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Now that RCU flavors have been consolidated, an RCU-preempt
rcu_read_unlock() in an interrupt or softirq handler cannot possibly
end the RCU read-side critical section. Consider the old vulnerability
involving rcu_read_unlock() being invoked within such a handler that
interrupted an __rcu_read_unlock_special(), in which a wakeup might be
invoked with a scheduler lock held. Because rcu_read_unlock_special()
no longer does wakeups in such situations, it is no longer necessary
for __rcu_read_unlock() to set the nesting level negative.
This commit therefore removes this recursion-protection code from
__rcu_read_unlock().
[ paulmck: Let rcu_exp_handler() continue to call rcu_report_exp_rdp(). ]
[ paulmck: Adjust other checks given no more negative nesting. ]
Signed-off-by: Lai Jiangshan <laijs@linux.alibaba.com>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
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The ->rcu_read_unlock_special.b.deferred_qs field is set to true in
rcu_read_unlock_special() but never set to false. This is not
particularly useful, so this commit removes this field.
The only possible justification for this field is to ease debugging
of RCU deferred quiscent states, but the combination of the other
->rcu_read_unlock_special fields plus ->rcu_blocked_node and of course
->rcu_read_lock_nesting should cover debugging needs. And if this last
proves incorrect, this patch can always be reverted, along with the
required setting of ->rcu_read_unlock_special.b.deferred_qs to false
in rcu_preempt_deferred_qs_irqrestore().
Signed-off-by: Lai Jiangshan <laijs@linux.alibaba.com>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
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Now that RCU flavors have been consolidated, an RCU-preempt
rcu_read_unlock() in an interrupt or softirq handler cannot possibly
end the RCU read-side critical section. Consider the old vulnerability
involving rcu_preempt_deferred_qs() being invoked within such a handler
that interrupted an extended RCU read-side critical section, in which
a wakeup might be invoked with a scheduler lock held. Because
rcu_read_unlock_special() no longer does wakeups in such situations,
it is no longer necessary for rcu_preempt_deferred_qs() to set the
nesting level negative.
This commit therefore removes this recursion-protection code from
rcu_preempt_deferred_qs().
[ paulmck: Fix typo in commit log per Steve Rostedt. ]
Signed-off-by: Lai Jiangshan <laijs@linux.alibaba.com>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
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The scheduler is currently required to hold rq/pi locks across the entire
RCU read-side critical section or not at all. This is inconvenient and
leaves traps for the unwary, including the author of this commit.
But now that excessively long grace periods enable scheduling-clock
interrupts for holdout nohz_full CPUs, the nohz_full rescue logic in
rcu_read_unlock_special() can be dispensed with. In other words, the
rcu_read_unlock_special() function can refrain from doing wakeups unless
such wakeups are guaranteed safe.
This commit therefore avoids unsafe wakeups, freeing the scheduler to
hold rq/pi locks across rcu_read_unlock() even if the corresponding RCU
read-side critical section might have been preempted. This commit also
updates RCU's requirements documentation.
This commit is inspired by a patch from Lai Jiangshan:
https://lore.kernel.org/lkml/20191102124559.1135-2-laijs@linux.alibaba.com
This commit is further intended to be a step towards his goal of permitting
the inlining of RCU-preempt's rcu_read_lock() and rcu_read_unlock().
Cc: Lai Jiangshan <laijs@linux.alibaba.com>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
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This commit adds stubs for KCSAN's data_race(), ASSERT_EXCLUSIVE_WRITER(),
and ASSERT_EXCLUSIVE_ACCESS() macros to allow code using these macros
to move ahead.
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
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This commit adds rcu_gp_might_be_stalled(), which returns true if there
is some reason to believe that the RCU grace period is stalled. The use
case is where an RCU free-memory path needs to allocate memory in order
to free it, a situation that should be avoided where possible.
But where it is necessary, there is always the alternative of using
synchronize_rcu() to wait for a grace period in order to avoid the
allocation. And if the grace period is stalled, allocating memory to
asynchronously wait for it is a bad idea of epic proportions: Far better
to let others use the memory, because these others might actually be
able to free that memory before the grace period ends.
Thus, rcu_gp_might_be_stalled() can be used to help decide whether
allocating memory on an RCU free path is a semi-reasonable course
of action.
Cc: Joel Fernandes <joel@joelfernandes.org>
Cc: Uladzislau Rezki <urezki@gmail.com>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
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We can relax the correctness of counting of number of queued objects in
favor of not hurting performance, by locklessly sampling per-cpu
counters. This should be Ok since under high memory pressure, it should not
matter if we are off by a few objects while counting. The shrinker will
still do the reclaim.
Signed-off-by: Joel Fernandes (Google) <joel@joelfernandes.org>
[ paulmck: Remove unused "flags" variable. ]
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
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To reduce grace periods and improve kfree() performance, we have done
batching recently dramatically bringing down the number of grace periods
while giving us the ability to use kfree_bulk() for efficient kfree'ing.
However, this has increased the likelihood of OOM condition under heavy
kfree_rcu() flood on small memory systems. This patch introduces a
shrinker which starts grace periods right away if the system is under
memory pressure due to existence of objects that have still not started
a grace period.
