2 PID: 9348 at fs/sysfs/file.c:327
sysfs_create_file_ns+0x7f/0x90
kernel: CPU: 2 PID: 9348 Comm: bash Kdump: loaded Not tainted
5.1.0-rc6-vdevbus+ #6
kernel: Hardware name: Supermicro SYS-6028U-TR4+/X10DRU-i+, BIOS 2.0b
08/09/2016
kernel: RIP: 0010:sysfs_create_file_ns+0x7f/0x90
kernel: Call Trace:
kernel: remove_store+0xdc/0x100 [mdev]
kernel: kernfs_fop_write+0x113/0x1a0
kernel: vfs_write+0xad/0x1b0
kernel: ksys_write+0x5a/0xe0
kernel: do_syscall_64+0x5a/0x210
kernel: entry_SYSCALL_64_after_hwframe+0x49/0xbe
Reviewed-by: Cornelia Huck <cohuck@redhat.com>
Signed-off-by: Parav Pandit <parav@mellanox.com>
Signed-off-by: Alex Williamson <alex.williamson@redhat.com>
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In following sequences, child devices created while removing mdev parent
device can be left out, or it may lead to race of removing half
initialized child mdev devices.
issue-1:
--------
cpu-0 cpu-1
----- -----
mdev_unregister_device()
device_for_each_child()
mdev_device_remove_cb()
mdev_device_remove()
create_store()
mdev_device_create() [...]
device_add()
parent_remove_sysfs_files()
/* BUG: device added by cpu-0
* whose parent is getting removed
* and it won't process this mdev.
*/
issue-2:
--------
Below crash is observed when user initiated remove is in progress
and mdev_unregister_driver() completes parent unregistration.
cpu-0 cpu-1
----- -----
remove_store()
mdev_device_remove()
active = false;
mdev_unregister_device()
parent device removed.
[...]
parents->ops->remove()
/*
* BUG: Accessing invalid parent.
*/
This is similar race like create() racing with mdev_unregister_device().
BUG: unable to handle kernel paging request at ffffffffc0585668
PGD e8f618067 P4D e8f618067 PUD e8f61a067 PMD 85adca067 PTE 0
Oops: 0000 [#1] SMP PTI
CPU: 41 PID: 37403 Comm: bash Kdump: loaded Not tainted 5.1.0-rc6-vdevbus+ #6
Hardware name: Supermicro SYS-6028U-TR4+/X10DRU-i+, BIOS 2.0b 08/09/2016
RIP: 0010:mdev_device_remove+0xfa/0x140 [mdev]
Call Trace:
remove_store+0x71/0x90 [mdev]
kernfs_fop_write+0x113/0x1a0
vfs_write+0xad/0x1b0
ksys_write+0x5a/0xe0
do_syscall_64+0x5a/0x210
entry_SYSCALL_64_after_hwframe+0x49/0xbe
Therefore, mdev core is improved as below to overcome above issues.
Wait for any ongoing mdev create() and remove() to finish before
unregistering parent device.
This continues to allow multiple create and remove to progress in
parallel for different mdev devices as most common case.
At the same time guard parent removal while parent is being accessed by
create() and remove() callbacks.
create()/remove() and unregister_device() are synchronized by the rwsem.
Refactor device removal code to mdev_device_remove_common() to avoid
acquiring unreg_sem of the parent.