With this patch, I do not observe an OOM anymore on a system with 512MB
RAM and 8 CPUs, with the following rcuperf options:
rcuperf.kfree_loops=20000 rcuperf.kfree_alloc_num=8000
rcuperf.kfree_rcu_test=1 rcuperf.kfree_mult=2
Otherwise it easily OOMs with the above parameters.
NOTE:
1. On systems with no memory pressure, the patch has no effect as intended.
2. In the future, we can use this same mechanism to prevent grace periods
from happening even more, by relying on shrinkers carefully.
Cc: urezki@gmail.com
Signed-off-by: Joel Fernandes (Google) <joel@joelfernandes.org>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
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This allows us to increase memory pressure dynamically using a new
rcuperf boot command line parameter called 'rcumult'.
Signed-off-by: Joel Fernandes (Google) <joel@joelfernandes.org>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
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This commit converts the ULONG_CMP_LT() in rcu_nohz_full_cpu() to
time_before() to reflect the fact that it is comparing a timestamp to
the jiffies counter.
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
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This commit converts the ULONG_CMP_GE() in rcu_initiate_boost() to
time_after() to reflect the fact that it is comparing a timestamp to
the jiffies counter.
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
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This commit converts the ULONG_CMP_GE() in rcu_gp_fqs_loop() to
time_after() to reflect the fact that it is comparing a timestamp to
the jiffies counter.
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
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Coccinelle reports a warning at use_softirq declaration
WARNING: Assignment of 0/1 to bool variable
The root cause is
use_softirq a variable of bool type is initialised with the integer 1
Replacing 1 with value true solve the issue.
Signed-off-by: Jules Irenge <jbi.octave@gmail.com>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
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Coccinelle reports warnings at rcu_read_lock_held_common()
WARNING: Assignment of 0/1 to bool variable
To fix this,
the assigned pointer ret values are replaced by corresponding boolean value.
Given that ret is a pointer of bool type
Signed-off-by: Jules Irenge <jbi.octave@gmail.com>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
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The rcu_state structure's gp_seq field is only to be modified by the RCU
grace-period kthread, which is single-threaded. This commit therefore
enlists KCSAN's help in enforcing this restriction. This commit applies
KCSAN-specific primitives, so cannot go upstream until KCSAN does.
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
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This commit escapes *ret, because otherwise the documentation system
thinks that this is an incomplete emphasis block:
./kernel/rcu/update.c:65: WARNING: Inline emphasis start-string without end-string.
./kernel/rcu/update.c:65: WARNING: Inline emphasis start-string without end-string.
./kernel/rcu/update.c:70: WARNING: Inline emphasis start-string without end-string.
./kernel/rcu/update.c:82: WARNING: Inline emphasis start-string without end-string.
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
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This reverts commit f452ee096d95482892b101bde4fd037fa025d3cc.
The workaround became unnecessary with commit 43756e347f21
("scripts/kernel-doc: Add support for named variable macro arguments").
Signed-off-by: Jonathan Neuschäfer <j.neuschaefer@gmx.net>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
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It is possible that an over-long grace period will end while the RCU
CPU stall warning message is printing. In this case, the estimate of
the offending grace period's duration can be erroneous due to refetching
of rcu_state.gp_start, which will now be the time of the newly started
grace period. Computation of this duration clearly needs to use the
start time for the old over-long grace period, not the fresh new one.
This commit avoids such errors by causing both print_other_cpu_stall() and
print_cpu_stall() to reuse the value previously fetched by their caller.
Signed-off-by: Zhaolong Zhang <zhangzl2013@126.com>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
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Even if some CPUs have excessive numbers of callbacks, RCU's grace-period
kthread will still wait normally between successive force-quiescent-state
scans. The first two are the most important, as they are the ones that
enlist aid from the scheduler when overloaded. This commit therefore
omits the wait before the first and the second force-quiescent-state
scan under callback-overload conditions.
This approach was inspired by a discussion with Jeff Roberson.
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
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Older compilers either want two extra pairs of curly braces around the
initializer for local variable desc, or they want a single pair of curly
braces with nothing inside. Because current Linux-kernel practice favors
the latter, this commit makes it so.
Suggested-by: Chris Wilson <chris@chris-wilson.co.uk>
Suggested-by: Joe Perches <joe@perches.com>
Suggested-by: Christoph Hellwig <hch@infradead.org>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
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Although the accesses used to determine whether or not a stall should
be printed are an integral part of the concurrency algorithm governing
use of the corresponding variables, the values that are simply printed
are ancillary. As such, it is best to use data_race() for these accesses
in order to provide the greatest latitude in the use of KCSAN for the
other accesses that are an integral part of the algorithm. This commit
therefore changes the relevant uses of READ_ONCE() to data_race().
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
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The rcu_node structure's ->boost_tasks field is read locklessly, so this
commit adds the WRITE_ONCE() to an update in order to provide proper
documentation and READ_ONCE()/WRITE_ONCE() pairing.
This data race was reported by KCSAN. Not appropriate for backporting
due to failure being unlikely.
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
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The srcu_data structure's ->srcu_lock_count and ->srcu_unlock_count arrays
are read and written locklessly, so this commit adds the data_race()
to the diagnostic-print loads from these arrays in order mark them as
known and approved data-racy accesses.
This data race was reported by KCSAN. Not appropriate for backporting due
to failure being unlikely and due to this being used only by rcutorture.
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
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The rcu_node structure's ->boost_tasks field is read locklessly, so this
commit adds the READ_ONCE() to one load in order to avoid destructive
compiler optimizations. The other load is from a diagnostic print,
so data_race() suffices.
This data race was reported by KCSAN. Not appropriate for backporting
due to failure being unlikely.
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
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There are lockless loads from the rcu_node structure's ->exp_tasks field,
so this commit causes all stores to use WRITE_ONCE() and all lockless
loads to use READ_ONCE() or data_race(), with the latter for debug
prints. This code also did a unprotected traversal of the linked list
pointed into by ->exp_tasks, so this commit also acquires the rcu_node
structure's ->lock to properly protect this traversal. This list was
traversed unprotected only when printing an RCU CPU stall warning for
an expedited grace period, so the odds of seeing this in production are
not all that high.
This data race was reported by KCSAN.
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
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The rcu_state structure's ncpus field is only to be modified by the
CPU-hotplug CPU-online code path, which is single-threaded. This
commit therefore enlists KCSAN's help in enforcing this restriction.
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
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This commit adds stubs for KCSAN's data_race(), ASSERT_EXCLUSIVE_WRITER(),
and ASSERT_EXCLUSIVE_ACCESS() macros to allow code using these macros to
move ahead.
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
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This commit adds stubs for KCSAN's data_race(), ASSERT_EXCLUSIVE_WRITER(),
and ASSERT_EXCLUSIVE_ACCESS() macros to allow code using these macros to
move ahead.
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
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Stefano Garzarella says:
====================
vsock/virtio: fixes about packet delivery to monitoring devices
During the review of v1, Stefan pointed out an issue introduced by
that patch, where replies can appear in the packet capture before
the transmitted packet.
While fixing my patch, reverting it and adding a new flag in
'struct virtio_vsock_pkt' (patch 2/2), I found that we already had
that issue in vhost-vsock, so I fixed it (patch 1/2).
v1 -> v2:
- reverted the v1 patch, to avoid that replies can appear in the
packet capture before the transmitted packet [Stefan]
- added patch to fix packet delivering to monitoring devices in
vhost-vsock
- added patch to check if the packet is already delivered to
monitoring devices
v1: https://patchwork.ozlabs.org/project/netdev/patch/20200421092527.41651-1-sgarzare@redhat.com/
====================
Signed-off-by: David S. Miller <davem@davemloft.net>
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In virtio_transport.c, if the virtqueue is full, the transmitting
packet is queued up and it will be sent in the next iteration.
This causes the same packet to be delivered multiple times to
monitoring devices.
We want to continue to deliver packets to monitoring devices before
it is put in the virtqueue, to avoid that replies can appear in the
packet capture before the transmitted packet.
This patch fixes the issue, adding a new flag (tap_delivered) in
struct virtio_vsock_pkt, to check if the packet is already delivered
to monitoring devices.
In vhost/vsock.c, we are splitting packets, so we must set
'tap_delivered' to false when we queue up the same virtio_vsock_pkt
to handle the remaining bytes.
Signed-off-by: Stefano Garzarella <sgarzare@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
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We want to deliver packets to monitoring devices before it is
put in the virtqueue, to avoid that replies can appear in the
packet capture before the transmitted packet.
Signed-off-by: Stefano Garzarella <sgarzare@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
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drm_dp_mst_wait_tx_reply() returns > 1 if time elapsed in
wait_event_timeout() before check_txmsg_state(mgr, txmsg) evaluated to
true. However, we make the mistake of returning this time from
drm_dp_send_dpcd_write() on success instead of returning the number of
bytes written - causing spontaneous failures during link probing:
[drm:drm_dp_send_link_address [drm_kms_helper]] *ERROR* GUID check on
10:01 failed: 3975
Yikes! So, fix this by returning the number of bytes written on success
instead.
Signed-off-by: Lyude Paul <lyude@redhat.com>
Fixes: cb897542c6d2 ("drm/dp_mst: Fix W=1 warnings")
Cc: Benjamin Gaignard <benjamin.gaignard@st.com>
Cc: Sean Paul <sean@poorly.run>
Acked-by: Alex Deucher <alexander.deucher@amd.com>
Reviewed-by: Sean Paul <sean@poorly.run>
Link: https://patchwork.freedesktop.org/patch/msgid/20200424190722.775284-1-lyude@redhat.com
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The hwsp_cacheline pointer from i915_request is very, very flimsy. The
i915_request.timeline (and the hwsp_cacheline) are lost upon retiring
(after an RCU grace). Therefore we need to confirm that once we have the
right pointer for the cacheline, it is not in the process of being
retired and disposed of before we attempt to acquire a reference to the
cacheline.