Fixes: 7b96953 ("vfio: Mediated device Core driver")
Signed-off-by: Parav Pandit <parav@mellanox.com>
Reviewed-by: Cornelia Huck <cohuck@redhat.com>
Signed-off-by: Alex Williamson <alex.williamson@redhat.com>
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Ido Schimmel says: ==================== mlxsw: Various fixes This patchset contains various fixes for mlxsw. Patch #1 fixes an hash polarization problem when a nexthop device is a LAG device. This is caused by the fact that the same seed is used for the LAG and ECMP hash functions. Patch #2 fixes an issue in which the driver fails to refresh a nexthop neighbour after it becomes dead. This prevents the nexthop from ever being written to the adjacency table and used to forward traffic. Patch Patch #4 fixes a wrong extraction of TOS value in flower offload code. Patch #5 is a test case. Patch #6 works around a buffer issue in Spectrum-2 by reducing the default sizes of the shared buffer pools. Patch #7 prevents prio-tagged packets from entering the switch when PVID is removed from the bridge port. Please consider patches #2, #4 and #6 for 5.1.y ==================== Signed-off-by: David S. Miller <davem@davemloft.net>
heikomat
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Currently the calcuation of end_pfn can round up the pfn number to more than the actual maximum number of pfns, causing an Oops. Fix this by ensuring end_pfn is never more than max_pfn. This can be easily triggered when on systems where the end_pfn gets rounded up to more than max_pfn using the idle-page stress-ng stress test: sudo stress-ng --idle-page 0 BUG: unable to handle kernel paging request at 00000000000020d8 #PF error: [normal kernel read fault] PGD 0 P4D 0 Oops: 0000 [#1] SMP PTI CPU: 1 PID: 11039 Comm: stress-ng-idle- Not tainted 5.0.0-5-generic #6-Ubuntu Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.10.2-1ubuntu1 04/01/2014 RIP: 0010:page_idle_get_page+0xc8/0x1a0 Code: 0f b1 0a 75 7d 48 8b 03 48 89 c2 48 c1 e8 33 83 e0 07 48 c1 ea 36 48 8d 0c 40 4c 8d 24 88 49 c1 e4 07 4c 03 24 d5 00 89 c3 be <49> 8b 44 24 58 48 8d b8 80 a1 02 00 e8 07 d5 77 00 48 8b 53 08 48 RSP: 0018:ffffafd7c672fde8 EFLAGS: 00010202 RAX: 0000000000000005 RBX: ffffe36341fff700 RCX: 000000000000000f RDX: 0000000000000284 RSI: 0000000000000275 RDI: 0000000001fff700 RBP: ffffafd7c672fe00 R08: ffffa0bc34056410 R09: 0000000000000276 R10: ffffa0bc754e9b40 R11: ffffa0bc330f6400 R12: 0000000000002080 R13: ffffe36341fff700 R14: 0000000000080000 R15: ffffa0bc330f6400 FS: 00007f0ec1ea5740(0000) GS:ffffa0bc7db00000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00000000000020d8 CR3: 0000000077d68000 CR4: 00000000000006e0 Call Trace: page_idle_bitmap_write+0x8c/0x140 sysfs_kf_bin_write+0x5c/0x70 kernfs_fop_write+0x12e/0x1b0 __vfs_write+0x1b/0x40 vfs_write+0xab/0x1b0 ksys_write+0x55/0xc0 __x64_sys_write+0x1a/0x20 do_syscall_64+0x5a/0x110 entry_SYSCALL_64_after_hwframe+0x44/0xa9 Link: http://lkml.kernel.org/r/20190618124352.28307-1-colin.king@canonical.com Fixes: 33c3fc7 ("mm: introduce idle page tracking") Signed-off-by: Colin Ian King <colin.king@canonical.com> Reviewed-by: Andrew Morton <akpm@linux-foundation.org> Acked-by: Vladimir Davydov <vdavydov.dev@gmail.com> Cc: Michal Hocko <mhocko@suse.com> Cc: Mike Rapoport <rppt@linux.vnet.ibm.com> Cc: Mel Gorman <mgorman@techsingularity.net> Cc: Stephen Rothwell <sfr@canb.auug.org.au> Cc: Andrey Ryabinin <aryabinin@virtuozzo.com> Cc: <stable@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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Device: E200HALinux: Lubuntu 18.10I ran the script and it seemed to run fine, however upon reboot Linux was unable to boot, saying that the kernel needed to be loaded first. I was able to go to the advanced options and boot from the old entry, but not the new one that would support audio.How can I get this to work, or is lubuntu simply not supported?Edit: I'm an idiot and didn't realize Secure Boot had re-enabled after the BIOS reset. Please delete.
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