<3>[ 547.208237] BUG: KASAN: use-after-free in active_debug_hint+0x6a/0x70 [i915]
<3>[ 547.208366] Read of size 8 at addr ffff88822a0d2710 by task gem_exec_parall/2536
<4>[ 547.208547] CPU: 3 PID: 2536 Comm: gem_exec_parall Tainted: G U 5.7.0-rc2-ged7a286b5d02d-kasan_117+ #1
<4>[ 547.208556] Hardware name: Dell Inc. XPS 13 9350/, BIOS 1.4.12 11/30/2016
<4>[ 547.208564] Call Trace:
<4>[ 547.208579] dump_stack+0x96/0xdb
<4>[ 547.208707] ? active_debug_hint+0x6a/0x70 [i915]
<4>[ 547.208719] print_address_description.constprop.6+0x16/0x310
<4>[ 547.208841] ? active_debug_hint+0x6a/0x70 [i915]
<4>[ 547.208963] ? active_debug_hint+0x6a/0x70 [i915]
<4>[ 547.208975] __kasan_report+0x137/0x190
<4>[ 547.209106] ? active_debug_hint+0x6a/0x70 [i915]
<4>[ 547.209127] kasan_report+0x32/0x50
<4>[ 547.209257] ? i915_gemfs_fini+0x40/0x40 [i915]
<4>[ 547.209376] active_debug_hint+0x6a/0x70 [i915]
<4>[ 547.209389] debug_print_object+0xa7/0x220
<4>[ 547.209405] ? lockdep_hardirqs_on+0x348/0x5f0
<4>[ 547.209426] debug_object_assert_init+0x297/0x430
<4>[ 547.209449] ? debug_object_free+0x360/0x360
<4>[ 547.209472] ? lock_acquire+0x1ac/0x8a0
<4>[ 547.209592] ? intel_timeline_read_hwsp+0x4f/0x840 [i915]
<4>[ 547.209737] ? i915_active_acquire_if_busy+0x66/0x120 [i915]
<4>[ 547.209861] i915_active_acquire_if_busy+0x66/0x120 [i915]
<4>[ 547.209990] ? __live_alloc.isra.15+0xc0/0xc0 [i915]
<4>[ 547.210005] ? rcu_read_lock_sched_held+0xd0/0xd0
<4>[ 547.210017] ? print_usage_bug+0x580/0x580
<4>[ 547.210153] intel_timeline_read_hwsp+0xbc/0x840 [i915]
<4>[ 547.210284] __emit_semaphore_wait+0xd5/0x480 [i915]
<4>[ 547.210415] ? i915_fence_get_timeline_name+0x110/0x110 [i915]
<4>[ 547.210428] ? lockdep_hardirqs_on+0x348/0x5f0
<4>[ 547.210442] ? _raw_spin_unlock_irq+0x2a/0x40
<4>[ 547.210567] ? __await_execution.constprop.51+0x2e0/0x570 [i915]
<4>[ 547.210706] i915_request_await_dma_fence+0x8f7/0xc70 [i915]
Fixes: 85bedbf191e8 ("drm/i915/gt: Eliminate the trylock for reading a timeline's hwsp")
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Cc: <stable@vger.kernel.org> # v5.6+
Reviewed-by: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20200427093038.29219-1-chris@chris-wilson.co.uk
(cherry picked from commit 2759e395358b2b909577928894f856ab75bea41a)
Signed-off-by: Rodrigo Vivi <rodrigo.vivi@intel.com>
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While the ggtt vma are protected by their object lifetime, the list
continues until it hits a non-ggtt vma, and that vma is not protected
and may be freed as we inspect it. Hence, we require the obj->vma.lock
to protect the list as we iterate.
An example of forgetting to hold the obj->vma.lock is
[1642834.464973] general protection fault, probably for non-canonical address 0xdead000000000122: 0000 [#1] SMP PTI
[1642834.464977] CPU: 3 PID: 1954 Comm: Xorg Not tainted 5.6.0-300.fc32.x86_64 #1
[1642834.464979] Hardware name: LENOVO 20ARS25701/20ARS25701, BIOS GJET94WW (2.44 ) 09/14/2017
[1642834.465021] RIP: 0010:i915_gem_object_set_tiling+0x2c0/0x3e0 [i915]
[1642834.465024] Code: 8b 84 24 18 01 00 00 f6 c4 80 74 59 49 8b 94 24 a0 00 00 00 49 8b 84 24 e0 00 00 00 49 8b 74 24 10 48 8b 92 30 01 00 00 89 c7 <80> ba 0a 06 00 00 03 0f 87 86 00 00 00 ba 00 00 08 00 b9 00 00 10
[1642834.465025] RSP: 0018:ffffa98780c77d60 EFLAGS: 00010282
[1642834.465028] RAX: ffff8d232bfb2578 RBX: 0000000000000002 RCX: ffff8d25873a0000
[1642834.465029] RDX: dead000000000122 RSI: fffff0af8ac6e408 RDI: 000000002bfb2578
[1642834.465030] RBP: ffff8d25873a0000 R08: ffff8d252bfb5638 R09: 0000000000000000
[1642834.465031] R10: 0000000000000000 R11: ffff8d252bfb5640 R12: ffffa987801cb8f8
[1642834.465032] R13: 0000000000001000 R14: ffff8d233e972e50 R15: ffff8d233e972d00
[1642834.465034] FS: 00007f6a3d327f00(0000) GS:ffff8d25926c0000(0000) knlGS:0000000000000000
[1642834.465036] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[1642834.465037] CR2: 00007f6a2064d000 CR3: 00000002fb57c001 CR4: 00000000001606e0
[1642834.465038] Call Trace:
[1642834.465083] i915_gem_set_tiling_ioctl+0x122/0x230 [i915]
[1642834.465121] ? i915_gem_object_set_tiling+0x3e0/0x3e0 [i915]
[1642834.465151] drm_ioctl_kernel+0x86/0xd0 [drm]
[1642834.465156] ? avc_has_perm+0x3b/0x160
[1642834.465178] drm_ioctl+0x206/0x390 [drm]
[1642834.465216] ? i915_gem_object_set_tiling+0x3e0/0x3e0 [i915]
[1642834.465221] ? selinux_file_ioctl+0x122/0x1c0
[1642834.465226] ? __do_munmap+0x24b/0x4d0
[1642834.465231] ksys_ioctl+0x82/0xc0
[1642834.465235] __x64_sys_ioctl+0x16/0x20
[1642834.465238] do_syscall_64+0x5b/0xf0
[1642834.465243] entry_SYSCALL_64_after_hwframe+0x44/0xa9
[1642834.465245] RIP: 0033:0x7f6a3d7b047b
[1642834.465247] Code: 0f 1e fa 48 8b 05 1d aa 0c 00 64 c7 00 26 00 00 00 48 c7 c0 ff ff ff ff c3 66 0f 1f 44 00 00 f3 0f 1e fa b8 10 00 00 00 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 8b 0d ed a9 0c 00 f7 d8 64 89 01 48
[1642834.465249] RSP: 002b:00007ffe71adba28 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
[1642834.465251] RAX: ffffffffffffffda RBX: 000055f99048fa40 RCX: 00007f6a3d7b047b
[1642834.465253] RDX: 00007ffe71adba30 RSI: 00000000c0106461 RDI: 000000000000000e
[1642834.465254] RBP: 0000000000000002 R08: 000055f98f3f1798 R09: 0000000000000002
[1642834.465255] R10: 0000000000001000 R11: 0000000000000246 R12: 0000000000000080
[1642834.465257] R13: 000055f98f3f1690 R14: 00000000c0106461 R15: 00007ffe71adba30
Now to take the spinlock during the list iteration, we need to break it
down into two phases. In the first phase under the lock, we cannot sleep
and so must defer the actual work to a second list, protected by the
ggtt->mutex.
We also need to hold the spinlock during creation of a new vma to
serialise with updates of the tiling on the object.
Reported-by: Dave Airlie <airlied@redhat.com>
Fixes: 2850748ef876 ("drm/i915: Pull i915_vma_pin under the vm->mutex")
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Cc: Dave Airlie <airlied@redhat.com>
Cc: <stable@vger.kernel.org> # v5.5+
Reviewed-by: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20200422072805.17340-1-chris@chris-wilson.co.uk
(cherry picked from commit cb593e5d2b6d3ad489669914d9fd1c64c7a4a6af)
Signed-off-by: Rodrigo Vivi <rodrigo.vivi@intel.com>
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igt_ppgtt_pin_update() invokes i915_gem_context_get_vm_rcu(), which
returns a reference of the i915_address_space object to "vm" with
increased refcount.
When igt_ppgtt_pin_update() returns, "vm" becomes invalid, so the
refcount should be decreased to keep refcount balanced.
The reference counting issue happens in two exception handling paths of
igt_ppgtt_pin_update(). When i915_gem_object_create_internal() returns
IS_ERR, the refcnt increased by i915_gem_context_get_vm_rcu() is not
decreased, causing a refcnt leak.
Fix this issue by jumping to "out_vm" label when
i915_gem_object_create_internal() returns IS_ERR.
Fixes: a4e7ccdac38e ("drm/i915: Move context management under GEM")
Signed-off-by: Xiyu Yang <xiyuyang19@fudan.edu.cn>
Signed-off-by: Xin Tan <tanxin.ctf@gmail.com>
Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Link: https://patchwork.freedesktop.org/patch/msgid/1587361342-83494-1-git-send-email-xiyuyang19@fudan.edu.cn
(cherry picked from commit e07c7606a00c4361bad72ff4e72ed0dfbefa23b0)
Signed-off-by: Rodrigo Vivi <rodrigo.vivi@intel.com>
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Clay reports that OP_STATX fails for a test case with a valid fd
and empty path:
-- Test 0: statx:fd 3: SUCCEED, file mode 100755
-- Test 1: statx:path ./uring_statx: SUCCEED, file mode 100755
-- Test 2: io_uring_statx:fd 3: FAIL, errno 9: Bad file descriptor
-- Test 3: io_uring_statx:path ./uring_statx: SUCCEED, file mode 100755
This is due to statx not grabbing the process file table, hence we can't
lookup the fd in async context. If the fd is valid, ensure that we grab
the file table so we can grab the file from async context.
Cc: stable@vger.kernel.org # v5.6
Reported-by: Clay Harris <bugs@claycon.org>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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Under some circumstances, i.e. when test is still running and about to
time out and user runs, for example,
grep -H . /sys/module/dmatest/parameters/*
the iterations parameter is not respected and test is going on and on until
user gives
echo 0 > /sys/module/dmatest/parameters/run
This is not what expected.
The history of this bug is interesting. I though that the commit
2d88ce76eb98 ("dmatest: add a 'wait' parameter")
is a culprit, but looking closer to the code I think it simple revealed the
broken logic from the day one, i.e. in the commit
0a2ff57d6fba ("dmaengine: dmatest: add a maximum number of test iterations")
which adds iterations parameter.
So, to the point, the conditional of checking the thread to be stopped being
first part of conjunction logic prevents to check iterations. Thus, we have to
always check both conditions to be able to stop after given iterations.
Since it wasn't visible before second commit appeared, I add a respective
Fixes tag.
Fixes: 2d88ce76eb98 ("dmatest: add a 'wait' parameter")
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Nicolas Ferre <nicolas.ferre@microchip.com>
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Acked-by: Nicolas Ferre <nicolas.ferre@microchip.com>
Link: https://lore.kernel.org/r/20200424161147.16895-1-andriy.shevchenko@linux.intel.com
Signed-off-by: Vinod Koul <vkoul@kernel.org>
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DMA synchronization hook checks whether interrupt is raised by testing
corresponding bit in a hardware status register, and thus, clock should
be enabled in this case, otherwise CPU may hang if synchronization is
invoked while Runtime PM is in suspended state. This patch resumes the RPM
during of the DMA synchronization process in order to avoid potential
problems. It is a minor clean up of a previous commit, no real problem is
fixed by this patch because currently RPM is always in a resumed state
while DMA is synchronized, although this may change in the future.
Fixes: 6697255f239f ("dmaengine: tegra-apb: Improve DMA synchronization")
Signed-off-by: Dmitry Osipenko <digetx@gmail.com>
Link: https://lore.kernel.org/r/20200426190835.21950-1-digetx@gmail.com
Signed-off-by: Vinod Koul <vkoul@kernel.org>
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When the channel register code was changed to allow hotplug operations,
dynamic indexing wasn't taken into account. When channels are randomly
plugged and unplugged out of order, the serial indexing breaks. Convert
channel indexing to using IDA tracking in order to allow dynamic
assignment. The previous code does not cause any regression bug for
existing channel allocation besides idxd driver since the hotplug usage
case is only used by idxd at this point.
With this change, the chan->idr_ref is also not needed any longer. We can
have a device with no channels registered due to hot plug. The channel
device release code no longer should attempt to free the dma device id on
the last channel release.
Fixes: e81274cd6b52 ("dmaengine: add support to dynamic register/unregister of channels")
Reported-by: Yixin Zhang <yixin.zhang@intel.com>
Signed-off-by: Dave Jiang <dave.jiang@intel.com>
Tested-by: Yixin Zhang <yixin.zhang@intel.com>
Link: https://lore.kernel.org/r/158679961260.7674.8485924270472851852.stgit@djiang5-desk3.ch.intel.com
Signed-off-by: Vinod Koul <vkoul@kernel.org>
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fs_info::journal_info
[BUG]
One run of btrfs/063 triggered the following lockdep warning:
============================================
WARNING: possible recursive locking detected
5.6.0-rc7-custom+ #48 Not tainted
--------------------------------------------
kworker/u24:0/7 is trying to acquire lock:
ffff88817d3a46e0 (sb_internal#2){.+.+}, at: start_transaction+0x66c/0x890 [btrfs]
but task is already holding lock:
ffff88817d3a46e0 (sb_internal#2){.+.+}, at: start_transaction+0x66c/0x890 [btrfs]
other info that might help us debug this:
Possible unsafe locking scenario:
CPU0
----
lock(sb_internal#2);
lock(sb_internal#2);
*** DEADLOCK ***
May be due to missing lock nesting notation
4 locks held by kworker/u24:0/7:
#0: ffff88817b495948 ((wq_completion)btrfs-endio-write){+.+.}, at: process_one_work+0x557/0xb80
#1: ffff888189ea7db8 ((work_completion)(&work->normal_work)){+.+.}, at: process_one_work+0x557/0xb80
#2: ffff88817d3a46e0 (sb_internal#2){.+.+}, at: start_transaction+0x66c/0x890 [btrfs]
#3: ffff888174ca4da8 (&fs_info->reloc_mutex){+.+.}, at: btrfs_record_root_in_trans+0x83/0xd0 [btrfs]
stack backtrace:
CPU: 0 PID: 7 Comm: kworker/u24:0 Not tainted 5.6.0-rc7-custom+ #48
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 0.0.0 02/06/2015
Workqueue: btrfs-endio-write btrfs_work_helper [btrfs]
Call Trace:
dump_stack+0xc2/0x11a
__lock_acquire.cold+0xce/0x214
lock_acquire+0xe6/0x210
__sb_start_write+0x14e/0x290
start_transaction+0x66c/0x890 [btrfs]
btrfs_join_transaction+0x1d/0x20 [btrfs]
find_free_extent+0x1504/0x1a50 [btrfs]
btrfs_reserve_extent+0xd5/0x1f0 [btrfs]
btrfs_alloc_tree_block+0x1ac/0x570 [btrfs]
btrfs_copy_root+0x213/0x580 [btrfs]
create_reloc_root+0x3bd/0x470 [btrfs]
btrfs_init_reloc_root+0x2d2/0x310 [btrfs]
record_root_in_trans+0x191/0x1d0 [btrfs]
btrfs_record_root_in_trans+0x90/0xd0 [btrfs]
start_transaction+0x16e/0x890 [btrfs]
btrfs_join_transaction+0x1d/0x20 [btrfs]
btrfs_finish_ordered_io+0x55d/0xcd0 [btrfs]
finish_ordered_fn+0x15/0x20 [btrfs]
btrfs_work_helper+0x116/0x9a0 [btrfs]
process_one_work+0x632/0xb80
worker_thread+0x80/0x690
kthread+0x1a3/0x1f0
ret_from_fork+0x27/0x50
It's pretty hard to reproduce, only one hit so far.
[CAUSE]
This is because we're calling btrfs_join_transaction() without re-using
the current running one:
btrfs_finish_ordered_io()
|- btrfs_join_transaction() <<< Call #1
|- btrfs_record_root_in_trans()
|- btrfs_reserve_extent()
|- btrfs_join_transaction() <<< Call #2
Normally such btrfs_join_transaction() call should re-use the existing
one, without trying to re-start a transaction.
But the problem is, in btrfs_join_transaction() call #1, we call
btrfs_record_root_in_trans() before initializing current::journal_info.
And in btrfs_join_transaction() call #2, we're relying on
current::journal_info to avoid such deadlock.
[FIX]
Call btrfs_record_root_in_trans() after we have initialized
current::journal_info.
CC: stable@vger.kernel.org # 4.4+
Signed-off-by: Qu Wenruo <wqu@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
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When we have an inode with a prealloc extent that starts at an offset
lower than the i_size and there is another prealloc extent that starts at
an offset beyond i_size, we can end up losing part of the first prealloc
extent (the part that starts at i_size) and have an implicit hole if we
fsync the file and then have a power failure.
Consider the following example with comments explaining how and why it
happens.
$ mkfs.btrfs -f /dev/sdb
$ mount /dev/sdb /mnt
# Create our test file with 2 consecutive prealloc extents, each with a
# size of 128Kb, and covering the range from 0 to 256Kb, with a file
# size of 0.
$ xfs_io -f -c "falloc -k 0 128K" /mnt/foo
$ xfs_io -c "falloc -k 128K 128K" /mnt/foo
# Fsync the file to record both extents in the log tree.
$ xfs_io -c "fsync" /mnt/foo
# Now do a redudant extent allocation for the range from 0 to 64Kb.
# This will merely increase the file size from 0 to 64Kb. Instead we
# could also do a truncate to set the file size to 64Kb.
$ xfs_io -c "falloc 0 64K" /mnt/foo
# Fsync the file, so we update the inode item in the log tree with the
# new file size (64Kb). This also ends up setting the number of bytes
# for the first prealloc extent to 64Kb. This is done by the truncation
# at btrfs_log_prealloc_extents().
# This means that if a power failure happens after this, a write into
# the file range 64Kb to 128Kb will not use the prealloc extent and
# will result in allocation of a new extent.
$ xfs_io -c "fsync" /mnt/foo
# Now set the file size to 256K with a truncate and then fsync the file.
# Since no changes happened to the extents, the fsync only updates the
# i_size in the inode item at the log tree. This results in an implicit
# hole for the file range from 64Kb to 128Kb, something which fsck will
# complain when not using the NO_HOLES feature if we replay the log
# after a power failure.
$ xfs_io -c "truncate 256K" -c "fsync" /mnt/foo
So instead of always truncating the log to the inode's current i_size at
btrfs_log_prealloc_extents(), check first if there's a prealloc extent
that starts at an offset lower than the i_size and with a length that
crosses the i_size - if there is one, just make sure we truncate to a
size that corresponds to the end offset of that prealloc extent, so
that we don't lose the part of that extent that starts at i_size if a
power failure happens.
A test case for fstests follows soon.
Fixes: 31d11b83b96f ("Btrfs: fix duplicate extents after fsync of file with prealloc extents")
CC: stable@vger.kernel.org # 4.14+
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
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When jumping to the out_put_disk label, we will call put_disk(), which will
trigger a call to disk_release(), which calls blk_put_queue().
Later in the cleanup code, we do blk_cleanup_queue(), which will also call
blk_put_queue().
Putting the queue twice is incorrect, and will generate a KASAN splat.
Set the disk->queue pointer to NULL, before calling put_disk(), so that the
first call to blk_put_queue() will not free the queue.
The second call to blk_put_queue() uses another pointer to the same queue,
so this call will still free the queue.
Fixes: 85136c010285 ("lightnvm: simplify geometry enumeration")
Signed-off-by: Niklas Cassel <niklas.cassel@wdc.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
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... to protect the modification of mp->m_count done by it. Most of
the places that modify that thing also have namespace_lock held,
but not all of them can do so, so we really need mount_lock here.
Kudos to Piotr Krysiuk <piotras@gmail.com>, who'd spotted a related
bug in pivot_root(2) (fixed unnoticed in 5.3); search for other
similar turds has caught out this one.
Cc: stable@kernel.org
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
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This patch fixes a regression in 5.7-rc1+
In commit 8fe75cd4cddf ("phy: qcom-qusb2: Add generic QUSB2 V2
PHY support"), the change was made to add "qcom,qusb2-v2-phy"
as a generic compat string. However the change also removed
the "qcom,sdm845-qusb2-phy" compat string, which is documented
in the binding and already in use.
This patch re-adds the "qcom,sdm845-qusb2-phy" compat string
which allows the driver to continue to work with existing dts
entries such as found on the db845c.
Cc: Andy Gross <agross@kernel.org>
Cc: Bjorn Andersson <bjorn.andersson@linaro.org>
Cc: Rob Herring <robh+dt@kernel.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Doug Anderson <dianders@chromium.org>
Cc: Manu Gautam <mgautam@codeaurora.org>
Cc: Sandeep Maheswaram <sanm@codeaurora.org>
Cc: Matthias Kaehlcke <mka@chromium.org>
Cc: Stephen Boyd <swboyd@chromium.org>
Cc: Kishon Vijay Abraham I <kishon@ti.com>
Cc: linux-arm-msm@vger.kernel.org
Cc: devicetree@vger.kernel.org
Reviewed-by: Stephen Boyd <swboyd@chromium.org>
Reviewed-by: Douglas Anderson <dianders@chromium.org>
Reviewed-by: Bjorn Andersson <bjorn.andersson@linaro.org>
Fixes: 8fe75cd4cddf ("phy: qcom-qusb2: Add generic QUSB2 V2 PHY support")
Reported-by: YongQin Liu <yongqin.liu@linaro.org>
Signed-off-by: John Stultz <john.stultz@linaro.org>
Signed-off-by: Kishon Vijay Abraham I <kishon@ti.com>
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The uapi is the same on 32 and 64 bit, but the number isn't. Everyone
who botched this please re-read:
https://www.kernel.org/doc/html/v5.4-preprc-cpu/ioctl/botching-up-ioctls.html
Also, the type argument for the ioctl macros is for the type the void
__user *arg pointer points at, which in this case would be the
variable-sized char[] of a 0 terminated string. So this was botched in
more than just the usual ways.
Cc: Sumit Semwal <sumit.semwal@linaro.org>
Cc: Chenbo Feng <fengc@google.com>
Cc: Greg Hackmann <ghackmann@google.com>
Cc: Daniel Vetter <daniel.vetter@ffwll.ch>
Cc: linux-media@vger.kernel.org
Cc: linaro-mm-sig@lists.linaro.org
Cc: minchan@kernel.org
Cc: surenb@google.com
Cc: jenhaochen@google.com
Cc: Martin Liu <liumartin@google.com>
Signed-off-by: Daniel Vetter <daniel.vetter@intel.com>
Tested-by: Martin Liu <liumartin@google.com>
Reviewed-by: Martin Liu <liumartin@google.com>
Signed-off-by: Sumit Semwal <sumit.semwal@linaro.org>
[sumits: updated some checkpatch fixes, corrected author email]
Link: https://patchwork.freedesktop.org/patch/msgid/20200407133002.3486387-1-daniel.vetter@ffwll.ch
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Transitioned power state logged at the end of setting ACPI power.
However, D3cold won't be in the message because state can only be
D3hot at most.
Use target_state to corretly report when power state is D3cold.
Cc: All applicable <stable@vger.kernel.org>
Signed-off-by: Kai-Heng Feng <kai.heng.feng@canonical.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
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Currently the kernel threads are not frozen in software_resume(), so
between dpm_suspend_start(PMSG_QUIESCE) and resume_target_kernel(),
system_freezable_power_efficient_wq can still try to submit SCSI
commands and this can cause a panic since the low level SCSI driver
(e.g. hv_storvsc) has quiesced the SCSI adapter and can not accept
any SCSI commands: https://lkml.org/lkml/2020/4/10/47
At first I posted a fix (https://lkml.org/lkml/2020/4/21/1318) trying
to resolve the issue from hv_storvsc, but with the help of
Bart Van Assche, I realized it's better to fix software_resume(),
since this looks like a generic issue, not only pertaining to SCSI.
Cc: All applicable <stable@vger.kernel.org>
Signed-off-by: Dexuan Cui <decui@microsoft.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
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Make a note of the first time we discover the turbo mode has been
disabled by the BIOS, as otherwise we complain every time we try to
update the mode.
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
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This new Lenovo ThinkCenter has two front mics which can't be handled
by PA so far, so apply the fixup ALC283_FIXUP_HEADSET_MIC to change
the location for one of the mics.
Cc: <stable@vger.kernel.org>
Signed-off-by: Hui Wang <hui.wang@canonical.com>
Link: https://lore.kernel.org/r/20200427030039.10121-1-hui.wang@canonical.com
Signed-off-by: Takashi Iwai <tiwai@suse.de>
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configfs_rmdir() invokes configfs_get_config_item(), which returns a
reference of the specified config_item object to "parent_item" with
increased refcnt.
When configfs_rmdir() returns, local variable "parent_item" becomes
invalid, so the refcount should be decreased to keep refcount balanced.
The reference counting issue happens in one exception handling path of
configfs_rmdir(). When down_write_killable() fails, the function forgets
to decrease the refcnt increased by configfs_get_config_item(), causing
a refcnt leak.
Fix this issue by calling config_item_put() when down_write_killable()
fails.
Signed-off-by: Xiyu Yang <xiyuyang19@fudan.edu.cn>
Signed-off-by: Xin Tan <tanxin.ctf@gmail.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
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